PODKLADY PRO HABILITAČNÍ ŘÍZENÍ

VYSOKÉ UČENÍ TECHNICKÉ V BRNĚ FAKULTA CHEMICKÁ ÚSTAV CHEMIE A TECHNOLOGIE MATERIÁLŮ PURKYŇOVA 464/118 612 00 BRNO

PODKLADY PRO HABILITAČNÍ ŘÍZENÍ Základní údaje uchazeče: Jméno: Bydliště: Datum a místo narození: Národnost: Státní příslušnost: Pracoviště: Osobní VUT číslo:

Ing. Pavel Diviš, Ph.D. Chelčického 18, Opava 747 05 19. 12. 1979 česká ČR Vysoké učení technické v Brně, Fakulta chemická, Ústav chemie potravin a biotechnologií, odborný asistent 10823

E-mail: Tel.:

[email protected] +420 541 149 454

Dokument obsahuje následující podklady: Žádost o zahájení habilitačního řízení Odborný životopis Notářsky ověřené kopie diplomů Přehled pedagogické činnosti Přehled vědecké a odborné činnosti Přehled a kopie nejvýznamnějších publikací a výsledků Návrh témat veřejné pedagogické přednášky

BRNO 2013

Vážený pan prof. Ing. Jaromír Havlica, DrSc. Děkan FCH VUT v Brně Purkyňova 464/118 Brno 612 00 Návrh na zahájení habilitačního řízení Vážený pane děkane, dovoluji si Vám předložit návrh na zahájení habilitačního řízení v oboru Chemie a technologie ochrany životního prostředí na Fakultě chemické Vysokého učení technického v Brně. Ke svému návrhu přikládám: 1. Habilitační práci: Vývoj a aplikace techniky difúzního gradientu v tenkém filmu pro stanovení rtuti v přírodních vodách 2. Životopis 3. Doklady o dosaženém vysokoškolském vzdělání 4. Doklady osvědčující vědeckou kvalifikaci 5. Doklady osvědčující pedagogickou praxi 6. Seznam všech svých vědeckých a pedagogických prací 7. Reprinty 5-ti nejvýznamnějších prací z posledních let 8. Souhrnný přehled kvantifikovaných kriterií

V .......... Brně .............. dne .... 18.4 2013 ........

.................................................... Ing. Pavel Diviš, Ph.D.

EUROPEAN CURRICULUM VITAE FORMAT

Ing. Pavel Diviš, Ph.D.

OSOBNÍ ÚDAJE Jméno a příjmení

PAVEL DIVIŠ

Adresa trvalého bydliště

CHELČICKÉHO 18, OPAVA 747 05

Korespondenční adresa

GROHOVA 49, BRNO 602 00

Telefon

+420 607 915 312

E-mail

[email protected]

Národnost

Česká

Datum narození (věk)

19. PROSINEC 1979

PRACOVNÍ ZKUŠENOSTI Datum (od – do) Jméno a adresa zaměstnavatele Zaměření Pozice Hlavní aktivity

Datum (od – do) Jméno a adresa zaměstnavatele Zaměření Pozice

1.3.2007 Vysoké učení technické v Brně, Fakulta Chemická, Ústav Chemie a Technologie Ochrany Životního prostředí, Ústav chemie potravin a biotechnologií, Purkyňova 118, Brno 612 00 Analýza pitných a povrchových vod, analýza odpadních vod, vzorkování vod, biomonitoring, analýza potravin Odborný asistent - Výuka předmětů Analýza vod, Praktikum z analytické chemie, Analytická chemie potravin, Odpadové hospodářství v potravinářském průmyslu - Vývoj a práce s gelovými vzorkovacími technikami - Využití biomonitoringu ke sledování kvality povrchových vod - Sledování mikro a makro prvků v potravinách - Stanovení základních nutričních parametrů potravin 1.1.2006 – 28.2.2007 Labtech s.r.o., Polní 23, Brno 639 00 Analýza pitných a povrchových vod, analýza odpadních vod, analýza půd, kalů, sedimentů a odpadů. Vývojový pracovník, laboratorní technik specialista

Hlavní aktivity

-

Datum (od – do) Jméno a adresa zaměstnavatele Zaměření Pozice Hlavní aktivity

Datum (od – do) Jméno a adresa zaměstnavatele Zaměření Pozice Hlavní aktivity

Optimalizace postupů pro rozklad materiálů životního prostředí a jiných materiálů Optimalizace a vývoj analytických metod Analýza vzorků různého původu technikami ET-AAS, HG-AAS, ICP-OES a ICP-MS

2003-2006 Vysoké učení technické v Brně, Fakulta Chemická, Ústav Chemie a Technologie Ochrany Životního prostředí, Purkyňova 118, Brno 612 00 Studium procesů probíhajících v životním prostředí, vývoj a aplikace analytických metod pro environmentální analýzu Doktorand - Výuka analytické chemie (cvičení - Analytická chemie 1 a 2, praktikum – Praktikum z analytické chemie 1 a 2 - Studium koloběhu prvků na fázovém rozhraní voda-sediment - Vývoj in situ gelových technik pro měření biodostupných forem kovů - Biomonitoring kovů v povrchových vodách

únor 2004 – červenec 2004 Vrije Universiteit of Brussel, Pleinlaan 2, Brussel Studium procesů probíhajících v životním prostředí, vývoj a aplikace analytických metod pro environmentální analýzu Doktorand - Vzorkování mořských a říčních vod, sedimentů - Studium koloběhu prvků na fázovém rozhraní voda-sediment - Vývoj in situ gelových technik pro měření biodostupných forem kovů

VZDĚLÁNÍ Datum (od – do) Jméno a adresa instituce

Stručná náplň studia a získané zkušenosti

Získaný akademický titul Datum (od – do) Jméno a adresa instituce

2003-2006 Vysoké učení technické v Brně, Fakulta Chemická, Ústav Chemie a Technologie Ochrany Životního prostředí, Purkyňova 118, Brno 612 00 Chemie a technologie ochrany životního prostředí, postgraduální stadium zabývající se vzorkováním a analýzou těžkých kovů ve vodách a v sedimentech pomocí spektroskopických metod. Aplikace technik difúzní rovnováhy a difúzního gradientu v tenkém filmu, biomonitoring. Název disertační práce: “Vývoj in situ gelových technik pro měření biodostupných forem kovů v přírodních vodách” Ph.D. 1998-2003 Vysoké učení technické v Brně, Fakulta Chemická, Ústav Chemie a Technologie Ochrany Životního prostředí, Purkyňova 118, Brno 612 00

Stručná náplň studia a získané zkušenosti

Získaný akademický titul Datum (od – do) Jméno a adresa instituce Stručná náplň studia a získané zkušenosti

Komplexní vzdělání v oblasti ochrany atmosféry, pedosféry, hydrosféry, čisticí technologie, odpadové hospodářství, environmentální chemie, ekotoxikoogie, detekce a měření ionizujícího záření, principy trvale udržitelného rozvoje a čistší produkce. Diplomová práce: ‘Gelové techniky pro měření biodostupných forem kovů‘ Ing. 1994-1998 Střední průmyslová škola chemická, Krátká 7, Lovosice 41002 Analytická chemie – monitorování životního prostředí

DOVEDNOSTI Rodný jazyk

Čestina

Ostatní jazyky (znalost) Čtení Psaní Řeč

Angličtina B2 B2 B2

Pracovní dovednosti

Zkušenosti s metodami atomové spektroskopie: F-AAS, ET-AAS, HG-AAS, ICP-OES, AES, ICP-MS, UV-VIS spektrometrie, práce s gelovými technikami DET a DGT, vzorkování vod a sedimentů, biomonitoring, volumetrie, potenciometrie. Znalost MS Office, práce s vědeckými knižními databázemi řidičský průkaz sk.B.

Ostatní dovednosti

DOPLŇUJÍCÍ INFORMACE Ocenění vědeckou komunitou

2003 druhé místo v soutěži o nejlepší práci v oboru analytická chemie Merck2003, Pardubice, 2005 zvláštní ocenění v soutěži o Cenu děkana FCH VUT za nejlepší studentskou práci ,2006 cena rektora VUT v Brně, 2006 3.místo v soutěži mladých spektroskopiků Spektroskopické společnosti J.M. Marci

Další vzdělání

Odpadové hospodářství – 3- týdenní kurz zakončený písemnou zkouškou, VŠCHT Praha, 2010 Spektrometrie s indukčně vázaným plazmatem – 3 denní kurz, Spektrometrická společnost Jana marka Marci, 2011 Zahraniční stáže: Vrije Universiteit Brussel, Belgium (2004, 2008, 2009) Universite des sciences at technologies de Lille, France (2009, 2010, 2011) University of Huelva, Spain (2009)

PŘEHLED PEDAGOGICKÉ ČINNOSTI Doklad A:

PŘEHLED PEDAGOGICKÉ ČINNOSTI

Tento dokument obsahuje vyjádření vztahu k VUT požadované podle čl. 2 směrnice rektora č. 1/2006 „Postup při jmenovacím řízení na Vysokém učení technickém v Brně“ a jejího úplného znění z 1.9. 2008. Uchazeč, Ing. Pavel Diviš, Ph.D., je absolventem Vysokého učení technického v Brně, Fakulty chemické (viz přiložený životopis). Od roku 2007 až do současnosti je zaměstnán na Fakultě chemické. 9 Za uvedené období se podílel či podílí na výuce následujících předmětů: PŘEDMĚT BCO_ACP1

NÁZEV Analytická chemie potravin I

ROLE Garant, Vyučující

Analytické metody v kontrolní praxi potravinářského průmyslu. Metody stanovení přírodních součástí potravin. Základní živiny (cukry, dusíkaté látky, lipidy, bílkoviny), minoritně zastoupené nutriční složky (vitamíny, biogenní prvky) a senzoricky a biologicky aktivní látky (kyseliny, přírodní barviva, aromatické látky, třísloviny a jiné). Metody stanovení cizorodých látek znečišťujících potraviny (kontaminantů), přidávaných do potravin (aditiv) a endogenních cizorodých látek.

MCO_ACP1

Food analysis

Garant, Vyučující

Analytické metody v kontrolní praxi potravinářského průmyslu. Metody stanovení přírodních součástí potravin. Základní živiny (cukry, dusíkaté látky, lipidy, bílkoviny), minoritně zastoupené nutriční složky (vitamíny, biogenní prvky) a senzoricky a biologicky aktivní látky (kyseliny, přírodní barviva, aromatické látky, třísloviny a jiné). Metody stanovení cizorodých látek znečišťujících potraviny (kontaminantů), přidávaných do potravin (aditiv) a endogenních cizorodých látek. Senzorické metody hodnocení potravin založené na posuzování jejich organoleptických vlastností smyslovými orgány.

MCO_OHO

Odpadové hospodářství v potravinářském průmyslu


Legislativa v odpadovém hospodářství, odpady a jejich vlastnosti, odpadní vody, aerobní procesy, anaerobní procesy, termofilní zpracování odpadů, využití energie z biomasy, kompostování odpadů, recyklace odpadů, skládkování odpadů, analýza odpadů, nakládání s odpady, praktická část

MCA_ISA_P

Praktikum z instrumentální a strukturní analýzy

Vyučující

Atomová absorpční spektrometrie – AAS, Hmotnostní spektrometrie s indukčně vázaným plazmatem - ICP-MS, Elektromigrační metody – CZE, Elektromigrační metody - gelová elektroforéza, Elektronová paramagnetická resonance – EPR, Nukleární magnetická resonance – NMR, Kapalinová chromatografie – HPLC, Kapalinová chromatografie s hmotnostní detekcí – LCMS, Plynová chromatografie – GC, Plynová chromatografie s hmotnostní detekcí - GC-MS, Spektrofotometrie - UV-VIS, Fluorescenční mikroskopie

MCO_DS_P

Diplomový seminář

Vyučující

Prezentace a seminární diskuse k tématům zadaných diplomových prací. Součástí úvodní části semináře budou prezentace vybraných prací studentů DSP přehledně dokumentujících komplexní odbornou problematiku řešenou na ústavu.

MCO_DS_P

Diploma seminar

Vyučující

Prezentace a seminární diskuse k tématům zadaných diplomových prací. Součástí úvodní části semináře budou prezentace vybraných prací studentů DSP přehledně dokumentujících komplexní odbornou problematiku řešenou na ústavu.

BCO_AVO

Analýza vody


Druhy vod a jejich charakteristika, systém norem pro stanovení jakosti vod, odběr a úprava vzorku různých druhů vod, základní fyzikálně-chemický rozbor vody, stanovení teploty, pH, vodivosti, BSK, CHSK, alkality, acidity, stanovení rozpuštěných, nerozpuštěných a extrahovatelných látek, organoleptické vlastnosti vody, stanovení anorganických složek vod, stanovení Ca, Mg, Na, K, dusíkatých sloučenin, sloučenin síry, halogenidů, stanovení Fe, Mn, Al, stanovení těžkých a ostatních kovů, stanovení B, Si, P, stanovení organických složek vody, stanovení ropných látek, nižších mastných kyselin, fenolů, aromatických uhlovodíků, polyaromatických uhlovodíků, halogenovaných uhlovodíků a huminových kyselin.

Ing.Pavel Diviš, Ph.D.

Stránka |1

PŘEHLED PEDAGOGICKÉ ČINNOSTI

PŘEDMĚT BCO_AVO_P

NÁZEV Praktikum z analýzy vody

ROLE Vyučující

Stanovení základních fyzikálních a chemických ukazatelů jakosti pitné vody, zhodnocení naměřených parametrů s platnou legislativou (pH, organoleptické vlastnosti, základní chemické ukazatele). Analýza ostatních typů vod - povrchová voda, podzemní voda, minerální voda a odpadní voda. Stanovení anorganických a organických látek přítomných ve vodách. Při stanovení budou využity základní instrumentální metody a metody mobilní analytiky.

BCA_ANC2_P

Praktikum z analytické chemie II

Vyučující

Praktická výuka vybraných základních instrumentálních analytických metod: potenciometrie, automatická titrace, spektrofotometrie, fluorimetrie, emisní plamenová fotometrie, tenkovrstvá chromatografie, ionexová chromatografie, elektrogravimetrie.

9 V tomto období byly pod jeho vedením realizovány následující dizertační, diplomové a bakalářské práce:

NÁZEV PRÁCE

STUDENT

TYP PRÁCE

ROK ŘEŠENÍ

Studium bioakumulace vybraných kovů vodním mechorostem Fontinalis antipyretica

L. Jaskowiecová

Diplomová práce

2007/08

Testování modifikovaných sorbetů Iontosorb pro užití v technice difúzního gradientu v tenkém filmu (DGT)

R. Szkandera

Diplomová práce

2007/08

Studium vlastností sorpčních gelů pro stanovení rtuti technikou DGT.

H. Frišhansová

Diplomová práce

2008/09

Využití hmotnostního spektrometru a separačních technik k stanovení různých forem kovů v potravinách

S. Křížová

Bakalářská práce

2008/09

Speciační a frakcionační analýza kovů v zemědělských půdách

P. Lepař


2008/09

Možnosti stanovení germania v potravinách

P. Musilová


2008/09

Speciační analýza selenu v kvasinkách kultivovaných v médiu s přídavkem selenu

T. Motlová

Diplomová práce

2009/10

Analýza vína pomocí moderních analytických metod

P. Škařupa


2009/10

Stanovení alergenních a potenciálně alergenních kovů v kosmetických přípravcích

L. Krakovková

Diplomová práce

2009/10

Stanovení kovů v ovocných šťávách

M. Drobilová

Diplomová práce

2010/11

Stanovení rtuti v rybách a v rybíchproduktech

K. Kroupová

Diplomová práce

2010/11

Stanovení kovů ve vinné révě pěstované různými způsoby

L. Kubicová

Diplomová práce

2010/11


Stránka |2

PŘEHLED PEDAGOGICKÉ ČINNOSTI Stanovení polokovových prvků v potravinách

E. Galová

Diplomová práce

2010/11

Stanovení vybraných prvků v netradičních druzích ovoce

S. Křížová

Diplomová práce

2010/11

Vývoj techniky difúzního gradientu v tenkém filmu (DGT) pro stanovení rtuti ve vodných systémech /školitel-specialista/

R. Szkandera

Disertační práce

2008/11

Stanovení vybraných kovů v ovocných kompotech

P. Hauerlandová

Diplomová práce

2011/12

Možnosti určení původu vína z prvkového složení

P. Škařupa

Diplomová práce

2011/12

Porovnání extrakčních metod pro prvkovou analýzu zemědělských půd

V. Štursa


2011/12

Stanovení výskytu toxických prvků ve víně

I. Hajdučková

Diplomová práce

2011/12

Doc. Ing.. Jiřina Omelková, CSc.

doc. Ing. Josef Čáslavský, CSc.

Fakulta chemická VUT v Brně

Fakulta chemická VUT v Brně

Ústav chemie potravin a biotechnologií - ředitel ústavu

Ústav chemie a technologie ochrany životního prostředí - ředitel ústavu


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SEZNAM PUBLIKOVANÝCH PRACÍ DOKLAD B:

SEZNAM

PUBLIKOVANÝCH A PŘEHLED ODEZVY

PRACÍ,

VÝZNAMNÝCH

REALIZOVANÝCH

DĚL

Tento dokument obsahuje seznam významných výsledků, který je požadován podle čl. 2 směrnice rektora č. 1/2006 „Postup při jmenovacím řízení na Vysokém učení technickém v Brně“ a jejího úplného znění z 1.9. 2008.

Položka

Bibliografické údaje

Počet citací

1

Szkandera, R., Dočekalová, H., Kadlecová, M., Trávníčková, J., Diviš, P.: Sorpční gel s oxidem titaničitým pro stanovení rtuti technikou difuzního gradientu v tenkém filmu (2013) Chemicke Listy, 107 (2), pp. 160-164.

0

2

Diviš, P., Machát, P., Szkandera, R., Dočekalová, H.: In situ measurement of bioavailable metal concentrations at the downstream on the Morava river using transplanted aquatic mosses and DGT technique (2012) International Journal of Environmental Research, 6 (1), pp. 87-94.

6

3

Diviš, P., Szkandera, R., Dočekalová, H.: Characterization of sorption gels used for determination of mercury in aquatic environment by diffusive gradients in thin films technique(2010) Central European Journal of Chemistry, 8 (5), pp. 1103-1107.

1

4

Matúš, P., Hagarová, I., Bujdoš, M., Diviš, P., Kubová, J.: Determination of trace amounts of total dissolved cationic aluminium species in environmental samples by solid phase extraction using nanometer-sized titanium dioxide and atomic spectrometry techniques (2009) Journal of Inorganic Biochemistry, 103 (11), pp. 1473-1479.

9

5

Diviš, P., Szkandera, R., Brulík, L., Dočekalová, H., Matúš, P., Bujdoš, M.: Application of new resin gels for measuring mercury by diffusive gradients in a thin-films technique (2009) Analytical Sciences, 25 (4), pp. 575-578.

6

6

Diviš, P., Dočekalová, H., Brulík, L., Pavliš, M., Hekera, P.: Use of the diffusive gradients in thin films technique to evaluate (bio)available trace metal concentrations in river water (2007) Analytical and Bioanalytical Chemistry, 387 (6), pp. 2239-2244.

15

7

Gao, Y., Leermakers, M., Gabelle, C., Divis, P., Billon, G., Ouddane, B., Fischer, J.-C., Wartel, M., Baeyens, W.: High-resolution profiles of trace metals in the pore waters of riverine sediment assessed by DET and DGT (2006) Science of the Total Environment, 362 (1-3), pp. 266-277.

14

8

Diviš, P., Dočekalová, H., Řezáčová, V.: Gelové techniky pro měření in situ ve vodách, v půdách a v sedimentech (2005) Chemicke Listy, 99 (9), pp. 640-646.

6

9

Diviš, P., Leermakers, M., Dočekalová, H., Gao, Y.: Mercury depth profiles in river and marine sediments measured by the diffusive gradients in thin films technique with two different specific resins (2005) Analytical and Bioanalytical Chemistry, 382 (7), pp. 1715-1719.

12

10

Dočekalová, H., Diviš, P.: Application of diffusive gradient in thin films technique (DGT) to measurement of mercury in aquatic systems (2005) Talanta, 65 (5), pp. 1174-1178.

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SEZNAM PUBLIKOVANÝCH PRACÍ

11

Diviš, P., Dočekalová, H., Smetková, V.: Hloubkové profily labilních kovových species v sedimentech a jejich in situ měření technikou difuzního gradientu v tenkém filmu (2003) Chemicke Listy, 97 (12), pp. 1184-1189.


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VLASTNÍ HODNOCENÍ UCHAZEČE Doklad C: VLASTNÍ HODNOCENÍ UCHAZEČE Tento dokument obsahuje vlastní hodnocení uchazeče nebo také autoevaluační kritéria požadované podle čl. 3 směrnice rektora č. 1/2006 „Postup při jmenovacím řízení na Vysokém učení technickém v Brně“ a jejího úplného znění z 1.9. 2008. Uchazeč: Datum narození: Bydliště:

Ing. Pavel Diviš, Ph.D. 19.12. 1979 Chelčického 18 747 05, Opava

Podklad k návrhu na jmenování:

Docentem

A) VĚDECKÁ A ODBORNÁ ČINNOST OZN. POLOŽKA A1 Monografie A2 Původní vědecká práce ve vědeckém časopisu s impact faktorem větším než 0,5. A4 Původní vědecká práce ve vědeckém časopisu s impact faktorem menším než 0,5 nebo bez impakt faktoru A6 Citace jiným autorem dle SCI A10 Abstrakt ve sborníku světového nebo evropského kongresu, symposia, vědecké konference A11 Přípěvek ve sborníku národního nebo mezinárodního kongresu, sympozia, vědecké konference A13 Abstrakt ve sborníku národního nebo mezinárodního kongresu, sympozia, vědecké konference, příspěvek ve sborníku odborné konference A14 Citace jiným autorem v publikaci bez SCI A22 Členství v programovém výboru národního nebo mezinárodního kongresu, symposia, vědecké konference A24 Získání externího grantu (řešitel, spoluřešitel) A27 Posudek zahraniční publikace nebo projektu, znalecký posudek, expertiza. B) PEDAGOGICKÁ ČINNOST OZN. POLOŽKA B1 Za každý rok pedagogického působení na vysoké škole na plný úvazek B3 Zavedení předmětu, který byl vyučován v posledních 5 letech B4 Vedoucí obhájené bakalářské/ diplomové práce B5 Školitel/školitel specialista studenta, který získal Ph.D., CSc., Dr.

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Minimální požadavky k podání žádosti uchazečem k návrhu: ŠKOLITEL POLOŽKA

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Následuje rozpis jednotlivých součástí. Ing.Pavel Diviš, Ph.D.

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Bujdoš, M.; Diviš, P.; Dočekalová, H.; Fišera, M.; Hagarová, I.; Kubová, J.; Machát, J.; Matúš, P.; Medveď, J.; Remeteiová, D.; Vitoulová, E.; Špeciacia, špeciačná analýza a frakcionácia chemických prvkov v životnom prostredí. ZSVTS. Bratislava, Univerzita Komenského v Bratislavě. 2008. 224p. ISBN 978-80-223-2540-0.

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PŮVODNÍ VĚDECKÁ PRÁCE VE VĚDECKÉM ČASOPISU S IMPACT FAKTOREM (IF) VĚTŠÍM NEŽ 0,5. Szkandera, R., Dočekalová, H., Kadlecová, M., Trávníčková, J., Diviš, P.: Sorpční gel s oxidem titaničitým pro stanovení rtuti technikou difuzního 1 gradientu v tenkém filmu (2013) Chemicke Listy, 107 (2), pp. 160-164. Diviš, P., Machát, P., Szkandera, R., Dočekalová, H.: In situ measurement of bioavailable metal concentrations at the downstream on the Morava river 2 using transplanted aquatic mosses and DGT technique (2012) International Journal of Environmental Research, 6 (1), pp. 87-94. Diviš, P., Szkandera, R., Dočekalová, H.: Characterization of sorption gels used for determination of mercury in aquatic environment by diffusive 3 gradients in thin films technique(2010) Central European Journal of Chemistry, 8 (5), pp. 1103-1107. Matúš, P., Hagarová, I., Bujdoš, M., Diviš, P., Kubová, J.: Determination of trace amounts of total dissolved cationic aluminium species in environmental samples by solid phase extraction using nanometer-sized titanium dioxide 4 and atomic spectrometry techniques (2009) Journal of Inorganic Biochemistry, 103 (11), pp. 1473-1479. Diviš, P., Szkandera, R., Brulík, L., Dočekalová, H., Matúš, P., Bujdoš, M.: Application of new resin gels for measuring mercury by diffusive gradients in 5 a thin-films technique (2009) Analytical Sciences, 25 (4), pp. 575-578. Diviš, P., Dočekalová, H., Brulík, L., Pavliš, M., Hekera, P.: Use of the diffusive gradients in thin films technique to evaluate (bio)available trace 6 metal concentrations in river water (2007) Analytical and Bioanalytical Chemistry, 387 (6), pp. 2239-2244. Gao, Y., Leermakers, M., Gabelle, C., Divis, P., Billon, G., Ouddane, B., Fischer, J.-C., Wartel, M., Baeyens, W.: High-resolution profiles of trace 7 metals in the pore waters of riverine sediment assessed by DET and DGT (2006) Science of the Total Environment, 362 (1-3), pp. 266-277. Diviš, P., Dočekalová, H., Řezáčová, V.: Gelové techniky pro měření in situ ve vodách, v půdách a v sedimentech (2005) Chemicke Listy, 99 (9), pp. 8 640-646. Diviš, P., Leermakers, M., Dočekalová, H., Gao, Y.: Mercury depth profiles in river and marine sediments measured by the diffusive gradients in thin films 9 technique with two different specific resins (2005) Analytical and Bioanalytical Chemistry, 382 (7), pp. 1715-1719. Dočekalová, H., Diviš, P.: Application of diffusive gradient in thin films technique (DGT) to measurement of mercury in aquatic systems (2005) 10 Talanta, 65 (5), pp. 1174-1178. Diviš, P., Dočekalová, H., Smetková, V.: Hloubkové profily labilních kovových species v sedimentech a jejich in situ měření technikou difuzního 11 gradientu v tenkém filmu (2003) Chemicke Listy, 97 (12), pp. 1184-1189. CELKEM ZA A2 A2


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(IF) 0,1 NEBO VE VĚDECKÉM ČASOPISE BEZ IF Kubová, J., Matúš, P., Bujdoš, M., Hagarová, I., Medveď, J., Diviš, P., Dočekalová, H.: Optimized BCR 3-step sequential and dilute HCl single extraction 1 protocols-The suitable tools for soil plant metal transfer prediction in polluted areas? (2008) Transaction of the Universities of Košice, 3, pp. 50-58. Matúš, P., Bujdoš, M., Kubová, J., Hagarová, I., Medveď, J., Diviš, P., Mládková, Z..: Comparison of five different methods for the separation and 2 determination of aluminium phytoavailable and phytotoxic fractions (2008) Transaction of the Universities of Košice , 3, pp. 86-96. Matúš, P., Čerňanský, S., Urík, M., Medveď, J., Bujdoš, M., Kramařívá, Z., kališ, m., Hagarová, I., Kubová, J., Ševc, J., Diviš, P., Brulík, L. Quantification of biosorption, bioaccumulation and biovolatilization of labiále 3 aluminium and thalium species by fungl biomass using the atomic spectroscopy techniques (2008) Transaction of the Universities of Košice , 3, pp. 97-105. CELKEM ZA A4 VĚDECKÁ PRÁCE VE VĚDECKÉM ČASOPISU S IMPACT FAKTOREM

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CITACE JINÝM AUTOREM PODLE SCIENCE CITATION INDEX (SCI) Ferreira, D., Ciffroy, P., Tusseau-Vuillemin, M.-H., Bourgeault, A., Garnier, J.-M. DGT as surrogate of biomonitors for predicting the bioavailability of copper in freshwaters: An ex situ validation study (2013) Chemosphere, 91 (3), pp. 241-247. Hsu-Kim, H., Kucharzyk, K.H., Zhang, T., Deshusses, M.A.: Mechanisms regulating mercury bioavailability for methylating microorganisms in the aquatic environment: A critical review (2013) Environmental Science and Technology, 47 (6), pp. 2441-2456. Jordan, P., Cassidy, R., Macintosh, K.A., Arnscheidt, J.: Field and laboratory tests of flow-proportional passive samplers for determining average phosphorus and nitrogen concentration in revers (2013) Environmental Science and Technology, 47 (5), pp. 2331-2338. Gregusova, M., Docekal, B.: High resolution characterization of uranium in sediments by DGT and DET techniques ACA-S-12-2197 (2013) Analytica Chimica Acta, 763, pp. 50-56. Cesa, M., Baldisseri, A., Bertolini, G., Dainese, E., Col, M.D., Vecchia, U.D., Marchesini, P., Nimis, P.L.: Implementation of an active 'bryomonitoring' network for chemical status and temporal trend assessment under the Water Framework Directive in the Chiampo Valley's tannery district (NE Italy) (2013) Journal of Environmental Management, 114, pp. 303-315. Zhou, Y., Stotesbury, T., Dimock, B., Vreugdenhil, A., Hintelmann, H.: Novel silica sol-gel passive sampler for mercury monitoring in aqueous systéme (2013) Chemosphere, 90 (2), pp. 323-328. Fernández-Gómez, C., Bayona, J.M., Díez, S.: Laboratory and field evaluation of diffusive gradient in thin films (DGT) for monitoring levels of dissolved mercury in natural river water (2012) International Journal of Environmental Analytical Chemistry, 92 (15), pp. 1689-1698. Ullah, S., Zhang, H., Heathwaite, A.L., Binley, A., Lansdown, K., Heppell, K., Trimmer, M.: In situ measurement of redox sensitive solutes at high spatial resolution in a riverbed using Diffusive Equilibrium in Thin Films (DET) (2012) Ecological Engineering, 49, pp. 18-26. Nwabanne, J.T., Igbokwe, P.K.: Kinetic modeling of heavy metals adsorption on fixed bed column (2012) International Journal of Environmental Research, 6 (4), pp. 945-952. Singh, S.R., Singh, A.P.: Treatment of water containg chromium (VI) using rice husk carbon as a newlow cost adsorbent (2012) International Journal of Environmental Research, 6 (4), pp. 917-924.


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Blagojević, J., Jovanović, V., Stamenković, G., Jojić, V., Bugarski-Stanojević, V., Adnadević, T., Vujošević, M.: Age differences in bioaccumulation of heavy metals in populations of the black-striped field mouse, Apodemusagrarius(Rodentia, Mammalia) (2012) International Journal of Environmental Research, 6 (4), pp. 1045-1052. Jiang, X., Huang, K., Deng, D., Xia, H., Hou, X., Zheng, C.: Nanomaterials in analytical atomic spektrometry (2012) TrAC - Trends in Analytical Chemistry, 39, pp. 38-59. Colaço, C.D., Yabuki, L.N.M., Alcântara, A.L., Menegário, A.A.: Diffusion coefficients of metals in non-conventional materials (agarose and cellulose acetate) used in the diffusive gradients in thin films technique (2012) Quimica Nova, 35 (7), pp. 1360-1364. Pescim, G.F., Marrach, G., Vannuci-Silva, M., Souza, L.A., Menegário, A.A.: Speciation of lead in seawater and river water by using Saccharomyces cerevisiae immobilized in agarose gel as a binding agent in the diffusive gradients in thin films technique(2012) Analytical and Bioanalytical Chemistry, 404 (5), pp. 1581-1588. Lucas, A., Rate, A., Zhang, H., Salmon, S.U., Radford,N.: Development of the diffusive gradients in thin films technique for the measurement of labile gold in natural waters (2012) Analytical Chemistry, 84 (16), pp. 6994-7000. Motesharezadeh, B., Savaghebi, G.R.: Interaction between cadmium and lead and the effects of these on the concentration of zinc and manganese in sunflower (2012) International Journal of Environmental Research, 6 (3), pp. 793-800. Ogundiran, M.B., Ogundele, D.T., Afolayan, P.G., Osibanjo, O.:Heavy metals levels in forage grasses, leachate and lactating cows reared around lead slag dumpsites in Nigeria(2012) International Journal of Environmental Research, 6 (3), pp. 695-702. Shwetha, A., Hosetti, B.B., Dube, P.N.: Toxic effects of zinc cyanide on some protein metabolites in fresh water fish, Cirrhinus mrigala (Hamilton) (2012) International Journal of Environmental Research, 6 (3), pp. 769-778. Krika, F., Azzouz, N., Ncibi, M.C.: Removal of hexavalent chromium from aqueous media using mediterranean Posidonia oceanica biomass: Adsorption studies and salt competition investigation (2012) International Journal of Environmental Research, 6 (3), pp. 719-732. Gkritzalis-Papadopoulos, A., Palmer, M.R., Mowlem, M.C.: Adaptation of an osmotically pumped continuous in situ water sampler for application in riverine environments (2012) Environmental Science and Technology, 46 (13), pp. 7293-7300. Yalnkaya, Ö., Erdoǧan, H., Çiftçi, H., Türker, A.R.:Preconcentration of aluminum on nano ZrO 2/B 2O 3 and its determination by flame atomic absorption spectrometry (2012) Spectroscopy Letters, 45 (5), pp. 344-351. Demarchi, C.A., Debrassi, A., Rodrigues, C.A.: The use of Jatobá bark for removal of cationic dyes (2012) Coloration Technology, 128 (3), p. 208-217. Almeida, E.D., Nascimento Filho, V.F.D., Menegário, A.A.: Paper-based diffusive gradients in thin films technique coupled to energy dispersive X-ray fluorescence spectrometry for the determination of labile Mn, Co, Ni, Cu, Zn and Pb in river water (2012) Spectrochimica Acta - Part B Atomic Spectroscopy, 71-72, pp. 70-74. Hagarová, I., Matúš, P., Bujdoš, M., Kubová, J.: Analytical application of nano-sized titanium dioxide for the determination of trace inorganic antimony in natural waters (2012) Acta Chimica Slovenica, 59 (1), pp. 102-108. Gao, Y., Leermakers, M., Pede, A., Magnier, A., Sabbe, K., Lourino Cabana, B., Billon, G., Baeyens, W., Gillan, D.C.: Response of diffusive equilibrium in thin films (DET) and diffusive gradients in thin films (DGT) trace metal profiles in sediments to phytodetritus mineralisation (2012) Environmental Chemistry, 9 (1), pp. 41-47.


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Davison, W., Zhang, H.: Progress in understanding the use of diffusive gradients in thin films (DGT) back to basics (2012) Environmental Chemistry, 9 (1), pp. 1-13. Banks, J., Ross, D.J., Keough, M.J.: Short-term (24 h) effects of mild and severe hypoxia (20% and 5% dissolved oxygen) on metal partitioning in highly contaminated estuarine sediments (2012) Estuarine, Coastal and Shelf Science, 99, pp. 121-131. Panther, J.G., Bennett, W.W., Teasdale, P.R., Welsh, D.T., Zhao, H.: DGT measurement of dissolved aluminum species in waters: Comparing chelex100 and titanium dioxide-based adsorbents (2012) Environmental Science and Technology, 46 (4), pp. 2267-2275. Docekal, B., Gregusova, M.: Segmented sediment probe for diffusive gradient in thin films technique (2012) Analyst, 137 (2), pp. 502-507. Bennett, W.W., Teasdale, P.R., Welsh, D.T., Panther, J.G., Jolley, D.F.: Optimization of colorimetric DET technique for the in situ, two-dimensional measurement of iron(II) distributions in sediment porewaters (2012) Talanta, 88, pp. 490-495. Mengistu, H., Roeyset, O., Tessema, A., Abiye, T.A., Demlie, M.B.: Diffusive gradient in thin-films (DGT) as risk assessment and management tools in the central witwatersrand goldfield, South Africa (2012) Water SA, 38 (1), pp. 1522. Díaz, A., Arnedo, R., Céspedes-Sánchez, R., Devesa, R., Martin-Alonso, J. Monitoring of (bio)available labile metal fraction in a drinking water treatment plant by diffusive gradients in thin films (2012) Environmental Monitoring and Assessment, 184 (1), pp. 539-548. Gao, Y., De Canck, E., Leermakers, M., Baeyens, W., Van Der Voort, P. : Synthesized mercaptopropyl nanoporous resins in DGT probes for determining dissolved mercury concentrations(2011) Talanta, 87 (1), pp. 262-267. Cesa, M., Bizzotto, A., Ferraro, C., Fumagalli, F., Luigi Nimis, P.: Oven-dried mosses as tools for trace element detection in polluted waters: A preliminary study under laboratory conditions (2011) Plant Biosystems, 145 (4), pp. 832840. Mundus, S., Tandy, S., Cheng, H., Lombi, E., Husted, S., Holm, P.E., Zhang, H.: Applicability of diffusive gradients in thin films for measuring Mn in soils and freshwater sediments(2011) Analytical Chemistry, 83 (23), pp. 89848991. Fernández-Gómez, C., Dimock, B., Hintelmann, H., Díez, S.: Development of the DGT technique for Hg measurement in water: Comparison of three different types of samplers in laboratory assays (2011) Chemosphere, 85 (9), pp. 1452-1457. Baeyens, W., Bowie, A.R., Buesseler, K., Elskens, M., Gao, Y., Lamborg, C., Leermakers, M., Remenyi, T., Zhang, H.: Size-fractionated labile trace elements in the Northwest Pacific and Southern Oceáne (2011) Marine Chemistry, 126 (1-4), pp. 108-113. Aguilar-Martínez, R., Gómez-Gómez, M.M., Palacios-Corvillo, M.A.: Mercury and organotin compounds monitoring in fresh and marine waters across Europe by Chemcatcher passive samolet (2011) International Journal of Environmental Analytical Chemistry, 91 (11), pp. 1100-1116. Hong, Y.S., Rifkin, E., Bouwer, E.J.: Combination of diffusive gradient in a thin film probe and IC-ICP-MS for the simultaneous determination of CH3Hg+ and Hg2+ in oxic water (2011) Environmental Science and Technology, 45 (15), pp. 6429-6436. Liu, J., Feng, X., Qiu, G., Yao, H., Shang, L., Yan, H.: Intercomparison and applicability of some dynamic and equilibrium approaches to determine methylated mercury species in pore water (2011) Environmental Toxicology and Chemistry, 30 (8), pp. 1739-1744.


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Panther, J.G., Teasdale, P.R., Bennett, W.W., Welsh, D.T., Zhao, H.. Comparing dissolved reactive phosphorus measured by DGT with ferrihydrite and titanium dioxide adsorbents: Anionic interferences, adsorbent capacity and deployment time (2011) Analytica Chimica Acta, 698 (1-2), pp. 20-26. Fathi, M.R., Pourreza, N., Ardan, Z.: Determination of aluminum in food samples after preconcentration as aluminon complex on microcrystalline naphthalene by spectrophotometry (2011) Quimica Nova, 34 (3), pp. 404407. Roig, N., Nadal, M., Sierra, J., Ginebreda, A., Schuhmacher, M., Domingo, J.L.: Novel approach for assessing heavy metal pollution and ecotoxicological status of rivers by means of passive sampling methods (2011) Environment International, 37 (4), pp. 671-677. Wu, Z., He, M., Lin, C.: In situ measurements of concentrations of Cd, Co, Fe and Mn in estuarine porewater using DGT(2011) Environmental Pollution, 159 (5), pp. 1123-1128. Tonello, P.S., Goveia, D., Rosa, A.H., Fraceto, L.F., Menegário, A.A.: Determination of labile inorganic and organic species of Al and Cu in river waters using the diffusive gradients in thin films technique (2011) Analytical and Bioanalytical Chemistry, 399 (7), pp. 2563-2570. Quinones, J.L., Carpi, A.: An investigation of the kinetic processes influencing mercury emissions from sand and soil samples of varying thickness (2011) Journal of Environmental Quality, 40 (2), pp. 647-652. Clarisse, O., Dimock, B., Hintelmann, H., Best, E.P.H.: Predicting net mercury methylation in sediments using diffusive gradient in thin films measurements(2011) Environmental Science and Technology, 45 (4), pp. 1506-1512. Menegário, A.A., Tonello, P.S., Durrant, S.F.: Use of Saccharomyces cerevisiae immobilized in agarose gel as a binding agent for diffusive gradients in thin films (2010) Analytica Chimica Acta, 683 (1), pp. 107-112. Tejada, M., Gómez, I., Hernández, T., García, C.: Response of Eisenia fetida to the application of different organic wastes in an aluminiumcontaminated soil (2010) Ecotoxicology and Environmental Safety, 73 (8), pp. 1944-1949. Santner, J., Prohaska, T., Luo, J., Zhang, H.: Ferrihydrite containing gel for chemical imaging of labile phosphate species in sediments and soils using diffusive gradients in thin films (2010) Analytical Chemistry, 82 (18), pp. 7668-7674. Huang, Y., Zhou, Q., Xiao, J., Xie, G.: Determination of trace organophosphorus pesticides in water samples with TiO2 nanotubes cartridge prior to GC-flame photometric detection (2010) Journal of Separation Science, 33 (14), pp. 2184-2190. Duquène, L., Vandenhove, H., Tack, F., Van Hees, M., Wannijn, J. Diffusive gradient in thin FILMS (DGT) compared with soil solution and labile uranium fraction for predicting uranium bioavailability to ryegrass (2010) Journal of Environmental Radioactivity, 101 (2), pp. 140-147. Gao, Y., Lesven, L., Gillan, D., Sabbe, K., Billon, G., De Galan, S., Elskens, M., Baeyens, W., Leermakers, M.: Geochemical behavior of trace elements in sub-tidal marine sediments of the Belgian coast (2009) Marine Chemistry, 117 (1-4), pp. 88-96. Alexa, N., Zhang, H., Lead, J.R.: Development of a miniaturized diffusive gradients in thin films (DGT) device (2009) Analytica Chimica Acta, 655 (12), pp. 80-85. Fan, H., Bian, Y., Sui, D., Tong, G., Sun, T.: Measurement of free copper(II) ions in water samples with polyvinyl alcohol as a binding phase in diffusive gradients in thin-films (2009) Analytical Sciences, 25 (11), pp. 1345-1349.


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Fan, H., Sun, T., Li, W., Sui, D., Jin, S., Lian, X.: Sodium polyacrylate as a binding agent in diffusive gradients in thin-films technique for the measurement of Cu2+ and Cd2+ in waters (2009) Talanta, 79 (5), pp. 12281232. Sherwood, J.E., Barnett, D., Barnett, N.W., Dover, K., Howitt, J., Ii, H., Kew, P., Mondon, J.: Deployment of DGT units in marine waters to assess the environmental risk from a deep sea tailings outfall (2009) Analytica Chimica Acta, 652 (1-2), pp. 215-223. Charriau, A., Bodineau, L., Ouddane, B., Fischer, J.-C.: Polycyclic aromatic hydrocarbons and n-alkanes in sediments of the Upper Scheldt River Basin: Contamination levels and source apportionment (2009) Journal of Environmental Monitoring, 11 (5), pp. 1086-1093. Dytrtová, J.J., Jakl, M., Kolihová, D., Miholová, D., Tlustoš, P.: Vliv přítomnosti nízko-molekulaírních organických kyselin na stanovení kadmia technikou Difuzního Gradientu v Tenkém Filmu (2009) Chemicke Listy, 103 (5), pp. 401-406. Cattani, I., Zhang, H., Beone, G.M., Del Re, A.A.M., Boccelli, R., Trevisan, M.: The role of natural purified humic ad modifying mercury accessibility in water and soil (2009) Journal of Environmental Quality, 38 (2), pp. 493-501. Clarisse, O., Foucher, D., Hintelmann, H.: Methylmercury speciation in the dissolved phase of a stratified lake using the diffusive gradient in thin film technique (2009) Environmental Pollution, 157 (3), pp. 987-993. Aguilar-Martínez, R., Gómez-Gómez, M.M., Greenwood, R., Mills, G.A., Vrana, B., Palacios-Corvillo, M.A. Application of Chemcatcher passive sampler for monitoring levels of mercury in contaminated river water (2009) Talanta, 77 (4), pp. 1483-1489. Panther, J.G., Stillwell, K.P., Powell, K.J., Downard, A.J. Perfluorosulfonated ionomer-modified diffusive gradients in thin films: Tool for inorganic arsenic speciation analysis (2008) Analytical Chemistry, 80 (24), pp. 9806-9811. Lesven, L., Gao, Y., Billon, G., Leermakers, M., Ouddane, B., Fischer, J.-C., Baeyens, W.: Early diagenetic processes aspects controlling the mobility of dissolved trace metals in three riverine sediment columns (2008) Science of the Total Environment, 407 (1), pp. 447-459. Garmo, Ø.A., Davison, W., Zhang, H.: Effects of binding of metals to the hydrogel and filter membrane on the accuracy of the diffusive gradients in thin films technique (2008) Analytical Chemistry, 80 (23), pp. 9220-9225. Dragun, Z., Raspor, B., Roje, V.: The labile metal concentrations in Sava River water assessed by diffusive gradients in thin films (2008) Chemical Speciation and Bioavailability, 20 (1), pp. 33-46. Pernet-coudrier, B., Clouzot, L., Varrault, G., Tusseau-vuillemin, M.-H., Verger, A., Mouchel, J.-M.: Dissolved organic matter from treated effluent of a major wastewater treatment plant: Characterization and influence on copper toxicity (2008) Chemosphere, 73 (4), pp. 593-599. Jordan, M.A., Teasdale, P.R., Dunn, R.J.K., Lee, S.Y.: Modelling copper uptake by Saccostrea glomerata with diffusive gradients in a thin film measurements(2008) Environmental Chemistry, 5 (4), pp. 274-280. Panther, J.G., Stillwell, K.P., Powell, K.J., Downard, A.J.: Development and application of the diffusive gradients in thin films technique for the measurement of total dissolved inorganic arsenic in waters (2008) Analytica Chimica Acta, 622 (1-2), pp. 133-142. Garmo, Ø.A., Davison, W., Zhang, H.: Interactions of trace metals with hydrogels and filter membranes used in DET and DGT techniques (2008) Environmental Science and Technology, 42 (15), pp. 5682-5687. Monbet, P., Mckelvie, I.D., Worsfold, P.J.: Combined gel probes for the in situ determination of dissolved reactive phosphorus in porewaters and characterization of sediment reactivity (2008) Environmental Science and Technology, 42 (14), pp. 5112-5117.


