RISK BASED SOIL REMEDIATION OF HEAVY METAL POLLUTED SOILS IN THE CAMPINE REGION (FLANDERS - BELGIUM) Erik Meers1 B. Cornelis2, A. De Vocht2, S. Van Slycken1, K. Adriaensen3, F. Tack1, J. Vangronsveld3 1 Laboratory
of Analytical Chemistry and Applied Ecochemistry, Ghent University 2 PHL University College, Department Bio 3 Laboratory of Environmental Biology, University of Hasselt
Localisation
Soil pollution Flemish & Dutch Kempen region – 700 km2 historically contaminated with heavy metals History: End 19th century – 1970 pyrometallurgic processing of Zn and Pb ore in the Kempen
Soil pollution Emissions: - Zn, Pb, Cd (relatively volatile) - Diffusion ⇒ elevated concentrations 700 km2 affected 350 km2 Cd > 1 mg/kg (Netherlands and Flanders) Residues: - Ashes, slags - 1300 km roads have been constructed with Zn rich slags Discharge on surface water: - Contaminated sediments - Contaminated riparian zones and flooding areas - Contaminated disposal sites Soil characteristics Sandy soils, low pH (pH KCl ~ 5,5)
Contaminated soils
Conventional Remediation • Excavation • Treatment or dumping + Ex situ treatment + Small areas + High contamination level + Short sanitation period - Not for diffuse contamination - Loss of soil texture - High cost
Risk based alternatives Phytoremediation Phytoextraction Phyto-attenuation Phytostabilisation Chemical stabilization + In situ treatment + Extended areas + Low/moderate contamination level + Low cost + Negative impact of metals reduced - Not for heavily polluted soils - Standardized assessment - Metals remain or gradual removal - In case of phyto-extr./att. - time
Particular interest for Cd Attention for cadmium: - Human toxic at relatively low concentrations - Kidney damage - Bone decalcification - (Lung) cancer Observations: - Elevated Cd concentrations in urin and blood - Elevated Cd concentrations in crops - Elevated Cd concentrations in cattle (kidney, liver)
Particular interest for Cd
Particular interest for Cd 120
100
% Cd
80
60
40 SR1 SR2 SR3 SR4
20
0
BA1 FA1 0
2
4
6
8
pH
10
12
14
Particular interest for agriculture
Cd: 0.5-0.7 mg/kg, (background Flanders: 0.8 mg/kg) Carrots, black salsify > EU standards
Risk based approach to Cd remediation
A
B
Sol Exch Res
Voor
Na
Risk-reduction by influencing soil metal fractionation (e.g. chemical stabilization)
Voor
Na
Risk reduction by selective removal of soluble/bioavailable Metals (e.g. phyto-extraction)
Strategy 1
The use of non-food crops for phyto-attenuation of Cd / Zn
Stimulated attenuation of soil contamination
Sustainable, renewable energy production
Metal sequestration during biomass processing
Alternative farmer income
Metal introduction in human food chain FAVV EU
Currently in use for food and feed production
Agricultural land containing (elevated) levels of heavy metals
Phytoremediation crops Non-food crops
Alternative land use ?
Energy crops
Extensive field-experiments
Case study – Energiemaïs
Energiemaïs = non-food teelt die met behulp van vergisting wordt omgezet in groene stroom en groene warmte
Wat is vergisting ? Biomassa
Biogas
Vergisting = anaeroob microbiologisch proces waarbij organisch materiaal uit mest, organisch-biologisch afval en energieteelten wordt omgezet in een hernieuwbare, methaanrijke energiedrager (biogas)
Overzicht evaluatie energiemaïs ●
●
●
●
Agrarisch potentieel –
Biomassa productie (6 cultivars)
–
Bemestingsproeven (4 regimes)
Fytoremediatie potentieel –
Totale extractie van zware metalen
–
Remediatie duur
Energie-recuperatie potentieel –
Concentratie metalen in diverse componenten
–
Impact op vergisting
Kwaliteit digestaat -
Concentratie metalen in digestaat
- Digestaatbehandeling
Resultaten: biomassa productie
●
20 ± 3 ton DS (36 ± 6 %DS-inhoud) ~ 60-70 t/ha VS
●
Geen significante verschillen tussen de 6 geteste cultivars
●
Geen verschillen t.o.v. maïs op niet verontreinigde grond
Resultaten: biomassa productie
●
Bemestingsproeven: 0, 85, 170, 250 kg N/ha
●
Biomassa opbrengst : 30 tot > 80 t/ha FM
●
Nitraatuitloging via opvolging Bodemkundige Dienst = onder norm voor alle behandelingen
Resultaten: fytoremediatie potentieel
●
Totale extractie: 18 ± 3 g Cd ha-1 (opm. Zn ~ 5.000 g/ha.j)
●
Geen significante verschillen tussen de cultivars
●
Lange remediatie periode => NIET eerste doelstelling !!! –
2 naar 1.2 mg Cd kg-1 ~ ± 200 jaren
–
5 naar 2 mg Cd kg-1 ~± 500 jaren
Resultaten: biomassa gebruik (normen) ●
Gebruik als –
–
Voederteelt ●
Norm : 1.1 mg Cd/kg DM
●
Metaal concentratie > voedernorm voor ons terrein
●
Opm. korrelmaïs wel < norm
Non-food – anaerobe vergisting ●
Norm : 6 mg Cd/kg DM
Resultaten: energie conversie ●
Energie conversie –
Batch testen ●
●
–
Geen verschillen in biogas-opbrengst ‘gecontamineerd’ vs. niet gecontamineerd Biogaspotentieel voornamelijk in de kolf (2/3) !