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VLASTNÍ HODNOCENÍ UCHAZEČE Cattani, I., Spalla, S., Beone, G.M., Del Re, A.A.M., Boccelli, R., Trevisan, M.: Characterization of mercury species in soils by HPLC-ICP-MS and 72 measurement of fraction removed by diffusive gradient in thin films (2008) Talanta, 74 (5), pp. 1520-1526. Aguilar-Martínez, R., Greenwood, R., Mills, G.A., Vrana, B., PalaciosCorvillo, M.A., Gómez-Gómez, M.M.: Assessment of Chemcatcher passive sampler for the monitoring of inorganic mercury and organotin compounds in 73 water (2008) International Journal of Environmental Analytical Chemistry, 88 (2), pp. 75-90. Kot-Wasik, A., Zabiegała, B., Urbanowicz, M., Dominiak, E., Wasik, A., Namieśnik, J.: Advances in passive sampling in environmental studies 74 (2007) Analytica Chimica Acta, 602 (2), pp. 141-163. Kizek, R., Adam, V.: Impaktové faktory časopisů vydávaných v České 75 Republice za rok 2006 (2007) Chemicke Listy, 101 (8), pp. 680-682. Fuchs, B.M., Spring, S., Teeling, H., Quast, C., Wulf, J., Schattenhofer, M., Yan, S., Ferriera, S., Johnson, J., Glöckner, F.O., Amann, R.: Characterization of a marine gammaproteo-bacterium capable of aerobic 76 anoxygenic photosynthesis (2007) Proceedings of the National Academy of Sciences of the United States of America, 104 (8), pp. 2891-2896. Gao, Y., Leermakers, M., Elskens, M., Billon, G., Ouddane, B., Fischer, J.C., Baeyens, W.: High resolution profiles of thallium, manganese and iron 77 assessed by DET and DGT techniques in riverine sediment pore waters (2007) Science of the Total Environment, 373 (2-3), pp. 526-533. Merritt, K.A., Amirbahman, A.: Mercury mobilization in estuarine sediment porewaters: A diffusive gel time-series study (2007) Environmental Science 78 and Technology, 41 (3), pp. 717-722. Clarisse, O., Hintelmann, H.: Measurements of dissolved methylmercury in natural waters using diffusive gradients in thin film (DGT)(2006) Journal of 79 Environmental Monitoring, 8 (12), pp. 1242-1247. Lehto, N.J., Davison, W., Zhang, H., Tych, W.: An evaluation of DGT performance using a dynamic numerical model (2006) Environmental 80 Science and Technology, 40 (20), pp. 6368-6376. Rezacova-Smetkova, V., Dočekal, B., Dočekalová, H. :Použití techniky difuzního gradientu v tenkém filmu při charakterizaci půd (2005) Chemicke 81 Listy, 99 (8), pp. 594-599. CELKEM ZA A6

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DIVIŠ, P., DOČEKALOVÁ, H. In situ measuring of mercury in aquatic systems by diffusive gradients in thin films technique (DGT). In International analytical symposium Analytical forum 2004. Warsaw. 2004. p. 194 - 194. ISBN 83-88442-84-8. DOČEKALOVÁ, H., DIVIŠ, P., HERNÍKOVÁ, V. Determination of Mercury in Aquatic Systems by Diffusive Gradient in Thin Films Technique (DGT). In 6th Europian Furnace Symposium and 11th Solid Sampling Colloquium with Atomic Spectrometry BoA. Balatonföldvár. 2004. p. 42 - 42. DIVIŠ, P., LEERMAKERS, M., DOČEKALOVÁ, H., GAO, Y. Application of diffusive gradients in thin films technique to sampling of mercury species in sediment pore water. In DGT Workshop 2005. Lancaster, UK, DGT research. 2005. p. 32 - 32. BRULÍK, L.; DIVIŠ, P.; DOČEKALOVÁ, H. APPLICATION OF WATER SAMPLING TECHNIQUES FOR ASESSMENT OF BIOAVAILABLE METAL CONCENTRATIONS IN THE SVITAVA RIVER. In Book of abstracts. Hamburg, Germany. 2006. p. 8 - 8.


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DOČEKALOVÁ, H.; DIVIŠ, P.; BRULÍK, L. Determination of phytoavailable trace metals using diffusive gradient in thin films technique (DGT) and aquatic moss Frontinalis antipyretica. In Book of abstracts. 1. St. Petersburg, Russia. 2006. p. 81 - 81. DIVIŠ, P.; BRULÍK, L.; DOČEKALOVÁ, H. Investigation of diffusive gradients in thin films technique applicability for mercury speciation measurements. In Final Program of TraceSpec 2007 event. EVISA&IAEAC. 2007. p. 131 - 131. H. DOČEKALOVÁ, P. DIVIŠ. Gel techniques in environmental analysis. In Abstract book of 1st Sino-Hungarian workshop on toxic substances in the environment. China, China University of Geosciences. 2007. p. 33 - 34. DIVIŠ, P.; BRULÍK, L.; SZKANDERA, R.; Preparation of new resin gels for determination of mercury by diffusive gradients in thin films technique. Book of abstracts 35th ISEAC. Gdansk, IAEAC. 2008. p. 63 – 63. ISBN 978-83925754-4-3. BRULÍK, L.; DIVIŠ P.; DOČEKALOVÁ H.; MATÚŠ, P. USE OF DIFFERENT WATER SAMPLING TECHNIQUES FOR MONITORING OF TRACE METALS CONCENTRATIONS IN THE MORAVA RIVER. In Book of abstracts 35th ISEAC. Gdansk, IAEAC. 2008. p. 186 - 186. ISBN 978-83925754-4-3. BRULÍK, L.; BUJDOŠ, M; ČERŇANSKÝ, S.; DIVIŠ, P.; KRAMAROVÁ, Z.; MATÚŠ, P.; MEDVEĎ, J.; ŠEVC, J.; URÍK,M. Fractionation and speciation analysis of aluminium and thalium after bioaccumulation and biosorption their labile species by microscopic filamentous fungi and computer modeling. Book of abstract 35th ISEAC. Gdansk, IAEAC. 2008. p. 187 - 187. ISBN 978-83-925754-4-3. MATÚŠ, P.; URÍK, P.; ČERŇANSKY, S.; MEDVED, J.; BUJDOŠ, M.; KRAMAROVÁ, Z.; KUBOVÁ, J.; HAGAROVÁ, I.; ŠEVC, J.; DIVIŠ, P.; BRULÍK, L. Determination of bioavailable species of aluminium and thallium in the environment by spectrometry using the analysis of microbial fungi bioindicators a laboratory study of metal biosorption, bioaccumulation and biovolatilization. Book of abstracts. Yobix Co. Ltd. 2008. p. 104 - 104. DIVIŠ, P.; SZKANDERA, R.; FRIŠHANSOVÁ, H. Characterization of resin gels used for determination of different mercury fractions in natural waters by DGT technique. 12th Workshop on progress in analytical methodologies for trace metal speciation. 2009. p. 94. HAGAROVÁ, I.; MATÚŠ, P.; KUBOVÁ, J.; BUJDOŠ, M.; DIVIŠ, P. Speciation analysis of inorganic antimony in natural waters using the combination of extraction procedures and electrothermal atomic absorption spectrometry. 12th Workshop on progress in analytical methodologies for trace metal speciation. 2009. p. 78. HAGAROVÁ, I.; MATÚŠ, P.; KUBOVÁ, J.; BUJDOŠ, M.; DIVIŠ, P. Comparison of some reaction media for the determination of arsenites by hydride generation atomic absorption spectrometry. 12th Workshop on progress in analytical methodologies for trace metal speciation. 2009. p. 105. DIVIŠ, P.; SZKANDERA, R.; DOČEKALOVÁ, H. Improvement of mercury determination in surface water by the DGT technique. Conference on DGT and the Environment. 2009. p. 48 - 48. KADLECOVÁ, M.; DIVIŠ, P.; KOVAŘÍKOVÁ , V.; DOČEKALOVÁ , H.; OUDDANE, B.; Determination of dissolved mercury species in river ecosystem using DGT technique with thiol groups in resin gel. Conference on DGT and the Environment. 2009. p. 63 - 63. HAGAROVÁ, I.; KUBOVÁ, J.; BUJDOŠ, M.; MATÚŠ, P.;DIVIŠ, P. Coupling of SPE and ETAAS for the determination of ultratrace inorganic antimony in waters. 6th International conference on instrumental methods of analysis, modern trends and applications, Athens, Greece. 2009. p. 164 - 164. DIVIŠ, P.; MACHÁT, J. The use of aquatic moss Fontinalis antipyretica for monitoring of metal pollution in Morava river. ISEAC 36: BOOK OF ABSTRACTS. 2010. p. 111. ISBN 978-88-8286-228-2.


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KADLECOVÁ, M.; DIVIŠ, P.; SZKANDERA, R.; TRÁVNÍČKOVÁ, J.; DOČEKALOVÁ, H.; OUDDANE, B. Application of diffusive gradients in thin films technique with different specific resins in contaminated and uncontaminated river sediments and its comparation with other common techniques. The 36th International symposium on environmental analytical chemistry: Abstract book. 2010. p. 145. ISBN 978-88-8286-228-2. SZKANDERA, R.; DIVIŠ, P.; KADLECOVÁ, M.; TRÁVNÍČKOVÁ, J.; DOČEKALOVÁ, H. Use of TiO2 in diffusive gradients in thin films technique for mercury determination in aquatic environment. The 36th International symposium on environmental analytical chemistry: Abstract book. 2010. p. 38. ISBN 978-88-8286-228-2. POŘÍZKA, J.; DIVIŠ, P.; OMELKOVÁ, J. Influence of the agriculture on elemental content of vineyard components and total antioxidat activity of Czech wines (pilot study). 2nd International ISEKI_Food Conference. Milan, Italy, ISEKI Food Association. 2011. p. 232. ISBN 978-88-905-9890-6.

DIVIŠ, P.; POŘÍZKA, J.; ŠKAŘUPA, P. Application of ICP-MS and chemometrics for determination of the wine origin. European symposium on 22 atomic spectrometry 2012 - Book of abstracts. 2012. p. 124. ISBN 978-80223-3292-7. POŘÍZKA, J.; DIVIŠ, P.; OMELKOVÁ, J. Influence of the different farming systems on elemental content of Vitis vinifera and on antioxidant properties 23 of wine. European symposium on atomic spectrometry 2012 - Book of abstracts. 2012. p. 181. ISBN 978-80-223-3292-7. Celkem za A10

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PŘÍPĚVEK VE SBORNÍKU NÁRODNÍHO NEBO MEZINÁRODNÍHO KONGRESU, SYMPOZIA, VĚDECKÉ KONFERENCE. DIVIŠ, P., DOČEKALOVÁ, H. Technika DGT a její použití pro speciační měření v přírodních vodách. In Mikroelementy 2003. Český Těšín, 2Theta. 2003. p. 94 - 97. ISBN 80-86380-20-3. DIVIŠ, P., DOČEKALOVÁ, H., ŘEZÁČOVÁ, V. In situ measuring of bioavailabile trace metals depth profiles in the sediment pore water by diffusive gradients in thin films technique. In Mikroelementy 2003. Český Těšín, 2Theta. 2003. p. 88 - 92. ISBN 80-86380-20-3. ŘEZÁČOVÁ, V., DOČEKALOVÁ, H., DOČEKAL, B., DIVIŠ, P. Použití techniky DGT pro in situ měření biodostupnosti kovů v půdě. In Sborník konference Mikroelementy 2003. Český Těšín, 2theta. 2003. p. 84 - 87. ISBN 80-86380-20-3. HERNÍKOVÁ, V., DIVIŠ, P., DOČEKALOVÁ, H. The diffusive gradient in thin films technique (DGT) for the mercury determination in aquatic systems. Chemické listy. 2005. 99(14). p. 142 - 143. ISSN\~0009-2770. DIVIŠ P., BRULÍK L., DOČEKALOVÁ H. A comparison of DGT technique with biomonitoring technique using aquatic moss Fontinalis Antipyretica. Chemické listy. 2005. 99(13). p. 112 - 113. ISSN\~0009-2770. DIVIŠ, P. Použití techniky difúzního gradientu v tenkém filmu k monitorování kvality povrchových vod. In Sborník 2. konference Hydroanalytika 2007. CSlab spol. s r.o. 2007. p. 179 - 180. ISBN 978-80-239-9815-3. DIVIŠ, P.; SZKANDERA, R.; MATÚŠ, P.; APPLICATION OF A 6MERCAPTOPURINE FUNCTIONALIZED SORBENT FOR DIFFUSIVE GRADIENTS IN THIN FILMS TECHNIQUE. Chemické listy. 2008. 102(15). p. s355-s356. ISSN\~1213-7103. DIVIŠ, P. Stanovení biodostupných forem kovů technikou DGT. Workshop speciační analýza. Spektroskopická společnost Jana Marka Marci. 2009. p. 10 - 11.


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VLASTNÍ HODNOCENÍ UCHAZEČE MATÚŠ, P.; KALIŠ, M.; BUJDOŠ, M.; HAGAROVÁ, I.; KUBOVÁ, J.; DIVIŠ, P.; Speciace, speciační analýza a frakcionace tália ve vodách a v půdách s 9 využitím spektrochemických metod. In Workshop speciační analýza. Spektroskopická společnost Jana Marka Marci. 2009. p. 8 - 9. DIVIŠ, P.; POŘÍZKA, J. Prvková analýza moravských vín a její využití v 10 praxi. In Mikroelementy 2012. 2012. p. 100 - 105. ISBN 978-80-86380-63-6. Celkem za A11:

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DIVIŠ, P., LEERMAKERS, M., DOČEKALOVÁ, H. Measuring of mercury fluxes in sediments by diffusive gradients in thin films technique. In XVII slovak spectroscopic conference. 2004. p. 48 - 48. ISBN 80-8073-167-5. KUBOVÁ, J.; MATÚŠ, P.; BUJDOŠ, M.; HAGAROVÁ, I.; MEDVEĎ, J.; DIVIŠ, P.; DOČEKALOVÁ, H. Use of optimized BCR three step sequential and dilute HCl single extraction protocols for the prediction of soil-plant metal transfer processes. In Book of abstracts XIXth Slovak-Czech Spectroscopic Conference. 2008. p. 103 - 103. ISBN 978-80-223-2557-8. DIVIŠ, P.; BRULÍK, L.; SZKANDERA, R.; DOČEKALOVÁ, H.; MATÚŠ, P. Study of possible alternatives to Spheron Thiol resin gels in diffusive gradients in thin films technique. Book of abstracts XIXth Slovak-Czech Spectroscopic Conference. 2008. p. 88 - 88. ISBN 978-80-223-2557-8. BRULÍK, L.; DIVIŠ, P.; JASKOWIECOVÁ, L.; DOČEKALOVÁ, H.; MATÚŠ, P. Bioavailable Fraction of Trace Metals in Rivers of South Moravia. Book of abstracts XIXth Slovak-Czech Spectroscopic Conference. 2008. p. 84 - 84. ISBN 978-80-223-2557-8. MATÚŠ, P.; ČERŇANSKÝ, S.; URÍK, M.; MEDVED, J.; BUJDOŠ, M.; KRAMAROVÁ, Z.; KALIŠ, M.; HAGAROVÁ, I.; KUBOVÁ, J.; ŠEVC, J.; DIVIŠ, P.; BRULÍK, L. Quantitative assessment of biosorption, bioaccumulation and biovolatilization of labile aluminium and thalium species by fungal biomass using atomic spectrometry. In Book of abstracts XIXth Slovak-Czech Spectroscopic Conference. 2008. p. 111 - 111. ISBN 978-80-223-2557-8. DIVIŠ, P.; MACHÁT, J.; DOČEKALOVÁ, H.; SZKANDERA, R. Use of aquatic moss Fontinalis antipyretica and DGT technique for determination of (bio)available metal concentration in Morava river. Sborník 14. Česko-Slovenské spektroskopické konference. 2010. DIVIŠ, P.; SZKANDERA, R.; KADLECOVÁ, M.; OUDDANE, B.; TRÁVNÍČKOVÁ, J. Testování sorpčního gelu s TiO2 pro stanovení rtuti v přírodních vodách technikou DGT. Sborník 14. Česko-Slovenské spektroskopické konference. 2010. CETKOVSKÁ, J.; VESPALCOVÁ, M.; DIVIŠ, P.; POŘÍZKA, J. Analysis of non traditional fruits (Hippophae Rhamnoides and Cornus Mas). Chemické listy. 2011. 105(18). p. s1002 (1 p.). ISSN 0009-2770. POŘÍZKA, J.; DIVIŠ, P.; OMELKOVÁ, J. Elemental composition and total antioxidant capacity of Czech wines deriving from grapes growned by different agriculture methods. Chemické listy. 2011. 105(18). p. s1025 (1 p.). ISSN 00092770.

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CITACE JINÝM AUTOREM V PUBLIKACI BEZ SCI Wen, S., Shan, B., Zhang, H.: Metals in sediment/pore water in Chaohu Lake: Distribution, trends and flux (2012) Journal of Environmental Sciences (China), 24 (12), pp. 2041-2050.


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Öhlander, B., Forsberg, J., Österlund, H., Ingri, J., Ecke, F., Alakangas, L.: Fractionation of trace metals in a contaminated freshwater stream using membrane filtration, ultrafiltration, DGT and transplanted aquatic moss (2012) Geochemistry: Exploration, Environment, Analysis, 12 (4), pp. 303-312. Zhang, H., Weng, L., Luo, Y., Yu, H.: Measuring mercury form in Ca(NO3) 2 solutions using Donnan membrane technique (2012) Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae, 32 (8), pp. 1842-1849. Varrault, G., Rocher, V., Bracmort, G., Louis, Y., Matar, Z.: Towards a new method for labile metal assessment in aquatic environments (2012) Techniques - Sciences - Methodes, (4), pp. 56-66. Chen, H., Dong, J., Niu, Y.-X., Sun, T.: Determination of ni 2+ in waters with sodium polyacrylate as a binding phase in diffusive gradients in thin-films (2011) Chemical Research in Chinese Universities, 27 (4), pp. 703-707. Liu, X.-Y., Yang, L.-J., Jin, Y.-L., Zhang, L., Xu, T.-C., Li, N.:Adsorption properties of nano-TiO 2 for Cd(II)(2011) Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals, 21 (11), pp. 2971-2977. Hongtao, F., Dianpeng, S., Hong, C., Jia, D., Shuyan, Z., Ting, S.: In-situ passive sampling techniques(2010) Progress in Chemistry, 22 (8), pp. 1672-1678. Qian, S., Huang, Z., Fu, J., Kuang, J., Hu, C.:Preconcentration of ultra-trace arsenic with nanometre-sized TiO 2 colloid and determination by AFS with slurry sampling(2010) Analytical Methods, 2 (8), pp. 1140-1143. Hongtao, F., Ting, S., Dianpeng, S., Yuqian, B., Xiaodong, Z., Xiaojing, L.: In-situ passive sampling techniques for environmental monitoring-diffusive equilibrium in thin-films and diffusive gradients in thin-films technique (2009) Chemistry Bulletin / Huaxue Tongbao, 72 (5), pp. 421-426. Yin, X.-B., Lu, X.-Q., Yao, C.-X., Song, J., Qian, W., Luo, Y.-M., Liang, Y.-Q., Sun, L.-G.: Study on decreasing the instrument detection limit of atomic fluorescence spectrometry (AFS-930) for Hg (2009) Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis, 29 (5), pp. 1431-1433. Davison, W., Zhang, H., Warnken, K.W.: Chapter 16 Theory and applications of DGT measurements in soils and sediments (2007) Comprehensive Analytical Chemistry, 48, pp. 353-378. Sui, D., Sun, T., Fan, H., Liu, C., Zhu, X.: Diffusive gradients in thin-films technique - A technique for in situ sampling (2007) Chemistry Bulletin / Huaxue Tongbao, 70 (12), pp. 954-960. Warnken, K.W., Zhang, H., Davison, W.: Chapter 11 In situ monitoring and dynamic speciation measurements in solution using DGT (2007) Comprehensive Analytical Chemistry, 48, pp. 251-278.

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ZÍSKÁNÍ EXTERNÍHO GRANTU (ŘEŠITEL/ SPOLUŘEŠITEL). Projekt číslo G4/912/2003 Studium a využití techniky DGT pro speciační analýzu, zahájení: 01.01.2003, ukončení: 31.12.2003 Poskytovatel MŠMT. Projekt číslo MEB080813, Speciační analýza a frakcionace vybraných toxických prvků v environmentálních vzorcích s využitím spektro-chemických metod, zahájení: 01.01.2008, ukončení: 31.12.2009 Poskytovatel MŠMT Projekt číslo GP525/09/P583, In situ měření biodostupnosti vybraných toxických a esenciálních kovů v malých a středních tocích jižní Moravy , zahájení: 01.01.2009, ukončení: 31.12.2010 Poskytovatel GAČR Projekt číslo MEB020918, Vývoj a použití nových metod pro studium osudu a biodostupnosti toxických kovů a organokovů v říčních a mořských sedimentech a přírodních vodách, zahájení: 01.01.2009, ukončení: 31.12.2010 Poskytovatel MŠMT

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POSUDEK ZAHRANIČNÍ PUBLIKACE NEBO PROJEKTU, ZNALECKÝ POSUDEK, EXPERTIZA. Posudek projektu VEGA 1/0298/10 Analýza platinových kovov v pôdach a poletavých prachoch v lokalitách zaťažených automobilovou dopravou metódou ICP-MS. Posudek projektu VEGA 1/0860/11 Analytické a agrochemické hodnotenie biodostupnosti, biosorpcie, bioakumulácie a biotransformácie chemických špécií, resp. frakcií hliníka a iných esenciálnych a toxických prvkov vo vybraných zložkách životného prostredia, ktoré vstupujú do potravinového reťazca Posudek projektu VEGA 1/0083/12 Inovatívne postupy hodnotenia miery anorganickej kontaminácie pôd v lokalitách so známymi zdrojmi znečistenia a návrhy remediačných postupov využiteľných pri jej odstraňovaní Posudek publikace pro časopis International Journal of Environmental Analytical Chemistry, i.č. GEAC-2010-0570 Žužul, Silva; Vađić, Vladimira; Godec, Ranka; Pehnec, Gordana: Arsenic Levels in Fine Particulate Matter in Zagreb Air Posudek publikace pro časopis Fresenius Environmental Bulletin i.č. F-2011-317 I. Hagarová, M. Bujdoš, P. Matúš Evaluation of electrothermal absorption spectrometry for trace determination of antimony in different environmental samples using chemical modification Posudek publikace pro časopis Talanta i.č. TAL-D-11-01530 Joaquim Araujo Nobrega; Rodrigo F Salazar; Marcelo B Guerra; Edenir R Pereira-Filho: Internal standardization as an auxiliary tool for inductively coupled plasma quadrupole mass spectrometer with a collision-reaction interface. Posudek publikace pro časopis Journal of Oceanography and Marine Science i.č. JOMS-10-011 Khalid M. Dewidar and Omran E. Frihy: Distribution levelsof some trace metals in the surface sediment fractions at northen Safaga bay, Red sea, Egypt Posudek publikace pro časopis International Journal of Environmental Analytical Chemistry, i.č. GEAC-2012-0150 Blašková, Jana; Vojtekova, Viera; Nováková, Jarmila; Mackových, Daniela; Bazeľ, Jaroslav; Lapčík, Lubomír; Abusenaina, Ashraf : The sonoextraction as a pretreatment approach for the element mobility evaluation of sediment samples Posudek publikace pro časopis Chemosphere i.č. CHEM26237 Daniel Ferreiraa, b, Philippe Ciffroya*, Marie-Hélène Tusseau-Vuilleminc, Jean-Marie Garnier: DGT as Surrogate of Biomonitors for Predicting the Bioavailability of Copper in freshwaters: an ex situ Validation Study Posudek publikace pro časopis Geochemistry: Exploration, Environment, Analysis i.č. 12-IAGS-125 Jerry Forsberg, Heléne Österlund, Johan Ingri, Frauke Ecke, Lena Alakangas: Speciation of trace metals in a contaminated steam using membrane filtration, ultrafiltration, DGT and transplanted aquatic moss Posudek pro časopis Science of the Total Environment i.č. STOTEN-D-13-00871 Assessment of mercury bioavailability to benthic macroinvertebrates using diffusive gradients in thin films (DGT) Posudek pro časopis Environmental Engineering and Management Journal i.č. 767_Senila_12 Marin Senila, Andreja Drolc, Albin Pintar, Cecilia Roman: Assesment of mercury availability in environmental samples using DGT and TDAAS techniques

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VEDOUCÍ OBHÁJENÉ BAKALÁŘSKÉ/ DIPLOMOVÉ PRÁCE Diplomová práce: L. Jaskowiecová, Studium bioakumulace vybraných kovů vodním mechorostem Fontinalis antipyretica, rok řešení 2007/08. Diplomová práce: . R. Szkandera, Testování modifikovaných sorbetů Iontosorb pro užití v technice difúzního gradientu v tenkém filmu (DGT), rok řešení 2007/08. Diplomová práce: . H. Frišhansová, Studium vlastností sorpčních gelů pro stanovení rtuti technikou DGT, rok řešení 2008/09. Bakalářská práce: S. Křížová, Využití hmotnostního spektrometru a separačních technik k stanovení různých forem kovů v potravinách, rok řešení 2008/09. Bakalářská práce: P. Lepař, Speciační a frakcionační analýza kovů v zemědělských půdách, rok řešení 2008/09. Bakalářská práce: P. Musilová, Možnosti stanovení germania v potravinách, rok řešení 2008/09. Diplomová práce: T. Motlová, Speciační analýza selenu v kvasinkách kultivovaných v médiu s přídavkem selenu, rok řešení 2009/10. Diplomová práce: L. Krakovková, Stanovení alergenních a potenciálně alergenních kovů v kosmetických přípravcích, rok řešení 2009/10. Bakalářská práce: P. Škařupa, Analýza vína pomocí moderních analytických metod, rok řešení 2009/10. Diplomová práce: M. Drobilová, Stanovení kovů v ovocných šťáváchi, rok řešení 2010/11. Diplomová práce: K. Kroupová, Stanovení rtuti v rybách a v rybích produktech, rok řešení 2010/11. Diplomová práce: L. Kubicová., Stanovení kovů ve vinné révě pěstované různými způsoby, rok řešení 2010/11. Diplomová práce: S. Křížová., Stanovení vybraných prvků v netradičních druzích ovoce, rok řešení 2010/11. Diplomová práce: E. Galová., Stanovení polokovových prvků v potravinách, rok řešení 2010/11. Diplomová práce: P. Hauerlandová, Stanovení vybraných kovů v ovocných kompotech, rok řešení 2011/12. Diplomová práce: P. Škařupa, Možnosti určení původu vína z prvkového složení, rok řešení 2011/12. Bakalářská práce: V. Štursa, Porovnání extrakčních metod pro prvkovou analýzu zemědělských půd, rok řešení 2011/12. Diplomová práce: I. Hajdučková, Stanovení výskytu toxických prvků ve výnech, rok řešení 2011/12.

B4 CELKEM B5 1

ŠKOLITEL/ŠKOLITEL SPECIALISTA STUDENTA, KTERÝ ZÍSKAL PH.D., CSC., DR. R. Szkandera: Vývoj techniky difúzního gradientu v tenkém filmu (DGT) pro stanovení rtuti ve vodných systémech (obhájeno 2011)

B5 CELKEM


BODŮ 2 2 2 1 1 1 2 2 1 2 2 2 2 2 2 2 1 2 31 BODŮ 15 15

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KOPIE NEJVÝZNAMNĚJŠÍCH PUBLIKACÍ Doklad D: ORIGINÁLY NEBO KOPIE NEJVÝZNAMNĚJŠÍCH PUBLIKACÍ Tento dokument obsahuje seznam a kopie významných publikací, přehled odezvy a podklady pro významné dosažené výsledky, který je požadován podle čl. 2 směrnice rektora č. 1/2006 „Postup při jmenovacím řízení v Vysokém učení technickém v Brně“ a jejího úplného znění z 1.9. 2008. 9 DOKLAD D OBSAHUJE KOPIE NÁSLEDUJÍCÍCH PUBLIKACÍ: 1) SORPČNÍ GEL S OXIDEM TITANIČITÝM PRO STANOVENÍ RTUTI TECHNIKOU DIFUZNÍHO GRADIENTU V TENKÉM FILMU

Chemicke Listy, 2013, 107 (2), pp. 160-164. Szkandera, Roman; Dočekalová, Hana; Kadlecová, Milada; Trávníčková, Jana; Diviš, Pavel Počet citací: 0 2) IN SITU MEASUREMENT OF BIOAVAILABLE METAL CONCENTRATIONS AT THE DOWNSTREAM ON THE MORAVA RIVER USING TRANSPLANTED AQUATIC MOSSES AND DGT TECHNIQUE International Journal of Environmental Research, 2012, 6 (1), pp. 87-94. Diviš, Pavel; Machát, Jiří; Szkandera, Roman; Dočekalová, Hana Počet citací: 6 3) CHARACTERIZATION OF SORPTION GELS USED FOR DETERMINATION OF MERCURY IN AQUATIC ENVIRONMENT BY DIFFUSIVE GRADIENTS IN THIN FILMS TECHNIQUE

Central European Journal of Chemistry, 2010, 8 (5), pp. 1103-1107. Diviš, Pavel; Szkandera, Roman; Dočekalová, Hana. Počet citací: 0 4) APPLICATION OF NEW RESIN GELS FOR MEASURING MERCURY BY DIFFUSIVE GRADIENTS IN A THIN-FILMS TECHNIQUE Analytical Sciences, 2009, 25 (4), pp. 575-578. Diviš, Pavel; Szkandera, Roman; Brulík, Lukáš; Dočekalová, Hana; Matúš, Peter; Bujdoš, Marek.

Počet citací: 6

5) DETERMINATION OF TRACE AMOUNTS OF TOTAL DISSOLVED CATIONIC ALUMINIUM SPECIES IN ENVIRONMENTAL SAMPLES BY SOLID PHASE EXTRACTION USING NANOMETER-SIZED TITANIUM DIOXIDE AND ATOMIC SPECTROMETRY TECHNIQUES

Journal of Inorganic Biochemistry, 2009, 103 (11), pp. 1473-1479. Matúš, Peter; Hagarová, Ingrid; Bujdoš, Marek; Diviš, Pavel; Kubová, Jana. Počet citací: 9 Ing.Pavel Diviš, Ph.D.

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KOPIE NEJVÝZNAMNĚJŠÍCH PUBLIKACÍ 6) USE OF THE DIFFUSIVE GRADIENTS IN THIN FILMS TECHNIQUE TO EVALUATE (BIO)AVAILABLE TRACE METAL CONCENTRATIONS IN RIVER WATER Analytical and Bioanalytical Chemistry,2007, 387 (6), pp. 2239-2244. Diviš, Pavel; Dočekalová, Hana; Brulík, Lukáš; Pavliš, Marek; Hekera, Petr. Počet citací: 15 7) HIGH-RESOLUTION PROFILES OF TRACE METALS IN THE PORE WATERS OF RIVERINE SEDIMENT ASSESSED BY DET AND DGT Science of the Total Environment, 2006, 362 (1-3), pp. 266-277. Gao, Yue; Leermakers, Martine; Gabelle, Cedric; Divis, Pavel; Billon, G. ; Ouddane, Baghdade; Fischer, Jean-Claude; Wartel, Michel; Baeyens, Willy. Počet citací: 14 8) APPLICATION OF DIFFUSIVE GRADIENT IN THIN FILMS TECHNIQUE (DGT) TO MEASUREMENT OF MERCURY IN AQUATIC SYSTEMS

Talanta, 2005, 65 (5), pp. 1174-1178. Dočekalová, Hana; Diviš, Pavel. Počet citací: 38 9) MERCURY DEPTH PROFILES IN RIVER AND MARINE SEDIMENTS MEASURED BY DIFFUSIVE GRADIENTS IN THIN FILMS TECHNIQUE WITH TWO DIFFERENT SPECIFIC RESINS

Analytical and Bioanalytical Chemistry, 2005, 382 (7), pp. 1715-1719.. Diviš, Pavel; Leermakers, Martine; Dočekalová, Hana; Gao Yue Počet citací: 12 10) GELOVÉ TECHNIKY PRO MĚŘENÍ IN SITU VE VODÁCH, V PŮDÁCH A V SEDIMENTECH Chemické Listy, 2005, 99 (9), pp. 640-646. Diviš, Pavel; Dočekalová, Hana; Smetková, Veronika Počet citací: 6 11) HLOUBKOVÉ PROFILY LABILNÍCH KOVOVÝCH SPECIES V SEDIMENTECH A JEJICH IN SITU MĚŘENÍ TECHNIKOU DIFÚZNÍHO GRADIENTU V TENKÉM FILMU

Chemické Listy, 2003, 97 (12), pp. 1184-1189. Diviš, Pavel; Dočekalová, Hana; Smetková, Veronika Počet citací: 11


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NÁVRH TÉMAT VEŘEJNÉ PEDAGOGICKÉ PŘEDNÁŠKY Doklad E:

Návrh témat veřejné pedagogické přednášky

Tento dokument obsahuje návrh tří témat pro veřejnou pedagogickou přednášku, které jsou požadovány podle čl. 2 směrnice rektora č. 1/2006 „Postup při jmenovacím řízení na Vysokém učení technickém v Brně“ a jejího úplného znění z 1.9. 2008. Navrhovaná témata: 1) VYUŽITÍ IN SITU GELOVÝCH TECHNIK V ANALÝZE ŽIVOTNÍHO PROSTŘEDÍ 2)

FRAKCIONAČNÍ A SPECIAČNÍ ANALÝZA KOVŮ V ŽIVOTNÍM PROSTŘEDÍ

3) STANOVENÍ BIODOSTUPNÝCH FOREM KOVŮ TECHNIKOU DGT


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Chem. Listy 107, 160164(2013)

Laboratorní pĜístroje a postupy

LABORATORNÍ PěÍSTROJE A POSTUPY filmu (Diffusive Gradients in Thin films technique, DGT) 16,17 , jejíž další nespornou výhodou pro mČĜení velmi nízkých koncentrací, je kromČ použití in situ i prekoncentraþní schopnost. Technika DGT je dnes již bČžnČ používána pro stanovení koncentrací široké škály labilních kovových specií stopových, ale i minoritních a majoritních kovĤ v pĜírodních vodách, jezerech, Ĝekách a v moĜích17,18. Je využívána i pro mČĜení koncentraþních gradientĤ a tokĤ látek v pĤdách19,20 a sedimentech21–23. PĜedností techniky DGT je její jednoduchost, finanþní nenároþnost, možnost stanovení celé Ĝady prvkĤ a již zmiĖovaná prekoncentraþní schopnost. Technika DGT využívá dva typy hydrogelĤ: difuzní a sorpþní. Oba typy gelĤ jsou spoleþnČ s membránovým filtrem utČsnČny ve vzorkovací jednotce ve tvaru pístu. Ionty kovĤ, jejich mobilní a labilní formy, difundují kruhovým okénkem vzorkovací jednotky DGT o ploše A (cm2) difuzní vrstvou známé tloušĢky ǻg (cm) a vážou se na vhodné sorpþní médium zakotvené v sorpþním gelu. Množství kovu M (ng) vázaného bČhem doby expozice t (s) v sorpþním gelu se obvykle stanovuje po eluci sorpþního gelu kyselinou dusiþnou metodami atomové spektrometrie, v pĜípadČ rtuti lze s výhodou použít stanovení rtuti bez eluce pĜímo v disku sorpþního gelu pomocí jednoúþelového atomového absorpþního spektrometru AMA 254 . BČžnČ používaným hydrogelem je polyakrylamidový hydrogel, který slouží jako difuzní gel. Polyakrylamidový sorpþní gel má v sobČ zabudováno sorpþní médium, pro stanovení kovĤ a jejich specií to bývá iontomČniþ Chelex-100. Tento typ DGT s polyakrylamidovým difuzním gelem nelze použít pro stanovení rtuti, protože rtuĢ se váže na volné aminové skupiny hydrogelu, což omezuje její difuzi k iontomČniþi. Proto byl polyakrylamidový difuzní gel nahrazen agarosovým gelem23. Pro záchyt vČtšího poþtu specií rtuti bylo místo iontomČniþe Chelex-100 navrženo použití iontomČniþe Spheron-Thiolu s –SH skupinami, které silnČ vážou ionty rtuti a jsou schopny konkurovat i pevnČjším komplexĤm rtuti s pĜírodními ligandy23. PĜi studiu chování rtuti v sedimentech bylo prokázáno, že koncentrace rtuti nalezené DGT se Spheron-Thiolem odpovídají celkové rozpuštČné rtuti zmČĜené klasickým postupem po centrifugaci. NásobnČ nižší obsahy nalezené DGT s Chelexem-100 pak odpovídají rtuti v iontové formČ a rtuti ve slabých anorganických a malých organických komplexech23,24. Vzhledem k souþasné komerþní nedostupnosti Spheron-Thiolu byly hledány, syntetizovány, validovány a pĜi analýze reálných vzorkĤ použity iontomČniþe obsahující thiolové skupiny, Duolit a Iontosorb21,25. Byly pĜipraveny a použity iontomČniþe umožĖující stanovení methylrtuti26,27. Tato práce se zabývá optimalizací pĜípravy a testováním sorpþního gelu s þásticemi oxidu titaniþitého jako

SORPýNÍ GEL S OXIDEM TITANIýITÝM PRO STANOVENÍ RTUTI TECHNIKOU DIFUZNÍHO GRADIENTU V TENKÉM FILMU ROMAN SZKANDERAa, HANA DOýEKALOVÁb, MILADA KADLECOVÁa,c, JANA TRÁVNÍýKOVÁa a PAVEL DIVIŠa a

Vysoké uþení technické v BrnČ, Fakulta chemická, PurkyĖova 118, 612 00 Brno, b Mendelova univerzita v BrnČ, ZemČdČlská 1/1665, 613 00 Brno, ýeská republika, c Technická univerzita Lille 1, LaboratoĜ geosystémĤ, 59655 Villeneuve dÁscq, Francie [email protected] Došlo 18.3.11, pĜepracováno 17.10.11, pĜijato 8.12.11.

Klíþová slova: DGT, TiO2, rtuĢ, sorpþní gel

Úvod RtuĢ patĜí pro své toxické vlastnosti a vysokou schopnost bioakumulace k prvkĤm, kterým je vČnována mimoĜádná pozornost. Rychlý rozvoj analytických metod v posledních desetiletích vedl k vývoji nových analytických technik umožĖujících stanovení rtuti a jejich slouþenin v rĤzných složkách životního prostĜedí, jež byly následnČ použity v mnoha environmentálních studiích1–4. Stanovení rtuti v jednotlivých matricích životního prostĜedí se však i pĜes tento pokraþující vývoj stále potýká s Ĝadou problémĤ. Ty pĜevážnČ souvisí s nízkou koncentrací rtuti a jejich specií v mČĜených vzorcích, þasto na úrovni ng kg–1 resp. ng dm–3. Stanovení tak nízkých koncentrací vyžaduje použití speciálních zaĜízení5,6 a bezkontaminaþních postupĤ7,8. S takto nízkou koncentrací souvisí výskyt možných ztrát a na druhé stranČ možnost kontaminace vzorku bČhem odbČru, transportu a úpravy k analýze9–15. Se zmČnou fyzikálnČ-chemických parametrĤ mĤže docházet rovnČž ke zmČnám speciace. Minimalizaci manipulace se vzorkem a zamezení þi výraznému snížení kontaminace Ĝeší použití in situ technik. I pĜes více jak deset let práce v oblasti in situ mČĜení je však v souþasnosti možno mluvit pouze o poþátcích praktického používání in situ metod, neboĢ jejich vývoj a ovČĜení jsou þasto velmi obtížné a zdlouhavé. Pokrokem v in situ mČĜení solutĤ ve vodných systémech je v 90. letech minulého století vyvinutá vzorkovací gelová technika, technika difuzního gradientu v tenkém 160

Chem. Listy 107, 160164(2013)


sorpþního média pro stanovení rtuti v pĜírodních vodách technikou DGT. Oxid titaniþitý je znám jako velmi dobré adsorpþní médium pro kovové ionty. Je úspČšnČ používán pro zakoncentrování široké škály kovĤ metodou extrakce tuhou fází (SPE) pro jejich stanovení pomocí spektrálních metod28–30, k odstraĖování tČžkých kovĤ z odpadních vod31,32 a k odstraĖování rtuti ze spalin pĜi spalování uhlí33,34. Použití oxidu titaniþitého jako sorpþního média pro techniku DGT popsali v nedávné dobČ Bennet a spol.35, kteĜí použili adsorbent Metsorb založený na þásticích TiO2 k pĜípravČ sorpþního gelu pro stanovení anorganických forem arsenu a selenu v pĜírodních vodách pomocí techniky DGT. Panther a spol.36 referovali o použití sorpþního gelu s oxidem titaniþitým na stanovení reaktivního fosforu v pĜírodních vodách.

Pracovní postupy Difuzní a sorpþní gely byly pĜipravovány dle postupu doporuþovaného Zhang a Davisonem17 s mírnými modifikacemi. Difuzní agarosový gel (1,5%) byl pĜipraven rozpuštČním pĜíslušného množství agarosy v horké deionizované vodČ a vzniklý roztok byl nalit mezi dvČ skla oddČlená distanþní fólií o tloušĢce 0,5 mm. Ochlazením na teplotu místnosti roztok ztuhl a vytvoĜil agarosový hydrogel. PĜi pĜípravČ sorpþního gelu s TiO2 se vycházelo ze zkušeností s pĜípravou gelĤ s iontomČniþi Spheron-Thiol18 a Chelex100 (cit.23). K navážce 0,4 g suchého TiO2, která zaruþovala dostateþnou sorpþní kapacitu disku DGT jednotky pro dlouhodobé použití v reálných systémech pĜírodních vod, byly pĜidány 2 ml gelového roztoku a smČs byla míchána na míchaþce 5 min. Pro homogennČjší rozložení þástic TiO2 ve vzniklém gelu byl gelový roztok s TiO2 vložen do ultrazvukové láznČ, což usnadnilo dávkování do sklenČné formy a vznik kvalitnČjšího gelu. Z plátkĤ vyrobených gelĤ byly plastovým nožem vykrajovány kruhové disky o prĤmČru 25 mm. Disky difuzního agarosového a sorpþního gelu s oxidem titaniþitým byly pĜed použitím uchovávány v deionizované vodČ. Vzorkovací jednotky DGT byly sestaveny tČsnČ pĜed použitím tak, že na vnitĜní stranu jednotky byl uložen disk sorpþního gelu, pĜekryt diskem difuzního gelu a nakonec polyethersulfonovým membránovým filtrem (Supor®-450, Pall Corporation USA) s póry o velikosti 0,45 Pm pro ochranu proti poškození. Jednotka byla uzavĜena prstencovým krytem s expoziþním okénkem o prĤmČru 2 cm. PĜipravené jednotky DGT byly vloženy do míchaných modelových roztokĤ rtuti o objemu pČti litrĤ za vybraných podmínek bez a za pĜítomnosti dalších látek. Koncentrace rtuti v modelových roztocích byla 20 Pg dm–3. Hodnota pH v základním modelovém roztoku byla upravena na hodnotu 6. pH roztokĤ k testování vlivu kyselosti se pohybovalo v rozmezí 2–10. Pro testování vlivu iontové síly byly pĜipraveny modelové roztoky rtuti o iontové síle 0,001 až 0,5 mol dm–3. Koncentrace chloridĤ v testovaných roztocích byla 0,001–0,5 mol dm–3 a koncentrace huminových kyselin 0,01–10 mg dm–3. Po uplynutí expoziþní doby byly jednotky z roztoku vyjmuty, rozebrány a jednotlivé vrstvy gelĤ oddČleny. Pro srovnávací mČĜení byly z modelových roztokĤ odebírány alikvotní vzorky roztoku, a to pĜed vložením a po vytažení jednotek a zfiltrovány pĜes membránový filtr o velikosti pórĤ 0,45 Pm a okyseleny kyselinou dusiþnou. Koncentrace rtuti v odebraných vzorcích roztokĤ CSOL a obsah rtuti v sorpþních gelech byl stanoven na pĜístroji AMA 254. DGT þasovČ prĤmČrná koncentrace CDGT byla vypoþítána dle rovnice: CDGT = M ǻg / D t A (1) kde M (ng) je množství rtuti navázané na sorpþní gel bČhem doby expozice t (s). A (cm2) je plocha expoziþního okénka a ǻg (cm) je tloušĢka difuzního gelu, D je difuzní koeficient rtuti v agarosovém gelu.

Experimentální þást Použité chemikálie Pro pĜípravu sorpþního gelu byl použit akrylamid (Boehringer, SRN), patentované agarosové síĢovadlo (DGT Research, Lancaster, UK), peroxosíran amonný (Lachema, ýR), N,N,N‘,N‘-tetramethylethylendiamin TEMED (Sigma-Aldrich, SRN) a oxid titaniþitý (SigmaAldrich, SRN) – anatáza, velikost þástic menší než 44 Pm. Ve všech experimentech byly použity chemikálie þistoty p.a. a deionizovaná voda (Milli-Q Academic, Millipore, USA). Pro pĜípravu agarosového difuzního gelu byla použita agarosa (Merck, SRN). Pro pĜípravu modelových roztokĤ rtuti byl použit standardní roztok Hg o koncentraci 1 mg cm–3 (Astasol®, Analytika Praha, ýR). Pro úpravu iontové síly v modelových roztocích rtuti byl použit dusiþnan sodný (Lachema). Hodnota pH modelových roztokĤ byla upravována pomocí hydroxidu sodného Suprapur® 30% (Merck) a kyseliny dusiþné Suprapur® 65% (Merck). Pro studium vlivu pĜírodních ligandĤ na sorpci rtuti v sorpþním gelu byly použity chlorid sodný (Lachema) a smČs huminových kyselin (Prod. Num. 53680, Fluka, Švýcarsko). Vzorkovací jednotky DGT s expoziþní plochou 3,14 cm2 byly zakoupeny u firmy DGT Research Ltd. (Lancaster, UK). Použité pĜístroje Ke stanovení celkového množství rtuti v modelových roztocích a sorpþních gelech byl použit jednoúþelový atomový absorpþní spektrometr AMA-254 (Advanced Mercury Analyser, Altec, Praha, ýR). Pro dispergaci oxidu titaniþitého v gelovém roztoku byla použita ultrazvuková lázeĖ Powersonic PSO 3000 A (Ultrashalltechnik AG, Straubehhardt, SRN). Modelové roztoky rtuti byly míchány laboratorní míchaþkou Hei-Standard (Schwabach, SRN) a pH tČchto roztokĤ bylo sledováno pH metrem WTW 320 (Weilheim, SRN) kalibrovaného pufraþními roztoky o pH 4,0 a 7,0 (Analytika Praha, ýR).

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Výsledky a diskuse

350

300 300 M, ng

Charakteristiky sorpþního gelu

250

V pĜipravených sorpþních gelech s TiO2 byl stanoven obsah rtuti, který byl odeþítán od obsahu rtuti nalezeného po expozici jednotek DGT v roztocích. PrĤmČrná hodnota množství rtuti nalezená v neexponovaných gelech byla 0,13 ± 0,05 ng (n = 10), což pĜi expoziþní dobČ DGT vzorkovacích jednotek 24 hodin odpovídá minimální mČĜitelné koncentraci rtuti 3,4 ng dm–3. Nižší koncentraci rtuti lze mČĜit zvýšením expoziþní doby jednotek DGT. PĜi nČkolikanásobném pĜetížení disku ionty rtuti byla nalezena kapacita diskĤ 2,5 Pmol/disk (obr. 1), která je dostateþnČ vysoká pro nČkolikatýdenní i nČkolikamČsíþní expozici jednotky DGT s tímto sorpþním gelem v pĜírodních vodných systémech.

M [ng]

200 200 150

100 100 50

00 0

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44

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88

6

t, h

t [h]

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Obr. 2. Závislost množství rtuti MHg (ng) sorbované v jednom sorpþním disku na þase t (h) pro koncentraci rtuti v roztoku 20 Pg dm–3, þárkovaná þára znázorĖuje teoretickou závislost z rovnice (1)

n, Pmol/disk -1 n [P mol.disk ]

3,0 3,0 2,5

Vliv pH, iontové síly a vybraných pĜírodních ligandĤ na stanovení rtuti DGT s TiO 2

2,0 2,0 1,5

1,0 1,0

Vliv kyselosti roztoku na sorpci rtuti byl sledován v rozmezí pH 2–10. Bylo prokázáno, že sorpþní gel váže rtuĢ plnČ v rozmezí pH 4–8 (obr. 3). PĜi nižším pH dochází k neutralizaci povrchového náboje a k pĜekrytí aktivních míst na povrchu TiO2, což vede k celkovému snížení adsorpce39. Hodnota pH pĜírodních povrchových vod se pohybuje v rozmezí 6,5–9. Techniku DGT se sorpþním gelem obsahující TiO2 tedy lze bez problémĤ ve vČtšinČ pĜírodních vod použít. Vliv iontové síly na sorpci rtuti v sorpþním gelu s TiO2 byl v rozmezí hodnot 0,001 až 0,01 mol dm–3 zanedbatelný. Tyto hodnoty odpovídají bČžnému rozsahu iontové síly v povrchových vodách (0,002–0,02 mol dm–3). K 20% poklesu sorpce rtuti v sorpþním gelu docházelo až

0,5

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0

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2

4

4

6

8

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c [P mol.dm -3]

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10 12 c, Pmol dm–3

Obr. 1. Závislost akumulovaného množství rtuti n (Pmol) v disku na její koncentraci v roztoku c (Pmol dm–3)

D = D ǻg / A C

cDGT/cSOL

Koncentrace rtuti vypoþtená z množství rtuti navázané na sorpþní gel za þtyĜi hodiny pomocí rovnice (1) odpovídala koncentraci rtuti zmČĜené pĜímo v roztoku. Odchylky mezi koncentracemi nepĜesahovaly 5 % a splnily tak kritéria doporuþovaná DGT Research37. Množství rtuti vázané v sorpþním gelu rostlo lineárnČ s þasem expozice (obr. 2) a odpovídalo teoretickému množství vypoþítanému z rovnice (1). Tyto výsledky ukazují, že technika DGT se sorpþním gelem s TiO2 poskytuje spolehlivá data pro stanovení rtuti. Ze smČrnice závislosti (D) navázaného množství rtuti (M, ng) na sorpþní gel za þas (t, s), tloušĢky difuzního gelu (ǻg, cm), expoziþní plochy (A, cm2) a koncentrace rtuti v roztoku (CSOL, ng ml–1) byl vypoþítán difuzní koeficient pro rtuĢ v agarosovém gelu s sorpþním gelem TiO2

CDGT/CSOL

Validace techniky DGT se sorpþním gelem s TiO 2

1,2 1,2 1,0 1,0

0,8 0,8

0,6 0,6

0,4 0,4

(2) í6

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2 í1

0,2 0 0

Jeho hodnota (8,90 ± 0,13)10 cm s odpovídala hodnotám nalezeným pro Chelex 100 a Spheron Thiol23 a hodnotČ difuzního koeficientu rtuti ve vodČ 9,1310í6 cm2 sí1 z tabulek38.

2

2

4

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6 pH

8

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10

12

10

12 pH

Obr. 3. Závislost sorpce rtuti na hodnotČ pH vnČjšího roztoku

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CDGT/CSOL

1,0 1,0

cDGT/cSOL

cDGT/cSOL

CDGT/CSOL

1,2 1,2

0,8 0,8

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0,8 0,8 0,6

0,4 0,4

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-0,5

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-0,5 log (cm)

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0,5

1,5 log(cm)

Obr. 4. Závislost sorpce rtuti na iontové síle vnČjšího roztoku c (mol dm–3)

Obr. 6. Závislost sorpce rtuti na koncentraci huminových kyselin cm (mg dm–3)

pĜi iontové síle roztoku 0,1 mol dm–3 (obr. 4). Zásadní vliv na stanovení rtuti technikou DGT má koncentrace pĜírodních ligandĤ. V této práci byl studován vliv chloridĤ a smČsi huminových kyselin. Již pĜi koncentraci chloridĤ v modelovém roztoku 0,03 mg dm–3 docházelo k 25% poklesu sorpce rtuti. Zvyšování obsahu chloridĤ v roztoku na hodnotu 3 mg dm–3 vedlo k tvorbČ stabilních chlorokomplexĤ, které nebyly technikou DGT zachyceny (obr. 5). PĜítomnost huminových kyselin v roztoku rovnČž ovlivĖovala množství rtuti zachycené v sorpþním gelu tvorbou pevných komplexĤ (obr. 6). Již koncentrace huminových kyselin 1 mg dm–3 zpĤsobila snížení záchytu rtuti o 40 %, koncentrace 10 mg dm–3 potom o 80 %. Koncentrace chloridĤ v þistých povrchových vodách nepĜesahuje 0,05 mg dm–3 a koncentrace huminových kyselin se pohybuje v jednotkách mg dm–3 v pĜírodních vodách40. Výsledky provádČných testĤ prokázaly, že techniku

DGT se sorpþním gelem s TiO2 nelze použít pro mČĜení koncentrací rtuti v moĜských vodách, neboĢ zde je rtuĢ díky vysoké koncentraci chloridĤ (až 22 g dm–3) pĜítomna ve stabilních chlorokomplexech. RovnČž v pĜírodních vodách s velkým obsahem huminových látek je rtuĢ vázána v pevných komplexech, které nejsou jednotkou DGT se sorpþním gelem s TiO2 zachyceny. V pĜírodních povrchových vodách s obsahem huminových látek do 1 mg dm–3 je možné techniku DGT s TiO2 sorpþním gelem s úspČchem použít pro stanovení labilních specií rtuti. Kombinace DGT jednotek s TiO2 s jednotkami se sorpþním gelem obsahujícím thiolové skupiny, jako je Spheron-Thiol nebo Duolit GT73, umožĖuje odhad rĤzných forem rtuti v pĜírodních vodných systémech.

ZávČr Techniku DGT se sorpþním gelem obsahujícím TiO2 lze použít pro stanovení labilních specií rtuti ve vČtšinČ sladkovodních pĜírodních vod. Není vhodná pro stanovení rtuti v moĜské vodČ, která obsahuje vysokou koncentraci chloridĤ, s nimiž rtuĢ tvoĜí stabilní komplexy. Naopak lze DGT s TiO2 použít ve vodách obsahujících huminové kyseliny do 1 mg dm–3 obdobnČ jako s iontomČniþi s thiolovými skupinami Duolite GT73 a Spheron-Thiol41. Stanovení s bČžnČ používaným iontomČniþem Chelex-100 je ovlivĖováno ĜádovČ nižšími koncentracemi huminových kyselin.

C /C cDGT/cSOL DGT SOL

0,8 0,8

0,6 0,6

0,4 0,4

0,2 0,2

Tato práce vznikla díky finanþní podpoĜe projektu GA ýR P 503/10/2002.

0,00 -3,5

-3,5

-2,5

-2,5

-1,5

-1,5 log (c)

-0,5

0,5

-0,5

0,5

LITERATURA

log(c)

1. Gavis J., Ferguson J. F.: Water Res. 6, 989 (1972). 2. Vandal G. M., Mason R. P., Fitzgerald W. F.: Water Air Soil Pollut. 80, 665 (1991).

Obr. 5. Závislost sorpce rtuti na koncentraci chloridĤ c (mol dm–3)

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3. Mason R. P., Fitzgerald J., Hurley J. K., Hanson A. K., Donaghay P. L., Sieburth J.: Limnol. Oceanogr. 38, 1227 (1993). 4. Mason R. P., Fitzgerald W. F., Morel F. M.: Geochim. Cosmochim. Acta 58, 3191 (1994). 5. Reimann P., Schmidt D., Schomaker K.: Mar. Chem. 14, 43 (1983). 6. Brügmann L., Geyer E., Kay R.: Mar. Chem. 21, 91 (1987). 7. Laxen D. P. H., Harrison R. M.: Anal. Chem. 53, 345 (1981). 8. Kinsella B., Willis R. L.: Anal. Chem. 54, 2614 (1982). 9. Coyne R. V., Collins J. A.: Anal. Chem. 44, 1093 (1972). 10. Rosain R. M., Wai C. M.: Anal. Chim. Acta 65, 279 (1973). 11. Bothner M. H., Robertson D. E.: Anal. Chem. 47, 592 (1975). 12. Krivan V., Haas H. F.: Freseniusૅ Z. Anal. Chem. 332, 1 (1988). 13. Copeland D. D., Facer M., Newton R., Walker P. J.: Analyst 121, 173 (1996). 14. Carron J., Agemian H.: Anal. Chim. Acta 92, 61 (1977). 15. Štefanidesová V., Seidlerová J., Dvorská P.: Chem. Listy 96, 117 (2002). 16. Davison W., Zhang H.: Nature 367, 546 (1994). 17. Zhang H., Davison W.: Anal. Chem. 67, 3391 (1995). 18. Diviš P., Doþekalová H., ěezáþová V.: Chem. Listy 99, 640 (2005). 19. Cattani O., Fabbri D., Salvati M., Trombini C., Vassura I.: Environ. Toxic. Chem. 18, 1801 (1999). 20. Cattani I., Zhang H., Beone G.M., Del Re A.A.M., Boccelli R., Trevisan M.: J. Environ. Qual. 38, 493 (2008). 21. Merritt A. K., Amirbahman A.: Environ. Sci. Technol. 41, 717 (2007). 22. Zhang H., Davison W., Miller S., Tych W.: Geochim. Cosmochim. Acta 59, 4181 (1995). 23. Doþekalová H., Diviš P.: Talanta 65, 1174 (2005). 24. Diviš P., Leermakers M., Doþekalová H., Gao Y.: Anal. Bioanal. Chem. 382, 1715 (2005). 25. Diviš P., Szkandera R., Brulík L., Doþekalová H., Matúš P., Bujdoš M.: Anal. Sci. 25, 575 (2009). 26. Clarisse O., Hintelmann H.: J. Environ. Monit. 8, 1242 (2006). 27. Clarisse O., Foucher D., Hintelmann H.: Environ. Pollut. 157, 987 (2009). 28. Vassileva E., Proinova I., Hadjiivanov K.: Analyst 121, 607 (1996). 29. Worathanakul P., Kongkachuichay P., Noel J. D.,

30. 31. 32. 33. 34. 35. 36.

37. 38. 39. 40. 41.

Suriyawong A., Giammar D. E., Biswas P.: Environ. Eng. Sci. 25, 1061 (2008). Matúš P., Hagarová I., Bujdoš M., Diviš P., Kubová J.: J. Inorg. Biochem. 103, 1473 (2009). Visa M., Carcel R. A., Andronic L., Duta A.: Catal. Today 144, 137 (2009). Barakat M. A., Chen Y. T., Juany C. P.: Appl. Catal., B 5, 13 (2004). Li Y., Murphy P., Chang-Yu W.: Fuel Process. Technol. 89, 567 (2008). Suriyawong A., Smallwood M., Zhuang Y., Biswas P.: Aerosol Air Qual. Res. 9, 394 (2009). Bennett W. W., Teasdale P. R.: Anal. Chem. 82, 7401 (2010). Panther J. G., Teasdale P. R., Bennett W. W., Welsh D. T., Zhao H.: Environ. Sci. Technol. 44, 9419 (2010). http://www.dgtresearch.com, staženo 13.1.2011. CRS Handbook of Chemistry and Physics, 76. vyd., CRC Press Inc., Boca Raton 1995. Pei L., Zucheng J., Bin H., Yongchao Q., Jinggang P.: Anal. Sci. 17, a333 (2001). Pitter P.: Hydrochemie. 3. pĜeprac. vyd. Vydavatelství VŠCHT, Praha 1999. Diviš P., Szkandera R., Doþekalová H.: Cent. Eur. J. Chem. 8, 1103 (2010).

R. Szkanderaa, H. Doþekalováb, M. Kadlecováa,c, J. Trávníþkováa, and P. Diviša (a Department of Chemistry and Technology of Environmental Protection, Faculty of Chemistry, University of Technology, Brno, Czech Republic b Mendel University, Brno, Czech Republic, c Laboratory of Geosystems, University I – Science and Technology, Lille, France): A Sorption Gel with Titanium Dioxide for Mercury Determination by the Technique of Diffusion Gradient in Thin Film A new polyacrylamide sorption gel with titanium dioxide has been tested as a new alternative for the determination of labile mercury species in aquatic systems by diffusive gradients in a thin film (DGT) technique. The deployment experiments in model solutions gave linear mass uptake over time corresponding to the Fick´s 1st law of diffusion. The titanium dioxide resin gel provides reliable results in the pH range 4–8, independently of ionic strength (1 mmol dm–3 – 0.01 mol dm–3 NaNO3), which is a typical range for natural waters. The formation of strong and stabile complexes of mercury ions with chlorides decreases DGT response and limits its application in seawater. In contrast, the interference of humic acids in the sorption of mercury on titanium dioxide resin gel is several orders of magnitude lower in comparison with the commonly used Chelex-100 based resin, which favorites the new resin gel.

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In situ Measurement of Bioavailable Metal Concentrations at the Downstream on the Morava River using Transplanted Aquatic mosses and DGT Technique Diviš, P.1*, Machát, J. 2, Szkandera, R.1 and Doþekalová, H. 3 1

2

Brno University of Technology, Faculty of Chemistry, PurkyĖova 118, 612 00 Brno, Czech Republic

Research Centre for Environmental Chemistry and Ecotoxicology, Faculty of Science, Masaryk University, 625 00 Brno, Czech Republic, 3

Mendel University in Brno, ZemČdČlská 1, 613 00 Brno, Czech Republic

Received 31 Jan. 2011;

Revised 1 Sep. 2011;

Accepted 9 Sep. 2011

ABSTRACT:This work summarized the results of a long term monitoring programme performed downstream on the Morava river (Czech Republic). During this programme the total dissolved concentrations and bioavailable fraction of selected metals (Zn, Pb, Ni, Cu) were monitored. For the determination of bioavailable metals species, diffusive gradients in thin films technique (DGT) together with moss bags technique utilizing Fontinalis antipyretica moss species were used. All of the measured metal concentrations were compared with an amount of accumulated mass by Fontinalis antipyretica, represented as a concentration factor, CF. Obtained results shown that further investigation of DGT technique and metal accumulation processes by Fontinalis antipyretica is needed to conclude if the DGT technique is a good alternative for the biomonitoring technique using Fontinalis antipyretica moss bags as a means to measure (bio)available metal concentrations in natural water. Significant correlation with CF was found in the case of DGTZn and DGTPb concentrations. On the other site, accumulated mass of Cu by Fontinalis antipyretica correlated significantly with total dissolved concentration of Cu. In the case of Ni no correlation was found between total dissolved Ni concentrations, DGTNi concentration and CF of Fontinalis antipyretica. Key words: Diffusive gradient, Fontinalis antipyretica, Water analysis, Passive sampling, Metals

INTRODUCTION Metals water pollution can be measured by physical or chemical methods; however many of them have some limitations. The sampling schedule does not match the discharge events, elements of interest are presented in very low concentrations under the detection limits of analytical methods and the changes in metal speciation can occur during sampling and storage. The representativeness of obtained data is then questionable. Moreover, total and total dissolved metal concentration may not correspond to bioavailable fraction of metals (Tessier and Turner, 1995). These problems can be bypassed using in situ techniques and/or biomonitoring techniques. Biomonitoring techniques include the use of different kind of fish, invertebrates organisms or bivalves (Ji et al., 2010; Rybak and Uminska-Wasiluk, 2007; Gerhardt et al., 2007; Rhea et al., 2006; Fialkowski et al., 2003; Schilderman et al., 1999 Romeo et al., 2003; Smolders et al., 2002; Rainbow et al., 2000; Carru et al., 1996; Camusso et al.,

1994). However, thanks to its suitable properties and wide availability, aquatic mosses have become used in recent years for biomonitoring of inorganic and organic pollutants in aquatic environment (Cesa et al., 2006; Yurokova and Gecheva, 2004; Roy et al., 1996; Siebert et al., 1996; Mouvet et al., 1993; Say et al., 1981). The most commonly used in situ techniques in recent years include the use of Chemcatcher sampler and supported liquid membranes or permeation liquid membranes samplers (Vrana et al., 2005). In 1994 diffusive gradients in thin films technique has been introduced (Davison and Zhang, 1994) and later this technique has become widely used for in situ assessment of thermodynamically and kinetically labile metal species in aquatic systems. The DGT technique employs two layers of hydrogel, a diffusive layer and a binding phase. Diffusive layer is placed in the DGT unit on the top of the binding phase and covered with a membrane (usually 0.45 μm). These three layers are sealed in the DGT unit so that only the diffusive layer

*Corresponding author E-mail: [email protected]

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program was to monitor inorganic pollution by selected metals (Pb, Ni, Zn, Cd and Cu) at the down part of Morava river by the help of classical chemical analysis, passive sampling methods using DGT technique and aquatic moss Fontinals antipyretica as a bioindicator. The aim of this study was to compare the results obtained by Fontinalis antipyretica with DGT results and total dissolved concentrations of studied metals to find the best concept for assessment of bioavailable metals forms.

covered with membrane is exposed to the solution to be analyzed (Zhang and Davison, 1995). Dissolved metal species smaller than membrane pore size diffuse through a hydrated polyacrylamide gel, of thickness ǻg and area A, and are accumulated by a layer of binding agent. Most frequently an iminodiacetate chelating resin Chelex-100, is used and has been applied to a large number of divalent and trivalent metal ions (Garmo et al., 2003), including heavy metals and other elements of environmental interest. After exposition of the DGT unit for a time t in a solution, the amount of metal ions absorbed by the resin is analyzed and the mass M of captured metals determined. The time-average concentration of metal in the bulk solution, cDGT can be calculated with the help of Fick´s 1st law of diffusion as: cDGT = (M . ǻg)/t. A. D

MATERIALS & METHODS The river Morava is the major Moravian river and it flows from the north to the south of Moravia, one of the three historical parts of the Czech Republic. The total length of the Morava river is 354 km and the drainage area is about 27 000 km2. The lower reaches of the Morava river flows through agriculture areas and industrial cities with their textile, machinery and chemical industries. Location of sampling sites is shown on fig . 1. Temperature and pH in the river water were determined on-site. Filtered water samples were collected in glass bottles containing nitric acid as preservation agent using a plastic syringe and 0.45 Pm membrane filter placed in a plastic holder. Electrothermal atomic absorption spectrometr (AAS Zenit 60, Analytic Jena, Germany) was used for metal determination. The reference material (SLRS-4, river water, National Research Council of Canada, Canada) was used for method validation.

(1)

Where D is the diffusion coefficient of the metal in the gel, A an exposure surface area and ǻg the thickness of the gel layer. As numerous experiments show that the biological effects of trace metals are related to the free metal ion activity (Buffle and Horvai, 2000), it has been tempting for researchers to understand a DGT measured metal fraction as the bioavailable fraction. This study summarized the results from the monitoring programme performed on the Morava river during June 2007 and June 2008. The purpose of this

BČ lov (A)

Otrokovice

Na pa je dla

Spytihn Čv (B ) N 5km

Uher ské Hr ad ištČ (C)

Fig. 1. Location of sampling sites 88

Int. J. Environ. Res., 6(1):87-94, Winter 2012

The DGT sampling units with Chelex 100 resin gel and 0.8 mm thick polyacrylamide diffusive gel (Diviš et al., 2005) were tested in the test solution of the metals studied according the regulations of DGT Research Ltd (DGT research Ltd., 1998). At the samplig site three DGT sampling units (DGT Research, United Kingdom) were anchored to the sampling station using nylon string.Similarly, two moss bags containing approximately 20g tufts of Fontinalis antipyretica (collected at Mlynsky potok, in natural park Litovelské pomoraví) in perforated, 0.5 cm mesh size plastic bag were anchored to the sampling station. After 28 days of deployment, DGT sampling units and the moss bags were removed, washed and transported into the laboratory. The resin gels of known volume (Vg) were extracted and metal concentrations (ce) were determined after elution in 1 mL of nitric acid (Ve) . The DGT metals concentrations were calculated using equation (2) and (1) respectively. The elution factor (fe) was 0.85.

M

c e (Vg Ve ) fe

during the long term monitoring program, the average concentrations of total dissolved metals (Table 1) did not exceed the maximal long-term concentration limits warranting no negative impact upon aquatic ecosystem (US EPA, 1998). There were no large differences in the DGT measured concentrations of Zn, Cu and Ni throughout the monitoring programme. Average DGT Zn concentration was 0.74 ± 0.27 Pg/L, DGT Ni concentration 0.45 ± 0.14 Pg/L an d DGT Cu concentration 0.30 ± 0.12 Pg/L. Lower DGT concentration was measured in the case of Pb (average value 0.026 ± 0.009 Pg/L), but it corresponds to the lower total dissolved concentration of Pb in river water in comparison with Zn, Cu and Ni (Table 1). All DGT measured concentrations were approximately 10 times lower than total dissolved concentrations measured directly in the river water by atomic absorption spectrometry (Table 1). This indicated that some parts of dissolved metals in the Morava river was strongly complexed by dissolved organic carbon or by other strong natural ligands.

(2)

The amount of accumulated metals in Fontinalis antipyretica, expressed as concentration factor (CF), was correlated with DGT metal concentrations and total dissolved metal concentrations (Fig.2). Good correlations were found between measured DGTZn and DGTPb concentrations and CF. In the case of Cu measured values of CF correlated well with total dissolved Cu concentration, whereas no correlation was found to exist between all measured Ni concentrations and CF (Fig. 2). Similar results were also found in a previous study performed in the River Svitava (Diviš et al., 2007).

The Fontinalis antipyretica samples were mineralized in a microwave furnace (MLS 1200, Milestone, Italy) using nitric acid and hydrogen peroxide (Analpure, Analytika) mixture. Flame AAS was used for metal determinations in the mineralized moss samples (Varian SpectrAA 30, Varian, Australia). To check the accuracy of analysis, quality control material (Metranal 8, green algae, Analytika) was used. The concentration factor CF was calculated as the ratio of accumulated mass of metal in Fontinalis antipyretica cFA (μg/gdw) after exposition in the river water and the mass of metal in Fontinalis antipyretica c0 (μg/gdw) before exposition: cFA/c0 (Cesa et al., 2009).

The ability of aquatic mosses to accumulate not only inorganic copper, but also some copper bound in organic complexes has been reported by Ferreira et al. (Ferreira et al., 2008). There are no other data in the literature which compares the metal concentration obtained by simultaneous application of moss bag technique and DGT technique. However, comparison with DGT measured concentrations and concentrations recorded by other bioindicators can be found. Jordan et al. (Jordan et al., 2008) found good correlation of DGT measured concentrations witth copper accumulated in Saccostrea glomerata. In contrast to these results, experiments with Mytilus galloprovincialis showed a significant correlation between Cd and Pb concentrations measured in the mussel tissues and bioavailable metal levels in water and proved that transplanted mussels did not accumulate Cu and Ni, although DGT showed significant concentrations of bioavailable forms of these metals in water (Schintu et al., 2008). In the case

RESULTS & DISCUSSION All analytical methods used during this study passed the quality control tests. The recovery of Cu, Ni, Pb and Zn in material SLRS-4 (natural river water) measured by ET AAS were in the range 95-103 % and detection limits were sufficient for the metal analysis of selected samples. All prepared DGT sampling units meet the requirements of DGT Research Ltd. (DGT research Ltd., 1998). From the calculated CF (Table 1) according to the Mouvet scale for the aquatic mosses (Cesa et al., 2009), it can be say that at BČlov, there was no contamination by Zn and suspected contamination by Cu, Ni and Pb. At the SpytihnČv station, there was no contamination by Cu but suspected contamination by Zn, Ni and Pb. Similar situation was found at the Uherské HradištČ station. Although some contamination was found 89

1.5

6

1.2

5 cw (mg/L)

cDGT (mg/L)

In situ measurement of bioavailable metal concentrations

0.9 0.6 y = 0.3915x - 0.2054

0.3

3 2 y = 1.5166x - 0.1603

2

1

R = 0.5439 0.0

2

R = 0.4174

0 1

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3

4

1 Zn

CF

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0.25 cw (mg/L)

cDGT (mg/L)

4

0.03 0.02 y = 0.0041x + 0.0105

0.01

2

3 CF

0.20 0.15 y = 0.0128x + 0.1293

0.10

2

R = 0.6159

4

2

R = 0.1774

0.00

0.05 0

2

4

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6

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2

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0.4 0.3

y = 0.1137x + 0.0564 2

0.2

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cw (mg/L)

cDGT (mg/L)

0.5

R = 0.2429

2 1

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0 2

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CF

2

3

4

CF

Cu

0.8

3.0 2.5 c w (mg/L)

0.6 c DGT (mg/L)

R = 0.543

0 1

0.4 0.2

y = 0.038x + 0.2915 R2 = 0.1573 0

2

4

6

2.0 1.5 1.0

0

Ni

y = 0.9217x + 0.1654

y = 0.0933x + 1.4307 R2 = 0.1108

0.5

8

0

CF

Ni

2

4

6

8

CF

Fig . 2. Correlation of DGT measured concentrations and total dissolved concentrations with concentration factor of metals in Fontinalis antipyretica 90

91

0.014 ± 0.006

4.55 ± 1.27 2.25 ± 0.19 2.0

cDGT

cFA c0 CF

21 ± 5 6.5 ± 0.9 3.3

cFA c0 CF

0.12 ± 0.03

0.23 ± 0.05

cDGT

cw

1.72 ± 0.05

cw

57 ± 16 24 ± 3 2.3

cFA c0 CF

7.9 ± 1.9 2.53 ± 0.26 3.2

0.025 ± 0.004

0.23 ± 0.06

33 ± 7 8.14 ± 1.26 4.1

0.24 ± 0.13

1.63 ± 0.12

49 ± 6 18 ± 2 2.7

0.13 ± 0.04

2.73 ± 0.15

621 ± 118 228 ± 15 2.8

0.84 ± 0.12

2.94 ± 0.06

B-06-2007

10.4 ± 3.9 3.7 ± 0.3 2.8

0.038 ± 0.013

0.17 ± 0.04

35 ± 4 9.3 ± 0.7 3.8

0.26 ± 0.07

2.32 ± 0.08

29 ± 5 15 ± 3 1.9

0.24 ± 0.09

1.85 ± 0.03

539 ± 74 263 ± 13 2.0

0.64 ± 0.15

1.61 ± 0.13

C-06-2007

3.8 ± 0.8 1.92 ± 0.14 2.0

0.007 ± 0.003

0.117 ± 0.009

15 ± 3 7.2 ± 1.3 2.1

0.49 ± 0.11

1.57 ± 0.09

68 ± 12 26 ± 5 2.6

0.52 ± 0.16

2.33 ± 0.09

425 ± 52 251 ± 8 1.7

0.31 ± 0.09

2.33 ± 0.08

A-09-2007

5.9 ± 0.6 2.55 ± 0.21 2.4

0.018 ± 0.007

0.19 ± 0.04

23 ± 5 6.3 ± 0.6 3.7

0.38 ± 0.16

2.31 ± 0.16

39 ± 9 22 ± 2 1.8

0.17 ± 0.07

1.39 ± 0.05

782 ± 94 237 ± 17 3.3

0.79 ± 0.18

4.35 ± 0.16

B-09-2007

9.3 ± 1.4 2.3 ± 0.3 4.0

0.032 ± 0.005

0.13 ± 0.03

38 ± 7 5.9 ± 0.8 6.4

0.58 ± 0.12

2.68 ± 0.13

43 ± 14 29 ± 6 1.5

0.15 ± 0.06

1.42 ± 0.09

751 ± 83 301 ± 35 2.5

0.65 ± 0.04

4.7 ± 0.3

C-09-2007

6.2 ± 0.7 1.91 ± 0.15 3.3

0.017 ± 0.004

0.224 ± 0.009

35 ± 4 4.8 ± 0.7 7.2

0.48 ± 0.09

1.46 ± 0.09

53 ± 8 18 ± 4 2.9

0.41 ± 0.12

2.63 ± 0.12

452 ± 69 287 ± 28 1.6

0.35 ± 0.13

2.9 ± 0.2

A-12-2007

8.4 ± 0.5 2.5 ± 0.4 3.4

0.026 ± 0.009

0.15 ± 0.03

25 ± 6 8.1 ± 0.9 3.1

0.54 ± 0.14

1.41 ± 0.06

33 ± 7 14 ± 3 2.3

0.28 ± 0.08

1.78 ± 0.07

796 ± 109 327 ± 42 2.4

0.74 ± 0.15

3.9 ± 0.2

B-12-2007

cw = total dissolved concentration (Pg/L) n=4; cDGT = DGT concentration (Pg/L) n=3; cFA= accumulated mass of metal in Fontinalis antipyretica after exposition (Pg/ g dw) n=3; c0 = mass of metal in Fontinalis antipyretica before exposition (Pg/g dw) n=3; CF = concentration factor Table 1 (continuation): Measured concentrations in Morava river using conventional water sampling, DGT technique and moss bag technique

Pb

Ni

2.61 ± 0.07

0.37 ± 0.17

392 ± 65 245 ± 21 1.6

cFA c0 CF

cw

0.41 ± 0.08

cDGT

cDGT

1.12 ± 0.09

cw

Zn

Cu

A-06-2007

station

Table 1. Measured concentrations in Morava river using conventional water sampling, DGT technique and moss bag technique (Continues)


92

0.044 ± 0.016

10.6 ± 1.3 1.44 ± 0.26 7.6

cDG T

cF A c0 CF

41 ± 9 12.5 ± 1.6 3.3

cF A c0 CF

0.28 ± 0.09

0.49 ± 0.15

cDG T

cw

1.88 ± 0.13

cw

27 ± 6 19 ± 5 1.4

cF A c0 CF

4.35 ± 0.96 1.95 ± 0.27 2.2

0.016 ± 0.005

0.23 ± 0.04

18 ± 5 9.5 ± 1.3 1.9

0.35 ± 0.08

1.82 ± 0.05

76 ± 19 28 ± 4 2.8

0.35 ± 0.09

3.55 ± 0.13

528 ± 105 209 ± 31 2.5

1.28 ± 0.14

3.17 ± 0.05

A- 03-2008

8.9 ± 1.7 1.73 ± 0.19 5.2

0.033 ± 0.014

0.125 ± 0.018

59 ± 8 12.7 ± 1.5 4.6

0.72 ± 0.19

1.43 ± 0.09

37 ± 4 22 ± 5 1.7

0.35 ± 0.15

1.91 ± 0.05

824 ± 138 278 ± 55 3.0

0.92 ± 0.16

4.92 ± 0.07

B -03-2008

16.9 ± 2.7 2.4 ± 0.3 7.0

0.029 ± 0.012

0.23 ± 0.05

27 ± 6 7.5 ± 0.9 3.6

0.46 ± 0.13

1.28 ± 0.08

42 ± 8 17 ± 3 2.5

0.44 ± 0.07

2.75 ± 0.17

617 ± 82 236 ± 27 2.6

0.83 ± 0.09

3.21 ± 0.14

C-03-2008

6.3 ± 1.3 1.55 ± 0.27 4.1

0.019 ± 0.006

0.117 ± 0.013

29 ± 3 6.4 ± 0.8 4.5

0.39 ± 0.16

1.66 ± 0.15

63 ± 12 31 ± 6 2.0

0.31 ± 0.14

1.78 ± 0.15

728 ± 97 301 ± 38 2.4

0.59 ± 0.17

5.39 ± 0.18

A-06-2008

5.9 ± 0.6 2.55 ± 0.21 2.4

0.018 ± 0.007

0.19 ± 0.04

23 ± 5 6.3 ± 0.6 3.7

0.45 ± 0.16

1.60 ± 0.07

39 ± 9 22 ± 2 1.8

0.17 ± 0.07

1.69 ± 0.05

548 ± 94 237 ± 17 2.3

0.71 ± 0.15

4.35 ± 0.16

B-06-2008

9.3 ± 1.4 2.3 ± 0.3 4.0

0.022 ± 0.009

0.15 ± 0.06

51 ± 7 8.3 ± 1.2 6.2

0.65 ± 0.24

2.42 ± 0.18

29 ± 14 19 ± 7 1.5

0.34 ± 0.16

2.36 ± 0.08

759 ± 123 258 ± 65 2.9

1.15 ± 0.23

3.7 ± 0.4

C- 06-2008

cw = total dissolved concentration (Pg/L) n=4; cDGT = DGT concentration (Pg/L) n=3; cFA= accumulated mass of metal in Fontinalis antipyretica after exposition (Pg/g dw) n=3; c0 = mass of metal in Fontinalis antipyretica before exposition (Pg/g dw) n=3; CF = concentration factor

Pb

Ni

0.19 ± 0.07

cDG T

683 ± 71 249 ± 33 2.7

cF A c0 CF

1.29 ± 0.04

0.92 ± 0.18

cDG T

cw

4.1 ± 0.3

cw

Zn

Cu

C-12-2007

station

Table 1. Measured concentrations in Morava river using conventional water sampling, DGT technique and moss bag technique (Continuation)

Divis, P. et al.


of Ni, we suppose formation of strong complexes of Ni with dissolved organic matter. Metal species measured by DGT are limited by their volume and lability. Species larger than 5nm can not diffuse through diffusive gel and they are not detected by DGT technique as well as metal species which can not dissociate within the diffusion time-scale in the diffusive layer, or they are inert to binding phase (Li et al., 2005). Therefore colloids, large metal complexes or very stable complexes are not detected by DGT technique. On the other hand, Fontinalis antipyretica may be able to accumulate these fractions of metals, which cannot be measured by DGT. For the interpretation of measured results different metabolism of Ni by Fontinalis antipyretica in comparison to other monitored metals should be taken also in to the consideration. As in the literature there is entire lack of information about Ni accumulation processes by Fontinalis antipyretica more studies on this issue are necessary.

Chemosphere, 29 (4), 729-745. Carru, A. M., Teil, M. J., Blanchard, M., Chevreuil, M. and Chesterikoff, A. (1996) Evaluation of the roach (Rutilus rutilus) and the perch (Perca fluviatilis) for the biomonitoring of metal pollution. J. Environ. Sci. Heal., 31 (5), 11491158. Cesa, M., Bizzotto, A., Ferraro, C., Fumagalli, F. and Nimis, P. L. (2006) Assessment of intermittent trace element pollution by moss bags. Environ. Pollut., 144 (3), 886-892. Cesa, M., Azzalini, G., De Toffol, V., Fontanive, M., Fumagalli, F., Nimis, P. L. and Riva, G. (2009). Moss bags as indicators of trace element contamination in Pre-alpine streams. Plant Biosyst., 143 (1), 173-180. Davison, W. and Zhang, H. (1994) Insitu speciation measurements of trace components in natural waters using thin-film gels. Nature, 367, 546-548. DGT research Ltd., (1998). DGT for measurements in waters, soils and sediments, technical document, DGT Research Ltd., Lancaster, United Kingdom. Diviš, P., Doþekalová, H., Brulík, L., Pavliš, M. and Hekera, P. (2007). Use of the diffusive gradients in thin films technique to evaluate (bio)available trace metal concentrations in river water. Anal. Bioanal. Chem., 387 (6), 2239-2244.

CONCLUSION The study demonstrated that the concentrations of Zn and Pb measured by DGT in river water were comparable with the concentratation factor calculated from accumulated masses of metals in aquatic moss Fontinalis antipyretica. On the other hand, differences were observed between DGT Cu and DGT Ni concentrations and accumulated mass of metals in Fontinalis antipyretica. Significant correlation was found between the total dissolved concentration of Cu and mass of accumulated Cu in the aquatic moss. In the case of Ni, no correlation was found between the total dissolved and DGT measured Ni concentrations and concentration factor of Fontinalis antipyretica. Although we did not find any correlation between DGTCu , DGTNi concentrations and mass of metals accumulated by Fontinalis antipyretica, the diffusive gradients in thin films technique appeared to be a good alternative for the biomonitoring technique. However, further investigation of this promising in situ technique and metal accumulation processes by Fontinalis antipyretica is required.

Diviš, P., Doþekalová, H. and ěezáþová, V. (2005). Gel Techniques for in situ Measurement in Natural Waters, Soils and Sediments (in Czech), Chem. Listy, 99 (9), 640-646. Ferreira, D, Tousset, N., Ridame, C. and Tusseau-Vuillemin, M. H. (2008). More than inorganic copper is bioavailable to aquatic mosses at environmentally relevant concentrations. Environ. Toxicol. Chem., 27 (10), 21082116. Fialkowski, W., Fialkowska, E., Smith, B. D. and Rainbow, P. S. (2003). Biomonitoring survey of trace metal pollution in streams of a catchment draining a zinc and lead mining area of Upper Silesia, Poland using the amphipod Gammarus fossarum. Int. Rev. Hydrobiol., 88 (2), 187-200. Garmo, O. A., Royset, O., Steinnes, E. and Flaten, T. P. (2003). Performance study of diffusive gradients in thin films for 55 elements. Anal. Chem., 75 (14), 3573-3580. Gerhardt, A., Kienle, C., Allan, I. J., Greenwood, R. , Guigues, N., Fouillac, A. M., Mills, G. A. and Gonzalez, C. (2007). Biomonitoring with Gammarus pulex at the Meuse (NL), Aller (GER) and Rhine (F) rivers with the online Multispecies Freshwater Biomonitor. J. Environ. Monitor., 9 (9), 979-985.

ACKNOWLEDGEMENT This work was supported by Grant Agency of the Czech Republic (projects No. 525/09/P583 and P503/ 10/2002).

Ji, Y., Lu, G. H. and Wang, C. (2010). Fish transplantation and stress-related biomarkers as useful tools for assessing water quality. J. Environ. Sci.-China, 22 (11), 1826-1832.

REFERENCES Buffle, J. and Horvai, G. (2000). In situ monitoring of aquatic systems: Chemical analysis and speciation, John Wiley & Sons Ltd., Chichester, England.

Jordan, M. A., Teasdale, P. R., Dunn, R. J. K. and Lee, S. Y. (2008). Modelling copper uptake by accostrea glomerata with diffusive gradients in a thin film measurements. Environ. Chem., 5 (4), 274-280.

Camusso, M., Balestrini, R., Muriano, F. and Mariani, M. (1994). Use of fresh-water mussel dreissena-polymorpha to assess trace-metal pollution in the lower river Po (Italy).

Li, W., Zhao, H., Teasdale P. R., John, R. and Wang, F.

93

In situ measurement of bioavailable metal concentrations

US EPA, (1998) National recommended water quality criteria, Federal register, 63, 67548-67558.

(2005). Metal speciation measurement by diffusive gradients in thin films technique with different binding phases. Anal. Chim. Acta, 533 (2), 193-202.

Vrana, B., Mills, G. A., Allan I. J., Dominiak, E., Svensson, K., Knutsson, J., Morrison, G. and Greenwood, R. (2005) Passive sampling techniques for monitoring pollutants in water. TrAC Trends Anal. Chem., 24 (10), 845-868.

Mouvet, C., Morhain, E., Sutter, C. and Couturieux, N. (1993). Aquatic mosses for detection and flow-up of accidental discharges in suface waters. Water, Air and Soil polution, 66, 333-348.

Yurukova L. and Gecheva, G. (2004). Biomonitoring in Maritsa River using aquatic bryophytes. J. Environ. Prot. Ecol., 5 (4), 729-735.

Rainbow, P. S., Wolowicz, M., Fialkowski, W., Smith, B. D. and Sokolowski, A. (2000). Biomonitoring of trace metals in the Gulf of Gdansk, using mussels (Mytilus trossulus) and barnacles (Balanus improvisus). Water Res., 34 (6), 1823-1829.

Zhang, H. and Davison, W. (1995) Performance Characteristics of diffusion gradients in thin films technique for the in-situ measurement of trace-metals in aqueous solution. Anal. Chem., 67 (19), 3391-3400.

Rhea, D. T., Harper, D. D., Farag, A. M. and Brumbaugh, W. G. (2006). Biomonitoring in the Boulder River watershed, Montana, USA: Metal concentrations in biofilm and macroinvertebrates, and relations with macroinvertebrate assemblage. Environ. Monit. Assess., 115 (1-3), 381-393. Romeo, M., Mourgaud, Y., Geffard, A., Gnassia-Barelli, M., Amiard, J. C. and Budzinski, H. (2003). Multimarker approach in transplanted mussels for evaluating water quality in Charentes, France, coast areas exposed to different anthropogenic conditions. Environ. Toxicol., 18 (5), 295305. Roy, S., Sen, C. K., Hanninen, O. (1996). Monitoring of polycyclic aromatic hydrocarbons using ‘moss bags’: Bioaccumulation and responses of antioxidant enzymes in Fontinalis antipyretica Hedw. Chemosphere, 32 (12), 23052315. Rybak, J. and Uminska-Wasiluk, B. (2007). The use of benthic macro-invertebrates for the assessment of surface water quality. Ochrona Srodowiska, 29 (2), 55-60. Say, P. J., Harding J. P. C. and Whitton, B. A. (1981). Aquatic mosses as monitots of heavy metal contamination in the river Etherow, Great Britain. Environ. Pollut., 2 (4), 295307. Schilderman, P. A. E. L., Moonen, E. J. C., Maas, L. M., Welle, I. and Kleinjans, J. C. S. (1999). Use of crayfish in biomonitoring studies of environmental pollution of the river Meuse. Ecotox. Environ. Safe., 44 (3), 241-252. Schintu, M., Durante, L., Maccioni, A., Meloni, P., Degetto, S. and Contu, A. (2008). Measurement of environmental trace-metal levels in Mediterranean coastal areas with transplanted mussels and DGT techniques. Mar. Pollut. Bull., 57, 832-837. Siebert A., Bruns, I., Krauss, G. J., Miersch, J. and Markert, B. (1996). The use of the aquatic moss Fontinalis antipyretica L ex Hedw as a bioindicator for heavy metals. Sci. Tot. Environ., 177, 137-144. Smolders, R., Bervoets, L. and Blust, R. (2002). Transplanted zebra mussels (Dreissena polymorpha) as active biomonitors in an effluent-dominated river. Environ. Toxicol. Chem., 21 (9), 1889-1896. Tessier A. and Turner D. R. (1995) Metal speciation and bioavailability in aquatic systems. Wiley, New York.

94

Cent. Eur. J. Chem. • 8(5) • 2010 • 1103–1107 DOI: 10.2478/s11532-010-0090-3

Central European Journal of Chemistry

Characterization of sorption gels used for determination of mercury in aquatic environment by diffusive gradients in thin films technique Research Article

Pavel Diviš1*, Roman Szkandera1, Hana Dočekalová2 Brno University of Technology, Faculty of Chemistry, Brno, 61200, Czech Republic 1

Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, CZ-613 00 Brno, Czech Republic 2

Received 16 April 2010; Accepted 8 June 2010

Abstract: The influence of pH, ionic strength and selected natural ligands on the measurement of mercury by the diffusive gradients in thin films technique (DGT) using recently introduced sorption gels was determined. Sorption gels containing Chelex 100, Spheron-Thiol, Duolite GT73 and modified Iontosorb AV resins were investigated, with the sorption capacity determined for all used sorption gels. The minimum DGT measurable concentrations were calculated from 3 times the standard deviation of mercury amount in unexposed sorption gels. Keywords: Diffusive gradients in thin films technique • Mercury • Sorption gels • pH • Ionic strenght

© Versita Sp. z o.o.