Continue testen (ongoing) ●
Biogas potentieel over langere periode – impact M op biogas ?
Resultaten komen goed overeen met batch testen (137-258 Nm3/t, uitgemiddeld 195 m3/t VS)
Resultaten: energie opbrengst Energie (GJ/ha) Teelt energie-maïs
-8.3
Transport (maïs naar lokale vergister)
-2.4
Transport digestaat (export)
-1.8
Totaal fossiele energie input
-12.5
Energie inhoud biogas
224
Electriciteit
79
Warmte
30
Totaal energie productie
109
Netto energie winst
96
Resultaten: kwaliteit digestaat
Maïs ref Maïs Lommel Digestaat ref Digestaat Lommel
% DS
Cd mg kg -1
Zn mg kg-1
N g kg-1
P g kg-1
K g kg-1
Ca g kg -1
31±2 24±5
< DL 1.0±0.1
33±2 257±34
12±1 8.3±0.9
2.1±0.2 1.7±0.3
13±1 8.4±1
2.3±0.2 2.5±0.2
9.5±0.1 12±1
0.40±0.03 3.2±0.1
367±15 797±27
28±2 26±1
21±1 9.5±0.1
42±2 39±1
19±1 72±1
Opm. Vlarea-norm Cd:
6 mg/kg
Vlarea-norm Zn: 900 mg/kg
Resultaten: kwaliteit digestaat Selectieve metaal extractie bij digestaatverwerking = technisch haalbaar ? = praktisch zinvol ? niet voor micronutriënten (Zn, Ni, Cu, Co,…) voor microcontaminanten, afhankelijk van context in geval gebruik v/e excluder zoals mais niet
Conclusie Energie maïs voor fytoremediatie van metaal aangerijkte gronden & productie van energie ???
Conclusie: mogelijkheden van energie maïs
●
Lange remediatie periode
●
Goede productiviteit
●
Economisch valoriseerbaar
●
Energie conversie toont veelbelovende resultaten
Algemene conclusie
●
Een perfect alternatief op metaal aangerijkte gronden –
Houdt de landbouwer “in business”
–
Gecontroleerd & veilig gebruik van biomassa
–
Ecologisch & duurzaam
–
“Phyto-assisted attenuation”
References on phytoremediation research Meers, E., Hopgood, M., Lesage, E., Vervaeke, P., Tack, F.M.G. & Verloo, M. (2004). Enhanced Phytoextraction : In Search for EDTA Alternatives. International Journal of Phytoremediation, 6, 2, 95-109. Meers, E., Lamsal, S., Vervaeke, P., Hopgood, M., Lust, N., Tack, F.M.G. & Verloo, M.G. (2005). Availability of heavy metals for uptake by Salix viminalis on a moderately contaminated dredged sediment disposal site. Journal of Environmental Pollution, 137, 354-364. Meers, E., Ruttens, A., Samson, D., Hopgood, M. & Tack, F.M.G. (2005). Comparison of EDTA and EDDS as Potential Soil Amendments for Enhanced Phytoextraction of Heavy Metals. Chemosphere, 58, 1011-1022. Meers, E., Ruttens, A., Hopgood, M., Lesage, E. & Tack, F.M.G. (2005). Potential of Brassica rapa, Cannabis sativa, Helianthus annuus and Zea mays for phytoextraction of heavy metals from calcareous dredged sediment derived soils. Chemosphere, 61, 561-572. Meers, E., Lesage, E., Lamsal, S., Hopgood, M., Vervaeke, P., Tack, F.M.G. & Verloo, M.G. (2005). Enhanced Phytoextraction : I. Effect of EDTA & citric acid on heavy metal mobility in a calcareous soil. International Journal of Phytoremediation, 7, 129-142. Meers, E., Vandecasteele, B., Ruttens, A., Vangronsveld, J. & Tack, F.M.G. (2007). Potential of five willow species (Salix spp.) for phytoextraction of heavy metals. Journal of Experimental Environmental Botany, 120, 243-267. Meers, E., Tack, F.M.G., Van Slycken, S., Ruttens, A., Du Laing, G., Vangronsveld, J. & Verloo, M.G. (2008). Chemically-assisted phytoextraction: a review of potential soil amendments for increasing plant uptake of heavy metals. International Journal of