1. Introduction During the last 10 years, diffusive gradients in thin films technique (DGT) [1] was developed for determination of all common metals, some alkali metals and selected lanthanides and actinides in surface water [2,3]. In addition to that, some anions like sulphides or phosphates can be determined using DGT technique [2]. The DGT technique is based on a simple device consisting of two thin hydrogel layers protected from outside solution by filter membrane [2]. Dissolved species from aquatic system diffuse through diffusive gel and are immobilized in a layer of sorption gel containing selective resin. If the resin is not saturated, the concentration of dissolved species on the sorption gel surface is zero. This effect leads to formation of concentration gradient between the sorption gel and the outside solution, which provides the motivation for other solutes to diffuse through the diffusion gel. If Fick´s first law of diffusion is applied, concentration of dissolved, kinetically labile metal species can be calculated from the accumulated mass of metal species in the sorption gel using basic DGT equation: cDGT = m . r / A. t. D (1)

where m is accumulated mass of metal species in sorption gel, r is diffusive layer thickness, A is area of exposed gel, t is deployment time and D is diffusion coefficient of metal species. Only a little effort has been expended to measure mercury species by DGT technique, though they have attracted great attention concerning environmental contamination monitoring, due to their unique toxicity [4,5]. In the pilot study dealing with mercury determination by DGT, problems were found with commonly used polyacrylamide diffusive gel and thus, this gel was replaced with agarose diffusive gel [6]. Moreover, the iminodiacetic functional groups of Chelex 100 resin, commonly used as binding phase in sorption gel for wide range of metals, were found to capture only hydrated mercury ions and mercury bonded in labile inorganic and organic complexes [7]. On the other hand, the thiol functional groups of Spheron Thiol resin were found to be able to capture mercury bonded even in strong complexes with natural ligands. The concentrations obtained by Spheron-Thiol DGT corresponded to concentrations obtained by direct measurements of total dissolved mercury [7]. Following the concept introduced by Li and coworkers [8], simultaneous use of Chelex 100

* E-mail: [email protected] 1103

Characterization of sorption gels used for determination of mercury in aquatic environment by diffusive gradients in thin films technique

Figure 1.

influence of natural ligands to DGT measurements, sodium chloride (Lachema) and a mixture of humic substances (Fluka, Switzerland, product No.53680) were used. Diffusive gel was prepared using agarose (Sigma), while the sorption gels were prepared using acrylamide (Sigma), patented agarose cross-linker (DGT Research), amonium persulfate (Sigma) and N,N,N´,N´ tetramethylenediamine (Sigma). Preparation of all gels followed the procedure described previously [9]. Sorption isotherms of all tested sorption gels

and Spheron-Thiol DGT probes can provide valuable information about speciation of mercury in studied environment. Unfortunately, Spheron-Thiol resin is no longer available at present time and for this reason, new resins have to be introduced. As an alternative to Spheron-Thiol resin, Duolite GT73 and modified Iontosorb resins were used recently [9]. This work followed the last studies [6,9] and yields new knowledge needed for application of DGT technique with recently introduced sorption gels to measure mercury species in aquatic environment. An influence of pH, ionic strength and selected natural ligands to DGT mercury measurement was studied and other parameters like sorption capacity of all prepared sorption gels and minimum DGT measurable concentrations were determined.

2. Experimental Procedure 2.1. Reagents and chemicals

All reagents were of analytical grade. Mercury nitrate solution (1 g dm-3 Hg, Astasol, Analytika, Czech Republic) was used as Hg standard in atomic absorption spectrometric (AAS) measurement and in the preparation of all model solution. Concentration of all test solutions was 20 µg dm-3 if it is not given otherwise. For preparation of the sorption gels 0.3 g of Chelex 100 (Na form, 200-400 mesh, Biorad, USA), Duolite GT73 (Sigma, Germany), Spheron Thiol (Lachema, Czech Republic) and Iontosorb AV (Iontosorb, Czech Republic) resins were used. Iontosorb AV resin was modified by imidazole (Sigma) instead of 6-mercaptopurine according to the procedure described previously and final product was marked as Iontosorb AV-IM. Nitric acid (Analpure, Analytika) and sodium hydroxide (Penta, Czech Republic) solutions (2 mol dm-3) were added to adjust the final pH of the model solutions. Sodium nitrate and potassium sulfate (Lachema) were used to set the ionic strength. In experiments focused on the

1104

2.2. Apparaturs and instruments:

The DGT sampling units (piston type, 3.14 cm2 exposition area) were purchased from DGT Research Ltd. All solutions were stirred at 800 rpm using magnetic stirrer. For mercury analysis in model solutions and in sorption gels, an Advance Mercury Analyser AMA 254 (Altec, Czech Republic) was used. During the sorption capacity tests an atomic absorption spectrometer with flame atomization (SpectrAA 30, Varian, Australia) was used to determine mercury at wavelength 253.9 nm, lamp current 4 mA, spectral band 0.1 nm, burner height 12 mm, air flow 3.5 dm3 min-1 and acetylene flow 1.5 dm3 min-1.

2.3. Sorption capacity measurement

In order to obtain the information about the equilibrium process and capacity of prepared sorption gels, the adsorption isotherm was carried out. The amount of sorbed Hg in one sorption gel disc (n) was measured as a function of Hg concentration in the initial solution (c). The concentration of mercury ranged from 3 to 15 µmol dm-3 and the pH was arranged to be 6 in all solutions. After 8 hours, equilibrium concentration of mercury in model solutions was determined and from the depletion of Hg concentration, adsorbed amount of mercury was calculated. The molar amount of adsorbed Hg was plotted as a function of Hg concentration in model solutions. The adsorption capacity of the sorption gels for mercury was calculated from the Langmuir equation [10].

2.4.Effect of pH

The DGT sampling units were deployed in equilibrated model mercury solutions with different pH varied between 2 and 10 for 3 hours. After the deployment, sorption gels were extracted from DGT units and analyzed for mercury content. Calculated DGT mercury concentration (cDGT , Eq. 1) was then compared with those obtained by direct analysis of mercury in model solutions (cAAS). The ratio of cDGT / cAAS is expressed as R in further text of this article.

P. Diviš, R. Szkandera, H. Dočekalová

3. Results and Discussion

Figure 2. Influence

of pH to measurement of mercury by DGT technique with various sorption gels

Figure 3. Influence

of chloride concentration to measurement of mercury by DGT technique with various sorption gels

Table 1.

Mercury mass in unexposed sorption gels with standard deviation of measurement (n=10) and calculated minimum DGT measureable concentrations Spheron Thiol

Duolite GT73

Chelex 100

Iontosorb AV-IM

Hg mass (ng)

0.53 ± 0.16

0.15 ± 0.04

0.19±0,07

0.36 ± 0.11

cminDGT (ng L )

20

5

7

13

-1

2.5. Effect of ionic ligands

strength and natural

Three DGT sampling units were immersed stepwisely in mercury test solutions with different ionic strength in a range from 0.5 mmol dm-3 to 1 mol dm-3 for 3 hours. Subsequently, exposed sorption gels were analyzed using AMA 254 spectrometer. Similarly, experiments in mercury test solutions containing sodium chloride in concentrations range from 0.5 mmol dm-3 to 0.5 mol dm-3 were performed. In the experiment with humic substances test solutions containing 100 µg dm-3 of mercury were prepared. Subsequently, humic substances were added to the solutions in concentrations 0.01, 0.1, 1 and 10 mg dm-3. All solutions were left to equilibrate overnight and finally, DGT sampling units were immersed in all prepared solutions for 3 hours. All experiments were repeated at least three times. The error bars in graphs are not shown for better transparence of the pictures. The relative standard deviation in all measurements varied from 3 to 8%.

Fig. 1 shows the sorption isotherms of all tested sorption gels. The total sorption capacity of the sorption gels for mercury was found to be 5.7 µmol (Duolite GT73), 4.4 µmol (Iontosorb AV-IM), 4.3 µmol (Spheron-Thiol) and 3.9 µmol (Chelex 100). It is possible that the sorption capacity of Spheron-Thiol is slightly reduced, because thiol groups can be oxidized during the storage for longer time (several years). Available sorption capacities in real aquatic systems usually reach 5-10% of total sorption capacities because, in natural systems, oversaturation of functional groups present in sorption gel by mercury is not possible. Even this, the sorption capacity of all tested sorption gels is sufficient for long time deployment in natural waters. The investigation of Hg sorption as function of pH is shown in Fig. 2. Sorption was independent of pH (R~0.98) in the case of Duolite GT73 and Iontosorb AV-IM sorption gels. On the other hand, similar sorption (R~0.95) was observed by Spheron Thiol and Chelex100 only in the pH between 6 and 8. In solutions with pH less than 6, sorption of mercury decreased (R~0.85 for Spheron Thiol and R~0.60 for Chelex 100). Slovák et al. [11] found quantitative sorption of mercury for Spheron Thiol in presence of 0.05 mol dm-3 hydrochloric acid. In this study, test solution was acidified with nitric acid instead of hydrochloric acid to exclude the formation of stable chloride complexes. It is thus possible that some thiol groups were oxidized during the experiment. The sorption of mercury decreased even more (R~0.35) for both Spheron Thiol and Chelex 100 sorption gels in solutions with pH greater than 8. Decrease of the Hg sorption in the case of Chelex 100 DGT is caused by change in structure of Chelex 100 resin [12]. In solutions with pH greater than 8, hydrolysis reactions take place in Spheron-Thiol resin structure, which lead to lower sorption of mercury [13]. Effect of ionic strength on Hg sorption was negligible for all tested sorption gels. Higher concentration of chloride ions in tested solutions affected the DGT measurement mainly with the use of Chelex 100 sorption gel (Fig. 3). In the case of other tested sorption gels, recovery of mercury from test solutions fluctuated around 0.9 for all chloride concentrations. Beside chloride ions, mercury forms stable complexes with humic substances [14]. An influence of humic substances concentration to the DGT mercury measurement is shown in Fig. 4. It can be seen that only Duolite GT73 and Spheron Thiol sorption gels can effectively bond mercury present in stable humic substance complexes. On the other side, 1105

Characterization of sorption gels used for determination of mercury in aquatic environment by diffusive gradients in thin films technique

4. Conclusions

Figure 4. Influence

of humic substance concentration to measurement of mercury by DGT technique with various sorption gels

stability constant of mercury-iminodiacetic complex (Chelex 100) and mercury-imidazole complex (Iontosorb AV-IM) is lower than stability constant of mercury-humic substance complex, which leads to the effect that mercury-humic substance complexes are not measured by DGT [8]. The obtained results confirmed the early founding from real aquatic system [6,7,9]. From 3 times the standard deviation of mercury amount in the unexposed sorption gels the minimum concentration measurable by DGT technique (cminDGT) was calculated using Eq. 1. Calculated data are valid for the deployment time of 24 hours and diffusive layer thickness 0.63 mm (thickness of commonly used agarose diffusive gel and filter membrane). As can be seen from Table 1, minimum concentration measurable by DGT technique with various sorption gels vary between 5 and 20 ng dm-3. Concentrations of total dissolved mercury in unpolluted natural water ranged from 0.1 to 15 ng dm-3 [4,15]. Taking local variations from this range into consideration, concentration up to 100 ng dm-3 can be found in natural waters. From this point of view, all tested sorption gels should be used for mercury determination in aquatic system, but if it is possible, longer deployment time than 24 hours (3-5 days) is recommended to measure lower mercury concentration.

The highest sorption capacity for mercury was found for Duolite GT73 sorption gel. Other tested sorption gels had lower sorption capacity. However, this capacity is sufficient for long deployment time (weeks) of DGT technique in aquatic environment. The minimum DGT measurable concentrations allow for the measurement of mercury in most natural waters. Concentrations below 5 ng dm-3 can be measured if deployment time of DGT sampling units is about 3 - 5 days. The Duolite GT73 sorption gel can be used to measure mercury in wider variety of aquatic systems (i.e., waste waters or acid mine waters) in comparison with other tested sorption gels. This is because it works properly in wider pH range and it is capable of measuring mercury bonded even in strong complexes. All other tested sorption gels can be used for mercury measurement in aquatic systems with pH in range of 6-8 and except the Spheron-Thiol these sorption gels are able to capture only labile mercury species as inorganic ions and weak complexes. These properties can be used for speciation measurement in natural waters if combined DGT probe with different sorption gels is used.

Acknowledgements The authors thanks the Grant agency of Czech Republic for financial support (projects no. GAČR 525/09/P583 and GAČR P503/10/2002), Hana Frišhansová for her experimental assistance and Bohumil Dočekal for help with manuscript preparation.

References [1] H. Zhang, W. Davison, Anal. Chem. 67, 3391 (1995) [2] P. Diviš, H. Dočekalová, V. Řezáčová, Chem. Listy 99, 640 (2005) [3] O.A. Garmo, O. Royset, E. Steinnes, T.P. Flaten, Anal. Chem. 75, 3573 (2003) [4] P. Houserová, K. Janák, P. Kubáň, J. Pavlíčková, V. Kubáň, Chem. Listy 100, 862 (2006) [5] M.F. Wolfe, S. Schwarzbach, R.A. Sulaiman, Environ. Toxicol. Chem. 17, 146 (1998) [6] H. Dočekalová, P. Diviš, Talanta 65, 1174 (2005)

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[7] P. Diviš, M. Leermakers, H. Dočekalová, Y. Gao, Anal. Bioanal. Chem. 382, 1715 (2005) [8] W. Li , H. Zhao, P.R. Teasdale, R. John, F. Wang, Anal. Chim. Acta. 533, 193 (2005) [9] P. Diviš, R. Szkandera, L. Brulík, H. Dočekalová, P. Matúš, M. Bujdoš, Anal. Sci. 25, 575 (2009) [10] O. Hazer, S. Kartal, Anal. Sci. 25, 547 (2009) [11] Z. Slovák, M. Smrž, B. Dočekal, S. Slováková, Anal. Chim. Acta 111, 243 (1979) [12] Bio-Rad Laboratories: Chelex 100 and Chelex 20 chelating ion exchange resin instruction manual (1998)

P. Diviš, R. Szkandera, H. Dočekalová

[13] Z. Slovák, Lachema Bulletin 30, 34 (1979) [14] R.F.C. Mantoura, A. Dickson, J.P. Riley, Estuar. Coast. Mar. Sci. 6, 387 (1978) [15] O. Lindqvist, Tellus 37B, 136 (1985)

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Journal of Inorganic Biochemistry 103 (2009) 1473–1479

Contents lists available at ScienceDirect

Journal of Inorganic Biochemistry journal homepage: www.elsevier.com/locate/jinorgbio

Determination of trace amounts of total dissolved cationic aluminium species in environmental samples by solid phase extraction using nanometer-sized titanium dioxide and atomic spectrometry techniques Peter Matúš a,*, Ingrid Hagarová a, Marek Bujdoš a, Pavel Diviš b, Jana Kubová a a b

Comenius University in Bratislava, Faculty of Natural Sciences, Mlynská dolina 1, 84215 Bratislava, Slovakia Brno University of Technology, Faculty of Chemistry, Purkynˇova 118, Královo Pole, 61200 Brno, Czech Republic

a r t i c l e

i n f o

Article history: Received 9 April 2009 Received in revised form 8 July 2009 Accepted 9 August 2009 Available online 15 August 2009 Keywords: Aluminium Nanometer-sized titanium dioxide TiO2 Solid phase extraction Slurry sampling ET AAS ICP OES

a b s t r a c t Nanometer-sized titanium dioxide was used as a solid-phase extractant for the separation and preconcentration of trace amounts of Al(III) prior to its determination by electrothermal atomic absorption spectrometry (ET AAS) and inductively coupled plasma optical emission spectrometry (ICP OES). The optimal conditions for the proposed solid phase extraction (SPE; 50 mg TiO2, 10 min extraction time, pH 6.0, HCl and HNO3 as eluents) and ET AAS measurement (1500 °C pyrolysis and 2600 °C atomization temperatures, Mg(NO3)2 as matrix modifier) were obtained. The adsorption capacity of TiO2 was 4.1 mg Al g 1 TiO2. Two modes of the proposed procedure were compared, (I) batch and elution mode with the elution of Al from TiO2 phase by nitric or hydrochloric acid, and (II) batch and slurry mode (without elution) with the direct TiO2 phase-slurry sampling. Finally, the batch and slurry mode of nanometer-sized TiO2 SPE with slurry ET AAS detection and quantification was preferred and used for the determination of trace amounts of total dissolved cationic Al species in synthetic and natural water samples. The method accuracy was checked by the analysis of lake water CRM TMDA-61 and by the technique of analyte addition (sample spiking). Under the optimal conditions, the calibration curve for batch and slurry TiO2 SPE with a 10-fold preconcentration was linear up to 40 lg L 1 Al. The limit of detection (LOD) and the limit of quantification (LOQ) was 0.11 lg L 1 Al and 0.35 lg L 1 Al, respectively, with a preconcentration factor of 20 and a relative standard deviation (RSD) lower than 5%. Ó 2009 Elsevier Inc. All rights reserved.

1. Introduction During the last few decades aluminium and its distribution in the environment has attracted much attention because of its toxic effects on plants, animals and humans. High aluminium amounts limit the input and the transport of the nutriments and influence negatively the cell division and cell-walls of the plants. The chronical effect of Al compounds is often connected with mortality of some animals and Alzheimer or some other human neurodegenerative diseases [1–11]. Aluminium is usually not readily available in the environment and it is contained primarily in the structures od primary minerals and aluminosilicate clays. Because of its low solubility in a solution under neutral conditions, Al was regarded for a long time as a nontoxic element and its environmental and biological effects were not investigated until recently. As the soils become acidified through the weathering and/or possible anthropogenic activity,

* Corresponding author. E-mail address: [email protected] (P. Matúš). 0162-0134/$ - see front matter Ó 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jinorgbio.2009.08.004

these sources of aluminium solubilize, releasing Al in its readily available chemical species. It has been confirmed that acid deposition leads to considerable increases of dissolved Al concentrations in acidified soils and surface waters [1–11]. The Al concentration in different environmental samples varies widely. The distribution of aluminium species in pure Al water solution shows that ‘‘free” Al3+ cations dominate in it below pH 3.5. The cationic Al-hydroxycomplexes [Al(OH)]2+ and [Al(OH)2]+ are present above pH 3.5 and the colloid Al(OH)3 exists at pH > 6.0. The [Al(OH)4] species begin to form in solutions above pH 7.0 and are predominant at pH 8.0–9.0. The cationic and anionic sulphato, fluoro, phosphato and some organic complexes of Al are also present in common soluble forms [1–11]. The extent of Al complexation depends on the availability of Al, solution pH, concentrations of complexing ligands, ionic strength and temperature. Also the Al polymeric hydroxycomplexes (e.g. so-called Al13, [AlO4Al12(OH)24]7+) can be created by the hydrolysis of Al3+ ions. Mainly Al labile cationic species (‘‘free” Al3+, [Al(OH)]2+, [Al(OH)2]+, [AlO4Al12(OH)24]7+) are responsible for its toxic effects. The toxicity of [AlSO4]+ ions is not always accepted. Complexes of Al with organic ligands are considered practically non-toxic

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P. Matúš et al. / Journal of Inorganic Biochemistry 103 (2009) 1473–1479

[10,11]. Anyway, the knowledge of Al speciation (i.e. the distribution of its physico-chemical forms) is important because in the main this factor controls the toxicity of Al. While determination of high Al concentrations can be realized with no serious problem, reliable determination of its trace and ultratrace concentrations requires the development of advanced techniques for improving both, selectivity and also sensitivity for this analyte [1,11]. Solid phase extraction (SPE) using nanometersized TiO2 (anatase) as a solid sorbent can be utilized for the separation and preconcentration of trace amounts of aluminium in various samples. This subject is described insufficiently in present literature. Liang and colleagues developed the method for ultratrace Al(III) ions preconcentration using nanometer-sized TiO2 microcolumn with dynamically immobilized 8-hydroxyquinoline, 0.5 M HCl elution and inductively coupled plasma optical emission spectrometry (ICP OES) detection [12]. The adsorption capacity of TiO2 modified by 8-hydroxyquinoline was 5.23 mg Al g 1 TiO2 at pH 6.0. For the analysis of rice flour and lake water they achieved a detection limit of 1.96 ng mL 1 and a preconcentration factor of 50. On the contrary, many papers about the determination of other metal(loid)s in cationic or anionic form by TiO2 based SPE were published [13–31]. Sorption kinetics, isotherms and capacities, TiO2 regeneration and stability, analyte desorption and elution, effect of sample volume, TiO2 mass, extraction time, pH and coexisting ions, detection and quantification limits, precision, accuracy and various applications were studied. A critical parameter of TiO2 based SPE is the pH value. In most cases the adsorption of cations proceeds when the solution pH value is higher than the isoelectric point (IEP) of TiO2 (6.2–6.8), whereas for anion adsorption a pH value lower than IEP is required [13]. In general, it is believed that the adsorption of ions proceeds with the participation of TiO2 surface hydroxyl groups [13]. Two types of such hydroxyl groups are suggested to exist. One kind of OH groups is assumed to be bound to one Ti4+ site (terminal OH) and the second one is bound to two Ti4+ sites (bridged OH) [14]. At pH values higher than IEP, TiO2 surface is covered by OH groups and is negatively charged. It becomes active towards cation adsorption. In contrast, the positive surface charge at low pH is caused by adsorbed protons and is able to adsorb anions [13]. Various dilute acids (e.g. HCl, HNO3) are often used for the desorption of cations and dilute bases (e.g. NaOH) are used for the elution of anions. The adsorption behaviour of nanometer-sized TiO2 towards the cations Cu, Cr, Mn and Ni at pH 8.0 in batch [15] and microcolumn [16] system was investigated by Liang et al. [15,16], using ICP OES. The method was applied to digested certified reference materials (CRMs) of vehicle exhaust particulates, coal fly ash [15] and rice flour and to real samples of lake water [16]. TiO2 microcolumn preconcentration at pH 8.0 and ICP OES detection were used for the determination of rare earth elements (La, Y, Yb, Eu, Dy) in digested stream sediment and plant (citrus leaves) CRMs by Liang et al. [17]. Direct determination of trace rare earth elements (Tm, Sm, Ho, Nd) in digested stream sediment CRM by fluorination-assisted electrothermal vaporization (FETV) ICP OES with slurry sampling through nanometer-sized TiO2 separation/preconcentration at pH 7.0 was studied by Hang et al. [18]. Liu and colleagues used nanometersized TiO2 immobilized on silica gel for the preconcentration of Cd, Cr, Cu and Mn at pH 8.0 prior to their determination by ICP OES in decomposed CRMs of poplar leaves and natural lake water samples [19]. Flow injection TiO2 microcolumn preconcentration at pH 8.5 on-line coupled with ICP OES determination of Co, Cd, Cr, Cu, Mn, Ni, V, Ce, Dy, Eu, La and Yb in soil CRM, coal fly ash and various water samples was described by Huang et al. [14]. Wu and colleagues proposed a titania-coated capillary microextraction (CME) at pH 8.0 combined with ETV ICP mass spectrome-

try (MS) for the determination of V, Cr and Cu in rice flour and sargasso CRMs, lake water and urine samples [20]. Liu and Liang [21] determined cationic Au in digested gold ore CRM and filtered tap, lake and synthetic sea water sample by nanometer-sized TiO2 immobilized on silica gel microcolumn separation at pH 8.0 and flame atomic absorption spectrometry (F AAS) detection. Anions of noble metals (Au, Ag, Pd) in digested water deposit CRMs were determined using ICP OES after their preconcentration on TiO2 in static (batch) and dynamic mode at pH 5.5 by Qing et al. [22]. Trace Mo amounts in digested steel CRMs were determined by ICP OES after the separation and preconcentration of anionic Mo using TiO2 microcolumn at pH 1.0 (Liang et al. [23]). Concentrations of the total soluble anions As, Se and Sb on TiO2 at pH 2.0 by slurry electrothermal atomic absorption spectrometry (ET AAS) with Zr-coated tube were simultaneously determined in filtered tap and river water [24,25]. Zhang and colleagues showed data from the separation, preconcentration and determination of In(III) as InCl4 at pH 3.5 from decomposed soil CRMs with nanometer-sized TiO2 batch technique and spectrophotometry [26]. SPE by nanometer-sized TiO2 is often used for the speciation analysis of various elements. This separation technique using TiO2 microcolumn, F AAS, ET AAS and ICP OES was utilized for the determination of Cr(III) and Cr(VI) ions in natural water samples [13,27]. Likewise, Liang and colleagues reported the data from speciation analysis of Cr in tap and lake water samples by TiO2based microcolumn SPE and ICP OES [28]. The adsorption of arsenate and arsenite from synthetic solutions on TiO2 suspensions in static mode was investigated using ICP OES, ICP MS and spectrophotometry [29]. Also the Langmuir and Freundlich isotherms were used for the characterization of both As species sorption. Liang and Liu [30] similarly studied the speciation of inorganic As in water samples on TiO2 microcolumn by ET AAS. The results from the speciation analysis of inorganic As, Se and Sb in natural water were shown by Zhang et al. [31]. For this purpose they used TiO2 SPE, Pb pyrrolidinedithiocarbamate coprecipitation and slurry ET AAS detection. In this work, SPE using nanometer-sized TiO2 as a solid sorbent by batch technique and spectrometric methods such as ET AAS and ICP OES were employed for the separation, preconcentration and quantification of total dissolved cationic Al species in synthetic and natural water samples. Two manners of the suggested procedure were investigated, firstly, the elution of Al from TiO2 phase by nitric or hydrochloric acid prior to its determination by ET AAS or ICP OES, and secondly, the direct analyte-enriched TiO2 phase-slurry sampling to ET AAS without previous Al elution.

2. Experiments 2.1. Samples and certified reference material Synthetic river water (SRW) was prepared by dissolving CaCl22H2O (0.2942 g), NaCl (0.2160 g), MgSO47H2O (0.0862 g), KCl (0.0097 g) and (NH4)2HPO4 (0.0073 g) in 1000 mL of double distilled water (DDW). Drinking tap water (DTW) was sampled from laboratory tap. Non-contaminated natural lake water (NLW) was sampled from Lubietova (NE part of Slovenske Stredohorie Mts, Slovakia). Certified reference material (CRM) of lake water TMDA-61 (National Water Research Institute, Burlington, Canada) with certified value of Al concentration (58.4 ± 0.7 lg L 1) was used for checking the accuracy of the optimized procedure for total dissolved cationic Al species determination. All water samples and CRM were filtered through 0.40 lm cellulose nitrate membrane filters before the analysis.

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All used reagents of analytical grade (except TiO2) were produced by Merck (Darmstadt, Germany). TiO2 (anatase form, nanopowder, <25 nm, 99.7%, Aldrich, St. Louis, USA) was used as a solid phase in SPE. Magnesium nitrate solution (10 g L 1 Mg) was used after its 10-fold dilution as a matrix modifier in ET AAS. Aluminium nitrate solution (1 g L 1 Al) was used as an Al standard in the Al spectrometric measurement and in the preparation of Al model solution. Nitric acid and sodium hydroxide solutions (5 M) were added to adjust the final pH of the model and sample solutions. Nitric and hydrochloric acid solutions (0.1–5.0 M) were used for the elution of Al from TiO2 phase in SPE. 2.3. Procedures The filtered sample solution (50 mL) with pH adjusted to 6.0 (optimized pH value) was placed into a 100 mL HNO3-washed and dried high-density polyethylene (HDPE) bottle containing 50 mg (optimized mass) of nanometer-sized TiO2. The suspension was shaken by a mechanical shaker for 10 min (optimized extraction time) at 20 °C. Then, the mixture was centrifuged at 4000 rpm and 20 °C for 10 min and the bulk aqueous phase (supernatant) was easily decanted by simply inverting the bottle. Supernatant can be then analyzed by ET AAS or ICP OES for the fraction of nonextracted Al which is representing mainly the total dissolved noncationic Al species. Further procedure was dependent on the manner of extracted Al determination. Firstly, in batch and elution mode the solutions (20 mL) of nitric or hydrochloric acid (5.0 M, the highest but still insufficient concentration from studied ones) were added to TiO2 phase in a bottle and the suspension was shaken by a mechanical shaker for 10 min at 20 °C. Then, the mixture was centrifuged at 4000 rpm and 20 °C for 10 min and the bulk aqueous phase (eluate) was easily decanted. Eluate was then analyzed by ET AAS or ICP OES for the fraction of extracted Al which is representing the total dissolved cationic Al species. Secondly, in batch and slurry mode the volume of 5 mL of DDW was added to TiO2 phase to prepare a slurry sample. The slurry sample was then agitated for 1 min at 20 °C, transferred into an autosampler cup (immediately before injection into a graphite tube) and directly analyzed by slurry ET AAS for extracted Al which is representing the total dissolved cationic Al species. The described procedures were repeated four times for every sample solution. 2.4. Instrumentation The concentration of Al was measured by ET AAS using a Perkin–Elmer Model 3030 spectrometer equipped with a graphite furnace (Überlingen, Germany) or by ICP OES using a Jobin Yvon Model 70 Plus sequential spectrometer (Longjumeau, France). All measurements were performed in the peak area mode. The Al measurement conditions for both detection techniques are listed in Tables 1 and 2.

Table 1 Al measurement conditions for ET AAS. Graphite furnace Autosampler Background corrector Graphite tube Ar flow rate (mL min 1) Wavelength (nm) Slit (nm) Lamp Lamp current (mA) Injection sample volume (lL) Injection modifier volume (lL) Calibration range (lg L 1) LOD (lg L 1) LOQ (lg L 1)

HGA-600 AS-60 Zeeman Pyrolytic 250 309.3 0.7 Hollow cathode 25 20 10 50–400 3.7 12

LOD, limit of detection. LOQ, limit of quantification.

Table 2 Al measurement conditions for ICP OES. RF power (W) Outer Ar flow rate (L min 1) Sheath Ar flow rate (L min 1) Carrier Ar flow rate (L min 1) Sample flow rate (mL min 1) Wavelength (nm) Entrance slit (lm) Exit slit (lm) Monochromator Calibration range (lg L 1) LOD (lg L 1) LOQ (lg L 1)

900 12.0 0.20 0.35 1.0 396.152 20 25 Czerny–Turner (1 m focal length) 100–5000 15 50

LOD, limit of detection. LOQ, limit of quantification.

0.70

0.60

0.50 Absorbance

2.2. Reagents

0.40

0.30

0.20

PC: Al (no modifier) AC: Al (no modifier) PC: Al+Mg(NO3)2 AC: Al+Mg(NO3)2

0.10

0.00 300

600

900

1200

1500

1800

2100

2400

2700

Temperature (°C)

3. Results and discussion

Fig. 1. Pyrolysis (PC) and atomization (AC) curves measured with and without modifier Mg(NO3)2.

3.1. Optimization of the ET AAS measurement conditions To establish a suitable temperature program for Al determination in supernatant, eluate and slurry samples, the pyrolysis and atomization curves of 200 lg L 1 Al were investigated in the presence and the absence of magnesium nitrate matrix modifier (10 lg Mg) in the range of 500–2100 °C and 2000–2600 °C, respectively (see Fig. 1). Similarly, Srinivasan et al. [32] studied eight different temperature programs with Mg(NO3)2 as matrix modifier for

graphite furnace AAS determination of Al. The charring and atomization temperatures ranged from 1100 °C to 1700 °C and from 2500 °C to 2800 °C, respectively. They achieved very similar results. The highest absorbances were obtained for temperatures 1400– 1500 °C (pyrolysis) and 2600 °C (atomization) (see Fig. 1). Therefore, the pyrolysis temperature of 1500 °C and atomization tem-

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Table 3 Temperature program for ET AAS.

100 90 Ramp time (s)

Hold time (s)

Ar flow rate (mL min 1)

110 1500 2600 2650

10 10 0 1

20 20 3 1

250 250 0 250

80

perature of 2600 °C were selected in accord with other works [32– 34] and used in the temperature program (see Table 3) for following ET AAS measurements of Al concentration in supernatant, eluate and slurry samples. Since higher reproducibility of obtained results and slightly higher absorbance values were achieved in the presence of Mg(NO3)2 (see Fig. 1), this matrix modifier was used in further measurements. When using Mg(NO3)2 as a matrix modifier, Al is sequestered within the stable MgO crystals and hence the potential volatilization of Al, e.g. in the form of chloride (AlCl3 sublimes at 178 °C) is partially prevented [32]. Mechanisms that explain the stabilization of Al by Mg(NO3)2 were shown to involve two temperature regions. It is believed that Al atoms are formed in graphite furnace by the thermal dissociation of Al2O3(s) after drying and pyrolysis steps [32,33]. During the thermal pretreatment magnesium hydroxides and oxides are formed from Mg(NO3)2. This prevents Al losses as its hydroxides which were shown to occur between 1000 °C and 1300 °C. At temperature above 1300 °C analyte oxidation-dissociation sequence takes place involving the reduction of MgO (the created Mg is volatilizing at boiling point of 1090 °C). This results in the retention of adsorbed Al2O3 until the MgO is depleted, thereby delaying the atomization of Al to higher temperatures [33,34].

SPE recovery of Al (%)

Drying Pyrolysis Atomization Cleaning

Temperature (°C)

70 60 50 40 30 20 10 0 0

20

40 60 Mass of TiO2 (mg)

80

100

Fig. 2. Effect of TiO2 mass on the SPE recovery of Al.

100 90 SPE recovery of Al (%)

Step

80 70 60 50 40 30 20 10

3.2. Optimization of the TiO2 SPE procedure

0

3.2.1. Effect of TiO2 mass The effect of TiO2 mass on the SPE recovery of Al was studied under the experimental conditions listed in Table 4. While mass of TiO2 was up to 5.0 mg, recoveries of Al were above 95% and remain almost constant (see Fig. 2). Finally, the mass of 50 mg TiO2 was chosen and used in the optimized SPE procedure. 3.2.2. Effect of extraction time and kinetics The effect of extraction time and kinetics on the SPE recovery of Al was investigated using the experimental conditions listed in Table 4. The results after 5 min showed Al-recoveries above 95%, but relative standard deviation (RSD) of obtained data less than 5% was achieved when shaking time was up to 10 min (see Fig. 3). Finally, the extraction time of 10 min was chosen and used in the optimized SPE procedure. 3.2.3. Effect of pH The effect of pH value on the SPE recovery of Al was observed under the experimental conditions listed in Table 4. The obtained recoveries increased from 4.8% Al (pH 2.05) to 86.7% Al (pH

5

10

15 Time (min)

20

25

30

Fig. 3. Effect of extraction time on the SPE recovery of Al.

5.21), see Fig. 4. Recoveries of around 92.1 ± 1.8% Al were found for the pH range of 6.02–9.27. Finally, the pH 6.0 was chosen for further experiments in spite of the fact that it is slightly lower than the IEP value for TiO2 (6.2–6.8). The reason for this choice was finding that at higher pH the soluble cationic Al species can convert to colloid Al(OH)3 [11]. These colloid species cannot be extracted by TiO2 SPE because of their neutral character. Further, during the centrifugation after TiO2 SPE the nonsoluble Al(OH)3 can be separated from the supernatant together with the TiO2 phase. This can cause higher concentrations of the extracted Al fraction. Another factor, which can be affected by the pH, is the stability of TiO2 slurry for slurry ET AAS measurement. When the pH of the TiO2 suspension is lower, the spontaneous adsorption of H+ on titania results in a positive charge on the anatase surface. The reaction among these ions with the same positive charge can keep the slur-

Table 4 Studied and final optimized experimental conditions from the optimization of the TiO2 SPE procedure. Study/conditions Studied conditions Effect of TiO2 mass Effect of extraction time Effect of pH Effect of Al elution Final optimized conditions

TiO2 mass (mg)

Extraction time (min)

pH

Concentration of HCl and HNO3 eluents (M)

Al quantification method

Sample volume (mL)

Al concentration (lg L 1)

0–100 50 50 50 50

10 0–30 10 10 10

6.0 6.0 2.0–9.0 6.0 6.0

– – – 0.1–5.0 –

Slurry ET AAS Slurry ET AAS Slurry ET AAS ET AAS, ICP OES Slurry ET AAS

50 50 50 50 50

100 100 100 100 100

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AAS measurement in spite of used Mg(NO3)2 as matrix modifier (see Fig. 5). Anyway, the determination of Al in this medium was not possible by ET AAS because of chemical interference of chloride

100 90

70 100

60 50 40 30 20 10 0 1

2

3

4

5

6

7

8

9

10

pH

Al determined by ET AAS (µg -1 L)

SPE recovery of Al (%)

80

90 80 70 60 50 40 30 20 10

Fig. 4. Effect of pH on the SPE recovery of Al.

0

ry stable. In our experiments, RSD values less than 5% were achieved at the pH 6.0 and the TiO2 slurry remained stable at least 10 min. At higher pH values, the RSD increased. Finally, the pH 6.0 was chosen and used in the optimized TiO2 SPE procedure. The same pH value was used for SPE of Al using TiO2-oxine by Liang et al. [12].

2 3 Concentration of HCl (M)

Fig. 5. Effect of HCl on the determination of 100 lg L

4

1

5

Al by ET AAS.

100 Al determined by ICP OES (µg L-1)

3.2.4. Effect of Al desorption and elution The effect of Al desorption and elution on the SPE recovery of Al was examined using the experimental conditions listed in Table 4. Nitric and hydrochloric acid with various concentrations (0.1– 5.0 M) were used as eluents, see Tables 5 and 6. Recoveries of only 75% Al for 5 M HCl and 55% Al for 5 M HNO3 were found. Even such high concentrations of used mineral acids did not provide sufficient results for complete elution of Al from TiO2 phase. Higher acid concentrations were not studied (the main reasons are described in further paragraph). Besides that, increasing chloride concentration in the HCl eluate causes decreasing Al absorbance signals from 100% to 14% in ET

1

98 96 94 92 90 88 86 0

Table 5 Determination of Al in HCl eluates and TiO2 phase by ICP OES and slurry ET AAS, respectively. Al recovery determined in HCl eluate by ICP OES (%)

Al recovery determined in TiO2 phase by slurry ET AAS (%)

Sum (%)

0.1 0.5 1.0 3.0 5.0

42.3 49.2 58.6 68.4 75.4

51.5 43.0 37.2 29.4 21.4

93.8 92.2 95.8 97.8 96.8

Table 6 Determination of Al in HNO3 eluates and TiO2 phase by ET AAS and slurry ET AAS, respectively. Concentration of HNO3 eluent (M)

Al recovery determined in HNO3 eluate by ET AAS (%)

Al recovery determined in TiO2 phase by slurry ET AAS (%)

Sum (%)

0.1 0.5 1.0 3.0 5.0

38.6 44.0 47.8 49.6 54.8

58.5 51.1 45.6 41.6 38.0

97.1 95.1 93.4 91.2 92.8

2 3 Concentration of HNO3 (M)

Fig. 6. Effect of HNO3 on the determination of 100 lg L

4

1

5

Al by ICP OES.

5

4 Al adsorbed (mg g-1)

Concentration of HCl eluent (M)

1

3

2

1

0 0

2000

4000

6000

Al introduced (µg L-1) Fig. 7. Adsorption isotherm of Al(III).

8000

10000

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use clean and dry HDPE bottle (100 mL)

put 50 mg nano-sized TiO2

add 50 mL sample with pH 6.0

shake 10 min at 20 °C

centrifuge 10 min at 4000 rpm and 20 °C

remove bulk solution (supernatant)

in all cases higher than 90% of the total measured Al. These data confirmed the accuracy of the obtained results. Finally, the slurry ET AAS was found to be the most suitable measurement method for given purpose because the complete Al elution from TiO2 by HNO3 and HCl is not possible. Therefore, it is necessary to analyze the solid TiO2 phase for Al directly, without elution. 3.2.5. Adsorption isotherm and capacity The above results were obtained using relatively low concentrations of Al. In order to obtain the information about the adsorption kinetics, equilibrium process and capacity for Al, the adsorption isotherm was carried out. Fig. 7 shows the adsorption isotherm obtained after application of the SPE using the final optimized experimental conditions listed in Table 4 for various concentrations of Al (0–10,000 lg L 1). The profile of Al adsorption isotherm was gained by plotting the concentration of Al introduced to a solution versus the amount of Al adsorbed on TiO2 phase after SPE application. The adsorption capacity of TiO2 for Al(III) was evaluated from Al adsorption isotherm with 4.1 mg Al g 1 TiO2. This parameter determines the required amount of TiO2 for quantitative separation of Al from a given solution. The obtained value of adsorption capacity of TiO2 is close to the adsorption capacity of TiO2 modified by 8-hydroxyquinoline in the work of Liang et al. [12] with 5.23 mg Al g 1 TiO2.

add 5 mL double distilled water to TiO2 3.3. Analytical application

agitate 1 min at 20 °C

determine Al by slurry ET AAS Fig. 8. Scheme of proposed and developed batch and slurry TiO2 SPE.

ions which were present at very high level. This interference is caused by creating stable gaseous Al chlorides and by various gas-phase effects in the graphite tube of ET AAS (decreasing Al signal is mainly caused by the loss of volatile Al chloride species) [33]. The determination of Al in the HNO3 eluate by ICP OES was also affected. The intensity signals of Al in ICP OES measurement decreased significantly (from 100% to 86%) with increasing concentration of nitric acid (see Fig. 6). This is caused by various effects of HNO3 on the aerosol generation (aspiration and nebulization of sample), transport processes and plasma properties in ICP OES measurement (decreasing Al signal is mainly caused by the changing physical properties of the HNO3 solution, e.g. viscosity, density and surface tension) [35,36]. From these reasons Al recoveries in the HCl eluates were determined by ICP OES and Al recoveries in the HNO3 eluates were determined by ET AAS. The TiO2 phase samples, from which Al was not completely eluted by neither HNO3 nor HCl acids, were subsequently analyzed for Al by slurry ET AAS (see Tables 5 and 6). The amounts of Al recoveries obtained from the eluate and TiO2-slurry samples were

In order to apply the proposed method of batch SPE to real samples the obtained results should be resumed. The followed parameters were used for the separation and preconcentration of total dissolved cationic aluminium species using nanometer-sized TiO2 as solid phase and atomic spectrometry detection. The mass of 50 mg TiO2, sample volume of 50 mL, extraction time of 10 min, laboratory temperature of 20 °C, pH 6.0 (see Table 4) and slurry ET AAS were combined with appropriate results. Under these conditions, a preconcentration factor of 10 can be reached. If higher preconcentration of analyte is required, the sample volume has to be increased. Finally, the batch and slurry mode of nano-sized TiO2 SPE is preferred and was applied in further experiments. The scheme of proposed batch and slurry TiO2 SPE is shown in Fig. 8. Under proposed conditions, the calibration curve for batch and slurry TiO2 SPE with a 10-fold preconcentration was linear up to 40 lg L 1 Al with a correlation coefficient of 0.9991. The limit of detection (LOD) and the limit of quantification (LOQ) was 0.11 lg L 1 Al and 0.35 lg L 1 Al, respectively, with a preconcentration factor of 20 (100 mL sample used) and a relative standard deviation (RSD) lower than 5%. The accuracy of the proposed batch and slurry TiO2 SPE was checked by analyzing the filtered and: (a) 10-times diluted (with a preconcentration factor of 10) and (b) 20-times diluted (with a preconcentration factor of 20) CRM of lake water TMDA-61 (see Table 7). Recoveries (calculated from relevant certified values of Al concentration) in the range of 97–102% were obtained. To confirm that major matrix components of natural water such as K, Na, Mg, Ca and other elements do not influence the batch and

Table 7 Determination of Al in filtered dilute and spiked dilute CRM of lake water TMDA-61 by batch and slurry TiO2 SPE. Dilute CRM CRMa CRMb a b

Al determined in dilute CRM (lg L 1)

Al recovery (%)

5.65 ± 0.38 2.97 ± 0.13

96.7 102

Dilute CRM + Al addition (lg L CRMa + 5.0 CRMb + 2.5

CRM diluted 10-times, the relevant certified value of Al concentration: 5.84 ± 0.07 lg L CRM diluted 20-times, the relevant certified value of Al concentration: 2.92 ± 0.04 lg L

1

. .

1

1

)

Al determined in spiked dilute CRM (lg L 1)

Al recovery (%)

10.79 ± 0.28 5.44 ± 0.08

99.5 100

1479

P. Matúš et al. / Journal of Inorganic Biochemistry 103 (2009) 1473–1479 Table 8 Determination of Al in filtered spiked drinking tap water (DTW) and synthetic river water (SRW) samples by batch and slurry TiO2 SPE. Sample + Al addition (lg L

1

)

DTW + 0.0 DTW + 2.5 DTW + 5.0 DTW + 10.0

Al determined in spiked sample (lg L

1

)

0.87 ± 0.05 3.53 ± 0.07 5.78 ± 0.10 11.16 ± 0.17

Al recovery (%)

Sample + Al addition (lg L

– 105 98.5 103

SRW + 0.0 SRW + 2.5 SRW + 5.0 SRW + 10.0

LOQ, limit of quantification; LOQ of batch and slurry TiO2 SPE with preconcentration factor of 20 = 0.35 lg L

Table 9 Determination of Al in filtered non-contaminated natural lake water (NLW) samples by ET AAS and by batch and slurry TiO2 SPE.

Al determined in spiked sample (lg L

1

)

1

)

Al recovery (%) – 106 97.0 94.8

1

.

step can be used directly in the field using the TiO2 filled plastic microsyringes with filter holder.

Sample

Al determined by ET AAS (lg L 1)

Al determined by batch and slurry TiO2 SPE (lg L 1)

Al recovery (%)

Acknowledgements

NLW1 NLW2 NLW3 NLW4 NLW5 NLW6 NLW7 NLW8

14.07 ± 1.25 13.48 ± 1.87
13.94 ± 0.49 13.73 ± 0.62 3.76 ± 0.17 2.10 ± 0.15 3.01 ± 0.21 2.74 ± 0.28 36.18 ± 0.84 5.91 ± 0.21

99.1 102 – – – – 103 –

The authors would like to thank the anonymous reviewers for their useful comments and suggestions. The work was supported by Science and Technology Assistance Agency under the Contracts Nos. APVT-20-010204, LPP-0038-06, LPP-0146-09 and SK-CZ0044-07, by Scientific Grant Agency of the Ministry of Education of Slovak Republic and the Slovak Academy of Sciences under the Contracts Nos. VEGA 1/4464/07 and VEGA 1/0272/08 and by Ministry of Education, Youth and Sports of Czech Republic under the Contract No. MEB 080813.

LOQ, limit of quantification; LOQ of ET AAS = 12 lg L

1

.

slurry TiO2 SPE, filtered dilute CRM of lake water TMDA-61, synthetic river water (SRW) and drinking tap water (DTW) spiked with different concentrations of Al (analyte addition technique) were analyzed with a preconcentration factor of 10 or 20 by the proposed procedure (see Tables 7 and 8). Recoveries in the range of 95–106% were obtained. Finally, the proposed batch and slurry TiO2 SPE was used for the determination of trace amounts of total dissolved cationic aluminium species in filtered non-contaminated natural lake water (NLW) samples (see Table 9). It can be assumed that at a working pH value of 6.0 only dissolved cationic Al species are present in filtered samples [11]. For the comparison of the obtained results the concentrations of Al in filtered NLW samples were directly determined by ET AAS and ICP OES. The concentrations of Al in filtered NLW samples were unfortunately lower than the LOQ of ICP OES (50 lg L 1). Al recoveries of batch and slurry TiO2 SPE with the preconcentration factors of 10 or 20 for the samples with Al directly determined by ET AAS were in the range of 99–103%.

4. Conclusion In this study, the method of SPE using nanometer-sized TiO2 by batch technique and slurry ET AAS was developed for the determination of total dissolved cationic aluminium species at trace level in natural water samples. Proposed batch and slurry TiO2 SPE is limited mainly by LOD (LOQ) and linearity of slurry ET AAS calibration curve. It means that it is possible to determine the fraction of total dissolved cationic Al from concentrations 0.11 (0.35) lg L 1 (with a preconcentration factor of 20, 100 mL sample used) to 40 lg L 1 (with a preconcentration factor of 10, 50 mL sample used). This method offers the advantages of separation, preconcentration and direct quantification of Al fraction mostly responsible for its toxic effects in the environment. The developed procedure is relatively simple, rapid and without the need of high-cost instrumentation and can be a useful tool in the Al environmental risk assessment. In certain conditions its separation/preconcentration

References [1] P. Matus, J. Kubova, Chem. Listy 96 (2002) 174–181. [2] P. Dlapa, J. Kubova, P. Matus, V. Stresko, Fresen. Environ. Bull. 11 (2002) 626– 630. [3] P. Matus, J. Kubova, V. Stresko, Chem. Papers 57 (2003) 176–178. [4] P. Matus, J. Kubova, M. Bujdos, V. Stresko, J. Medved, Anal. Bioanal. Chem. 379 (2004) 96–103. [5] P. Matus, J. Kubova, M. Bujdos, J. Medved, Anal. Chim. Acta 540 (2005) 33–43. [6] J. Kubova, P. Matus, M. Bujdos, J. Medved, Anal. Chim. Acta 547 (2005) 119– 125. [7] P. Matus, J. Kubova, J. Inorg. Biochem. 99 (2005) 1769–1778. [8] P. Matus, J. Kubova, Anal. Chim. Acta 573–574 (2006) 474–481. [9] P. Matus, J. Kubova, M. Bujdos, J. Medved, Talanta 70 (2006) 996–1005. [10] P. Matus, J. Inorg. Biochem. 101 (2007) 1214–1223. [11] P. Matus, J. Kubova, in: A.N. Dubois (Ed.), Soil Contamination: New Research, Nova Science, New York, 2008, pp. 43–72. [12] P. Liang, L. Yang, B. Hu, Z. Jiang, Anal. Sci. 19 (2003) 1167–1171. [13] E. Vassileva, K. Hadjiivanov, T. Stoychev, C. Daiev, Analyst 125 (2000) 693–698. [14] C. Huang, Z. Jiang, B. Hu, Talanta 73 (2007) 274–281. [15] P. Liang, Y. Qin, B. Hu, C. Li, T. Peng, Z. Jiang, Fresen. J. Anal. Chem. 368 (2000) 638–640. [16] P. Liang, Y. Qin, B. Hu, T. Peng, Z. Jiang, Anal. Chim. Acta 440 (2001) 207–213. [17] P. Liang, B. Hu, Z. Jiang, Y. Qin, T. Peng, J. Anal. Atom. Spectrom. 16 (2001) 863– 866. [18] Y. Hang, Y. Qin, Z. Jiang, B. Hu, Anal. Sci. 18 (2002) 843–846. [19] Y. Liu, P. Liang, L. Guo, Talanta 68 (2005) 25–30. [20] Y. Wu, B. Hu, W. Hu, Z. Jiang, B. Li, J. Mass Spectrom. 42 (2007) 467–475. [21] R. Liu, P. Liang, Anal. Chim. Acta 604 (2007) 114–118. [22] Y. Qing, Y. Hang, R. Wanjaul, Z. Jiang, B. Hu, Anal. Sci. 19 (2003) 1417–1420. [23] P. Liang, Y. Liu, L. Guo, J. Anal. Atom. Spectrom. 19 (2004) 1006–1009. [24] L. Zhang, D. Ishi, K. Shitou, Y. Morita, A. Isozaki, Talanta 68 (2005) 336–342. [25] L. Zhang, Y. Morita, K. Yoshikawa, A. Isozaki, Anal. Sci. 23 (2007) 365–369. [26] L. Zhang, Y. Wang, X. Guo, Z. Yuan, Z. Zhao, Hydrometallurgy 95 (2009) 92–95. [27] E. Vassileva, Analysis 28 (2000) 878–884. [28] P. Liang, T. Shi, H. Lu, Z. Jiang, B. Hu, Spectrochim. Acta, Part B 58 (2003) 1709– 1714. [29] P.K. Dutta, A.K. Ray, V.K. Sharma, F.J. Millero, J. Colloids Interf. Sci. 278 (2004) 270–275. [30] P. Liang, R. Liu, Anal. Chim. Acta 602 (2007) 32–36. [31] L. Zhang, Y. Morita, A. Sakuragawa, A. Isozaki, Talanta 72 (2007) 723–729. [32] P.T. Srinivasan, T. Viraraghavan, K.S. Subramanian, Am. Lab. 32 (2000) 76–91. [33] E. Beinrohr, J. Mocak, X. Svobodova, O. Losova, Chem. Listy 85 (1991) 131–140. [34] W. Frech, A. Cedergren, in: M. Stoeppler (Ed.), Techniques and Instrumentation in Analytical Chemistry, Hazardous Metals in the Environment, vol. 12, Elsevier, Amsterdam, 1992, pp. 451–473. [35] I.I. Stewart, J.W. Olesik, J. Anal. Atom. Spectrom. 13 (1998) 1249–1256. [36] J.-L. Todoli, J.-M. Mermet, Spectrochim. Acta, Part B 54 (1999) 895–929.

ANALYTICAL SCIENCES APRIL 2009, VOL. 25 2009 © The Japan Society for Analytical Chemistry

575

Notes

Application of New Resin Gels for Measuring Mercury by Diffusive Gradients in a Thin-films Technique Pavel DIVIš,*† Roman SZKANDERA,* Lukáš BRULíK,* Hana DOCˇEKALOVá,* Peter MATúš,** and Marek BUJDOš** *Brno University of Technology, Faculty of Chemistry, Purkynˇova 118, Brno CZ-61200, Czech Republic **Comenius University in Bratislava, Faculty of Natural Sciences, Mlynská dolina 1, Bratislava SK-84215, Slovakia

A possible replacement of previously recommended Spheron-Thiol resin gel for measuring mercury by diffusive gradients in a thin film (DGT) was studied. Duolite GT73 resin and newly prepared 6-mercaptopurine modified Iontosorb AV as binding phases were tested. The preparation procedure of resin-embedded gels was optimized and DGT with new resin gels verified. The verified DGT containing new resin gels was used for in situ mercury measurement in Svitava River. (Received October 28, 2008; Accepted January 19, 2009; Published April 10, 2009)

Introduction The diffusive gradients in the thin-films technique (DGT), a relatively new analytical technique capable of measuring in situ concentrations of trace metals in an aquatic environment, has proved to be useful because of its simplicity and wide applicability. It is largely used for measuring kinetically labile metal species in natural waters1,2 or trace metal fluxes in sediments and soils.2,3 The DGT technique employs two layers of hydrogel, a diffusive layer and a binding phase. The choice of the binding agent and the diffusive layer defines the measured species. During recent years, DGT has been investigated for measuring more than 50 elements.2,4 Only a little effort has been expended to measure mercury species,5–8 though they have attracted great attention concerning environmental contamination monitoring, due to their unique toxicity.9 This paper follows our previous work5 dedicated to the determination of mercury by diffusive gradients in the thin-films technique. The commonly used polyacrylamide diffusive gel was not found to be suitable as a diffusive medium for mercury determination, because of mercury binding on the amine groups of polyacrylamide. An agarose diffusive gel having a different structure from polyacrylamide gel was tested and recommended. Moreover, the use of another resin, Spheron-Thiol with –SH groups, instead of the most frequently used Chelex-100 resin, has been described. Iminodiacetic groups of Chelex-100 enable one to assess only ionic mercury and mercury related to weak complexes. Thiol groups of Spheron-Thiol are capable of reacting with mercury bonded even in very strong complexes. The concentrations obtained by DGT with Speron-Thiol were found to be very similar to those obtained by direct measurements of total dissolved mercury.6 A resin with thiol groups presents the best choice for mercury determination. Spheron-Thiol prepared by Smrž and Hradil10 is not available in the market at present, and therefore possible alternatives were To whom correspondence should be addressed. E-mail: [email protected] †

studied in the present work. We studied an application of commercially available Duolite GT73 resin, recently used for the preconcentration of noble metals prior to determinations of these metals by ICP-OES,11,12 or in industrial processes for removing heavy metals from wastewater13,14 and the application of a new Iontosorb AV-MP resin synthesized in the laboratory. A 6-mercaptopurine functionalized sorbent was successfully used in foretime for the determination of mercury and silver in environmental samples by AAS.15 The preparation procedure of new resin gels was optimized and the DGT technique verified. The verified DGT containing new resin gels was used for in situ mercury measurements in Svitava River.

Experimental Reagents and chemicals All of the reagents were of analytical-reagent grade. All water used in this study was high-purity demineralized water (conductivity 0.05 mS cm–1, Millipore, USA). Mercury solutions were prepared from a 1 g L–1 stock standard solution (AstasolHg, Analytica Ltd., Czech Republic). The temperature of mercury solutions was 25 ± 1˚C and the pH 5. A hydrogel with incorporated Duolite GT73 resin (Sigma-Aldrich, Germany) was prepared using acrylamide (Sigma-Aldrich), N,N,N¢,N¢tetramethylethylendiamin (Sigma-Aldrich), ammonium persulfate (Sigma-Aldrich) and a patented agarose-based crosslinker (DGT Research Ltd., UK). Hydrogels with incorporated Iontosorb AV-MP resin and diffusive gels were prepared from agarose (Merck, Germany). To protect the outer surface of the diffusive gel, a 0.45-mm pore size membrane (Pall Corporation, USA) was used. For preparing of 6-mercaptopurine modified Iontosorb AV resin (Iontosorb AV-MP), Iontosorb AV (Iontosorb, Czech Republic), 6-mercaptopurine (Sigma-Aldrich) hydrochloric acid (Penta, Czech Republic), sodium nitrite (Lachema, Czech Republic) and potassium carbonate (Lachema) were used. For the quantitative determination of thiol groups in Iontosorb AV-MP resin, potassium iodine and sodium thiosulfate (Lachema) were used.

576 Apparatus DGT probes (piston type, 2.5 cm in diameter with an exposed area of 3.14 cm2) were obtained from DGT Research Ltd. (Lancaster, UK), and assembled as described previously.5 The determination of mercury was performed using a one-purpose atomic absorption spectrometer, AMA 254 (Altec, Czech Republic). For pretreating the resin, a porcelain mortar and a Teflon sieve (0.09 mm) were used. All testing solutions were stirred (900 rpm) using a magnetic stirrer. For measuring of the pH and the temperature, a WTW-320 multimeter (WTW, Germany) was used. Dissolved organic carbon was measured using a Shimadzu 5000 (Shimadzu, Japan) elemental analyzer. For the qualitative determination of thiol groups in Iontosorb AV-MP resin, an infrared spectrometer (Nicolet Impact 400, Nicolet, USA) was used. Duolite-GT73 pretreatment Because of the large diameter size of Duolite GT73 resin particles (0.5 – 0.7 mm), it was impossible to incorporate the resin into the polyacrylamide hydrogel (the thickness of plastic spacers determining the diameter size of the resin was 0.25 mm). For this reason, a pretreatment of the resin before use was necessary. The resin was ground in porcelain mortar, and then sieved with 0.09 mm Teflon sieve. The fraction passed through the sieve was soaked in a hydrochloric acid solution overnight, then washed several times with ultrapure water, and used for resin gel preparation. The resulting thickness of the prepared gel after swelling in deionized water was 0.4 mm. Iontosorb AV-MP synthesis and characterization Iontosorb AV (modified bead-form cellulose containing aminoaryl-b-ethylsulfone groups) was washed in ethanol, and then with ultrapure water. After the flushing of Iontosorb AV, this sorbent was modified using diazotation and coupling reactions.15,16 An amount of 5 g Iontosorb AV was washed with hydrochloric acid and then with ultrapure water until achieving neutral pH. After washing, diazotation was performed at 0 – 5˚C using 1 mol L–1 solutions of hydrochloric acid and sodium nitrite. Diazotation was stopped after adding of 40 mL of reagents. A yellow product was filtered out and washed several times with ultrapure water. Diazonium salt was then added to a continuously mixed and cooled reactor containing 3.5 g of 6mercaptopurine dissolved in 10% sodium carbonate. After 24 h a new red-brown product was filtered out, washed several times with ultrapure water and dried in an exicator. A qualitative test was performed using infrared spectroscopy. The infrared spectrum of a new functionalized resin was compared with a blank infrared spectrum of Iontosorb AV. A quantitative test of thiol groups was performed by iodometric titration at pH ~9. To 50 mg of modified Iontosorb AV, 25 mL of 0.001 mol L–1 potassium iodine was added, and after 5 min of shaking and 30 min of standing in the dark, the resulting solution was titrated by 0.001 mol L–1 ammonium thiosulfate. Hydrogels preparation The preparation of Duolite GT73 embedded gel, comprising 15% by volume acrylamide and a 0.3% cross-linker, followed a procedure used by Zhang and Davison.1 A freshly prepared ammonium persulfate initiator (15 mL) and a N,N,N¢,N¢tetramethylethylendiamin catalyst (5 mL) were added to 2 mL of gel solution containing 0.3 g of crushed Duolite GT73 resin. The resulting gel solution was cast between two glass plates separated by plastic spacers, and was set in an incubator at (42 ± 2)˚C for 45 min. Prepared hydrogel sheets were hydrated for at least 24 h in water, and then discs of 2.5 cm in diameter were

ANALYTICAL SCIENCES APRIL 2009, VOL. 25 cut from these sheets. Iontosorb AV-MP embedded gel was prepared by a different way. After an amount of 0.2 g of Iontosorb AV-MP was mixed together with a hot 2% agarose solution, this solution was transferred between two preheated glass plates separated by plastic spacers, and left to form the gel at room temperature. Similarly, agarose diffusive gels were prepared from a 2% agarose hot solution. All types of gels were stored in water before use. The thicknesses of the prepared gels were 0.4 mm for resin gels and 0.7 mm for diffusive gels. Basic DGT performance tests After deploying of a DGT unit for time t in a solution, the amount of metal ions absorbed by the resin is analyzed, and the mass M of captured metals determined. The amount of metal accumulated within the binding phase under these conditions is assumed to be equivalent to the amount of metal ion passing through the diffusive layer. The time-average concentration of metal in the bulk solution, cDGT, thus can be calculated with the help of Fick’s first law of diffusion, if the diffusion coefficient, D, of the metal in ion-permeable hydrogel, the thickness of the diffusive layer, Dg, and the exposure surface area, A, is known by Eq. (1): cDGT = M·Dg/t·A·D

(1)

Two basic tests1 were performed in order to test the validity of DGT. A 10 mg L–1 mercury solution was used in both of these experiments. In the recovery test, 10 DGT units were immersed into the test solution and after 3 h of exposure, mercury was determined in resin gels. During all of these tests, the concentration of mercury in solution was continuously controlled, because the significant adsorption of mercury on the surface of all types of containers is a well-known phenomenon.5 In the second test, 8 DGT units were immersed into the test solution, and after intervals of 2, 4, 6 and 8 h, two DGT units were taken out from the solution and the mass of accumulated mercury in resin gels was determined. Field application Five DGT sampling units filled with agarose diffusive gels and Duolite GT73 and Iontosorb AV-MP resin gel were deployed in situ in stream of Svitava River in the Obâny part of Brno, Czech Republic. The sampling units were anchored to a nylon string, fixed on a river bridge and suspended for 7 days approximately 0.5 m under the water surface. After the deployment time, DGT sampling units were rinsed with distilled water and kept in clean polyethylene bags for the transport to laboratory. On the first and last days of deployment, 1 L of a water sample was collected in a brown glass bottle containing preservation agents,17 and the temperature and pH of the river water were recorded. Dissolved organic carbon and mercury concentrations were measured in the laboratory.

Results and Discussion The successful incorporation of 6-mercaptopurine to Iontosorb AV was proved by the change in the resin color from white to red-brown. In a comparison with the Iontosorb AV infrared spectra, the infrared spectra of Iontosorb AV-MP showed new bands at 1520 cm–1 for N=N, 1626 cm–1 for C=N, 2360 cm–1 for –S–H and 3457 cm–1 for –N–H stretches. Other vibrations at 720, 1062, 1518 and 2918 cm–1 showed the presence of a 6-mercaptopurine skeleton in Iontosorb AV-MP (Fig. 1). The amount of thiol groups was determined by iodometric titration

ANALYTICAL SCIENCES APRIL 2009, VOL. 25

577 Table 1 Results from a DGT reproducibility test Sampling unit No.

DGT (Duolite GT3) concentration

DGT (Iontosorb AV-MP) concentration

1 2 3 4 5 Average concentration Standard deviation

8.4 7.8 8.3 8.1 8.5 8.22 0.28

7.5 8.2 7.9 8.2 7.7 7.9 0.3

All of concentrations are in mg L–1. Fig. 1 AV.

An infrared spectra of 6-mercaptopurine modified Iontosorb

to be 0.5 mmol g–1. This should be sufficient to prevent saturation of the functional groups when DGT sampling units are deployed in natural water locations. To be sure that the Duolite GT73 and Iontosorb AV-MP resin gel preparation procedure is correct and reproducible, several sheets of resin gels containing these sorbents were prepared, and 10 discs were cut randomly from the sheets, and were used to assemble the DGT units. Before starting the test, a 10 mg L–1 mercury solution was prepared and left to equilibrate overnight. Due to the absorption of mercury to the container walls, the mercury concentration in a prepared solution decreased and the final stable concentration measured by AAS was 8.4 ± 0.2 mg L–1. The DGT units were subsequently immersed in this stirred solution for 3 h. The results from the experiment are given in Table 1. The calculated DGT concentrations differ from each other by less than 10%; moreover, the average DGT concentration agrees with the concentration measured by an independent technique (AAS). It showed that resin gels can be prepared repeatedly with the same quality, and that they work well. The correct function of all prepared gels was tested again in a time dependence test.1 DGT units were exposed for up to 8 h in an equilibrated 10 mg L–1 mercury solution. The final stable concentration of mercury in this solution was 8.6 ± 0.3 mg L–1. As can be seen from Fig. 2, the mass of mercury accumulated in the resin gel increased linearly with the time, and the measured mass of accumulated mercury in DGT sampling units agrees with a theoretical prediction using Eq. (1). In July 2007, five DGT sampling units filled with agarose diffusive gel and Duolite GT73 resin gel were used to measure the in situ mercury concentration in the Svitava River in the Obâny part of Brno, Czech Republic. The average temperature during the deployment time was 17.5 ± 0.5˚C, and the average pH was 7.89 ± 0.12. The amount of dissolved organic carbon during the deployment was 6.4 ± 0.2 mg L–1. In our previous study,5 the diffusive coefficient, D25, of mercury in agarose diffusive gel was calculated to be 8.97 ¥ 10–6 cm2 s–1. Applying the correction equation,1 the diffusive coefficient D17.5 of 7.25 ¥ 10–6 cm2 s–1 was taken into account in order to calculate the DGT mercury concentration. The DGT measured concentration in the Svitava River was 62 ± 11 ng L–1. This value is slightly lower than the value of the total dissolved mercury concentration (94 ± 6 ng L–1), which indicates that some part of mercury in the river water is complexed by dissolved organic carbon. Mercury strongly complexed with dissolved organic carbon can pass through a 0.45-mm filter, and can be further analyzed, but in the case of DGT these complexes are excluded from the measurement.18 At the same place (Svitava River, Obâny part

Fig. 2 Measured mass of mercury in the resin layers (A, Duolite GT73; D, Iontosorb AV-MP) immersed in a Hg solution (10 mg L–1) for various periods. Equation (1) predicts the dashed line.

of Brno) in April, 2008, five DGT sampling units filled with agarose diffusive gel and Iontosorb AV-MP resin gel were deployed under comparable conditions. Similar results as in July 2007 were obtained. The DGT measured concentration in the Svitava River was 75 ± 9 ng L–1, while the total dissolved concentration was 102 ± 7 ng L–1.

Conclusions This study demonstrated that there are some possibilities to replace Spheron-Thiol resin gel in diffusive gradients in the thin-films technique in order to measure mercury in an aquatic environment. There are no mercury specific resins applicable for direct use in the DGT technique on the market; however, some available resins can be used after a pretreatment in the laboratory. As an example of this approach, we used Duolite GT73 resin. After graining, sieving and acid washing of this resin it was useable for incorporation into the polyacrylamide gel. Another possibility is to prepare characteristic resin directly in the laboratory. For this purpose, we used Iontosorb AV resin, which was modified with 6-mercaptopurine using simple diazotation and coupling reactions. All resin gels prepared from Duolite GT73 or Iontosorb AV-MP resins match all of the requirements for a correct function of the DGT technique. After verification of DGT in the laboratory, the DGT technique with new resin gels was successfully used to measure the in situ mercury concentration in Svitava River.

578

Acknowledgements This work has been supported by grants No. GABR 525/09/P583, MEB 080813 and SK-CZ-0044-07. Mr. Oldîch Tokar is acknowledged for providing a free Iontosorb AV sample.

References 1. H. Zhang and W. Davison, Anal. Chem., 1995, 67, 3391. 2. P. Diviš, H. Dobekalová, and V. ≠ezábová, Chem. Listy, 2005, 99, 640. 3. M. P. Harper, W. Davison, and W. Tych, Aquat. Geochem., 1999, 5, 337. 4. O. A. Garmo, O. Royset, E. Steinnes, and T. P. Flaten, Anal. Chem., 2003, 75, 3573. 5. H. Dobekalová and P. Diviš, Talanta, 2005, 65, 1174. 6. P. Diviš, M. Leermakers, H. Dobekalová, and Y. Gao, Anal. Bioanal. Chem., 2005, 382, 1715.

ANALYTICAL SCIENCES APRIL 2009, VOL. 25 7. O. Clarisse and H. Hintelmann, J. Environ. Monit., 2006, 8, 1242. 8. I. Cattani, S. Spalla, G. M. Beone, A. A. M. Del Re, R. Boccelli, and M. Trevisan, Talanta, 2008, 74, 1520. 9. M. F. Wolfe, S. Schwarzbach, and R. A. Sulaiman, Environ. Toxicol. Chem., 1998, 17, 146. 10. M. Smrž and J. Hradil, Czech. Patent AO, 1978, 190171. 11. P. Pohl and B. Prusisz, Microchim. Acta, 2005, 150, 159. 12. P. Pohl and B. Prusisz, Anal. Sci., 2004, 20, 1367. 13. S. Chiarle, M. Ratto, and M. Rovatti, Water Res., 2000, 34, 2971. 14. J. A. Ritter and J. P. Bibler, Water Sci. Technol., 1992, 25, 165. 15. R. V. Davies, J. Kennedy, E. S. Lane, and J. L. Willans, J. Appl. Chem., 1958, 8, 68. 16. B. C. Mondal, D. Das, and A. K. Das, Anal. Chim. Acta, 2001, 450, 223. 17. V. Stefanidesová, J. Saidlerová, and P. Dvorská, Chem. Listy, 2002, 96, 117. 18. W. Li, H. Zhao, P. R. Teasdale, and F. Wang, Talanta, 2005, 67, 571.

Anal Bioanal Chem DOI 10.1007/s00216-006-0996-y

ORIGINAL PAPER

Use of the diffusive gradients in thin films technique to evaluate (bio)available trace metal concentrations in river water Pavel Diviš & Hana Dočekalová & Lukáš Brulík & Marek Pavliš & Petr Hekera

Received: 1 August 2006 / Revised: 11 October 2006 / Accepted: 7 November 2006 # Springer-Verlag 2006

Abstract Concentrations of Cd, Cu, Cr, Pb, Ni and Zn were monitored in the Svitava River (the Czech Republic) during April and September 2005. Total concentrations and total dissolved concentrations were obtained through regular water sampling, and the diffusive gradients in thin films technique (DGT) were used to gain information on the kinetically labile metal concentrations. Each measured concentration was compared with the corresponding average (bio)available concentration calculated from the mass of metal accumulated by the moss species Fontinalis antipyretica. The concentrations of Cd, Pb, Cr and Zn measured using DGT corresponded well with those obtained after the deployment of Fontinalis antipyretica moss bags in the Svitava River, but the concentrations of Cu and Ni did not. The calculated (bio)available Cu concentration correlated well with the total dissolved concentration of Cu, whereas no correlation was found to exist between the concentrations of Ni. Keywords Diffusive gradients in thin films technique . Bioavailabilty . Trace metals . Svitava River

Electronic supplementary material Supplementary material is available in the online version of this article at http://dx.doi.org/ 10.1007/s00216-006-0996-y and is accessible for authorized users. P. Diviš (*) : H. Dočekalová : L. Brulík Institute of Chemistry and Technology of Environmental Protection, Brno University of Technology, Faculty of Chemistry, Purkyňova 118, 61200 Brno, Czech Republic e-mail: [email protected] M. Pavliš : P. Hekera Department of Ecology, Palacký University, Faculty of Science, Tr. Svobody 26, 77146 Olomouc, Czech Republic

Introduction Measurements of (bio)available metal concentrations present a challenge to environmental and analytical chemists because they involve specific techniques and skills. Supported liquid membranes [1–3], ion exchange techniques [4–7] or anodic stripping voltammetry [1, 8, 9] have been used to perform such measurements in recent years. The main disadvantage of those methods is their limited applicability for in situ measurement. Such methods are performed in the laboratory, often many hours after sample collection. Given that changes in metal speciation can occur over this period of time, the representativeness of the data obtained is questionable. In 1994 Davison and Zhang introduced a new in situ technique for the measurement of kinetically labile metal species in natural waters [10], known as the “DGT” (diffusive gradients in thin films) technique. The DGT technique utilizes a three-layer system consisting of a sorption layer, a diffusion layer and a filter membrane [11]. For trace metal analysis, a sorption layer consisting of the Chelex 100 resin impregnated with a polyacrylamide hydrogel and a diffusion layer consisting of a clear polyacrylamide hydrogel are commonly used [11–13]. However, other sorption and diffusion layers have also been described [14–16]. Metal species from the bulk solution diffuse across the filter membrane (isolating the polyacrylamide hydrogels from particles in water) and across the diffusive gel layer. Finally, the metals are preconcentrated on the resin encapsulated within the sorption gel. Metal consumption within the sorption layer results in a zero concentration of metal species on the sorption gel surface. Therefore, a concentration gradient is established between the sorption layer and the bulk solution, which provides the motivation for other metal

Anal Bioanal Chem

species to diffuse through the diffusion layer. Applying Fick’s first law of diffusion, the concentration cDGT of the metal species in the bulk solution may be calculated using the mass m of metals accumulated in the sorption layer, the DGT sampler exposure time t, the thickness of the diffusion layer Δg, and the temperature-corrected molecular diffusion coefficient D for the metal of interest:

month from April to September 2005, and all of the concentrations measured using the different techniques were then compared.

cDGT ¼ m:Δg=D:A: t

Collection of moss samples and exposure procedure

Materials and methods

ð1Þ

As numerous experiments show that the biological effects of trace metals are related to the activities of the corresponding free metal ions [17–19], it has been tempting for researchers to assume that the DGT-measured metal fraction is the (bio)available fraction, although from geochemical, biological, and analytical perspectives, the term ‘‘bioavailable fraction’’ is context-specific and quantitatively elusive [20]. In order to be certain that the DGT technique can be used as a tool for the assessment of metal bioavailability in natural waters, a comparison of DGT-measured concentrations with the amount of metals accumulated by living organisms is needed. Until recently, very little work has been done in this field, and the most of it has been performed under laboratory conditions. Webb and Keough [21] compared the in situ DGT-measured concentrations with those recorded through the deployment of transplanted mussels. Nevertheless, this comparison of these two techniques was limited by the fact that the deployments took place in different years and for different deployment times. This work summarizes the results from experiments performed at the Svitava River (Czech Republic, southern Moravia). The aim of this experiment was to investigate the ability of the DGT technique to measure (bio)available trace metal concentrations. During this experiment, the concentrations of Cu, Cd, Cr, Pb, Ni and Zn were monitored using regular water sampling, the DGT technique, and also the moss bag technique (which used the Fontinalis antipyretica species of moss). Fontinalis antipyretica was chosen for the study because it is commonly found in most European rivers and it is widely used to gain time-integrated information about the biological impacts of trace metal pollution [22–26]. The moss bags and DGT sampling units were deployed together for 28 days each

Table 1 Medians and median standard deviations for the measured total dissolved concentrations of metals (μg dm−3) in Svitava River (n=8)

April May June July August September

Moss samples of Fontinalis antipyretica were collected each month from the Oslava River near the village of Dlouhá Loučka (longitude 49°50′8″N, latitude 17°12′41″E). The moss tufts were carefully rinsed in river water in order to remove any particles and epifauna attached and were then placed into precleaned polyethylene containers. The moss samples were subsequently transported to the monitoring station, where approximately 20 g of wet moss sample was placed into the monitoring device. It remained there for 28 days. The monitoring device was situated in Svitava River in the Obřany part of Brno (longitude 49°13′32″N, latitude 16°39′42″E). Analysis of moss samples The mosses were subsequently washed with distilled water in the laboratory and dried at 40 °C. The plant material was powdered in the mortar and then wet-ashed in a Milestone (Bergamo, Italy) 1200 microwave oven. Three subsamples each approximately 100 mg in dry weight were weighed into Teflon containers and decomposed with 6 ml of a mixture (2:1) of nitric acid (Merck, Darmstadt, Germany) and hydrogen peroxide (ML Chemica, Brno, Czech Republic) using a defined time–performance program. Cd, Pb and Ni analyses were performed with graphite furnace AAS (Varian SpectrAA-40, Mulgrave, VIC, Australia), while Zn and Cu were analyzed with flame AAS (Varian SpectrAA-30). A quality check material (Metranal-8, green algae, Analytika, Nymburk, Czech Republic) was used to control the quality of the method. The recovery rates were as follows for each of investigated elements (percentage with S.D.): Cd (95±4), Cu (98±5), Cr (94±3), Pb (94±5), Ni (105±6), Zn (102±4).

Cd

Cu

Cr

Pb

Ni

Zn

0.13±0.08 <0.10 0.10±0.06 0.12±0.04 <0.10 <0.10

2.2±0.5 0.5±0.2 1.2±0.1 1.1±0.4 1.4±0.3 1.0±0.2

2.1±0.7 1.9±0.6 0.56±0.08 1.5±0.4 0.9±0.2 0.23±0.04

0.26±0.04 <0.20 <0.20 0.29±0.05 <0.20 <0.20

2.8±0.4 1.5±0.3 1.6±0.3 1.7±0.4 2.3±0.2 1.6±0.4

14.3±2.5 3.3±0.5 8.7±2.8 8.6±1.6 4.2±1.0 3.5±1.2

Anal Bioanal Chem Table 2 Medians and median standard deviations for the measured total concentrations of metals (μg dm−3) in Svitava River (n=8)


Cd

Cu

Cr

Pb

Ni

Zn

0.19±0.04 0.12±0.02 0.14±0.02 0.17±0.03 <0.10 0.11±0.02

4.2±0.3 0.9±0.2 2.3±0.4 1.9±0.2 2.5±0.3 1.8±0.2

4.5±0.3 4.2±0.2 1.4±0.2 3.2±0.4 2.1±0.1 0.5±0.1

0.4±0.1 0.25±0.08 <0.20 0.6±0.2 0.23±0.04 0.3±0.1

3.6±0.3 1.9±0.2 2.1±0.1 2.2±0.2 3.2±0.2 2.0±0.1

25.5±4.5 6.2±0.8 15.9±1.5 14.8±2.3 7.6±1.2 5.9±1.5

The average concentrations of available trace metals in the river water (cw) recorded through the application of moss bags were calculated using Eq. 2: cw ¼ ½ðca cb Þ:k1: ρ=k1

ð2Þ

The uptake (k1) and release (k−1) constants for the metals of interest were determined experimentally in river water solution [Pavliš M, 2005, unpublished data] according to a procedure described elsewhere [27]. The parameter ca in Eq. 2 represents the accumulated concentration of metal in the moss tissue after 28 days of exposure in river water (μg kg−1), while cb is the blank concentration of metal in the moss tissue (μg kg−1) and ρ is the density of water (g cm−3). Water sampling and analysis Twice a week, at approximately the same time of day, two types of water samples were collected. One sample represented the total trace metal concentrations, while the second one, filtered through a 0.45-μm disposable filter unit, represented the dissolved only concentrations of the trace metals. Immediately after the samples had been collected, they were acidified with 1% nitric acid (Merck). Trace metal analysis was performed by graphite furnace AAS.

Results and discussion

Preparation of and exposure procedure for the DGT samplers

Dissolved and total trace metal concentrations Measured dissolved (0.45 μm filterable) and total (unfiltered) concentrations of the metals of interest are shown in Tables 1 and 2. Because the concentration data set for each month contained a wide range of values, median and median standard deviation values were used to estimate the position and variability parameters. The concentrations of Cd and Pb in the Svitava River were very low and they fluctuated around the limit of

Polyacryamide resin gels containing Chelex 100 resin (Naform, 200–400 mesh, Bio-Rad, Hercules, CA, USA) with a thickness of 0.4 mm and diffusive gels with a thickness of 0.8 mm were prepared according to the procedure described by Zhang and Davison [11]. The DGT samplers were assembled by inserting the Chelex 100 resin gel inside the piston-type DGT sampler (DGT Research Ltd., Lancaster, Table 3 Average and standard deviations of the DGTmeasured concentrations of metals (μg dm−3) in Svitava River (n=8)


UK). The resin gel was then covered with the diffusive gel and with a Millipore (Bedford, MA, USA) membrane filter (cellulose acetate, 0.45 μm pore size, 0.13 mm thickness). Finally, the DGT sampler was closed. The front part of the DGT sampler was equipped with a window. The precision of the DGT method during the laboratory tests performed in a model metal solution was better than 10% for all metals of interest, which match the requirements of DGT Research Ltd. for the correct application of DGT. Each month, at the same time as the moss deployment, eight DGT samplers were fixed to the monitoring device using a fishing-line. The DGT samplers floated freely approximately 15 cm below the river surface. After 28 days of exposure in the Svitava River, the DGT samplers were transferred in clean PE bags to the laboratory, where they were carefully rinsed with deionized water and the resin gels were extracted. The resin gels were then placed into 1.5 cm−3 centrifugation vials and 1 cm−3 of 1 mol dm−3 nitric acid was added. Following 24 hours of resin gel elution, trace metal analysis in the eluate was performed using graphite furnace AAS.

Cd

Cu

Cr

Pb

Ni

Zn

0.009±0.002 0.004±0.001 0.005±0.001 0.005±0.001 0.006±0.002 0.005±0.002

0.072±0.011 0.063±0.005 0.051±0.009 0.042±0.007 0.041±0.005 0.054±0.009

0.80±0.18 0.50±0.09 0.64±0.05 0.47±0.12 0.50±0.09 0.54±0.07

0.19±0.05 0.062±0.015 0.035±0.009 0.041±0.008 0.052±0.011 0.044±0.013

1.7±0.4 0.61±0.16 0.46±0.06 0.39±0.12 0.30±0.07 0.33±0.05

4.7±0.6 3.8±0.4 3.7±0.5 2.5±0.2 3.4±0.4 3.5±0.1

Anal Bioanal Chem Table 4 Means and standard deviations of the calculated (bio)available concentrations of metals (μg dm−3) in Svitava River (n=3)


Cd

Cu

Cr

Pb

Ni

Zn

0.0025±0.0011 0.0040±0.0020 0.0027±0.0032 0.0032±0.0015 0.0021±0.0009 0.0033±0.0017

1.3±0.2 0.77±0.15 1.06±0.21 0.75±0.17 0.71±0.12 0.57±0.15

0.17±0.08 0.11±0.09 0.45±0.15 0.35±0.12 0.41±0.04 0.38±0.05

0.051±0.015 0.060±0.021 0.029±0.007 0.012±0.005 0.023±0.011 0.030±0.013

0.12±0.04 0.10±0.06 0.042±0.008 0.05±0.02 0.043±0.014 0.051±0.018

3.8±0.2 2.6±0.3 5.0±0.2 1.7±0.2 4.5±0.3 5.2±0.4

detection, which was 0.1 μg dm−3 for Cd and 0.2 μg dm−3 for Pb. The highest concentrations of Cu, Cr, Ni and Zn were measured in April and, except for Zn (which exhibited a concentration of around 15 μg dm−3), they oscillated around 3 μg dm−3. The lowest concentrations of Cu, Zn and Ni were found in May, while the lowest concentrations of Cr were detected in September. All of the concentrations measured were under the maximum permissible values set by the United States Environmental Protection Agency [28].

captured in the resin inside the DGT sampling unit. The DGT concentrations of Cd, Pb and Zn fluctuated around 0.005, 0.05 and 3 μg dm−3, respectively (Table 3). The high DGT concentrations of metals measured in April (as well as the high concentrations of dissolved and total metals) are related to the spring flood on the Svitava River. This caused the resuspension of the bottom sediments and their transport downstream together with other solid particles. During this event, metals from solid particles can be released into the water column [29–31].

The DGT-measured concentrations

Mass of metals accumulated by Fontinalis antipyretica

There were no large differences in the concentrations of dissolved Ni, Cr and Cu in water samples from the Svitava River during the experiment (see Table 1); however, the DGT-measured concentrations of these metals differed substantially from each other. The results for the DGTmeasured concentrations are summarized in Table 3. While the DGTNi and DGTCr concentrations are comparable at about 0.5 μg dm−3, the DGTCu concentration is ten times lower than this. This indicates that the Cu in the dissolved fraction forms a different type of species compared to Ni and Cr. Most of the Cu probably bonded with strong natural ligands and can pass through the 0.45 μm pore size filter and diffuse through the diffusive gel, but it cannot be

The average blank concentrations of metals in Fontinalis antipyretica collected from the Oslava River were 0.015±0.006 μg kg−1 Cd, 0.020±0.005 μg kg−1 Cu, 0.030±0.012 μg kg−1 Cr, 0.010±0.005 μg kg−1 Pb, 0.040± 0.015 μg kg−1 Ni and 0.45±0.16 μg kg−1 Zn. These results correspond to the metal contents found in affected mosses in other European rivers. The average masses of accumulated metals were 4.1±1.7 μg kg−1 Zn, 0.48±0.23 μg kg−1 Cu , 0.31±0.09 μg kg−1 Cr, 0.25±0.13 μg kg−1 Ni, 0.17± 0.08 μg kg−1 Pb and 0.016±0.004 μg kg−1 Cd. Similar accumulation rates for Fontinalis antipyretica have been described for example after deployment in the Elbe River (Germany), the Tocce River (Italy) or in the streams of the

Fig. 1 Comparison of the concentrations (μg dm−3) of Zn in Svitava River obtained from Fontinalis antipyretica (black) and DGT (white). Similar dependencies were found for Pb, Cd and Cr

6 5 4 3 2 1 0 April

May

June

July

August

September

Anal Bioanal Chem Table 5 Coefficients of correlation between the DGT-measured concentrations and the calculated (bio)available concentrations (A) as well as the correlations between the measured total dissolved concentrations and the calculated (bio)available concentrations (B)

A B

Cd

Cr

Cu

Pb

Ni

Zn

0.6124 −0.5587

0.7137 −0.8414

0.2352 0.6436

0.6138 0.1039

0.0512 0.1049

0.7623 −0.2179

Walbrzyskie mountains (Poland) [32–34]. The average concentrations of (bio)available trace metals in the river water were calculated using Eq. 2 from the mass of metals accumulated in the moss Frontinalis antipyretica. The results are shown in Table 4. Comparison of all measured and calculated metal concentrations The ratios of the total to the total dissolved trace metal concentrations in Svitava River decreased in the following order: Ni (0.75) > Cd (0.72) > Pb (0.68) > Zn (0.55) > Cu (0.53) > Cr (0.45). This indicates that Ni, Cd and Pb were mainly bound in large colloids or on solid particles, whereas Zn, Cu and Cr occurred more as hydrated ions or small inorganic complexes in the water column and were thus potentially more bioavailable. These results from direct water sampling agree with the measured accumulated masses of metals in Fontinalis antipyretica, as the accumulation of metals in the plant tissue follows the sequence: Zn > Cu > Cr > Ni > Pb > Cd. The (bio)available concentrations of studied metals in the Svitava River calculated from the masses of each metal accumulated in Frontinalis antipyretica were compared with the kinetically labile fractions of metals measured by DGT. The DGT-measured fractions of Cd, Cr, Pb and Zn were proportionally related to the biological uptake of metals by Fig. 2 Comparison of the concentrations (μg cm−3) of Cu in Svitava River obtained from Fontinalis antipyretica (black), DGT (white), as well as the total dissolved Cu (shaded)

aquatic moss Frontinalis antipyretica (Fig. 1, Table 5). These results show that DGT can be used to evaluate the (bio)available proportions of metals in fresh water. Nevertheless, exceptions were found for Cu and Ni. The DGTCu concentration was 15 times lower than the calculated (bio) available concentration. This indicates that Fontinalis antipyretica is also able to accumulate dissolved Cu species other than DGT-labile ones. Calculated (bio)available concentrations for Cu correlate better with the dissolved concentrations of Cu in the river water (Fig. 2, Table 5). In contrast, the DGTNi concentration was found to be ten times higher than the calculated (bio)available concentration. In addition, none of the Ni concentrations obtained by DGT and aquatic moss Fontinalis antipyretica correlated with the dissolved fraction of Ni. Different incorporation mechanisms and uptakes of Ni and Cu to the Fontinalis antipyretica were probably the reason for this distinction.

Conclusion This study demonstrates that the concentrations of Cd, Cr, Pb and Zn measured by DGT in river water are comparable with the (bio)available concentrations obtained through the use of moss bags containing the Frontinalis antipyretica aquatic moss species. On the other hand, significant differences were observed between DGTCu and DGTNi concentrations and (bio)available concentrations. The biological membranes that largely influence the accumulation of trace metals by biota form complicated systems that are difficult to fully simulate with any passive sampler (including DGT) based on physical and chemical principles. Moreover, during the process of trace metal accumulation by biota, factors than the free diffusion of metals through biological membranes play significant roles (e.g., metabolism and organism conditions). These factors complicate result interpretation.

Anal Bioanal Chem

Despite some differences between the (bio)available concentrations calculated from the accumulation of metals in aquatic moss Frontinalis antipyretica and DGT-measured concentrations, the diffusive gradients in thin films technique is still at the present time the most promising in situ technique available for the assessment of (bio)available trace metal concentrations in natural waters, and further investigation of this technique in this field is therefore required. Acknowledgement The work was supported by the Ministry of Education, Youth and Sports of the Czech Republic (Projects No. MSM 0021630502 and G4/814/2005 of FRVS). J.P. Matousek is gratefully acknowledged for helpful comments and for help with manuscript preparation.