Phytoremediation, 10, 390-414. Meers, E., Van Slycken, S., Adriaensen, K., Vangronsveld, J., Du Laing, G., Witters, N., Thewys, T. & Tack, F.M.G. The use of bioenergy crops (Zea mays) for ‘phytoattenuation’ of heavy metals on moderately contaminated soils : a field experiment. Chemosphere, in press. Lesage E., Meers E., Vervaeke P., Lamsal S., Hopgood M., Tack F.M.G. & Verloo M.G. (2005). Enhanced Phytoextraction : II. Effect of EDTA & citric acid on heavy metal uptake by Helianthus annuus from a calcareous soil. International Journal of Phytoremediation, 7, 143-152. Van Ginneken, L., Meers, E., Guisson, R., Ruttens, A., Tack, F.M.G., Vangronsveld, J., Diels, L. & Dejonghe, W. (2007). Phytoremediation for heavy metal contaminated soils and combined bio-energy production. Journal of Environmental Engineering and Landscape Management, 4, 227-236. Saifullah, S., Meers, E., Qadir, M., de Caritat, P., Tack, F.M.G., Du Laing, G. and M. H. Zia (2009). A review on EDTA-assisted Pb phytoextraction. Chemosphere, 74, 1279-1291. Vervaeke, P., Luyssaert, S., Mertens, J., Meers, E., Tack, F.M.G. & Lust N. (2003). Phytoremediation prospects of willow stands on contaminated sediment: a field trial. Environmental Pollution, 126, 275-282. Mertens, J., Vervaeke, P., Meers, E. & Tack F.M.G. (2006). Seasonal changes of metals in willow (Salix sp.) stands for phytormediation on dredged sediment. Environmental Science and Technology, 40, 1962-1968. Vangronsveld, J., Herzig, R., Weyens, N., Boulet, J., Adriaensen, K., Ruttens, A., Thewys, T., Vassilev, A., Meers, E., Nehnevajova, E., van der Lelie, D., Mench, M. (2009) Phytoremediation of contaminated soils and groundwater: lessons from the field. Environmental Science and Pollution Research, in press.
Strategy 2
The use of soil amendments to reduce the solubility / mobility / bioavailability of heavy metals
The use of soil amendments to reduce metal solubility
Chemistry
Toxicology
Biology
Assessment standardization : Multi-disciplinary phased cascade approach to screening Amendment characterisation
pH dependent metal-mobility
Long term sustainability of stabilisation
Ecological availability & ecotoxicity
Human exposure assays
Assessment standardization : Multi-disciplinary phased cascade approach to screening Amendment characterisation
pH dependent metal-mobility
Soil treatment, incubation: (i) rhizon extraction, (ii) pH batch L:S 10:1
Assessment standardization : Multi-disciplinary phased cascade approach to screening Amendment characterisation
pH dependent metal-mobility
Long term sustainability of stabilisation
(i) Accelerated rainfall & percolation from treated soils (ii) Forced ageing of soils treated In previous step
Assessment standardization : Multi-disciplinary phased cascade approach to screening (i) CaCl2 (ii) TCLP (toxicity characteristic leaching procedure) (iii) Plant Tox © (Phaseolus vulgaris) (iv) Earthworms (growth, weight, reproduction, bait lamina)
(v) Reproduction (Eisenia fetida ; Folsomia candida)
(vi) ROTAS (Vibrio fischeri) (Rapid On-site Toxicity Audit System)
Ecological availability & ecotoxicity
Human exposure assays
Assessment standardization : Multi-disciplinary phased cascade approach to screening
(i) PBET (Physiologically Based Extraction Test ) (ii) Accumulation in vegetables
Human exposure assays