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Science of the Total Environment 362 (2006) 266 – 277 www.elsevier.com/locate/scitotenv

High-resolution profiles of trace metals in the pore waters of riverine sediment assessed by DET and DGT Y. Gao a , M. Leermakers a , C. Gabelle b , P. Divis c , G. Billon b , B. Ouddane b , J.-C. Fischer b , M. Wartel b , W. Baeyens a,⁎ a

b

Laboratory of Analytical and Environmental Chemistry (ANCH), Faculty of Sciences, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Laboratorie de Chimie Analytique et Marine, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France c Brno University of Technology, Brno, Czech Republic Received 30 June 2005; received in revised form 16 November 2005; accepted 20 November 2005 Available online 10 January 2006

Abstract The techniques of DET (diffusive equilibrium in thin films) and DGT (diffusive gradients in thin films) were applied to obtain high-resolution vertical profiles of trace metals in freshwater sediments. In the framework of the EU-Interreg project Stardust (http://www.vliz.be/projects/stardust/) between France and Belgium, in which the mobility of sediment bound metals is investigated, sediment samples were collected from the Upper Scheldt River (at Helkijn, Belgium) and the Leie River (at Warneton, located at the Belgian–French border). Intra- and inter-laboratory comparisons of the gel techniques were carried out between the two laboratories involved. In general, a good agreement was observed, taking sediment heterogeneity into account. At both stations, metal pore water profiles show more or less similar tendencies although the sediment at Warneton was more anoxic than at Helkijn. A strong correlation between Fe and Co was found at Helkijn as well as at Warneton. The metal gradients at the water/ sediment interface were calculated from the high resolution profiles and the conventional, low resolution profiles. Significant differences were observed. © 2005 Elsevier B.V. All rights reserved. Keywords: DET; DGT; Trace metals; High resolution

1. Introduction The river Scheldt (L'Escaut in France) is a lowlandriver, which takes its rise in the northern part of France (St. Quentin), and flows into the North Sea near Vlissingen (The Netherlands). The total catchment area is 22 × 103 km2. The total length of the river is 355 km, the fall over the total river length is at most 100 m and the mean depth of the Scheldt Estuary is about 10 ⁎ Corresponding author. Tel.: +32 2 629 3602; fax: +32 2 629 3274. E-mail address: [email protected] (W. Baeyens). 0048-9697/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2005.11.023

m. The river Leie (La Lys in France) is the major tributary of the river Scheldt in Flanders. It rises in the hills of Artois in France and flows NE to Gent forming the border between Belgium and France for 24 km. The pollution of the Scheldt Estuary (about 90 km long) has been studied into detail (Baeyens, 1998), but that of the upper river is not so well documented. In northern France, important metallurgical non-ferrous plants such as Metaleurop and Umicore are located along the river Deule, a major tributary of the upper Leie. High loads of numerous metals are discharged into the Deule, ranking this river as one of the most contaminated in Europe

Y. Gao et al. / Science of the Total Environment 362 (2006) 266–277

regarding water and sediment quality (Bourg et al., 1989). Part of this pollution is transported further downstream subsequently contaminating the river Leie and the Scheldt. In addition, the textile industry in southern Belgium (the area around Kortrijk) enhances the contamination level of the river Leie. Regarding heavy metals, the upper river Scheldt has a better water quality compared to the river Leie. The Spierre Canal (Canal de l'Espierre in France) connecting the river Leie (in France) to the Upper Scheldt (in Belgium) is a major contributor to the pollution level of the upper Scheldt River (see database of VMM, www.vmm.be). Going downstream, small factories (painting, dyes, metallurgy, and so on) also contribute to a further decrease of the water quality of the river. The important historical discharges of metals in the upper Scheldt and Leie rivers also lead to elevated levels in the bottom sediments. Due to the surface water characteristics, especially the low levels of dissolved oxygen, an important fraction of the metals are safely stored in the anoxic bottom sediments as stable metal sulfide species. However, European regulations, such as for example the water directive (Water Framework Directive 2000/60/EC), force the Member States to comply with the new water quality standards. Therefore, wastewater treatment plants are actually built or are yet operational improving progressively the water quality. We must be aware, however, that a sudden release of the metal burden from the sediments can be triggered by any modification, even seemingly insignificant, of the sediment environment (such as variation in pH or an increased supply of oxygen from the water column as a result of actual measures for waste water treatment or as a consequence of dredging). This phenomenon is called the sediment “time bomb” by geochemists studying contaminated anoxic sediments. Actually we are not able to predict the amount of trace metals that could be released from the sediments of the upper Scheldt and Leie rivers, as a consequence of abrupt changes in pH or redox. Therefore, understanding the behavior of trace metals (mobilization and transport) in those sediments becomes urgent. Because in a natural system trace metals can exist in a variety of species (differentiation can be carried out according to oxidation state, labile or non-labile bound to a ligand, colloid or dissolved, etc.), it is critical to know the distribution between these species as well as the processes controlling them. To study those complex processes in the river Scheldt and Leie sediments, the laboratories of Lille and Brussels universities joined forces. In strong anoxic estuarine sediments, where sulphate reducing bacteria are active, the heavy metals

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are trapped as poorly soluble metal complexes whereas in other sediment types (oxic or sub-oxic) metals tend to be redissolved due to the oxidation of organic matter or due to the reduction of particulate Fe and Mn oxyhydroxides (Panutrakul and Baeyens, 1991). Normally in an organic-rich area, Pb appears to be more associated with aluminosilicates and excess-Fe and Mnphases, while Cu and Zn are generally correlated with organic matter (Dehairs et al., 1985). The degradation of freshly deposited organic matter controls in fact the distribution of Pb, Cu and Zn in bottom sediments. The previous studies were all carried out with conventional techniques: trace metals in sediments were assessed after slicing the sediment core and centrifugation or squeezing of the slices, achieving a relatively low spatial resolution (N1 cm). Either for centrifugation or squeezing, sectioning sediment cores should be carried out in a plastic glove-bag which during operation is kept oxygen free, by means of high purity nitrogen gas. With these techniques, artifacts could be created because even a short contact with a limited amount of oxygen can disturb significantly the original species distribution. Fe2+ is very sensitive to oxidation and will then precipitate. In addition, the profiles given by these conventional techniques have a common limitation especially at the surface of the sediments because the spatial resolution (typically 1 cm) is insufficient for studying geochemical processes. Since the recent development of DET and DGT techniques (Davison et al., 1991; Davison and Zhang, 1994), high-resolution vertical profiles of metals in sediment pore waters can be assessed. With the DET technique, pore water concentration in sediment can be assessed directly (Davison et al., 1991). DET compares with the technique of dialysis peepers (vertical disposed set of dialysis cells, but instead of putting a solution in the compartments, it uses a gel that equilibrates much faster). According to Davison et al. (1991), equilibration for a typical dialysis cell (1 cm deep) and a DET gel (1 mm thick) would take 3 days and 42 minutes, respectively. According to Haper et al. (1997), equilibration for a dialysis cell (6 mm) and a DET gel (0.4 mm thick) would take 36 hours and 18 minutes, respectively. The DGT technique, based on mass transport control of the species of interest from natural water (Zhang et al., 1998a,b; Dahlqvist et al., 2002), soils (Zhang et al., 1998a,b; Harper et al., 1998) and sediment pore waters (Zhang et al., 2002; Fones et al., 2004), makes use of two hydrogel layers. A polyacrylamide gel is used as the diffusive layer, but it is backed up with a second thin film gel layer containing generally a chelex cationexchange resin selective for trace metals. The diffusive

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layer is placed in the DGT probe on top of the binding phase and covered with a membrane (0.45 μm). DGT does not directly measure the concentration of metals in bulk pore water, Cb, but rather the mean concentration, Cs, at the surface of the probe during deployment (Fones et al., 2004). The relationship between Cs and Cb depends upon the re-supply of the metal from the solid phase to solution. A full explanation of the relationship is given in Zhang et al. (2001), Harper et al. (1998) and Davison et al. (2000). Due to the structure of the DGT probe, this technique will measure only dissolved species with molecular sizes sufficiently smaller than the pore size of the hydrogel to allow them to diffuse freely through it, and which are sufficiently labile to bind on the resin's functional groups. Normally, the Chelex-100 resin is used, because the functional group, iminodiacetic acid, competes effectively with natural ligands for divalent and trivalent metal ions. However, alternative resins are described, such as the synthetic ferrihydrite resin for phosphates (Zhang et al., 1998a,b), AG50W-X cation-exchange resin for radioactive Cs and Sr (Chang et al., 1998) and the Spheron–Thiol resin for mercury (Docekalova and Decekalova, 2004; Divis et al., 2005). In this study, in the framework of the EU-Interreg project Stardust (http://www.vliz.be/projects/stardust/)

between France and Belgium, DET and DGT systems have been deployed in sediment pore waters of transboundary rivers in Northern France (Nord Pas de Calais) and Western Belgium (West-Flanders) area (see Fig. 1) for the determination of vertical high-resolution metal profiles. The results are compared to those obtained by classical techniques, which are less effective in terms of resolution, but can be applied as a kind of control. 2. Materials and methods 2.1. Sampling area Fine grain, muddy sediments were found at the sites of Warneton (river Leie, at the Belgian–French border), which is at the junction of an old natural river's stretch (navigation free) and a canalized part (used for navigation) and at Helkijn station, located in Belgium on the river Scheldt (Fig. 1). Samples were collected from a shallow flat close to the riverside. Plexiglas tubes and rubber stoppers were used for collection. The cores were retrieved by hand allowing 15 cm overlying water to remain above the sediment. Sampling was performed by research groups of both the Vrije Universiteit Brussels (VUB) and the Université des Science et Technologie de Lille (USTL).

Fig. 1. Sampling stations.


Sediment cores were collected for 1) the application of DET and DGT techniques, 2) pH and redox measurements and 3) the analysis of major ions, nutrients, alkalinity and trace metals in pore waters using the conventional sectioning and centrifugation technique. The DET and DGT techniques were then applied by both groups on their respective cores, allowing an interlaboratory comparison. Samples were collected always a few meters away from each other. 2.2. Measurement of redox potential and pH Field measurements of redox potential and pH performed on one of the tubes, which had pre-drilled holes at 1-cm intervals, covered with tape during collection of the sediments. Electrodes were inserted in the holes to measure redox potential and pH. Measurements were realized with a combination platinum electrode (Mettler Toledo/Pt4800) and measurements of pH were realized with a combination glass electrode (Mettler Toledo/Pt4800) made especially for abrasive and hard medium. For both electrodes, the reference electrode is Ag/AgCl, [KCl] = 3 M. 2.3. DET probe preparation The procedure is similar to that of Zhang et al. (1995). A gel containing 1.5% agarose was prepared by its dissolving in an appropriate volume of 80 °C warm Milli-Q water. The mixture was placed in a boiling water bath, covered and gently stirred until all the agarose was dissolved and the solution was immediately pipetted into a preheated gel-casting probe and left to cool down to its gelling temperature (36 °C or below). The constrained DET probe's material was obtained from DGT Research Ltd. The size of the DET probes was 180 mm × 40 mm, with a window of 150 mm × 18 mm open to the aquatic system. After the gels were set, they were covered with a 0.45-μm cellulose acetate filter (Millipore). Finally the window plate was put on top of the probe and all the elements gently pressed together. Before deployment of the DET probes, they were stored in Milli-Q water. 2.4. DGT probe preparation Diffusive gel and resin gel were prepared as described by Zhang et al. (1995). The DGT probes (DGT Research Ltd.) were 180 mm × 40 mm in size, with a window of 150 mm × 18 mm open to the aquatic system. The resin gel was covered by diffusive gel and a 0.45-μm pore size cellulose acetate filter. The front

269

window plate gently pressed the various layers together. The probes were stored at 4 °C in a closed plastic bag containing 1 ml 0.01 M trace metal free NaCl solution (5–10 g Chelex-100 were added for removing trace metals). 2.5. The deployment of handling of DET and DGT probes Before deployment, the entire DET gel assemblies were de-oxygenated by immersing them for 24 h in a container filled with Milli-Q water and bubbling with nitrogen, whereas DGT probes were deoxygenated for 24 h in a container filled with metal free (using Chelex100) NaCl (0.1%) solution. After sampling, the cores to be used for deployment of the DET and the DGT were immediately taken back to the laboratory. Deployment was performed at laboratory temperature at 20 °C ± 0.5 °C during 24 h. A couple of DET and DGT probes, arranged back to back, was inserted into one core. The interface of water and sediment was marked when the probes were retrieved from the sediment core. In the laboratory all the manipulation of the gels were carried out in a laminar flow hood located in a clean room. The DET gels (typically 20 μl) were transferred into preweighed 2-ml tubes, weighed and eluted in 1 ml 1 N HNO3. They were generally not further diluted for analysis. The DGT probes were opened, the filter and diffusive gel were removed and the resin gel was cut into 5-mm intervals using a Plexiglas gel cutter. Each gel slice was eluted in 1 ml 1 N HNO3 for 24 h and further diluted to 10 ml for analysis by ICPMS. Blank DET and DGT went through all previous described steps including casting, probe construction, and deoxygenation except for the deployment step. They were treated in the same way as the sample probes. The DGT probe was sliced into 32 intervals of 5 mm; 10 slices were randomly chosen for analysis. For the DET probe, 10 of 75 blank slices were randomly chosen for analysis. 2.6. Conventional sampling and centrifugation All handling including sample sectioning and filtration was carried out inside a nitrogen flushed glove-bag. The cores collected with conventional presectioned core samplers were cut after removing each time the plastic cover, and put in the centrifuge vessels. The samples were then sealed in order to prevent oxidation. Then they were centrifuged for 30 min at 2500 rpm. To eliminate residual small size particles, the obtained pore water was further filtered

270


through a 0.45-μm cellulose acetate disposable filter, collected in a clean polyethylene tube and acidified with 1% HNO3. 2.7. Analysis A high-resolution inductively coupled mass spectrometry (HR-ICPMS) (Thermo Finnigan Element II) was used to determine the concentrations of the elements As, Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn by VUB. USTL used a Thermo Elemental X7 Series ICPMS for the determination of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn. Fe and major elements were determined by a Varian VistaPro ICP–AES (USTL) and a Thermo Optek Iris ICP–AES (VUB). Metals in the solid sediment phase were determined by HR-ICPMS (Thermo Finnigan Element II) after aqua regia digestion in a microwave oven (CEM Mars 5). NO3− , SO42− , Cl − , F − were determined by ion chromatography (DIONEX DX 500) using an anionic column AS11. NO3− , NO2−, NH4+, PO43− were also determined with classic colorimetric techniques. Alkalinity was measured by potentiometric microtration on a 1-ml sample using an automatic titrator (Metrohm, Titrino 736GP). 3. Results 3.1. Ion balances in the pore waters of Helkijn and Warneton sampling stations In sediment pore waters of Helkijn and Warneton sampling stations, all major cations and anions were determined after conventional sectioning of the core and centrifugation of the slices (see Materials and methods). The sum of all major cation concentration should match that of the anion concentration. The goodness of fit of the ion balance is an indication of the quality of analysis. In addition, for modeling the trace metal behavior in sediments, the major ion concentrations are necessary. At four different depths, ion balances were calculated (Table 1a–b). The concentrations of carbonate and bicarbonate were derived from the total alkalinity, the pH, the temperature and the thermodynamic stability constants involved in the various equilibria of the carbonate system. The sum of positive ion concentrations (mM) = 3 * (Al3+) + 2 * (Ca2+) + 2 * (Fe2+) + 2 * (Mg2+) + 2 * (Mn2+) + 2 * (Zn2+) + 2 * (Sr2+ ) + 4 * (Si4+) + (Na+ ) + (K+) + (NH4+). The sum of negative ion concentrations (mM) = 2 * (HPO42−) + 2 * (SO42−) + 2 * (CO32−) + (NO3−) + (Cl−) + (F−) + (HCO3−). The ionic balance was very good at Warneton

Table 1 Ion balances at (a) Warneton and (b) Helkijn calculated from the concentrations of positive and negative ions Depth (cm)

Concentration of positive ions (mM)

Concentration of negative ions (mM)

(a) Warneton −1 16.1 −5 15.8 −9 17.6 − 17 25.5

16.5 15.2 19.2 25.9

(b) Helkijn −3 −7 − 11 − 15

11.1 10.1 10.9 11.4

8.9 8.4 9.0 9.2

(differences are less than 10%), somewhat less good at Helkijn with a largest difference of 20%. 3.2. Comparison between blanks from DET and DGT gels and in situ concentration ranges measured with those gels Blanks for DET gels (VUB and USTL) are shown in Table 2. Comparing those blanks with metal concentration ranges observed in the sediment cores at Helkijn and Warneton stations, it appears that the concentrations of some elements are sometimes lower than the blanks. Blanks for DGT gels (VUB) and (USTL) are also shown in Table 2. Blanks were calculated using a deployment time of 24 h. The concentration ranges observed with the DGT gels at Helkijn and Warneton stations were only for the lowest Ni and Zn concentrations at the limit of quantification. 3.3. Laboratory comparisons 3.3.1. Intra-laboratory comparison (VUB) In order to validate the DET and DGT techniques, two couples of DET and DGT probes arranged back to back were inserted into two sediment cores from Warneton which had been sampled close to each other. The statistical method Pearson's Product Moment Correlation was used to test the correlation between the two DET probes. Iron, manganese and cobalt were taken as examples for the intra-laboratory comparison. Pearson's Product Moment Correlation yielded highly significant correlations with R ≥ 0.757 (P b 0.0001) for all the comparisons. The good correlation between the two DET profiles of Fe, Mn and Co in sediment cores at Warneton is also visible in Fig. 2a–c. The moving average method was applied to the initial data resulting in a limited smoothing of the original profiles.

Table 2 Blanks and concentration ranges observed with DET and DGT probes (VUB and USTL) Element

DET blank

DGT blank VUB −2

DGT blank USTL −1

−2

DGT observed range −1

VUB (μg l− 1)

USTL (μg l− 1)

VUB (μg l− 1)

USTL (μg l− 1)

(ng cm )

(μg l )

(ng cm )

(μg l )

VUB (μg l− 1)

USTL (μg l− 1)

0.22 ± 0.04 5.60 ± 0.97 9.66 ± 2.60 197 ± 51 0.28 ± 0.13 77 ± 6 6.6 ± 2 173 ± 61 0.14 ± 0.05

0.23 ± 0.02 3.92 ± 0.61 1.24 ± 0.31 476 ± 73 0.26 ± 0.19 17 ± 8 14.7 ± 0.21 39 ± 4.4

bdl–11 bdl–62 630–4900 170–42 000 0.34–4.2 bdl–1800 bdl–100 bdl–1000 0.6–13

0.14–8.3 bdl–62 144–3218 bdl–86 000 0.9–3.8 bdl–58 6–73 bdl–360

0.017 ± 0.006 0.43 ± 0.21 0.35 ± 0.24 4.9 ± 3 0.019 ± 0.009 3.16 ± 1.13 0.73 ± 0.29 16 ± 4

0.004 ± 0.001 0.070 ± 0.034 0.076 ± 0.054 1.019 ± 0.771 0.004 ± 0.002 0.69 ± 0.25 0.15 ± 0.06 3.3 ± 0.9

0.02 ± 0.009 0.40 ± 0.1 1.30 ± 0.62 17.17 ± 8.6 0.029 ± 0.007 2.96 ± 1.4 2.73 ± 0.46 12 ± 4

0.004 ± 0.001 0.06 ± 0.016 0.23 ± 0.11 2.91 ± 1.47 0.006 ± 0.001 0.63 ± 0.3 0.54 ± 0.09 2.5 ± 0.8

0.0–0.85 0.9–1 190–750 170–1800 0.08–0.37 0.43–17 0.400–5.5 2–650

0.05–0.74 0.36–5.48 393–1560 71–5270 0.09–0.88 1.14–10.99 1.54–6.25 6.48–88.4

bdl–20

4.9 ± 2.1

depth cm 4

2

0

-2

-4

-6

-8

-10

-12

-14

4

2

0

-2

-4

-6

-8

-10

-12

-14

4

2

0

-2

-4

-6

-8

-10

-12

-14

0

0

DET Fe

40000

concentration µg•l-1

600

DET Mn

400

DET Co

3


2


DET-1 DET-2

20000

DET-1 DET-2

200

DET-1 DET-2

1

60000

800

4

a

b

c

271

80000

1000

5

Similarly to the DET profiles, DGT profiles were also determined in the sediment cores at Warneton, and as an example the profiles of Fe, Mn, Co and Cu are discussed for the intra-laboratory comparison (Fig. 3a– d). Pearson's Product Moment Correlation yielded significant correlation with R ≥ 0.718 (P b 0.0002) for all the comparisons. In addition, the moving average

depth cm

0

Fig. 2. Depth profiles of Fe (a), Mn (b) and Co (c) obtained from two DET probes at sampling station Warneton.

depth cm


Cd Pb Mn Fe Co Ni Cu Zn As Cr

DET observed range

272


DGT Fe

DGT Mn 4

4

a

0

0

-2

-2 DGT-1 DGT-2

-4

b

2

depth cm

depth cm

2

-6 -8

DGT-1 DGT-2

-4 -6 -8

-10

-10

-12

-12

-14

-14 -16

-16 0

500

1000

1500

2000

2500

3000

3500

0

20

40

DGT Co

100 120 140 160 180 200

4

c

2

d

2

0

0

-2

-2 DGT-1 DGT-2

-4

depth cm

depth cm

80

DGT Cu

4

-6 -8

-4 DGT-1 DGT-2

-6 -8

-10

-10

-12

-12

-14

-14

-16 0.0

60


-1

concentration µg l •

-16 0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8


0

2

4

6

8

10


Fig. 3. Depth profiles of Fe (a), Mn (b), Co (c) and Cu (d) obtained from two DGT probes at sampling station Warneton.

method was performed on the initial trace metal data, smoothing the original profiles. The differences in DET and DGT profiles observed between two sediment cores can be explained by sediment heterogeneity as reported by Shuttleworth et al. (1999) and Fones et al. (2004). 3.3.2. Inter-laboratory comparison between VUB and USTL Trace metal profiles in the sediments of the Helkijn sampling station were assessed both by Vrije Universiteit Brussels (VUB) and Université des Science et Technologie de Lille (USTL), thus performing an interlaboratory comparison of the gel techniques. For most metals a good agreement was obtained between the two laboratories (see for example also Leermakers et al., 2005). One of the more difficult elements is iron because of the high sensitivity of Fe2+ to oxidants; therefore, we show here these profiles in some more detail. The smoothed profiles of Fe obtained by VUB and USTL with the DET and also the DGT samplers show the same features. In view of spatial heterogeneity in sediment

composition, the agreement between the two laboratories is fairly good (Fig. 4a–b). The depth profiles of Fe obtained from the DET and DGT samplers by the two laboratories (Fig. 4a–b) show comparable trends, whereas the concentrations are not exactly the same. The reduction zones of Fe for both DET and DGT samplers, starts from the interface until around 7–8 cm depth; this was observed in the two laboratories. Oxygen depletion in Helkijn riverine pore waters explains those results. The reducing conditions benefit the dissolution of Fe(III) to Fe(II), the reduced Fe(II) species being much more soluble than the solid Fe (III)-oxides. The concentrations of Fe obtained by the DET technique are much higher (10 times for USTL and 40 times for VUB) than those obtained by DGT but also by centrifugation (results not shown). No direct explanation for the lower factor (10) observed by USTL is available except for sediment heterogeneity. In the pore waters of the river Rupel, which is a tributary of the river Scheldt (Leermakers et al., 2005), Fe concentrations observed with DGT were also a factor


DET Fe

4

a

2 0

depth cm

-2 VUB USTL

-4 -6 -8 -10 -12 -14 0

10000

20000

30000

40000

50000


DGT Fe

4

b

2 0 VUB USTL

depth cm

-2 -4 -6 -8 -10 -12 -14 0

500

1000

1500

2000

2500

3000

-1


Fig. 4. Depth profiles of Fe obtained by DET (a) and DGT (b) from two laboratories at sampling station Helkijn.

10 lower than observed with DET. As explained in many articles (Davison and Zhang, 1994; Harper et al., 1998; Fones et al., 2004), DET and DGT concentrations are different due to (1) the sampling of different kinds of species (labile versus non-labile) and (2) the resupply rate for DGT.

273

core. The depletion of oxygen in the pore waters at Warneton is also responsible for the increase or production of iron(II) and manganese(II), two redoxsensitive elements involved as electron acceptors in the degradation of organic matter, from just below the interface. The maximum concentrations of Fe and Mn, for both DET and DGT samplers, appear at a depth of around 4 cm beneath the interface in the two sediments, but remain high in fact (much higher than the concentrations in the overlying water column) until the bottom of the core. The DGT depth profiles for Fe, Mn, Co and Cu in the two sediment cores compare very well regarding their shape: production (increase) and consumption (decrease) zones are found at the same sediment depth layers. However, the intensity of the production– consumption process can differ significantly. For example, the Cu concentration maxima at about 2.5 cm depth (Fig. 3d) differ by a ratio of 1 to 2. The concentrations of Fe, Mn and Co obtained with the DET technique (Fig. 2a–c) are significantly higher than those resulting from the DGT technique (Fig. 3a–c). 4.1.2. Pore water measurements Compared to the classic centrifugation technique, the concentrations of trace metals in pore water obtained by DET are much higher, especially for Fe. The most plausible reason to explain these differences is that despite the use of oxygen-free glove-bag for handling the cores during sectioning and centrifugation, oxygen still comes into contact with the pore water and oxidizes dissolved Fe(II) into solid Fe(III). Other trace elements, except Fe, Mn and Co were not available with the DET technique, because of the high blank values of the agarose gel compared to the naturally occurring 0 -5

4. Discussion

4.1.1. Redox potential profiles The redox potential profile (Fig. 5) shows a completely anoxic environment for the Warneton sediment. The redox values in the whole core (25 cm depth) were around − 300 to − 400 mV compared to the Ag/AgCl redox couple. This is confirmed by the absence of oxygen (unpublished results) and the very low nitrate concentration (around detection limit) from the sediment interface to the bottom of the sediment

depth cm

4.1. Warneton sampling station

-10 -15

Helkijn Warneton

-20 -25 -30 -35 -40 -500

-450

-400

-350

-300

-250

-200

-150

Eh mV Fig. 5. Redox potential profiles in sediment pore waters at sampling stations Warneton and Helkijn.


Table 3 R value obtained at the Warneton sampling station Average Trace Average metal concentration concentration (μg l− 1) DET (μg l− 1) centrifugation Cd Pb Mn Fe Co Ni Cu Zn

– – 566 39 001 2.4 – – –

0.16 1.3 222 1151 1.6 8.7 3.0 46

Average concentration (μg l− 1) DGT

R value DGT/ centrifugation (DET)

0.069 0.65 132 1825 0.33 1.7 1.6 19

0.44 0.49 0.59 (0.23) N1 0.20 (0.13) 0.19 0.52 0.40

DET Fe

4

a

2 0 -2

depth cm

concentrations (see also Table 2). Compared to the centrifugation or classic technique, the concentrations of Fe obtained by the DGT technique are slightly higher, but the latter concentrations are about a factor of 10 lower than the concentrations resulting from the DET technique. The concentrations of Cd, Pb Mn, Co, Ni, Cu and Zn obtained by the DGT technique are between 2 and 4 times lower than those resulting from centrifugation. Comparison between the centrifugation or classical technique and the DGT technique should be carried out with caution. DGT measures the localized interfacial concentration (this is depleted due to metal uptake by the DGT probe) in a very small volume of sediment adjacent to the DGT probe, whereas classical techniques measure bulk pore water concentration averaged from a much bigger volume (100 to 1000 times bigger ) of sediment. While the profiles of Fe and Mn obtained with the DET probes are more or less similar (see Fig. 2a–b), that of Co differs in the deeper layers (below 6 cm depth) where it steadily increases (Fig. 2c). In contrast, the DGT profiles of Co decrease below 4 cm while those of Fe and Mn remain more or less constant in the same depth layers (Fig. 3a–c). The DGT profiles of Cu show a pronounced maximum at 2–4 cm of depth (Fig. 3d). When pore water concentrations are measured independently by an alternative technique, DGT observed results can be expressed in terms of a ratio R (DGT/DET or DGT/centrifugation, with 0 b R b 1) (Harper et al., 1998). In our case, the ratio R can be described as the average metal concentration from DGT divided by the average metal concentration from DET or centrifugation (Table 3). The R values (based on DGT/ centrifugation unless otherwise indicated) for trace elements show us the following order: Fe (N 1) N Mn (0.59) N Cu (0.52) N Pb (0.49) N Cd (0.44) N Zn (0.40) N Mn (0.23 DGT/DET) N Cr (0.23) N Co (0.20) N Ni (0.19) N Co (0.13 DGT/DET) N Fe (0.05 DGT/DET). The differences between centrifugation or DET and

Helkijn Warneton

-4 -6 -8 -10 -12 -14 0

20000

40000

60000

80000


DET Co

4

b

2 0 -2

depth cm

274

Helkijn Warneton

-4 -6 -8 -10 -12 -14 0

1

2

3

4

5

concentration µg•l-1 Fig. 6. Depth profiles of Fe (a) and Co (b) obtained from DET at Helkijn and Warneton.

DGT can be due to several factors such as for example the pore size of the gels (about 20 nm for DET and 2 nm for DGT), the competition between the DGT resin and complexing ligands when metal complexes are abundant, depletion of the pore waters during DGT sampling and so on. There is a large difference in R values when using Fe concentrations from DET probes or from centrifugation. As explained before, slight contact with oxygen during centrifugation will strongly reduce the dissolved Fe levels. The close R values of Ni and Co can point towards a similar chemistry and mineralogy of Ni and Co and also indicate similar release of labile Co and Ni. 4.2. Helkijn sampling station 4.2.1. Redox potential profiles and pore water measurement The redox potential profile at Helkijn (Fig. 5) differs from that observed at Warneton, especially in the top 10 cm of the sediment. It decreases from about − 170 mV at


DGT Fe

4

a

2 0

depth cm

-2 -4 -6 Helkijn Warneton

-8 -10 -12 -14 -16 0

500

1000

1500

2000

2500

3000

3500


DGT Co

4

b

2 0

depth cm

-2 -4 Helkijn Warneton

-6 -8 -10 -12 -14 -16 0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-1


Fig. 7. Depth profiles of Fe (a) and Co (b) obtained from DGT at Helkijn and Warneton.

3 to 4 cm depth to about − 400 mV at 10 cm depth. Further downwards, the redox remains relatively stable, with minor fluctuations, around a value of − 420 mV. For interpretations of major and minor element profiles at Helkijn, it is thus important to notice that the upper sediment is gradually changing from a sub-oxic to a complete anoxic system. The concentration of nitrate for example decreased very fast from about 35 mg l− 1 to the detection limit. The sub-oxic conditions in the first 10 cm of the sediments at Helkijn result in trace metal profiles showing different trends from those obtained at Warneton. The DET profile of Fe at Warneton is significantly higher than the one at Helkijn and the depth range of increased concentration is also much broader: from 2 to 14 cm at Warneton and from 2 to 7 cm at Helkijn (Fig. 6a). Similar results for Co were observed, except that from 8 to 10 cm depth on, the Co concentrations again increase (this was not the case for Fe), both at Warneton and at Helkijn (Fig. 6b). The similar behavior of, or at least the strong correlation between, the total dissolved Co and Fe

275

concentrations (including colloidal species) at Helkijn and Warneton for the upper 8–10 cm, confirms their similar redox sensitive characteristics (Fig. 6a–b). In the deeper layers, this is no longer true. There, total dissolved Fe does not show any particular features, while total dissolved Co increases, especially at Helkijn. This is also observed by the DGT technique (Fig. 7a–b). The DGT profile of Fe and the corresponding concentration gradient at Helkijn is also much lower than the one at Warneton (Fig. 7a). This is probably linked to the much larger redox gradient in the upper sediment at Warneton. In addition, the DGT profile of Co agrees much better with the Fe DGT profile at Warneton than at Helkijn (Fig. 7a–b). Both DET and DGT Co profiles are very similar in the deeper layers at Helkijn. Compared to the concentrations obtained by the centrifugation technique, the concentrations of Fe resulting from the DET technique are more than 10 times higher (Davison et al., 2000). This is less in the case for Mn and Co, and was also observed at Warneton. The R values were also calculated at Helkijn (Table 4) similar to what was done at Warneton. The R values indicated the following order: Fe (0.46) N Zn (0.40) N Pb (0.31) N Co (0.26) N Mn (0.22) N Co (0.17 DGT/DET) N Mn (0.15 DGT/DET) N Cu (0.10) N Ni (0.08) N Fe (0.04 DGT/DET) N Cd (0.03). Compared to Warneton, the R values of Fe, Cd and Cu strongly decreased while only that of Co (for both expressions of R) increased slightly. 4.2.2. Metal concentration gradients at the water– sediment interface The high resolution profiles obtained with the DET and DGT probes provide much more accurate estimates of the metal concentration gradients at the water– sediment interface than those obtained by the classic centrifugation technique. It is clear that these concentration gradients are spatially specific and that 2-D DET Table 4 R value obtained at the Helkijn sampling station Average Trace Average metal concentration concentration (μg l− 1) DET (μg l− 1) centrifugation Cd Pb Mn Fe Co Ni Cu Zn

– – 2251 20 952 0.83 – – –

5.1 8.0 1532 1795 0.54 17 11 64

Average R value concentration DGT/ (μg l− 1) DGT centrifugation (DET) 0.14 2.3 331 833 0.14 1.2 0.98 28

0.03 0.31 0.22 (0.15) 0.46 (0.04) 0.26 (0.17) 0.08 0.10 0.40

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and DGT probes (eventually even cylindrical) should be used to calculate more reliable fluxes for that area (see also Fones, 1998). Our intention is only to illustrate the error that may result from the use of low-resolution profiles. Iron and manganese gradients at the water– sediment interface calculated from the DET profiles and those calculated from classic centrifugation profiles at Warneton were compared. For both metals, the subsurface concentration gradients obtained from the DET probes are much higher than those obtained by the classic centrifugation. Large over- or underestimation of epibenthic fluxes can result from the use of low resolution profiles and this is not only valid for metals but also for nutrients, organochlorine compounds, etc. 5. Conclusion In sediment pore waters of Helkijn and Warneton sampling stations (rivers Scheldt and Leie, Belgium), major cations and anions were determined after conventional sectioning of the core and centrifugation of the slices. The balance was very good at Warneton (differences are less than 10%), somewhat less good at Helkijn with a largest difference of 20%. High DET or DGT blanks can sometimes hamper the assessment of trace metal profiles in relatively low polluted aquatic sediments. Comparing the DET blanks with metal concentration ranges observed in the sediment cores at Helkijn and Warneton stations, it appears that the concentrations of some elements in sediment cores are sometimes lower than the blanks. The concentration ranges observed with the DGT gels at Helkijn and Warneton stations, were only for the lowest Ni and Zn concentrations at the limit of quantification. In order to validate the DET and DGT techniques, intra- and inter-laboratory comparisons were carried out. For the intra-laboratory comparison, two couples of DET and DGT probes arranged back to back were inserted into two sediment cores close to each other. The DET as well as DGT profiles were very similar in magnitude and shape. The inter-laboratory comparisons were carried out at Helkijn. The smoothed profiles of Fe obtained by VUB and USTL with the DET and also the DGT samplers show the same features. In view of spatial heterogeneity in sediment composition, the agreement between the two laboratories is fairly good. The results observed at Warneton and Helkijn were also compared. The redox potential profile at Helkijn differs from that observed at Warneton, especially in the top 10 cm of the sediment. At Warneton, the redox potential profiles show a completely anoxic sediment environment. At Helkijn, the redox dec-

reases from about − 170 mV at 3 to 4 cm depth to about − 400 mV at 10 cm depth. Further downwards, the redox remains relatively stable, with minor fluctuations, around a value of − 420 mV. For interpretations of major and minor element profiles at Helkijn, it is thus important to notice that the upper sediment is gradually changing from a sub-oxic to a complete anoxic system, while at Warneton it is immediately completely anoxic. The DET profile of Fe at Warneton is significantly higher than the one at Helkijn and the depth range of increased concentration is also much broader: from 2 to 14 cm at Warneton and from 2 to 7 cm at Helkijn. Similar results for Co are observed, except that from 8 to 10 cm depth on, the Co concentrations again increase (this was not the case for Fe), both at Warneton and at Helkijn. The DGT profile of Fe at Helkijn is also much lower than the one at Warneton, while the concentration gradient at Helkijn is much smaller than at Warneton. This is probably linked to the much larger redox gradient in the upper sediment at Warneton. In addition, the DGT profile of Co agrees much better with the Fe DGT profile at Warneton than at Helkijn. Both DET and DGT Co profiles are very similar in the deeper layers at Helkijn. Compared to the concentrations obtained by the centrifugation technique, the concentrations of Fe resulting from the DET technique are more than 10 times higher. This is less the case for Mn and Co, and is similar to the results from Warneton. We have also shown that large over- or underestimation of epibenthic fluxes can result from the use of low resolution profiles. Acknowledgements The authors want to thank the EU-Commission for financial support via the INTERREG III Programme as well as the International Copper Association (ICA) and European Copper Institute (ECI) for a special grant. They also appreciate the constructive comments of two anonymous reviewers. References Baeyens W. Trace metals in the Westerschelde Estuary: a case-study of a polluted, partially anoxic estuary. Kluwer Academic Publishers; 1998. Bourg ACM, Darmendrail D, Ricour J. Geochemical filtration of riverbank and migration of heavy metals between the Deule River and the Ansereuilles alluvion-chalk aquifer. Geoderma 1989;44(2–3):229–44. Chang LY, Davison W, Zhang H, Kelly M. Performance characteristics for the measurement of Cs and Sr by diffusive gradients in thin films (DGT). Anal Chim Acta 1998;368:243–53.

Y. Gao et al. / Science of the Total Environment 362 (2006) 266–277 Dahlqvist R, Zhang H, Ingri J, Davison W. Performance of the diffusive gradients in thin films technique for measuring Ca and Mg in freshwater. Anal Chim Acta 2002;460:247–56. Davison W, Zhang H. In situ speciation measurements of trace components in natural waters using thin film technique. Nature 1994;367:546–8. Davison W, Grime GW, Morgen JAW, Clarke K. Distribution of dissolved iron in sediment pore waters at submillimetre resolution. Nature 1991;352:323–4. Davison W, Fones GR, Harper M, Teasdale P, Zhang H. Dialysis, DET and DGT: in situ diffusional techniques for studying water, sediments and soils. In: Buffle J, Horvai G, editors. In-situ monitoring of aquatic systems: chemical analysis and speciation. IUPAC. Wiley Publishers; 2000. p. 495–569. Dehairs F, Gillain G, Debondt M, Vandenhoudt A. The distribution of trace and major elements in Channel and North Sea suspended matter. Proceedings “Progress in Belgian Oceanographic Research” Brussels; 1985. p. 136–46. Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy, OJEC No. L 327, p. 1 ff. Divis P, Leermakers M, Docekalova H, Gao Y. Measurement of mercury concentrations in sediment pore waters using centrifugation and diffusive gradients in thin film sampling techniques. Anal Bioanal Chem 2005;382:1715–9. Docekalova H, Divis P. Application of diffusive gradient in thin films technique (DGT) to measurement of mercury in aquatic systems. Talanta 2004;65(5):1174–8. Fones GR, Davison W, Grime GW. Development of constrained DET for measurements of dissolved iron in surface sediments at sub-mm resolution. Sci Total Environ 1998;221:127–37. Fones GR, Davison W, Hamilton-Taylor J. The fine-scale remobilization of metals in the surface sediment of the North-East Atlantic. Cont Shelf Res 2004;24:1485–504.

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Haper MP, Davison W, Tych W. Temporal, spatial, and resolution constraints for in situ sampling devices using diffusional equilibration: dialysis and DET. Environ Sci Technol 1997;31:3110–9. Harper MP, Davison W, Zhang H, Tych W. Kinetics of metal exchange between solids and solutions in sediments and soils interpreted from DGT measured fluxes. Geochim Cosmochim Acta 1998;62 (16):2757–70. Leermakers M, Gao Y, Gabeille C, Lojen S, Ouddane B, Wartel M, et al. Determination of high resolution pore water profiles of trace metals in sediments of the Rupel River (Belgium) using DET (diffusive equilibrium in thin films) and DGT (diffusive gradients in thin films) techniques. Water Air Soil Pollut 2005;166:265–86. Panutrakul S, Baeyens W. Behaviour of heavy metals in a mud flat of the Scheldt Estuary, Belgium. Mar Pollut Bull 1991;22(3):128–34. Shuttleworth SM, Davison W, Hamilton-Taylor J. Two-dimensional and fine structure in the concentrations of iron and manganese in sediment pore-waters. Environ Sci Technol 1999;33:4169–75. Zhang H, Davison W, Miller S, Tych W. Performance characteristics of diffusive gradients in thin films for the in situ measurement of trace metals in aqueous solution. Anal Chem 1995;67:3391–400. Zhang H, Davison W, Gadi R, Kobayashi T. In situ measurement of dissolved phosphorus in natural waters using DGT. Anal Chim Acta 1998a;370:29–38. Zhang H, Davison W, Knight B, McGrath S. In situ measurements of solution concentrations and fluxes of trace sulfate in soils using DGT. Environ Sci Technol 1998b;32:704–10. Zhang H, Zhao FJ, Sun B, Davison W, McGrath SP. A new method to measure effective soil solution concentration predicts copper availability to plants. Environ Sci Technol 2001;35:2602–7. Zhang H, Davison W, Mortimer RJG, Krom MD, Hayes PJ, Davies IM. Localised remobilization of metals in marine sediment. Sci Total Environ 2002;296:175–87.

Talanta 65 (2005) 1174–1178

Application of diffusive gradient in thin films technique (DGT) to measurement of mercury in aquatic systems H. Doˇcekalová∗ , P. Diviˇs Faculty of Chemistry, Brno University of Technology, Purkyˇnova 118, 61200 Brno, Czech Republic Received 17 May 2004; received in revised form 12 August 2004; accepted 24 August 2004 Available online 12 October 2004

Abstract The diffusive gradient in thin films (DGT) technique was investigated and used to measure mercury concentration in river water. Mercury ions are covalently bound to amide nitrogen groups of commonly used polyacrylamide, which makes this gel unsuitable as a diffusive medium. In contrast, agarose gel was found as the diffusive gel for mercury measurements. Basic performance tests of agarose DGT verified the applicability of Fick’s first law for DGT measurements. Two selective resins, Chelex-100 with iminodiacetic groups and Spheron-Thiol with thiol groups were used. The measured diffusion coefficient in agarose gel was close to that in water. The concentration of mercury in Svitava river measured by DGT with Speron-Thiol resin gel was higher (0.0116 ± 0.0009 ␮g l−1 ) than those obtained by Chelex-100 (0.0042 ± 0.0005 ␮g l−1 ). Different capture efficiencies of two adsorbents enable to estimate fractions of mercury bonded in different complexes in the river water. The concentrations of mercury found by DGT both Chelex-100 and Speron-Thiol resin gels are much lower than that measured directly in the river water (0.088 ± 0.012 ␮g l−1 ). This difference indicates that DGT concerns inorganic ions and labile species only, and that it is not able to include inert organic species and colloids. © 2004 Elsevier B.V. All rights reserved. Keywords: Mercury; Diffusive gradients in thin films technique (DGT); Agarose diffusive gel

1. Introduction This paper follows previous work [1] dedicated to diffusive equilibrium in thin films technique (DET), using hydrogels for sampling solute species in aquatic systems. Use of DET, and especially the DGT technique for the pollution monitoring and other environmental studies is increasing. In the present paper, we introduce the possibility to follow mercury transfers in aquatic systems using DGT and appropriate mercury measurement techniques. The diffusive gradient in thin films technique, recently developed by Davison and Zhang [2] for in situ determination of kinetically labile metal species in aquatic systems has been successfully used as a means to follow the concentration of trace metals in natural waters [3–6], metal fluxes in sediments ∗ Corresponding author. Tel.: +420 5 41 149 432; fax: +420 5 41 211 697. E-mail address: [email protected] (H. Doˇcekalová).

0039-9140/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2004.08.054

[7,8] and soils [9–11] and also to estimate the concentration of metals in pore waters [12,13]. The DGT technique employs two layers of hydrogel: a diffusive layer and a binding phase. Diffusive layer is placed in the DGT unit on the top of the binding phase and covered with a membrane (usually 0.45 ␮m). These three layers are sealed in the DGT unit so that only the diffusive layer covered with membrane is exposed to the solution to be analyzed [14]. Dissolved metal species, which are smaller than membrane pore size, diffuse through a hydrated polyacrylamide gel (the diffusion gel layer), of thickness g and area A and are accumulated by an analyteselective adsorbent in binding phase. The use of synthetic ferrihydrite for phosphates [15], AG 50W-X cation-exchange resin for radioactive Cs and Sr [16] and silver iodide for sulfide [17] embedded in the binding phase are described. Most frequently, an iminodiacetate chelating resin, Chelex-100, is used and has been applied to a large number of divalent and trivalent metal ions [18], including heavy metals and other elements of environmental interest. After exposure of the DGT

H. Doˇcekalová, P. Diviˇs / Talanta 65 (2005) 1174–1178

unit for a time t in a solution, the amount of metal ions absorbed by the resin is analyzed and the mass M of captured metals determined. The amount of metal accumulated within the binding phase under these conditions is assumed to be equivalent to the amount of metal ion passing through the diffusive layer. The time-average concentration of metal in the bulk solution, cDGT can be calculated with the help of Fick’s first law of diffusion as: cDGT =

Mg tAD

(1)

where D is the diffusion coefficient of the metal in the gel, the exposure surface area A and g the thickness of the gel layer. Eq. (1) is valid only if the free metal ions are in rapid equilibrium with the resin, with a large binding constant and cbinding phase is effectively zero providing the resin is not saturated. The DGT technique gives useful information about a wide range of metal species but not for mercury. Mercury binding on the amide groups within polyacrylamide gel [19] rather than free diffusion does not allow use of this diffusive gel and this technique for mercury determination. In this work, an agarose diffusive gel having different structure from polyacrylamide gel has been tested. Results obtained with agarose diffusive gel were compared with those obtained for polyacrylamide diffusive gel. In addition to testing diffusive gels, two different resins Chelex-100 and Spheron-Thiol with –SH groups prepared by Smrˇz and Hradil [20] and intensively studied by Doˇcekal and Slovák [21], were used for the mercury DGT measurement.

2. Experimental 2.1. Apparatus DGT Research Ltd. (UK, www.dgtresearch.com) supplied DGT deployment units. Mercury in resin gels was measured using one-purpose atomic absorption spectrometer Advanced Mercury Analyser, model AMA 254 (Altec, Czech Republic) based on combustion of the sample in oxygen atmosphere and amalgamation preconcentration (www.leco.com/organic). 2.2. Reagents and materials All the reagents were of analytical-reagent grade. For dilutions, high-purity demineralized water provided by a Milli-Q Plus filter apparatus (Millipore, USA) was used. Mercury test solutions and mercury standards were prepared from 1 g l−1 stock standard solution (Analytica Ltd., Czech Republic). The pH of the test solution was adjusted to 5 by addition of 0.1 mol l−1 NaOH (Onex, Czech Republic). A 0.1 mol l−1 NaNO3 (Lachema, Czech Republic) medium was used in all experiments. The polyacrylamide resin gel and diffusive gel were prepared using acrylamide (Sigma-Aldrich, Germany), ammonium persulfate (Sigma-Aldrich, Germany), tetram-

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ethylethylenediamine (Sigma-Aldrich, Germany) and DGT cross-linker (DGT Research Ltd., UK). Chelex-100, Na form, 100–200 wet mesh (Bio-Rad Laboratories) and SpheronThiol (Lachema) resins were used. For the agarose diffusive gel preparation, a 1.5% solution of agarose (Prolabo, France) was used. To protect the outer surface of the diffusive gels, a 0.45 ␮m pore size membrane (Pall Corporation, USA) was placed between the diffusive gel and the plastic cap. The thickness of hydrated gels was measured using a dial micrometer. 2.3. Procedures 2.3.1. Gels preparation 2.3.1.1. Polyacrylamide gels. Preparation of resinembedded and ion-permeable diffusive gels followed the procedure used by Zhang and Davison [14]. Firstly, the pre-gel solution was prepared by mixing aqueous solutions of 15% acrylamide and 0.3% patented agarose-derived cross-linker (DGT Research Ltd., UK). Polymerization was initiated by adding 7 ␮l of freshly prepared ammonium persulfate and 2.5 ␮l of tetramethylethylenediamine (TEMED) per millilitre of a pre-gel solution. The resulting gel solution was cast between two glass plates separated by plastic spacers and the assemblage was maintained at about 40 ◦ C for 45 min. After removal, the gels were hydrated in demineralized water for at least 24 h to allow them to expand to a stable thickness. The thickness of hydrated gels was 0.82 ± 0.02 mm. The discs were cut using a plastic knife and stored in 0.01 mol l−1 NaNO3 . Resin gels were prepared from a pre-gel solution of the same composition. A 0.2 g wet weight of Chelex-100 or 0.12 g wet weight of Speron-Thiol resins were added per millilitre of the pre-gel solution. The polymerization rate was decreased by adding only 6 ␮l of ammonium persulfate and 2 ␮l of TEMED per millilitre of the pre-gel solution to allow settling of the resin on one side of the gel. After hydration, the discs were cut and stored in a small volume of demineralized water. The thickness of hydrated gels was 0.43 ± 0.02 mm. 2.3.1.2. Agarose gels. A diffusive gel containing 1.5% agarose was prepared by dissolving the agarose in an appropriate volume of 80 ◦ C warm demineralized water. The mixture was placed in a boiling water bath and gently stirred until all the agarose was dissolved and the solution became transparent. The hot gel solution was immediately pipetted between two preheated glass plates separated by plastic spacers of appropriate thickness and left to cool down to its gelling temperature (36 ◦ C or below). The discs of agarose diffusive gels were stored in demineralized water. Their thickness was varied between 0.50 and 1.22 mm. 2.4. DGT assembly Gels were placed on the top of the piston. The resin gel was covered by diffusive gel and by a 0.45 ␮m pore size

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cellulose nitrate membrane filter. The front cap was pressed tightly. 2.5. Diffusive gel testing Both agarose and polyacrylamide diffusive gels were tested in a mercury solution to established if mercury was binding to the gels. The mercury test solution containing 100 ␮g l−1 of mercury in 0.01 mol l−1 NaNO3 was stirred for 24 h to equilibrate. The DGT units, filled only with agarose and polyacrylamide diffusive gels and covered by a 0.45 ␮m pore size cellulose nitrate membrane filter were immersed into the equilibrated mercury solution, which was stirred using a magnetic follower. For this experiment, a 0.8 mm thick polyacrylamide diffusive gel and 0.5 mm agarose gel were used. Mercury was determined in the solution before DGT deployment and periodically during an experiment carried over 24 h. Two pistons, each filled with different diffusive gels, were removed for analysis at each testing time. The content of mercury in these gels was measured directly with the use of the AMA-254 spectrometer. When the amount of mercury in disc was more elevated than the available measurement range, the gel disc was cut for smaller pieces, and these were re-measured individually.

in the test solution was controlled. After 4 h of exposure, DGT units were taken from the solution, resin gels were extracted and the amount of mercury measured. Resin gel discs with high amounts of mercury were divided into smaller pieces for measurements. The total amount of mercury in each disc was than calculated as a sum of the masses in all these pieces. 2.7. Field applications DGT units were deployed in situ in the stream of Svitava river in the Husovice part of Brno. Ten DGT units, five with Chelex-100 resin and five with Spheron-Thiol and agarose diffusive gel were anchored to a nylon string. The units were suspended for 10 days in the middle of the river 0.5 m above the bottom and 0.5 m under the surface. During this time, a 1 l water sample was collected. To avoid any adsorption phenomena, this sample was stabilized by addition of potassium dichromate, nitric acid and hydrochloric acid [22]. The DGT units were rinsed with distilled water after retrieval from the river and kept in clean polyethylene bags for the transport to laboratory.

3. Results and discussion

2.6. Basic DGT performance tests

3.1. Stability of the mercury solution

In order to test the validity of DGT measurement for mercury analysis, the recommended tests [14] were carried out using a 100 ␮g l−1 mercury solution in 0.01 mol l−1 NaNO3 .

The significant adsorption of mercury on surfaces of all types of containers is a well-known phenomenon [23]. For this reason, the stability of mercury solution was checked before DGT deployment. Five litres of 100 ␮g l−1 mercury in 0.01 mol l−1 NaNO3 was placed in an HDPE container and stirred using a magnetic follower. The concentration of mercury in this solution was periodically checked. Due to the adsorption of mercury on the bottle walls, a 10% decrease of its concentration was observed during the first hour of stirring. After saturation of the walls, this concentration remained constant for 24 h. Subsequent immersion of DGT units lowered the mercury concentration further by 50% of its adsorption on the plastic DGT units. The actual concentration of mercury was measured during experiments and was taken into consideration for the calculation of DGT mercury concentration. This decrease of mercury concentration caused by adsorption on DGT units is significant because of the small volume of model solution relative to surface area of DGT units. It is assumed that this effect does not occur in environmental systems measured in situ.

2.6.1. Time-dependence experiments The DGT units were filled with resin and diffusive gels covered by membrane filter. Chelex-100 and Spheron-Thiol resin gels were combined with agarose and polyacrylamide diffusive gels and covered with membrane filters. The assembly was floated in a stirred solution for different time periods, up to 8 h. During the experiment, the concentration of mercury in the test solution was controlled. At each sampling time, three of each type of DGT units were taken from the solution, resin gels were extracted and the amount of mercury measured. Resin gel discs presenting high amount of mercury were divided into smaller pieces for measurement. The total amount of mercury in each disc was then calculated as a sum of mercury masses in all these pieces. 2.6.2. Diffusion layer thickness experiments The other recommended test confirming the validity of the Fick’s first law is the linear dependence of accumulated mass of metal in the resin on the reciprocal thickness of the diffusive gel. Agarose diffusive gels of three thicknesses (0.50, 0.72 and 1.22 mm) were used for this experiment. The DGT units with different thicknesses of diffusive gel and Chelex100 and Spheron-Thiol resin gels were exposed for 4h to a stirred model of 100 ␮g l−1 Hg solution in 0.01 mol l−1 NaNO3 . During the experiment, the concentration of mercury

3.2. Tests of gel-diffusion equilibration times The equilibration time for the agarose gel (thickness of 0.50 ± 0.02 mm) was measured directly by immersing it in a stirred solution of 100 ␮g l−1 Hg in 0.01 mol l−1 NaNO3 at 22.5 ◦ C. The amount of mercury in the gel increased with the exposure time, reaching a plateau within 8 h (Fig. 1). The concentration of mercury found in equilibrated agarose gel


Fig. 1. Mass of mercury in agarose gel discs exposed for various periods to a test solution of 100 ␮g l−1 Hg in 0.01 mol l−1 NaNO3 .

was 450 ␮g l−1 , which is 4.5 times higher than in solution. We assume that there are some impurities in the agarose, associated with specific binding groups. After their saturation, no more mercury is collected in agarose gel. The amount of bound mercury is not large and does not affect the use of DGT units with agarose diffusive gel for mercury measurement. The amount of mercury in the polyacrylamide gel increased more dramatically with time exposure. An average of 17 ␮g of mercury per polyacrylamide gel discs was found. It corresponds to concentration of mercury 70 mg l−1 in the polyacrylamide gel. The reactivity of the amide groups towards Hg(II) is known for more than 100 years: the Hg(II) ion appears to become covalently bound to one or two amide nitrogen atoms. Special dried polyacrylamide resin has been prepared for Hg removal and recovery [19]. When polyacrylamide diffusive gel is used in DGT units, it is not possible to interpret results because there is a competition for mercury ions between two resins, Chelex-100 and polyacrylamide. 3.3. Basic DGT performance tests Two experiments were performed to verify the applicability of Eq. (1) for DGT measurements of mercury with the systems described. The first experiment concerned the time dependence. DGT units with known agarose gel thickness were exposed for 8h to a 100 ␮g l−1 Hg stirred solution. The mass of accumulated mercury (M) normalized for mercury concentration in solution (c) was plotted against the exposure time (see Fig. 2). The two curves are linear for both Chelex-100 and Speron-Thiol sorbents and have simi-

Fig. 2. Measured mass of mercury in the resin layers immersed in Hg solution (100 ␮g l−1 ) for various periods. The agarose diffusive gel was used and two different resins in resin layers tested: Chelex-100 () and Spheron-Thiol (). Eq. (1) predicts the solid line.

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Fig. 3. Measured mass of mercury in the resin layers immersed in Hg solution (100 ␮g l−1 ) for various periods. The polyacraylamide diffusive gel was used and two different resins in resin layers tested: Chelex-100 () and Spheron-Thiol (). Eq. (1) predicts the dotted line.

lar slopes. Slopes obtained during the same experiment with DGT unit with polyacrylamide diffusive gel are much lower (Fig. 3) and differ for Chelex-100 and Speron-Thiol. Mercury is accumulated in the polyacrylamide gel and a competitive reaction takes place between two binding agents: the diffusive polyacrylamide gel and resin in resin gel. Spheron-Thiol resin has higher binding strength, so it can better compete with the adsorption of mercury in polyacrylamide gel structure. These competitive reactions do not allow interpretation of experimental data. The diffusion coefficients were calculated from plots furnished by the time experiment. Slope k of the dependance Mc−1 = f(t) can be expressed by Fick’s first law as: k = (DAt)g−1

(2)

From this equation, the diffusion coefficient can be calculated: kg (3) Dcal = At The calculated diffusion coefficient Dcal of mercury in agarose gel is (8.86 ± 0.11) × 10−6 cm2 s−1 for Chelex-100 and (9.08 ± 0.13) × 10−6 cm2 s−1 for Spheron-Thiol. The value in water is 9.13 × 10−6 cm2 s−1 [24]. The second recommended test experiment with DGT was also performed. The DGT units filled with agarose gels of different thickness were exposed for 4 h to a stirred solution of 100 ␮g l−1 mercury in 0.01 mol l−1 NaNO3 . The plot of the measured mass against the reciprocal gel thickness is linear (see Fig. 4). The mass in the figures is expressed as Mc−1 ,

Fig. 4. Measured mass of mercury in the resin layers, () Chelex-100, () Spheron-Thiol) immersed in Hg solution (100 ␮g l−1 ) for different thicknesses of agarose gel layer. Eq. (1) predicts the solid line.

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because of variable Hg concentrations in solution during experiments. Results of both testing experiments with agarose diffusive gel confirm the validity of basic DGT principles. The DGT with agarose diffusive gel is thus possible to use for reliable mercury measurements. 3.4. Field study In March 2004, the DGT technique was used to measure in situ mercury concentration in the Svitava river in the Husovice part of Brno, Czech Republic. Both Chelex100 and Spheron-Thiol resin embedded in polyacrylamide gel were used, covered by agarose diffusive gel with 0.5 mm thickness. Because of the low concentration of mercury in water, the preconcentration mode proposed by the AMA254 spectrometer was used for direct measurement of mercury in the water sample. The value of direct measurement (0.088 ± 0.012) ␮g l−1 Hg was higher than the DGT measured concentrations, (0.0042 ± 0.0005) ␮g l−1 for Chelex100 resin gel and (0.0116 ± 0.0009) ␮g l−1 or Spheron-Thiol. The differences between direct measurement and DGT measurement may be explained by the fact that DGT measures only ionic mercury and labile mercury species and does not include inert organic species and large colloids. Chelex-100 with iminodiacetic groups enable to assess ionic mercury, and mercury related to week complexes. Spheron-Thiol has a greater affinity for mercury than Chelex-100. Thiol groups of Spheron-Thiol are capable to react with mercury bonded even in very strong complexes. Consequently, the concentration measured by Spheron-Thiol DGT unit has to be higher than those given with Chelex-100. The DGT units filled with resins having different capture efficiencies to mercury could be used to distinguish between mercury complexes with different stability and fractionate various mercury species in the sample.

4. Conclusion DGT commonly used polyacrylamide gel is unsuitable as diffusive medium for the mercury determination. During diffusion to the resin embedded in the resin layer, mercury ions are covalently bound to amide groups of polyacrylamide diffusive gel. Competitive reactions between two adsorption agents do not allow interpretation of experimental data. On the other hand, agarose gel was found to be suitable as the diffusive gel for mercury measurements. Performing of the both recommended DGT tests has confirmed the usefulness of DGT principles. The diffusion coefficient of mercury in agarose gel calculated on the base of Fick’s law was found very similar (8.97 × 10−6 cm2 s−1 ) to that in water (9.13

× 10−6 cm2 s−1 ) for both Chelex-100 and Spheron-Thiol resins, in mercury solution. Concentration of mercury in the river water measured by DGT with Speron-Thiol resin layer (0.0116 ± 0.0009) ␮g l−1 was three times higher than that measured by Chelex-100 (0.0042 ± 0.0005) ␮g l−1 . This can be explained by the higher affinity of thiol groups to Hg(II) bound in non-labile complexes. In a real water sample, there are not only cations and small inorganic complexes of mercury, but also complexes with natural ligands as fulvic acids and humic acids. The DGT with Speron-Thiol resin measures even those species of mercury, which are more stable and are not measured by Chelex-100. References [1] H. Doˇcekalová, O. Clarisse, S. Salomon, M. Wartel, Talanta 57 (2002) 145–155. [2] W. Davison, H. Zhang, Nature 367 (1994) 545–546. [3] S. Denney, J. Sherwood, J. Leyden, Sci. Total Environ. 239 (1999) 71–80. [4] M.C. Alfaro De la Torre, P.Y. Beaullieu, A. Tessier, Anal. Chim. Acta 418 (2000) 53–68. [5] R. Dahlqvist, H. Zhang, J. Ingri, W. Davison, Anal. Chim. Acta 460 (2002) 247–256. [6] R.J. Dunn, P.R. Teasdale, J. Warnken, R.R. Schleich, Environ. Sci. Technol. (2003) 2794–2800. [7] H. Zhang, W. Davison, S. Miller, W. Tych, Geochim. Cosmochim. Acta 59 (1995) 4181–4192. [8] G.R. Fones, W. Davison, O. Holby, B.B. Jorgensen, B. Thampdrup, Limnol. Oceanogr. 46 (2001) 982–988. [9] H. Zhang, W. Davison, B. Knight, S. McGrath, Environ. Sci. Technol. 32 (1998) 704–710. [10] H. Zhang, F.J. Zhao, B. Sun, W. Davison, S.P. McGrath, Environ. Sci. Technol. 35 (2001) 2602–2607. [11] B. Doˇcekal, V. Smetková, H. Doˇcekalová, Chem. Pap. 57 (2003) 161–166. [12] H. Zhang, W. Davison, R.J.G. Mortimer, M.D. Krom, P.J. Hayes, I.M. Davies, Sci. Total Environ. 296 (2002) 175–187. [13] P. Diviˇs, H. Doˇcekalová, V. Smetková, Chem. Listy 97 (2003) 1184–1189. [14] H. Zhang, W. Davison, Anal. Chem. 67 (1995) 3391–3400. [15] H. Zhang, W. Davison, R. Gadi, T. Kobayashi, Anal. Chim. Acta 370 (1998) 29–38. [16] L.Y. Chang, W. Davison, H. Zhang, M. Kelly, Anal. Chim. Acta 368 (1998) 243–253. [17] P.R. Teasdale, S. Hayward, W. Davison, Anal. Chem. 71 (1999) 2186–2191. [18] O.A. Garmo, O. Royset, E. Steinnes, T.P. Flaten, Anal. Chem. 75 (2003) 3573–3580. [19] N. Bicak, D.C. Sherrington, React. Funct. Polym. 27 (1995) 155–161. [20] M. Smrˇz, J. Hradil, Czech. Patent AO 190171 (1978). [21] Z. Slovák, M. Smrˇz, B. Doˇcekal, S. Slováková, Anal. Chim. Acta 111 (1979) 243–249. [22] V. Stefanidesová, J. Seidlerová, P. Dvorská, Chem. Listy 96 (2002) 117–119. [23] L.P. Yu, X.P. Yan, Trends Anal. Chem. 22 (2003) 245–253. [24] CRS Handbook of Chemistry and Physics, 76th ed., CRC Press Inc., Boca Raton, USA, 1995, pp. 5–90.

Anal Bioanal Chem (2005) 382: 1715–1719 DOI 10.1007/s00216-005-3360-8

SH O RT CO MM U N IC A T IO N

P. Divisˇ Æ M. Leermakers Æ H. Docˇekalova´ Æ Y. Gao

Mercury depth profiles in river and marine sediments measured by the diffusive gradients in thin films technique with two different specific resins Received: 14 March 2005 / Revised: 19 May 2005 / Accepted: 22 May 2005 / Published online: 14 July 2005 Springer-Verlag 2005

Abstract The diffusive gradients in thin films technique (DGT) was used to measure depth profiles of mercury in river and marine sediments in situ to a spatial resolution of 0.5 cm. Agarose gel was used as the diffusive gel in the DGT probes. Two different selective resins—Chelex 100 with iminodiacetic groups and Spheron-Thiol with thiol groups incorporated in the polyacrylamide resin gel—were tested. The different capture efficiencies of the two adsorbents enabled the fractions of mercury bound in different species in sediment pore water to be estimated. Mercury concentrations obtained by DGT with Spheron-Thiol resin were very similar to those obtained after centrifugation. This indicates that DGT with SheronThiol resin reports on total dissolved mercury levels. The concentration of mercury measured by DGT with Chelex-100 resin was much lower (by a factor of 5–20) for the same sediment samples. Chelex-100 does not have such a high affinity to mercury as Spheron-Thiol, and so it only reports on the content of labile mercury species, such as inorganic ions and weak complexes. The content of labile mercury species in the river sediment was approximately 20% of the total dissolved mercury in pore water, whereas in marine sediment only 7% of the mercury was present as labile species. Keywords Diffusive gradients in thin films technique (DGT) Æ Mercury Æ Sediment Æ Pore water

P. Divisˇ (&) Æ H. Docˇekalova´ Faculty of Chemistry, Institute of Chemistry and Technology of Environmental Protection, Brno University of Technology, Purkynˇova 118, 61200 Brno, Czech Republic E-mail: [email protected] Tel.: +420-541-149435 Fax: +420-541-149435 M. Leermakers Æ Y. Gao Laboratory of Analytical and Environmental Chemistry, Faculty of Sciences, Vrije Universiteit Brussels, Pleinlaan 2, 1050 Brussels, Belgium

Introduction Mercury is a focus for analytical and environmental chemists, because of its toxicity and its tendency towards bioaccumulation in biota and biomagnification in food chains [1–3]. The environmental mobility and toxicological effects of mercury are strongly dependent on the chemical species present. Free metal ion and labile inorganic complexes play an essential role in the methylation of Hg since they are the Hg species available for methylation. However, most published studies dealing with the determination of mercury in pore waters only contain information on total mercury and methylmercury concentrations [4–7]. Recently a new technique for sampling solutes known as the diffusive gradients in thin films technique (DGT) has been developed [8]. The DGT technique measures only those metal species that are able to pass through the diffusive gel and that are likely to be captured by resin immobilized in thin film gel [9]. All of these metal species are considered to be bio-available [10, 11], and from this point of view the DGT technique can provide important information for environmental studies. The DGT technique is currently widely used for in situ measurements of trace metal concentrations and fluxes in natural waters, soils and sediments [12–16]. However, this technique has yet to be used to monitor mercury levels. The fact that mercury binds to the amide groups within polyacrylamide gel rather than diffusing freely means that this diffusive gel cannot be used for mercury determination [17]. In this work, we have used an agarose diffusive gel in a DGT device, which permits free diffusion of mercury [17], in order to measure mercury concentrations in sediment pore water. For comparison, centrifugation was also used to sample the pore water. The concentrations of mercury measured after sampling by centrifugation and by DGT were compared. Moreover, two resins with different capture efficiencies for mercury were

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tested in the DGT device. A commonly used Chelex-100 resin with iminodiacetic functional groups [18] was compared with Spheron-Thiol resin with thiol groups [19].

Materials and methods Principle of DGT The DGT technique is based on a simple device (a DGT probe) consisting of two thin hydrogel layers. Solutes from the bulk solution diffuse through diffusive gel and are immobilized in a layer of resin gel containing selective resin or some other sorption medium [9, 20, 21]. If the resin is not saturated, the concentration of solutes on the resin gel surface is zero. As a result of this, a concentration gradient is established between the resin gel and the bulk solution, which provides the motivation for other solutes to diffuse through the diffusion gel. The flux (F) of solutes from the bulk solution to the resin gel, and subsequently the in situ concentration of solutes in the bulk solution cb can be calculated from the mass m of solutes that diffuses through the diffusion area A after deployment time t: F ¼ Dcb =Dg ¼ m=At

resin gel was removed from the glass plates and soaked in deionized water overnight to allow it to expand to a stable thickness. The thickness of the hydrated gels was 0.4 mm. Agarose diffusive gels were prepared from a hot (80 C) 1.5% agarose (Bio-Rad) aqueous solution. This solution was pipetted between two glass plates separated by a 0.50 mm-thick Teflon spacer and left to cool down to room temperature. The thickness of 0.5 mm agarose gel does not change with immersion in water. Sheets of 16 · 2.7 cm in size were cut from the prepared gels using a plastic knife. The DGT probes were assembled by inserting the Chelex 100 or SpheronThiol resin gel sheets inside the rear part of the DGT probe (DGT Research Ltd., Lancaster, UK). These resin gels were then covered with the agarose diffusive gel sheet and with a Millipore (Bedford, MA, USA) membrane filter (cellulose acetate, 0.45 lm pore size, 0.13 mm thickness). The probes were then closed, with the front part of the DGT probe equipped with a window. Before being deployed in a sediment sample, the DGT probes were immersed in a container filled with deionized water and purged overnight with nitrogen in order to remove oxygen from the gels.

ð1Þ

where D is the diffusion coefficient of the ion in a diffusive gel, typically indistinguishable from the value of the free ion in water (on the order of 10–6 cm2 s1) [17, 22]. The use of Eq. 1 to calculate a solute concentration in a bulk solution cb is only valid for a mixed solution, such as natural, lake and seawater, where convective processes maintain constant concentrations of solutes. In non-mixed solutions (sediment and soil pore waters) cb may decrease with time, and the concentration measured by DGT is instead interpreted as the mean concentration at the DGT probe surface cs during the deployment time. The relationship of cb to cs depends upon the restocking of the solution with solutes from the solid phase [23, 24]. Preparation of DGT probes Polyacrylamide resin gels were prepared by polymerization of 15% acrylamide solution (Merck) containing 0.3% agarose cross-linker (DGT Research Ltd., Lancaster, UK) and the specified resin. Either 0.12 g of Spheron-Thiol (Lachema, CZ) or 0.20 g Chelex-100 (Bio-Rad) per 1 ml of solution was used. Polymerization was initiated by adding 7 ll of freshly-prepared ammonium persulfate (Merck) and 2.5 ll N,N,N¢,N¢tetramethylethylenediamine (Merck) to 1 ml of acrylamide solution. This solution was then pipetted immediately between two glass plates separated by a 0.25 mm thick Teflon spacer. The glass plates were then placed into an oven held at 44±2 C. After 45 min, the

Sediment sampling The river and marine sediments were collected in May 2004. The sampling stations were situated on the Leie river in the centre of the town of Menen (Belgium, longitude 5047¢60¢¢N, latitude 37¢0¢¢E) and in the North Sea in the Belgian coastal zone near Oostende (longitude 5116¢25¢¢N, latitude 254¢30¢¢E). The river sediment was obtained by by scuba diving and sampled into precleaned plastic cores. The marine sediment was collected from the research vessel R.V. Belgica using a Reineck core sampler. Sampling and analysis of pore water using DGT The deoxygenated DGT probes were carefully immersed into the sediment cores within a few seconds and the position of the sediment–water interface in relation to the probe was recorded. After 48 h of deployment, the DGT probes were retrieved from the sediment and thoroughly rinsed with deionized water to remove sediment particles attached to the probes. The resin gels were extracted from DGT probes and placed on a plastic plate in a laminar flow cabinet inside a clean room. The resin gels were cut into 0.5 cm wide strips using a plastic knife. Each strip was analyzed directly using a single-purpose atomic absorption spectrometer (Advanced Mercury Analyzer, Altec, Prague, Czech Republic) by combusting the sample in oxygen atmosphere and using amalgamation preconcentration.

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Sampling and analysis of pore water using centrifugation A sediment core was sectioned into 2 cm-long sections in a glove box filled with nitrogen, and each of these sections was transferred into Teflon centrifugation vials. Centrifugation was carried out at 3000 rpm for 20 min in a Jouan B3.11 (Jouan Inc., Winchester, VA, USA) centrifuge, and the supernatant was separated from the sediment in the glove box. The pore water was then filtered through 0.4 lm disposable filter units (Chromafil) and acidified with 1% HNO3 (Merck, Darmstadt, Germany, suprapur grade). Hg analysis was performed using an inductively-coupled plasma sector field mass spectrometer (ICP-SFMS, Thermo Finnigan, San Jose, CA, USA, Element II). Marine pore water samples were diluted tenfold before analysis.

Results and discussion Deployment of DGT in a river sediment sample The deployment of the two different DGT probes, containing either Chelex 100 or Spheron-Thiol resins, resulted in concentration depth profiles of mercury with similar trends but different concentration scales (Figs. 1 and 2). The concentration of mercury in pore water as measured by the Spheron-Thiol DGT probe was five times higher (average concentration: 0.035± 0.018 lg l1) than that of Chelex 100 DGT probe

Fig. 1 Concentration depth profile of mercury, from a Chelex 100DGT unit deployed in river sediment sampled on May 2004 in the Leie river, Belgium (temperature 20.6 C, pH 7.4)

Fig. 2 Concentration depth profile of mercury, from a SpheronThiol-DGT unit deployed in the river sediment (diamonds), compared with the concentration depth profile of mercury obtained using centrifugation for pore water sampling (triangles). Sediment sampled on May 2004 in the Leie river, Belgium (temperature 20.6 C, pH 7.4)

(average concentration: 0.007±0.013 lg l1). This is caused by the different binding efficiencies of the resins used. Iminodiacetic functional groups of Chelex 100 resin are only able to react with weak complexes of mercury: hydrated mercury ions and mercury bonded in labile inorganic and organic complexes. These are either able to dissociate during diffusion through the diffusive gel, or they have lower stability constants than the mercury-iminodiacetic acid complex. On the other hand, thiol groups of Spheron-Thiol are capable to react with mercury bound in even very strong complexes with natural ligands, inert organic species, organomercury species and some colloids. The DGT units filled with different resins with different capture efficiencies for mercury could be used to distinguish between mercury complexes with different stabilities and therefore to fractionate various mercury species from the sample. The Spheron-Thiol concentration depth profile (Fig. 2) is very similar to that obtained by direct sampling and analysis of pore water using centrifugation (average concentration: 0.036±0.020 lg l1). It shows that a DGT probe with Spheron-Thiol resin could be used to assess the total dissolved mercury in pore water. Two sharp maxima were observed in the mercury concentration depth profiles (Figs. 1 and 2). The first maximum occurs at a depth of 3 cm (0.095 lg l1) in the case of Spheron-Thiol and at 4 cm depth in case of Chelex-100 (0.070 lg l1), corresponding very well with

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the position of the iron reduction zone in sediment samples [M. Leermakers, 2004, unpublished data]. Some mercury bound to the surface of iron oxide [25] is probably released upon iron oxide reduction at this depth. The source of the second maximum in the Spheron-Thiol profile (7 cm; 0.090 lg l1) is not known; it could be caused by a local inhomogeneity of the sediment. Deployment of DGT in a marine sample The depth profiles of both labile Hg (Chelex 100 resin) and total Hg (Spheron-Thiol resin) show an increase in concentration in the surface sediment (0–4 cm) corresponding to the Fe and Mn reduction zone (unpublished data). Similar to the river sediment depth profiles, the marine depth profiles differ in terms of the concentration scale (Figs. 3 and 4). The concentrations of mercury in pore water of marine sediment measured by SpheronThiol DGT probe were very similar to those found in the river sediment (average concentration: 0.031±0.010 lg l1). These were significantly (twenty times) higher than those given by the Chelex 100 DGT probe (average concentration: 0.0017±0.0010 lg l1) and they were in good agreement with results obtained after centrifugation and direct analysis (average concentration: 0.045±0.021 lg l1) (Fig. 4). These results indicate that most of the mercury content is strongly

Fig. 4 Concentration depth profile of mercury from a SpheronThiol-DGT unit deployed in the marine sediment (diamonds) compared with the concentration depth profile of mercury obtained using centrifugation for pore water sampling (triangles). Sediment sampled on May 2004 in the North Sea near Oostende, Belgium (temperature 15.6 C, pH 7.9, salinity 34.25)

bound in natural complexes or is present as methyl mercury. The sediments in this coastal zone are fine grain, organic rich sediments enriched in trace metals such as mercury as well as being anoxic, which are favorable conditions for Hg methylation [26]. Previous results for mercury speciation in these sediments show pore water methyl mercury concentrations ranging from 0.001 to 0.006 lg l1 [27].

Conclusion

Fig. 3 Concentration depth profile of mercury from a Chelex 100DGT unit deployed in the marine sediment, sampled on May 2004 in the North Sea near Oostende, Belgium (temperature 15.6 C, pH 7.9, salinity 34.25)

The DGT technique using an agarose diffusive gel instead of the commonly used polyacrylamide diffusive gel is suitable for measuring mercury concentrations and fluxes in sediment pore water. By applying DGT probes filled with different resins with different capture efficiencies for mercury, measurements of labile only or total dissolved mercury concentrations are possible. The preconcentration capability of the DGT technique makes it possible to measure very low concentrations of mercury in sediment pore waters (sub ng l1 levels) with high vertical resolution. The results obtained using the DGT technique with Spheron-Thiol resin are in good agreement with the results obtained after centrifugation, showing that Spheron-Thiol-DGT is representative of the total dissolved mercury fraction in the sediments.

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Comparison between Spheron-Thiol DGT concentrations and Chelex-100 DGT concentrations shows that 20% of the total dissolved mercury in pore water is bound as labile species in the river sediment sample, whereas in the marine sediment sample investigated, only 7% of the mercury in pore water is present as labile mercury. Further method development will concentrate on coupling the DGT technique to chromatographic separation for the analysis of methylmercury in pore water. Acknowledgements The work was carried out in the framework of the FR-VL-1.3.1. EU-INTERREG III-STARDUST project and the project MSM0021630502 of the Ministry of Education, Youth and Sports of the Czech Republic. The authors wish to thank the project managers for their financial support.

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8. Davison W, Zhang H (1994) Nature 367:546–548 9. Zhang H, Davison W (1995) Anal Chem 67:3391–3400 10. Campbell PGC (1995) In: Tessier A, Turner DR (eds) Metal speciation and bioavailability in aquatic systems. Wiley, New York, p 45 11. Tusseau-Vuillemin MH, Gilbin R, Bakkaus E, Garric J (2004) Environ Toxicol Chem 23:2154–2161 12. Fones GR, Davison W, Hamilton-Taylor J (2004) Continental Shelf Res 24:1485–1504 13. Docˇekal B, Smetkova´ V, Docˇekalova´ H (2003) Chem Pap 57:161–166 14. Zhang H, Zhao FJ, Sun B, Davison W, McGrath SP (2001) Environ Sci Technol 35:2602–2607 15. Alfaro-De la Torre MC, Beaulieu PY, Tessier A (2000) Anal Chim Acta 418:53–68 16. Denney S, Sherwood J, Leyden J (1999) Sci Total Environ 239:71–80 17. Docˇekalova´ H, Divisˇ P (2005) Talanta 65:1174–1178 18. Pesavento M, Biesuz R, Gallorini M, Profumo A (1993) Anal Chem 65:2522–2527 19. Slova´k Z, Smrzˇ M, Docˇekal B, Slova´kova´ S (1979) Anal Chim Acta 111:243–249 20. Teasdale PR, Hayward S, Davison W (1999) Anal Chem 71:2186–2191 21. Zhang H, Davison W, Gadi R, Kobayashi T (1998) Anal Chim Acta 370:29–38 22. Garmo OA, Royset O, Steinnes E, Flaten TP (2003) Anal Chem 75:3573–3580 23. Zhang H, Davison W, Miller S, Tych W (1995) Geochim Cosmochim Acta 59:4181–4192 24. Harper MP, Davison W, Tych W (1999) Aquat Geochem 5:337–355 25. Inoue Y, Munemori M (1979) Anal Chem 13:443–445 26. Leermakers M, Galletti S, De Galan S, Brion N, Baeyens W (2001) Mar Chem 75:229–248 27. Galletti S (2000) MS Thesis, Vrije Universiteit Brussel, 75pp (in Dutch)

Chem. Listy 99, 640 − 646 (2005)

Referáty

GELOVÉ TECHNIKY PRO MĚŘENÍ IN SITU VE VODÁCH, V PŮDÁCH A V SEDIMENTECH Mezi nejběžněji používané techniky pro analýzu přírodních systémů in situ patří aplikace elektrod a mikroelektrod2−4, které kontinuálně zaznamenávají informace o koncentraci definovaných chemických forem ve sledovaném systému. Dalšími používanými technikami jsou voltametrie5,6 a dialýza7−9. Pokrok v měření in situ pak znamenají nové vzorkovací gelové techniky, a to technika difuzní rovnováhy v tenkém filmu (diffusive equilibrium in thin films technique − technika DET)10 a technika difuzního gradientu v tenkém filmu (diffusive gradients in thin films technique − technika DGT)11. V předkládaném příspěvku jsou představeny tyto nové in situ vzorkovací techniky, jejichž základem je ustavování rovnováhy a difuze sledovaných specií v tenkém filmu polyakrylamidového hydrogelu.

PAVEL DIVIŠ, HANA DOČEKALOVÁ a VERONIKA ŘEZÁČOVÁ Ústav chemie a technologie ochrany životního prostředí, Fakulta chemická, Vysoké učení technické v Brně, Purkyňova 118, 612 00 Brno [email protected] Došlo 27.8.04, přepracováno 18.3.05, přijato 7.4.05.

Klíčová slova: gelové techniky, difuzní gradient v tenkém filmu, difuzní rovnováha v tenkém filmu, přírodní vody, sediment, půda

2. Technika difuzní rovnováhy v tenkém filmu Technika difuzní rovnováhy v tenkém filmu (DET) byla vyvinuta z potřeby znalosti koncentračních gradientů na fázovém rozhraní voda-sediment s vysokým vertikálním rozlišením, neboť právě toto úzké milimetrové rozhraní je těsně spojeno s pohybem a chemickými změnami přírodních a antropogenních polutantů12. Technika DET pracuje na podobném principu jako dialyzační jednotky. K vzorkování však používá plátek (< 1 mm) polyakrylamidového hydrogelu, běžně používaného při elektroforetickém dělení bílkovin, který je uzavřen spolu s membránovým filtrem o velikosti pórů 0,45 µm v plastové sondě (obr. 1). Tento gel obsahuje 95 % vody a hodnoty difuzních koeficientů měřených specií v gelu jsou tak velmi blízké hodnotám ve vodě13. Velikosti pórů používaného polyakrylamidového gelu jsou 2−5 nm, takže

Obsah 1. 2. 3.

4.

Úvod Technika difuzní rovnováhy v tenkém filmu Technika difuzního gradientu v tenkém filmu 3.1. Použití techniky difuzního gradientu v tenkém filmu pro speciační analýzu 3.2. Použití techniky difuzního gradientu v tenkém filmu pro analýzu přírodních vod 3.3. Použití techniky difuzního gradientu v tenkém filmu pro analýzu sedimentů a půd Závěr

1. Úvod Získání plně spolehlivých informací o distribuci chemických forem kovů (specií) v jednotlivých složkách životního prostředí je obtížné. V průběhu odběru a během dalšího zpracování před vlastním analytickým stanovením probíhají totiž ve vzorku fyzikálně-chemické změny, které mají za následek změnu rozdělení specií a vedou tak k chybným závěrům při interpretaci získaných výsledků1. Těmto případným transformačním změnám se lze vyhnout měřením in situ. Výhodou měření in situ je kromě eliminace rušivých vlivů při vzorkování, a následně po vzorkování, také možnost získání detailních časových a prostorových dat, či měření koncentračních gradientů a toků látek na přírodních rozhraních. V dnešní době je i přes více než desetiletí práce v oblasti měření in situ možno mluvit pouze o počátcích praktického používání technik in situ, neboť jejich vývoj a ověření jsou často obtížné a zdlouhavé.

Obr. 1. Vzorkovací jednotka pro měření in situ v sedimentech technikami DET a DGT

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Referáty

hydratované kationty kovů s poloměry 0,2−0,3 nm a menší komplexy s organickými ligandy do gelu snadno difundují13. Rovnováha mezi koncentracemi chemických forem v gelu a v okolní vodě se na rozdíl od dialyzačních jednotek ustavuje velmi rychle (řádově hodiny na rozdíl od dnů až týdnů)14. Po dosažení koncentrační rovnováhy je sonda vytažena ze sedimentu, polyakrylamidový gel je vyjmut a nakrájen na pruhy o šířce řídící se požadovaným prostorovým rozlišením hloubkového koncentračního profilu. Koncentrace měřených specií v exponovaném gelu je stanovena vhodnou analytickou metodou po eluci gelu známým objemem eluentu, kterým je většinou zředěná kyselina dusičná. Nevýhodou použití techniky DET může být fakt, že pruh polyakrylamidového gelu je kontinuální vzorkovací médium. Měřené koncentrační hloubkové profily tak mohou být zkreslovány vlivem laterální difuze probíhající v samotném gelu, která roste s tloušťkou gelu13. Při vytažení sondy DET ze sedimentu se koncentrační profil v gelu rozmývá, a proto je nutné gel buď velmi rychle nařezat na příslušné pásky dle požadovaného prostorového rozlišení nebo ionty v gelu zafixovat13. U většiny iontů se fixace provádí ponořením sondy do zředěného roztoku NaOH nebo KOH (cit.10,13). Tloušťka gelu a rychlost fixace jsou určující pro velikost získaného hloubkového rozlišení. Zafixování iontů do 20 s umožňuje měření s milimetrovým rozlišením, pro rozlišení 1.10−3 mm je třeba použít velmi tenký gel a fixaci provést do 2 s (cit13). Problém rozmývání koncentračního profilu lze obejít použitím dělených DET sond, kde je gel již při přípravě sondy DET rozdělen do vzájemně izolovaných prostor14−16. Technika DET je v současnosti systematicky studována a aplikačně rozvíjena. Do dnešní doby byla použita v řadě studií, především pro stanovení hloubkových profilů iontů majoritních prvků Fe, Mn, Ca, Mg a K (cit.17−19), prvků minoritních i stopových Cd, Co, Cr, Cu, Ni, Pb, Se, Zn, As, Tl a dalších15, U, Mo, Re (cit.16) nebo aniontů Cl−, Br−, SO42−, NO3– (cit.15,18−21). Technika DET byla také použita pro sledování alkality a celkového obsahu CO2 v sedimentech18. Technikou DET lze tedy velmi snadno získat informace o koncentracích rozpuštěných specií v pórové vodě sedimentů s vysokým hloubkovým rozlišením. Koncentrace některých environmentálně zajímavých specií jsou však často velmi nízké a pod detekční schopností běžně dostupných analytických metod. Z toho důvodu byla vyvinuta technika DGT, která v sobě zahrnuje možnost zkoncentrování.

Obr. 2. Vzorkovací jednotka pro měření in situ ve vodách a v půdách technikou DGT

tické separaci specií z roztoku a jejich kumulaci v sorpčním médiu11. Pro měření hloubkových profilů v sedimentech využívá technika DGT stejné vzorkovací jednotky jako technika DET (obr. 1). Pro měření v půdách a ve vodách používá jednoduchou vzorkovací jednotku tvaru pístu vyrobenou z plastu (obr. 2), ve které jsou uzavřeny dvě vrstvy polyakrylamidového hydrogelu, sorpční a difuzní (obr. 3). První vrstva hydrogelu, která obsahuje specifické sorpční médium, je překryta vrstvou difuzního permeabilního hydrogelu tak, že jen tento difuzní gel přichází do styku s vnějším roztokem. Membránový filtr chrání difuzní gel před mechanickým poškozením (obr. 3). Po ponoření jednotky DGT do měřeného roztoku difundují ionty přes dobře definovanou vrstvu difuzního gelu o známé tloušťce ∆g k sorpčnímu médiu (obr. 4). Nejpoužívanějším sorpčním médiem pro stanovení kovů je chelatující iontoměnič Chelex-100 s vázanými skupinami kyseliny iminodioctové. Ionty prošlé difuzním gelem jsou na povrchu iontoměniče imobilizovány na funkčních skupinách, a to tak dlouho, dokud není jeho kapacita nasycena. V difuzním gelu se tak ve velmi krátké době (asi 60 s) ustaví lineární koncentrační gradient (obr. 4). Jestliže tento

membránový filtr difuzní gel sorpční gel

3. Technika difuzního gradientu v tenkém filmu

vnější část s expozičním oknem

Technika difuzního gradientu v tenkém filmu (DGT) byla poprvé popsána v roce 1994. Jejím základem je polyakrylamidový hydrogel stejného složení jako u techniky DET. Její použití není založeno na ustavení rovnováhy mezi roztokem a gelem jako u techniky DET, ale na kine-

píst

Obr. 3. Schéma uložení gelů ve vzorkovací jednotce DGT (cit66)

641

koncentrace (c)

Chem. Listy 99, 640 − 646 (2005)

vat, které formy kovů budou technikou DGT měřeny. Základní vlastností difuzního gelu je velikost pórů, která určuje velikost specií schopných procházet gelem. Velikost pórů v gelu lze určovat při přípravě gelu volbou monomeru a síťovadla. Nejběžněji používaný polyakrylamidový gel pro techniku DGT, zkráceně označovaný jako gel APA, je shodný s gelem používaným v technice DET. Gel je připravován polymerizací směsi monomerního akrylamidu a agarosového síťovadla (DGT Research, Lancaster, Velká Británie), po přidání katalyzátoru (N,N,N’,N’-tetramethylethylendiamin) a iniciátoru polymerizační reakce (NH4)2S2O8 (cit23). Připravený gel APA má velikost pórů 2−5 nm (cit24). Použitím jednotky s difuzní vrstvou gelu APA je tedy možno získat informace o mobilních anorganických a menších organických formách iontů ve sledovaném systému25. Změnou použitého síťovadla nebo změnou jeho koncentrace při přípravě gelu lze kromě výše popsaného gelu APA připravit také tzv. omezující gel, označovaný jako gel RG s velikostí pórů < 1 nm umožňující volnou difuzi iontů kovů, ale zabraňující difuzi objemnějších komplexních sloučenin24. Použitím gelu RG mohou být získány informace pouze o mobilních anorganických formách24,25. Zcela jiný než běžně používaný gel APA je agarozový gel, označovaný jako gel AGA. Agarosa, lineární polysacharid složený z opakujících se jednotek agarobiosy (vzájemně vázaná β-D-galaktopyranosa a 3,6-anhydro-α-L-galaktopyranosa), tvoří rozpouštěním v horké vodě dvojšroubovice, které jsou pak během chladnutí roztoku asociovány do trojrozměrné sítě vodíkovými vazbami a hydrofobními interakcemi. Vzniklý gel má póry > 20 nm a umožňuje difuzi i velkých přírodních komplexů s fulvovými a huminovými kyselinami24. Použitím gelů s různou velikostí pórů tak lze od sebe rozlišit anorganické formy kovů a kovy vázané v malých a velkých komplexech25,26. Vedle velikosti pórů difuzního gelu je významným faktorem při použití techniky DGT také tloušťka difuzního gelu. Na funkční skupiny iontoměniče v sorpčním gelu se vážou volné kovové ionty a ty frakce kovů, které jsou vázány v tzv. kineticky labilních komplexech, tedy komplexy, které v průběhu difuze vrstvou difuzního gelu stačí disociovat23. Čas t potřebný pro difuzi látky gelem tloušťky ∆g je dán rovnicí 3 (cit23):

c

sorpční gel

difúzní gel

Referáty

∆g

vzdálenost (x)

Obr. 4. Schématické znázornění koncentračního gradientu ve vzorkovací jednotce DGT

gradient zůstává během doby měření t konstantní, lze podle prvního Fickova zákona difuze vypočítat tok analytu F přes difuzní vrstvu ∆g podle vztahu (1) : F =

M D ⋅c = A ⋅t ∆g

(1)

M je množství kovu navázané na iontoměnič, A je plocha exponovaného difuzního gelu, D je difuzní koeficient kovu v gelu a c je koncentrace kovu v měřeném roztoku. Koncentrace c může být zpětně vypočtena z naměřeného toku F (rovnice 2).

c=

M ⋅ ∆g D ⋅t ⋅ A

(2)

Množství kovu M navázané na iontoměnič může být po vysušení gelu stanoveno přímým měřením nedestruktivními technikami, např. rentgenovou fluorescencí XRF nebo technikou PIXE (částicemi indukovaná rentgenová emise) 22 . Alternativou tohoto postupu pak může být eluce kovu z iontoměničového gelu za použití známého objemu elučního činidla (při stanovení kovů nejčastěji zředěné kyseliny dusičné) a analýza eluátu technikami atomové absorpční či atomové emisní spektrometrie23. Množství kovu zachyceného na iontoměnič a následně změřené analytickou metodou však nemusí vypovídat o jeho celkové koncentraci v okolním roztoku. Jednotka DGT automaticky hromadí pouze ty formy kovu, které se difuzí přes difuzní gel dostanou k iontoměniči a jsou schopny se na něj vázat. Tohoto faktu je možno využít pro speciační analýzu.

t=

∆g 2 π ⋅D

(3)

Pro běžně používanou tloušťku difuzního gelu 0,5 mm a D = 7.10−6 cm2 s−1 je t = 2 min. Zvyšováním tloušťky gelu je však možno prodloužit dobu difuze a umožnit tak disociaci i kineticky stabilnějším komplexům. Charakter měřených látek určuje také výběr sorpčního média v sorpčním gelu, neboť labilitu kovových komplexů je možné také ovlivnit výběrem iontoměniče s větší sorpční afinitou.

3.1.Použití techniky difuzního gradientu v tenkém filmu pro speciační analýzu Výběrem difuzního gelu a sorpčního média lze určo642

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Referáty

3.2. Použití techniky difuzního gradientu v tenkém filmu pro analýzu přírodních vod

pro měření stopových a ultrastopových koncentrací labilních kovových specií. Touto technikou lze pohodlně stanovovat koncentrace celé řady kovů řádově v jednotkách 1.10−12 g l−1 s přesností jednotek procent za současné kontroly toku iontů23 nezávisle na hydrodynamice vzorkovaného systému. Maximální doba expozice jednotek DGT závisí na kapacitě a selektivitě použitého sorbentu. Při použití neselektivního sorbentu v přírodních systémech je sorbent nasycen během několikahodinové expozice41 v důsledku kumulace majoritních iontů. Pro Chelex-100, který je selektivní k iontům stopových kovů, může být doba expozice v čistých přírodních vodách až několik měsíců, aniž se sorpční vrstva DGT vzorkovací jednotky nasytí23. Koncentrace naměřené technikou DGT představují průměrné koncentrace za daný čas expozice vzorkovacích jednotek DGT a lépe vypovídají o stavu sledovaného systému než údaje zjištěné při jednorázovém odběru. Významnými parametry ovlivňujícími měření technikou DGT je teplota, pH a iontová síla měřeného roztoku. Polyakrylamidový difuzní gel v rozmezí teplot 5–35 °C nemění svou strukturu a vlastnosti23, a proto je při výpočtech DGT možné počítat s tabelovanými hodnotami difuzních koeficientů iontů ve vodě odpovídající teploty a techniku DGT použít pro měření ve většině přírodních vod. Interval pH vhodný pro aplikaci techniky DGT je závislý na vlastnostech použitého sorbentu. Pro stanovení kovů za použití iontoměniče Chelex-100 bylo nalezeno optimální pH v rozmezí 4,5–9 (cit.23), což rovněž odpovídá hodnotám pH většiny přírodních vod. Technika DGT poskytuje spolehlivé výsledky při měření v roztocích o iontové síle větší než 2.10−4 M (cit.34). Pouze ve vodách s velmi nízkým celkovým obsa-

Technika DGT využívající chelatující iontoměnič Chelex-100 je dnes běžně používána pro stanovení celé škály labilních kovových specií in situ v přírodních vodách. Byla úspěšně použita pro měření koncentrací stopových, ale i minoritních a majoritních kovů v jezerech, v řekách a v mořích (tab. I). Garmo a spol. (cit.40) uvádí použití techniky DGT pro měření více než 30 vybraných kovů v přírodních vodách. V posledních letech byla vyzkoušena řada nových sorpčních gelů, které v mnoha případech umožňují stanovení širšího spektra chemických specií. Pro měření radionuklidů Cs a Sr ve vodách byl použit sorpční gel obsahující iontoměnič AG50W-X8 (cit.41) nebo gel obsahující vázaný fosfomolybdenan amonný42. Jako sorpční médium byly rovněž použity membrány na bázi celulosy s funkčními skupinami kyseliny fosforečné43. Tato modifikace techniky DGT se ukázala být vhodná pro měření Cu a Cd. Podobných výsledků bylo dosaženo při použití kopolymerního gelu z akrylamidoglykolové kyseliny a akrylamidu44. Popsána jsou také sorpční média založená na jiném principu než na iontové výměně, např. na srážení. Pro stanovení fosfátů tak bylo využito oxidů železa45 a pro stanovení sulfidů jodidu stříbrného fixovaného v sorpčním gelu46,47. Technika DGT umožňuje měřit v širokém rozsahu koncentrací kovových specií ve sledovaném systému. Při aplikaci jsou kovové ionty zkoncentrovány vazbou v sorbentu. Delší doba expozice vzorkovací jednotky DGT vede ke kumulaci většího množství kovu a tím ke snížení detekčního limitu měření. Technika DGT je proto vhodná

Tabulka I Příklady použití techniky difuzního gradientu v tenkém filmu pro sledování koncentrací kovů v přírodních vodách Kov Zn, Mn, Fe Cu, Cd, Mn Mn, Fe, Co, Al, Ba, Ni Cd, Cu, Ni, Ca, Mg, Fe, Mn, Zn, Cu, Cr, Pb, Ni, Ag, As Cd, Co, Cu, Ni, Pb, Zn Ca, Mg, Cd, Cu, Ni Cu Cd, Cu, Pb, Zn Cu, Zn, Ni, Cd, Pb, Mn Cu, Cd Fe, Mn; Cu, Zn Cu, Co, Cd, Pb Cu, Zn, Ni, Pb

Vzorkovací místo Anglie, Atlantický oceán, průliv Menai Straits Austrálie, Tasmánie, řeka Pieman; Victoria, řeka Hopkins Anglie, jezero Esthwaite Kanada, jezero Tantaré Itálie, Benátská laguna Nový Zeland, Dunedin; řeka Leith Švédsko, jezero Kutsasjarvi Kanada, zátoky Cape Cod a San Diego; ústí řeky Elizabeth Austrálie, zátoky Westernport Marina, Hastings Jetty, St. Kilda Marina, St. Kilda Pier Švýcarsko, jezero Greifen Kanada, jezero Tantaré Anglie, jezera Windermere, Hawes, Esthwaite, Abbeystead, Lavers Austrálie, Fort hill Wharf, zátoka Darwin Austrálie, moře, Gold Coast Broadwater 643

Lit. 11,23 19 26 27 28 29 30 31 32 33 34 35 36 37

Chem. Listy 99, 640 − 646 (2005)

Referáty

hem kationtů je difuze měřených iontů do jednotky DGT ovlivněna jinými ionty, především ionty Na+ uvolněnými z funkčních skupin iontoměniče Chelex-100, což vede k malé kladné chybě měření29.

cpv stanovena jinou, srovnatelnou a dostupnou technikou.

3.3.Použití techniky difuzního gradientu v tenkém filmu pro analýzu sedimentů a půd

Technika DGT představuje nový nástroj pro odhad dostupnosti kovů v půdách (tab. II). Na rozdíl od řady postupů doporučovaných pro charakterizaci půd64,65, které poskytují údaje spíše o celkovém množství, či o určitém extrahovatelném podílu kovu přítomného v půdě, má technika DGT tu výhodu, že může svým aktivním, nedestruktivním způsobem vzorkování vypovídat o podílu kovu dostupného pro kořenový systém rostlin. Jednotka DGT z půdního roztoku kumuluje ionty, hydratované ionty, mobilní a labilní kovové species, tedy právě ty formy kovů, které jsou dostupné pro rostliny. Interpretace naměřených výsledků při měření v půdách se řídí stejným principem jako při použití techniky DGT v sedimentech.

R=

Techniku DGT je podobně jako techniku DET možné použít k měření hloubkových profilů kovů ve vodě v pórech sedimentů (tab. II). Prekoncentrační schopnost techniky DGT umožňuje stanovení i těch kovových specií, které není možno v důsledku jejich nízké koncentrace stanovit technikou DET. Voda v pórech sedimentů představuje ve srovnání s přírodními vodami objemově omezený a nemíchaný systém. Při použití v sedimentu tak může jednotka DGT kvůli difuzi iontů difuzním gelem a následnému záchytu iontů v sorpčním médiu snižovat jejich koncentraci ve vodě v pórech55. Vypočtená koncentrace z rovnice (2) pak může být interpretována jako koncentrace iontů ve vodě v pórech pouze tehdy, je-li proces uvolňování iontů z tuhé fáze sedimentu do této vody velmi rychlý, takže stačí vyrovnávat deficit vzniklý odčerpáním iontů jednotkou DGT55,56. Jestliže sediment nedokáže rychle vyrovnávat koncentrační změny iontů ve vodě v pórech, je aktuální koncentrace iontů na povrchu jednotky DGT v každém časovém okamžiku za předpokladu lineární difuze definována druhým Fickovým zákonem difuze.

∂ 2c ∂c = D⋅ 2 ∂t ∂x

c DGT c pv

{0 < R < 1}

(5)

4. Závěr V předložené práci jsou představeny dvě nové gelové techniky pro vzorkování in situ, a to technika DET a technika DGT. Tyto techniky patří k novým, moderním přístupům používaných k analýze přírodních systémů, jejichž použití neustále roste. Technikou DET lze snadno měřit hloubkové koncentrační profily kationtů a aniontů ve vodě v pórech sedimentů s vysokým prostorovým rozlišením. Technika DGT je jednoduchá prekoncentrační technika pro řadu prvků, která je běžně používána ke stanovení průměrných koncentrací rozpustných látek ve vodných systémech. Pro svou schopnost koncentrace poskytuje možnost stanovení obsahu kovů, které se v přírodních systémech vyskytují ve stopových množstvích. Sorpce na selektivní sorpční médium současně odděluje měřené analyty od mnohdy komplikované matrice, čímž značně zjed-

(4)

Do jaké míry se doplňují ionty z tuhé fáze sedimentu do vody v pórech lze zjistit současnou aplikací dvou jednotek DGT s rozdílnou tloušťkou difuzní vrstvy ∆g1 a ∆g2 (∆g1 > ∆g2) (cit.51,54) nebo pomocí poměru R (rov. 5) (cit.55). Při výpočtech R musí být koncentrace kovu ve vodě v pórech

Tabulka II Příklady použití techniky difuzního gradientu v tenkém filmu pro sledování koncentrací kovů ve vodě v pórech sedimentů a půd Kova Cu, Co, Ni, Fe, Zn, Cd, Mn Zn, As, Fe, Mn Co, Cd, Fe, Mn

Vzorkovací místo Anglie, jezero Esthwaite Anglie, řeka Sankey Černé moře

Co, Ni, As, Mn, Fe Cd, Pb, Mn, Fe

Skotsko, jezero Duich 50,51,53 Česká republika, 54 rybník Ochoz

a

Lit. 10,48,52

Kovb Zn, Cu, Cd, Ni

Vzorkovací místo Lit. Německo, Braunschweig 57

22 49

Zn, Cu, Cd, Ni, Pb, Zn Zn, Cu, Cd, Ni, Pb, Zn

Skotsko, Lanarkshire Anglie, Stagnogley

58 59

Cu Cd,Cr,Ni, Cu, Cu

Anglie, Merseyside Česká republika, Zlín

60,63 61

Sedimenty, b půdy

644

Chem. Listy 99, 640 − 646 (2005)

Referáty

nodušuje konečnou analýzu. Kombinováním více jednotek s různými typy sorpčních a difuzních gelů lze techniku DGT úspěšně použít ke speciační analýze. Při použití jednotek DGT v sedimentech slouží získaná data k odhadu hmotnostních toků ze sedimentu do okolní vody v pórech a k vytvoření hloubkových profilů. Ze získaných dat je možno matematickými modely určit termodynamické a kinetické konstanty, jako např. distribuční koeficienty kovů charakterizující rozdělení labilních forem kovů mezi tuhou a kapalnou fázi v sedimentech a v půdách. V půdách pak umožňuje technika DGT ve srovnání s běžnými postupy používanými k jejich charakterizaci mnohem věrněji odhadnout množství dostupných forem kovů. Výběr nových sorpčních médií a modifikace sorpčních a difuzních gelů otevírají široké možnosti pro další rozvoj těchto nadějných technik in situ a jejich použití pro monitorování znečištění životního prostředí, studium procesů probíhajících v sedimentech, dostupnosti prvků v půdách a celkového koloběhu prvků v životním prostředí.

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P. Diviš, H. Dočekalová, and V. Smetková (Department of Chemistry and Technology of Environmental Protection, Faculty of Chemistry, University of Technology, Brno): Gel Techniques for in situ Measurement in Natural Waters, Soils and Sediments The diffusive equilibrium in thin films (DET) and diffusive gradient in thin films (DGT) gel techniques have been shown as a new approach to in situ measurements of trace metals and their species in aquatic systems. This review briefly demonstrates the ability of the DET technique to provide information about the depth profiles of solutes in sediment pore water with high resolution. The DGT technique, based on Fick´s First diffusion law, is introduced as a robust technique, which is easy to use for in situ measurement of metal species in natural waters. The DGT technique uses a simple device, which, after passage through a hydrogel, accumulates solutes on a sorbent, such as Chelex-100, acting as a well defined diffusion layer. By simply controlling the mass transport to the sorbent, it is possible to quantify the accumulated metals by measurement of flux or concentration. The quality of diffusive layer is the major factor in determination of the measured species. Metal ions are preconcentrated in situ in the sorbent layer; hence, very low detection limits are possible. The deployment times can vary from 1 h to several months in natural waters. The DGT provides a timeaveraged solute concentration and could be used for measuring mean concentrations over a time period. The other parameters of natural waters like temperature, pH and ionic strength do not affect the measurement. When used for assessment of element availability in soils and sediments, the DGT results are interpreted as fluxes from the solid phase to solution. Both the described gel techniques are very useful tools for monitoring of pollution as well as in study of metal availability in soils and sediments and trace metal circulation in the environment.

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HLOUBKOV… PROFILY LABILNÕCH KOVOV›CH SPECIES V SEDIMENTECH A JEJICH IN SITU MÃÿENÕ TECHNIKOU DIFUZNÕHO GRADIENTU V TENK…M FILMU PAVEL DIVIä*, HANA DO»EKALOV¡, VERONIKA SMETKOV¡

1. ⁄vod 2. Teoretick· Ë·st 3. Experiment·lnÌ Ë·st 3.1. P¯Ìprava gel˘ a sond pro DGT techniku 3.2. P¯Ìprava sedimentu 3.3. Aplikace vzorkovacÌch jednotek DGT 3.4. StanovenÌ prvk˘ v elu·tech 4. V˝sledky a diskuse 5. Z·vÏr

kov˘ s dostateËnÏ vysok˝m rozliöenÌm. Znalost tÏchto tok˘ je d˘leûit· pro studium kolobÏhu prvk˘ v ûivotnÌm prost¯edÌ a k odhadu moûnÈ kontaminace vod star˝mi z·tÏûemi uloûen˝mi v sedimentech v p¯ÌpadÏ zmÏn podmÌnek, ke kter˝m doch·zÌ bÏhem st¯Ìd·nÌ roËnÌch obdobÌ nebo bÏhem nenad·l˝ch ud·lostÌ, jako jsou povodnÏ. V pr˘bÏhu odbÏru vzorku sedimentu5 a jeho zpracov·nÌ centrifugacÌ6 nebo lisov·nÌm7,8 p¯ed vlastnÌm analytick˝m stanovenÌm doch·zÌ k chemick˝m zmÏn·m vedoucÌm k chybn˝m z·vÏr˘m p¯i interpretaci namÏ¯en˝ch v˝sledk˘9,10. Tento z·vaûn˝ problÈm lze obejÌt tzv. mÏ¯enÌm in situ11. K mÏ¯enÌ labilnÌch species in situ v sedimentech byly pouûity iontovÈ selektivnÌ elektrody a r˘znÈ typy mikroelektrod12,13. Mikroelektrody jsou vöak velmi subtilnÌ, pr·ce s nimi je obtÌûn· a i u komerËnÏ dod·van˝ch elektrod nenÌ jednoznaËn˝ n·vod k jejich pouûitÌ. KromÏ toho nejsou dostateËnÏ citlivÈ a jsou rovnÏû omezeny poËtem stanoviteln˝ch prvk˘. Dial˝za, bÏûnÏ pouûÌvan· metoda k mÏ¯enÌ koncentracÌ kov˘ in situ v pÛrovÈ vodÏ sediment˘14,15, vyûaduje dlouh˝ Ëas k ustavenÌ koncentraËnÌ rovnov·hy a nedosahuje poûadovanÈho rozliöenÌ a citlivosti. Tato pr·ce p¯edstavuje novou techniku in situ, zn·mou pod zkratkou DGT (diffusive gradients in thin films)16, kter· je schopna mÏ¯it p¯Ìmo koncentrace labilnÌch forem kov˘ ve vod·ch17ñ19, hmotnostnÌ toky iont˘ kov˘ v pÛrov˝ch vod·ch sediment˘20 a p˘d21,22, a jejÌ pouûitÌ p¯i mÏ¯enÌ hloubkov˝ch profil˘ a tok˘ vybran˝ch kov˘ v rybniËnÌm sedimentu.

1.

2.

⁄stav chemie a technologie ûivotnÌho prost¯edÌ, Fakulta chemick·, VysokÈ uËenÌ technickÈ v BrnÏ, PurkyÚova 118, 612 00 Brno e-mail : [email protected] Doölo 26.6.2003, p¯ ijato 13.10.2003. KlÌËov· slova: sediment, labilnÌ species, hloubkovÈ profily, Fe, Mn, Cd, Pb, DGT, AAS

Obsah

⁄vod

StanovenÌ chemick˝ch forem kov˘ (species) v p¯ÌrodnÌch vod·ch, sedimentech a p˘d·ch je st·lou v˝zvou pro environment·lnÌ analytiky. Nejv˝znamnÏjöÌ roli z toxikologickÈho hlediska hrajÌ labilnÌ species, kterÈ jsou mobilnÌ v ûivotnÌm prost¯edÌ, jsou p¯ijÌm·ny organismy a p¯ech·zejÌ tak snadno do potravnÌch ¯etÏzc˘. JednÌm z v˝znamn˝ch mÌst akumulace toxick˝ch l·tek produkovan˝ch v˝robou jsou ¯ÌËnÌ a sladkovodnÌ sedimenty.V poslednÌ dobÏ je vÏnov·na velk· pozornost mÏ¯enÌ koncentraËnÌch gradient˘ kovov˝ch species na f·zovÈm rozhranÌ vodañsediment. Toto rozhranÌ je frekventovan˝m mÌstem, kde se propojujÌ geochemickÈ cykly mnoha prvk˘ a kde doch·zÌ k ¯adÏ chemick˝ch a biologick˝ch proces˘1 . KovovÈ ionty mohou b˝t bÏhem tÏchto proces˘ uvolÚov·ny z oxid˘, hydroxid˘ a solÌ, kde jsou v·z·ny, nebo z rychle se oxidujÌcÌ organickÈ hmoty sedimentu. N·sledn˝ tok elektron˘ a ˙bytek organickÈ sloûky v sedimentu majÌ za n·sledek zmÏnu koncentraËnÌch gradient˘ kov˘ v sedimentu, souËasnÏ se zmÏnou gradientu pH, oxidaËnÏ-redukËnÌho potenci·lu a dalöÌch parametr˘2. Ke zmÏn·m forem kov˘ doch·zÌ ve velmi jemnÈm hloubkovÈm rozpÏtÌ (1ñ2 mm) a zmÏny gradient˘ jsou velmi ostrÈ3,4. Pro v˝poËet uvolÚov·nÌ kov˘ ze sedimentu a jejich toku do okolnÌ vodnÈ f·ze je proto nutnÈ zmÏ¯it hloubkovÈ profily *

Teoretick· Ë·st

Technika DGT vyuûÌv· dvou vrstev hydrogelu. PrvnÌ vrstva gelu obsahuje specifick˝ iontomÏniË (Chelex-100) s v·zan˝mi funkËnÌmi skupinami kyseliny iminodioctovÈ23, druh· vrstva iontovÏ permeabilnÌho hydrogelu s p¯esnÏ definovanou tlouöùkou p¯ekr˝v· prvnÌ vrstvu. Oba gely jsou spoleËnÏ sev¯eny ve vzorkovacÌ jednotce (obr. 1) tak, ûe jen iontovÏ

Obr.1. VzorkovacÌ jednotka DGT

Pavel Diviö zÌskal 2. mÌsto v soutÏûi o nejlepöÌ studentskou vÏdeckou pr·ci v oboru analytickÈ chemie O cenu firmy Merck 28.1.2003 v PardubicÌch.

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Cena Merck iontomÏniËov˝ gel

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4c

C

1

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expoziËnÌ okno

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difuznÌ gel

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Ca 3 dif˙znÌ gel

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Obr.3. SchÈmatickÈ zn·zornÏnÌ koncentraËnÌho gradientu kov˘ v difuznÌm gelu a v pÛrovÈ vodÏ sedimentu37 Obr.2. SchÈma uloûenÌ gel˘ ve vzorkovacÌ jednotce DGT (cit.37)

permeabilnÌ gel p¯ich·zÌ do styku s vnÏjöÌm roztokem. Toto experiment·lnÌ uspo¯·d·nÌ je uk·z·no na obr. 2. Ionty z roztoku difundujÌ p¯es svrchnÌ gel k iontomÏniËi zachycenÈm ve spodnÌ vrstvÏ, kde jsou imobilizov·ny sorpcÌ na funkËnÌch skupin·ch tak dlouho, dokud nenÌ kapacita iontomÏniËe nasycena. Transport iont˘ je ¯Ìzen koncentraËnÌm gradientem vznikl˝m na iontovÏ permeabilnÌm, difuznÌm gelu tlouöùky ∆g. Aby se zabr·nilo p¯ÌpadnÈmu mechanickÈmu poökozenÌ gelu, je gel chr·nÏn z vnÏjöÌ strany vhodn˝m membr·nov˝m filtrem, kter˝ klade stejn˝ odpor difuzi iont˘ kovu jako difuznÌ gel. Je-li koncentrace kovu v roztoku konstantnÌ, pak tÈû koncentraËnÌ gradient z˘st·v· konstantnÌ. V gelu tlouöùky cca 1 mm se tak ve velmi kr·tkÈ dobÏ nÏkolika minut ustavÌ line·rnÌ koncentraËnÌ gradient. Tok iont˘ F se pak ¯ÌdÌ I. Fickov˝m z·konem difuze: F=

D. c ∆g

(1)

kde c je koncentrace iontu v roztoku, D je difuznÌ koeficient iontu v difuznÌm gelu, kter˝ m· prakticky stejnou hodnotu jako v ËistÈ vodÏ24 (pro bÏûnÈ ionty p¯echodn˝ch prvk˘ cca (5ñ8)◊ 10ñ6 cm2.sñ1). Tok je tÈû definov·n jako mnoûstvÌ sorbovanÈho iontu M , proölÈ difuznÌ plochou A po dobu expozice t : F=

M A. t

(2)

Tok iont˘ kovu a n·slednÏ i koncentrace iont˘ c v roztoku in situ m˘ûe b˝t vypoËtena z nasorbovanÈho mnoûstvÌ kovu M, stanovenÈho po eluci iontomÏniËovÈho gelu vhodnou analytickou metodou, nap¯. atomovou absorpËnÌ spektrometriÌ s elektrotermickou atomizacÌ (ET AAS), atomovou emisnÌ spektrometriÌ s indukËnÏ v·zan˝m plazmatem (ICP AES), p¯ÌpadnÏ metodou hmotnostnÌ spektrometrie s indukËnÏ v·zan˝m plazmatem (ICP MS). Technika DGT tak m˘1185

ûe b˝t pouûita k monitorov·nÌ koncentracÌ labilnÌch forem kov˘ in situ v ¯ek·ch, jezerech, oce·nech, zdrojÌch pitn˝ch vod, pr˘myslov˝ch odpadnÌch vod·ch a jin˝ch kontaminovan˝ch tocÌch, kde je zajiötÏno dostateËnÈ konvektivnÌ promÌch·v·nÌ. Sonda DGT automaticky hromadÌ ty kovovÈ species, kterÈ se difuzÌ p¯es vrstvu difuznÌho gelu dostanou z mÏ¯enÈho roztoku k iontomÏniËi tak dlouho, dokud nedojde k vyËerp·nÌ kapacity iontomÏniËe, coû je pro uvedenÈ uspo¯·d·nÌ a aplikaci sondy v Ëist˝ch p¯ÌrodnÌch vod·ch aû po dobu nÏkolika mÏsÌc˘17. Tak je moûno pohodlnÏ urËovat koncentrace celÈ ¯ady kov˘ ¯·dovÏ v jednotk·ch 10ñ12 g.lñ1 s p¯esnostÌ jednotek procent za souËasnÈ kontroly toku iont˘ a nez·vislosti vzorkov·nÌ na hydrodynamice vzorkovanÈho systÈmu. ZÌskanÈ koncentrace jsou koncentrace pr˘mÏrnÈ za dan˝ Ëas expozice a lÈpe vypovÌdajÌ o stavu sledovanÈho systÈmu neû koncentrace zjiötÏnÈ po jednor·zovÈm odbÏru. V˝bÏr pouûitÈho iontomÏniËe a kvality a tlouöùky difuznÌho gelu urËuje, kterÈ species budou po aplikaci sondy zachyceny a zmÏ¯eny25. Velikost pÛr˘ difuznÌho gelu urËuje omezenÌ velikosti species. PouûitÌm DGT sond s r˘znou velikostÌ pÛr˘ v difuznÌm gelu je tedy moûno odliöit od sebe velkÈ a malÈ komplexy25. Na funkËnÌ skupiny iontomÏniËe se v·ûou volnÈ kovovÈ ionty a frakce kov˘, kterÈ jsou v·z·ny v tzv. labilnÌch komplexech, tj. komplexech schopn˝ch disociace. Labilitu kovov˝ch komplex˘, kterÈ obsahujÌ jako ligandy p¯ev·ûnÏ fulvenovÈ kyseliny a huminovÈ kyseliny, je moûno zv˝öit v˝bÏrem iontomÏniËe s vÏtöÌ sorpËnÌ schopnostÌ. PouûÌvan˝ iontomÏniË Chelex-100 s funkËnÌmi skupinami kyseliny iminodioctovÈ je p¯ÌrodnÌm ligand˘m dostateËnÏ siln˝m konkurentem. Labilita komplex˘ je urËena i kineticky. DGT sonda zachytÌ ty species, kterÈ v pr˘bÏhu difuze gelem staËÌ disociovat. »as t pot¯ebn˝ pro difuzi je d·n rovnicÌ (3) (cit.17): t=

∆g2 π .D

(3)

Pro tlouöùku gelu 0,5 mm a D = 7.10ñ6 cm2. sñ1 je t = 2 min.

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Species, kterÈ jsou sondou DGT zachyceny, jsou tedy d·ny tlouöùkou difuznÌho gelu a rychlostÌ difuze. TÏchto fakt˘ lze pouûÌt pro urËov·nÌ jednotliv˝ch forem kov˘ (species) ve vodn˝ch systÈmech26. V nepromÌch·van˝ch systÈmech, kde transport iont˘ probÌh· pouze difuzÌ, nap¯. v pÛrov˝ch vod·ch sediment˘ a p˘d, se koncentrace v blÌzkosti difuznÌho gelu sniûuje s rostoucÌ dobou expozice (viz k¯ivka 2 na obr. 3), pokud nejsou ionty souËasnÏ doplÚov·ny do roztoku z tuhÈ f·ze27 . Proces difuze m˘ûe b˝t komplikov·n sloûitou strukturou tuhÈ f·ze. KoncentraËnÌ profily, a tedy aktu·lnÌ koncentrace iont˘ u povrchu gelu v danÈm ËasovÈm okamûiku, jsou definov·ny II. Fickov˝m z·konem difuze ve tvaru:

∂c ∂ 2c = D. 2 ∂t ∂x

(4)

a to za p¯edpokladu platnosti line·rnÌ difuze. Pro zvolenÈ okrajovÈ podmÌnky je moûnÈ numericky ¯eöit uveden˝ vztah. V kaûdÈm ËasovÈm okamûiku m˘ûe b˝t vypoËÌt·n odpovÌdajÌcÌ tok iont˘ kovu z aktu·lnÌho gradientu u povrchu gelu (x = 0) (cit.28) F(t,x) = D .

∂ cbt , x g ∂x

(5)

Sonda DGT pak mÏ¯Ì st¯ednÌ hodnotu toku, kter· m˘ûe b˝t vypoËtena integracÌ rovnice (4) pro dobu expozice (0, t) (cit.28). MnoûstvÌ iont˘, kterÈ dos·hnou iontomÏniË v p¯ÌpadÏ procesu ¯ÌzenÈho jen difuzÌ, je mnohem menöÌ neû v p¯ÌpadÏ s dokonal˝m mÌch·nÌm (k¯ivka 3, obr.3). MÌru doplÚov·nÌ iont˘ z tuhÈ f·ze sedimentu do pÛrovÈ vody lze zjistit souËasnou aplikacÌ dvou jednotek DGT s rozdÌlnou tlouöùkou difuznÌ vrstvy ∆g1 a ∆g2 (kde ∆g1 > ∆g2). Z rovnice (1) a (2) lze v˝poËtem zÌskat dvÏ koncentrace ca1 a ca2 . Stav, kdy ca1 / ca2 ≅ 1, pak m˘ûe b˝t oznaËen jako p¯Ìpad 1 (obr. 3) (cit.29). Zde doch·zÌ k plynulÈmu doplÚov·nÌ iont˘ z tuhÈ f·ze sedimentu do pÛrovÈ vody a koncentrace iont˘ v pÛrovÈ vodÏ sedimentu p¯ilehlÈ k jednotce DGT se tedy bÏhem doby expozice jednotky DGT nesniûuje. P¯Ìpad 2 (obr.3), kdy je proces v˝mÏny iont˘ mezi tuhou f·zÌ a pÛrovou vodou pomal˝ a nezabr·nÌ sniûov·nÌ koncentrace iont˘ v pÛrovÈ vodÏ v blÌzkosti jednotky DGT, m˘ûeme identifikovat, jestliûe ca1 ≠ ca2, avöak podÌl tÏchto koncentracÌ je menöÌ neû podÌl tlouötÏk difuznÌch vrstev ∆g1 a ∆g2 (ca1 / ca2 < ∆g1 / ∆g2)29. V p¯ÌpadÏ 3 (obr.3), kdy v tuhÈ f·zi nejsou p¯Ìtomny û·dnÈ v˝mÏny schopnÈ kovy, lze p¯edpokl·dat, ûe F1 = F2, neboù ionty budou k jednotce DGT difundovat celou öÌ¯kou sedimentu a efekt difuznÌ vrstvy tak bude zanedbateln˝. Za tÏchto podmÌnek je tedy podÌl koncentracÌ ca1 a ca2 roven podÌlu tlouötÏk difuznÌch vrstev ∆g1 a ∆g2 (ca1 / ca2 = ∆g1 / ∆g2), jak vypl˝v· ze vztahu (1) (cit.29). MÏ¯enÌ technikou DGT odr·ûÌ koncentraci labilnÌch forem kov˘ v pÛrovÈ vodÏ sedimentu, rychlost jejich doplÚov·nÌ do pÛrovÈ vody z tuhÈ f·ze sedimentu a tÈû rychlost jejich transportu v sedimentu. Tyto faktory mohou znaËnÏ ovlivÚovat uvolÚov·nÌ toxick˝ch kov˘ v·zan˝ch v sedimentu do okolnÌ vodnÈ f·ze. 1186

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Experiment·lnÌ Ë·st

3.1. P¯Ìprava gel˘ a sond pro DGT techniku DifuznÌ gel i gel obsahujÌcÌ specifick˝ iontomÏniË byly p¯ipraveny na b·zi polyakrylamidovÈho hydrogelu za pouûitÌ 15 obj.% akrylamidu (Boehringer) a 0,3 obj.% agarosovÈho sÌùovadla (DGT Research Ltd., UK). Do 10 ml roztoku pro p¯Ìpravu gelu bylo p¯id·no 70 µl 10% iniciaËnÌho roztoku peroxosÌranu amonnÈho (Sigma-Aldrich) a 20 µl katalyz·toru TEMED (N,N,Ní,Ní-tetramethylethylendiamin) (Sigma-Aldrich). Do roztoku pro p¯Ìpravu iontomÏniËovÈho gelu byly jeötÏ p¯id·ny 2 g Chelexu-100 (Na-forma, zrnÏnÌ 200ñ 400 mesh, Bio-Rad). Po dokonalÈm promÌsenÌ na t¯epaËce byla smÏs nalita (pipetov·na) mezi dvÏ skla oddÏlen· teflonovou fÛliÌ o definovanÈ tlouöùce a ponech·na v suö·rnÏ po dobu 45 min, kde p¯i teplotÏ 42±2 ∞C doölo k polymeraci. Polymerace iontomÏniËovÈho gelu probÌhala pomaleji s menöÌm mnoûstvÌm inici·toru a katalyz·toru ve vodorovnÈ poloze, aby se Ë·steËky iontomÏniËe mohly usadit na jednÈ stranÏ tenkÈ vrstvy. VzniklÈ gely byly hydratov·ny v ultra ËistÈ vodÏ 24 hodin, neû nabobtnaly do stabilnÌ tlouöùky. Byly vyrobeny difuznÌ gely o tlouöùce 0,4 a 1,2 mm a iontomÏniËov˝ gel o tlouöùce 0,4 mm. Plastov˝m noûem byly z hydratovan˝ch gel˘ vy¯Ìznuty pruhy o velikosti 16 ◊ 2,7 cm, kterÈ byly vloûeny do vzorkovacÌch jednotek DGT (DGT Research Ltd., UK) a p¯ikryty membr·nov˝m filtrem (Pall Corp., USA) (obr.2). P¯ipravenÈ vzorkovacÌ jednotky byly p¯ed vlastnÌ aplikacÌ do sedimentu umÌstÏny do uzav¯enÈ z·sobnÌ n·doby s ultraËistou vodou upravenou systÈmem Ultraclear (SC Barsbtell, SRN), kter· byla probubl·v·na dusÌkem (Linde, »R). V tÈto n·dobÏ byly ponech·ny celkem 24 hodin, aby se z gelu odstranil veöker˝ kyslÌk, kter˝ by mohl zp˘sobovat oxidaci kovov˝ch iont˘ Fe2+ a Mn2+ v gelu a zvyöovat tak mÏ¯enÈ v˝sledky. 3.2. P¯Ìprava sedimentu Vzorek rybniËnÌho sedimentu byl v objemu 10 litr˘ odebr·n 15.8.2002 ze dna rybnÌka Ochoz v katastru obce NetÌn, okres éÔ·r nad S·zavou po vypuötÏnÌ rybnÌka. OdbÏr byl proveden do hloubky 10ñ15 cm, sediment byl uloûen do plastov˝ch vzorkovnic a p¯enesen do laborato¯e, kde byl zpracov·n. Ze sedimentu byly pomocÌ sÌta o velikosti ok 2 mm oddÏleny vÏtöÌ Ë·sti (zbytky rostlin, stÈbla, ko¯Ìnky) a upraven˝ vzorek sedimentu byl uloûen do sklenÏnÈ l·hve. Nad sedimentem byla ponech·na asi 3 cm vrstva rybniËnÌ vody. L·hev se sedimentem byla uloûena do tmy a ponech·na v klidu po dobu 10 t˝dn˘, aby v sedimentu mohly probÏhnout p¯ÌsluönÈ reakce. 3.3. Aplikace vzorkovacÌch jednotek DGT P¯ipravenÈ vzorkovacÌ jednotky byly vyÚaty ze z·sobnÌ n·doby a okamûitÏ bÏhem nÏkolika sekund kolmo zano¯eny do p¯ipravenÈho sedimentu, kde byly ponech·ny po dobu 48 hodin. Po vyjmutÌ byly jednotky DGT opl·chnuty destilovanou vodou a rozebr·ny. Gel s iontomÏniËem byl nakr·jen plastov˝m noûem na pl·tky o öÌ¯ce 0,5 cm. JednotlivÈ pl·tky byly p¯eneseny do polyethylenov˝ch vialek (Brand, SRN),

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p¯elity 1 ml z¯edÏnÈ kyseliny dusiËnÈ (ML Chemica, »R) a byly louûeny po dobu 24 hodin. 3.4. StanovenÌ prvk˘ v elu·tech V elu·tech byl stanoven obsah majoritnÌch prvk˘ (Fe a Mn) po p¯edchozÌm z¯edÏnÌ roztok˘ atomovou absorpËnÌ spektrometriÌ plamenovou technikou na p¯Ìstroji Varian SpectrAA 30 a obsah stopov˝ch prvk˘ (Cd a Pb) technikou elektrotermickÈ atomizace na p¯Ìstroji Perkin-Elmer 4110 ZL za pouûitÌ v˝bojek s dutou katodou nebo bezelektrodov˝ch v˝bojek a za bÏûnÏ doporuËovan˝ch podmÌnek. Kalibrov·no bylo metodou p¯Ìdavk˘ s pouûitÌm certifikovan˝ch standardnÌch roztok˘ ASTASOL (Analytika Praha).

4.

pomal·. Naproti tomu v hloubce 6ñ14 cm je patrnÈ, ûe zde doch·zÌ k dostateËnÏ rychlÈmu doplÚov·nÌ iont˘ Fe2+ z pevnÈ do kapalnÈ f·ze sedimentu (podÌl koncentracÌ Fe2+ ca(1,2) /ca(0,4) je v rozmezÌ tÈto hloubky roven hodnotÏ 1,16) a namÏ¯enÈ koncentrace Fe2+ mohou b˝t interpretov·ny jako koncentrace iont˘ Fe2+ v pÛrovÈ vodÏ sedimentu. Obsah olova v pÛrovÈ vodÏ studovanÈho sedimentu byl nÌzk˝. VyööÌ koncentrace olova byly namÏ¯eny v hloubce 0ñ5 cm (obr.6), v pr˘mÏru 0,5 µg.lñ1 (∆g = 1,2 mm) a 0,2 µg.lñ1 (∆g = 0,4 mm). V hloubce 6ñ14 cm se koncentrace olova pohybovaly kolem 0,05 µg.lñ1 pro obÏ tlouöùky difuznÌho gelu. VyööÌ koncentrace olova v hloubce 0ñ5 cm je patrnÏ zp˘sobe-

2

V˝sledky a diskuse

Do p¯ipravenÈho rybniËnÌho sedimentu byly vloûeny mÏ¯icÌ jednotky DGT s r˘zn˝mi tlouöùkami difuznÌ vrstvy (∆g1 = 1,2 mm, ∆g2 = 0,4 mm). Sledov·ny byly prvky mangan a ûelezo, neboù oxidy a sulfidy tÏchto kov˘ hrajÌ d˘leûitou roli v geochemickÈm cyklu ¯ady prvk˘, a olovo s kadmiem jako z·stupci toxick˝ch kov˘. HloubkovÈ profily jednotliv˝ch kov˘ byly zÌsk·ny vynesenÌm vypoËÌtan˝ch zd·nliv˝ch koncentracÌ ca1 a ca2 proti hloubce sedimentu. Nulov· hloubka byla urËena polohou f·zovÈho rozhranÌ vodañsediment. TÏsnÏ pod f·zov˝m rozhranÌm vodañsediment bylo nalezeno maximum koncentrace manganu 0,39 mg.lñ1 (∆g = 1,2 mm) a 0,18 mg.lñ1 (∆g = 0,4 mm) (obr.4). V tÈto hloubce z¯ejmÏ doch·zÌ k redukci MnO2 na Mn2+ amonn˝mi ionty30, kterÈ mohou vznikat p¯i oxidaci organickÈ hmoty spojenÈ s redukcÌ sÌran˘31. Koncentrace manganu s hloubkou d·le kles·, coû je pravdÏpodobnÏ zp˘sobeno oxidacÌ Mn2+ a zpÏtnou tvorbou m·lo rozpustnÈho MnO2. Od hloubky 4 cm se jiû koncentrace Mn2+ v˝raznÏ nemÏnÌ a pohybuje se kolem 0,20 mg.lñ1 (∆g =1,2 mm) a 0,10 mg.l ñ1 (∆g =0,4 mm). Ionty Mn2+ jsou v tÈto hloubce patrnÏ v·z·ny sulfidy v nerozpustnÈm MnS. Z podÌlu zd·nliv˝ch pr˘mÏrn˝ch koncentracÌ Mn2+ ca(1,2) / ca(0,4) = 2,3 je patrnÈ, ûe kinetika procesu uvolÚov·nÌ iont˘ Mn2+ z tuhÈ f·ze sedimentu do pÛrovÈ vody je v hloubce 0ñ5 cm pomal·, zatÌm co v hloubce 5ñ14 cm jsou ionty Mn2+ do pÛrovÈ vody sedimentu doplÚov·ny pomÏrnÏ rychle (ca(1,2) / ca(0,4) = 1,44). NamÏ¯enÈ koncentrace Mn2+ lze v tomto p¯ÌpadÏ interpretovat jako pr˘mÏrnÈ koncentrace iont˘ Mn2+ na povrchu vzorkovacÌ jednotky DGT bÏhem doby expozice, nebo jako integrovanÈ hodnoty toku iont˘ Mn2+ ze sedimentu do DGT jednotky. Koncentrace ûeleza od f·zovÈho rozhranÌ vodañsediment nar˘st· aû do hloubky 1,5 cm, kde bylo namÏ¯eno maximum koncentrace ûeleza 3 mg.lñ1 (∆g = 1,2 mm) a 1,8 mg.lñ1 (∆g = 0,4 mm) (obr. 5). Toto maximum urËuje hranici tzv. Fe-R zÛny32, zÛny redukce ûeleza, kde jsou oxidy (oxid-hydroxidy) vyuûÌv·ny jako substr·t pro oxidaci organickÈ hmoty bakteriemi33. S p¯ib˝vajÌcÌ hloubkou kles· koncentrace ûeleza aû na hodnoty 0,9 mg.lñ1 (∆g = 1,2 mm) a 0,7 mg.lñ1 (∆g = 0,4 mm). Pokles koncentrace ûeleza je zp˘soben redukcÌ p¯Ìtomn˝ch sÌran˘ na sirovodÌk34, kter˝ v·ûe ûelezo v nerozpustnÈm FeS. PodÌl zd·nliv˝ch pr˘mÏrn˝ch koncentracÌ Fe2+ ca(1,2) /ca(0,4) = 1,9 naznaËuje, ûe kinetika uvolÚov·nÌ iont˘ ûeleza ze sedimentu a jejich doplÚov·nÌ do kapalnÈ f·ze je v hloubce 0ñ5 cm 1187

hloubka, cm ñ2

ñ6

ñ10

ñ14 0,0

0,2 0,4 0,6 ñ1 c(Mn), mg.l

Obr.4. Hloubkov˝ profil manganu; u tlouöùka difuznÌ vrstvy 0,4 mm, s tlouöùka difuznÌ vrstvy 1,2 mm, teplota vody 21,3 ∞C, pH 6,7

2 hloubka, cm ñ2

ñ6

ñ10

ñ14 0

1

3 4 2 ñ1 c(Fe), mg.l

Obr.5. Hloubkov˝ profil ûeleza; u tlouöùka difuznÌ vrstvy 0,4 mm, s tlouöùka difuznÌ vrstvy 1,2 mm, teplota vody 21,3 ∞C, pH 6,7

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na oxidacÌ sulfidickÈho materi·lu v tÏchto hloubk·ch, coû vede k poklesu hodnot pH v sedimentu35. Jednoduch˝ ion Pb2+ je v oblastech s niûöÌm pH stabilnÌ36 a m˘ûe se tak vyskytovat volnÏ v pÛrovÈ vodÏ sedimentu. Naproti tomu v hloubce 6ñ14 cm m˘ûe doch·zet k p¯emÏnÏ p¯Ìtomn˝ch sulfid˘ na hydrogensulfidy, coû m· za n·sledek zvyöov·nÌ hodnot pH (cit.35). Ionty Pb2+ se v tomto p¯ÌpadÏ nenach·zejÌ volnÈ v pÛrovÈ vodÏ sedimentu, ale jsou v·z·ny v nerozpustn˝ PbS. PodÌl zd·nliv˝ch pr˘mÏrn˝ch koncentracÌ Pb2+ ca(1,2) /ca(0,4) = 2,5 v hloubce 0ñ6 cm naznaËuje, ûe v sedimentu doch·zÌ stejnÏ jako u ûeleza pouze k Ë·steËnÈmu doplÚov·nÌ iont˘ olova z tuhÈ do kapalnÈ f·ze sedimentu. Naproti tomu v hloubce

2

7ñ14 cm je patrnÈ, ûe zde doch·zÌ k dostateËnÈmu doplÚov·nÌ iont˘ Pb2+ z tuhÈ do kapalnÈ f·ze sedimentu (podÌl vypoËÌtan˝ch koncentracÌ Pb2+ ca(1,2) / ca(0,4) je v rozmezÌ tÈto hloubky roven hodnotÏ 1,17) a namÏ¯enÈ koncentrace Pb2+ mohou b˝t v tÏchto hladin·ch interpretov·ny jako koncentrace iont˘ Pb2+ v pÛrovÈ vodÏ sedimentu. Koncentrace kadmia od f·zovÈho rozhranÌ vodañsediment pozvolna tÈmÏ¯ line·rnÏ kles· s p¯ib˝vajÌcÌ hloubkou z 21 na 10 µg.lñ1 (∆g = 1,2 mm) a z 10 na 2 µg.lñ1 (∆g = 0,4 mm) (obr.7). PodÌl zd·nliv˝ch pr˘mÏrn˝ch koncentracÌ ca(1,2) /ca(0,4) = 2,7 ukazuje, ûe v pevnÈ f·zi sedimentu nejsou v·z·ny û·dnÈ v˝mÏny schopnÈ ionty kadmia a k doplÚov·nÌ iont˘ kadmia do pÛrovÈ vody p¯ilehlÈ k jednotce DGT doch·zÌ pouze difuzÌ z pÛrovÈ vody ve vzd·lenÏjöÌch vrstv·ch sedimentu.

5.

Z·vÏr

hloubka, cm ñ2

ñ6

ñ10

ñ14 0,0

0,2

0,4 0,6 0,8 ñ1 c(Pb), µg.l

Obr.6. Hloubkov˝ profil olova; u tlouöùka difuznÌ vrstvy 0,4 mm, s tlouöùka difuznÌ vrstvy 1,2 mm, teplota vody 21,3 ∞C, pH 6,7

2 hloubka, cm ñ2

DGT technika p¯edstavuje novÏ a dynamicky se rozvÌjejÌcÌ trend pro p¯ÌmÈ mÏ¯enÌ koncentracÌ labilnÌch forem kov˘ p¯i kontrole ûivotnÌho prost¯edÌ. V p¯edloûenÈ pr·ci byla pouûita na zmÏ¯enÌ hloubkov˝ch profil˘ majoritnÌch kov˘ (Fe a Mn) a stopov˝ch toxick˝ch prvk˘ (Cd a Pb) v rybniËnÌm sedimentu s rozliöenÌm 0,5 cm. ParalelnÌm pouûitÌm dvou vzorkovacÌch DGT jednotek s r˘znou tlouöùkou difuznÌho gelu (0,4 a 1,2 mm) byly urËeny hloubkovÈ vrstvy sedimentu, kde doch·zÌ k rychlÈmu uvolÚov·nÌ studovan˝ch kov˘ z tuhÈ f·ze sedimentu do pÛrovÈ vody a vrstvy, v nichû jsou kovy pevnÏ v·z·ny. V˝sledky spolu se znalostmi dalöÌch parametr˘, jako je pH, oxidaËnÏ-redukËnÌ potenci·l, obsah aniont˘ (sÌrany, dusiËnany, sulfidy) umoûnÌ odhadovat procesy probÌhajÌcÌ v sedimentu. Oproti vÏtöinÏ pouûÌvan˝ch metod pro mÏ¯enÌ hloubkov˝ch profil˘ kov˘ v sedimentech m· technika DGT ¯adu v˝hod. MÏ¯ÌcÌ jednotka DGT je velmi jednoduchÈ za¯ÌzenÌ, kterÈ pracuje in situ, prekoncentruje analyty, je souËasnÏ multielement·rnÌ (tj. umoûÚuje stanovenÌ vÌce prvk˘ vedle sebe) a poskytuje dostateËnÈ rozliöenÌ. Jde tedy o velmi nadÏjnou techniku pro studium kolobÏhu prvk˘ ve vodn˝ch systÈmech. NovÈ moûnosti pro studium dalöÌch analyt˘ a jejich species otevÌr· v˝bÏr sorpËnÌch mÈdiÌ a modifikace difuznÌho gelu. Tato pr·ce vznikla za finanËnÌ podpory MäMT ñ projekt G4/912/2003 FRVä.

ñ6

Seznam symbol˘ ñ10

ñ14 0,00

0,01 0,02 0,03 ñ1 c(Cd), mg.l

Obr.7. Hloubkov˝ profil kadmia; u tlouöùka difuznÌ vrstvy 0,4 mm, s tlouöùka difuznÌ vrstvy 1,2 mm, teplota vody 21,3 ∞C, pH 6,7

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A expoziËnÌ plocha, cm2 ca koncentrace iont˘ na povrchu jednotky DGT, µg.lñ1 ca1, ca2 zd·nlivÈ pr˘mÏrnÈ koncentrace iont˘ na povrchu jednotky DGT, µg.lñ1 c koncentrace iont˘ v pÛrovÈ vodÏ, µg.lñ1 D difuznÌ koeficient iont˘ v gelu, cm2.sñ1 DGT difuznÌ gradient v tenkÈm filmu F tok iont˘ (flux) do jednotky DGT, µg.cmñ2.sñ1 M mnoûstvÌ (hmotnost) sorbovan˝ch iont˘, µg t doba expozice, s ∆g tlouöùka difuznÌ vrstvy, cm

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