1. S. Sauvé1,2, A. Dumestre1, M. McBride1 and W. Hendershot2
Sauvé et al. (NERI's Bioavailability Conference, December , Washinton, DC)
Derivation of Soil Quality Criteria Based on Chemical Speciation of Pb2+ and Cu2+
S. Sauvé1,2, A. Dumestre1, M. McBride1 and W. Hendershot2
I will talk about...
Research part of cooperation between
1Cornell University-Soil Crop and Atmospheric Sciences (NY)
2McGill University-Macdonald Campus (QC, Canada) (

2. Free Ion Activity Model
Sauvé et al. (NERI's Bioavailability Conference, December , Washinton, DC)
Free Ion Activity Model
Metal toxicity is controlled by free metal ion activity in aquatic systems
In soils, we need to:
distinguish between soil total metal (insoluble), solution dissolved concentrations and solution free metal activity
quantify the impact of soil pH and soil organic matter on metal speciation
Bioavailability, mobility and chemical reactivity depends on the speciation of the metals present in the soil solution

3. Sauvé et al. (NERI's Bioavailability Conference, December 3-4 1998, Washinton, DC)
Pb Distribution
Sauvé S, Dumestre A, McBride M, Hendershot W «Derivation of soil quality criteria using predicted chemical speciation of Pb2+ and Cu 2+ » Environmental Toxicology and Chemistry 17:

4. Experimental Soils Soils from various origins:
Sauvé et al. (NERI's Bioavailability Conference, December , Washinton, DC)
Experimental Soils
Soils from various origins:
urban, agricultural, orchard, industrial, forest
from Ithaca (NY), Québec (Can), Denmark and France
Contamination: pesticides, sewage sludge, battery recycling and industrial sources
Soil “Totals” by HNO3 digestions, dissolved metals by GFAAS of 0.01 M KNO3 extracts and free metal by ion selective electrode (Cu2+) and differential pulse anodic stripping voltammetry (Pb2+)

5. Sauvé et al. (NERI's Bioavailability Conference, December 3-4 1998, Washinton, DC)
Pb2+ and Cu2+ Solubility
Sauvé S «Chemical speciation, solubility and bioavailability of lead, copper and cadmium in contaminated soils » Ph.D. Dissertation, Department of Soil, Crop and Atmosphetric Sciences, Cornell University, Ithaca, NY.

6. Sauvé et al. (NERI's Bioavailability Conference, December 3-4 1998, Washinton, DC)
Adsorption Model
Assuming competitive binding of H+ and Me2+ to a deprotonated surface (S):
with certain assumptions can be simplified to:
Applied with succes to the soil solution speciation of Cd2+, Cu2+ and Pb2+

7. Regressions for Solution Free Metal Activity
Sauvé et al. (NERI's Bioavailability Conference, December , Washinton, DC)
Regressions for Solution Free Metal Activity
Sauvé S, Dumestre A, McBride M, Hendershot W «Derivation of soil quality criteria using predicted chemical speciation of Pb2+ and Cu 2+ » Environmental Toxicology and Chemistry 17:

8. Pb2+, pH and Total Pb
Sauvé S, McBride M, Hendershot W «Speciation of lead in contaminated soils » Environmental Pollution 98:

9. Cu2+, pH and Total Cu
Sauvé S «Chemical speciation, solubility and bioavailability of lead, copper and cadmium in contaminated soils » Ph.D. Dissertation, Department of Soil, Crop and Atmosphetric Sciences, Cornell University, Ithaca, NY.

10. Soil Solution Free Metal Activity
Only a very small fraction of the total metal is free and available for chemical reactions
This free metal fraction can be predicted using simply soil total metal and pH
A semi-mechanistic model is successful independently of the soil origin and of the source of the metal contamination
Soil organic matter can be incorporated into the regression, soil OM decreases free Cu2+ activity

11. Bioassay Model
where the biological endpoint (yield reduction, process inhibition etc.) were as reported in the literature and the parameter was either total soil Cu or Pb or predicted free Cu2+ or Pb2+, a and b were fitted by the statistical software

12. Sauvé et al. (NERI's Bioavailability Conference, December 3-4 1998, Washinton, DC)
Inhibition
Sauvé S, Dumestre A, McBride M, Hendershot W «Derivation of soil quality criteria using predicted chemical speciation of Pb2+ and Cu 2+ » Environmental Toxicology and Chemistry 17:

13. Sauvé et al. (NERI's Bioavailability Conference, December 3-4 1998, Washinton, DC)
Inhibition
Sauvé S, Dumestre A, McBride M, Hendershot W «Derivation of soil quality criteria using predicted chemical speciation of Pb2+ and Cu 2+ » Environmental Toxicology and Chemistry 17:

14. Sauvé et al. (NERI's Bioavailability Conference, December 3-4 1998, Washinton, DC)
Inhibition
Sauvé S, Dumestre A, McBride M, Hendershot W «Derivation of soil quality criteria using predicted chemical speciation of Pb2+ and Cu 2+ » Environmental Toxicology and Chemistry 17:

15. Soil Criteria
Sauvé S, Dumestre A, McBride M, Hendershot W «Derivation of soil quality criteria using predicted chemical speciation of Pb2+ and Cu 2+ » Environmental Toxicology and Chemistry 17:

16. Sauvé et al. (NERI's Bioavailability Conference, December 3-4 1998, Washinton, DC)
Conclusion
Soil solution free metal activity of Pb2+ and Cu2+ may be predicted using a simple model
Estimated free metal activities are better predictor of bioavailability than total soil metal
Soil quality criteria and risk assessment must consider soil pH to reflect its predominant influence on soil solution chemical speciation and bioavailability

17. Sauvé et al. (NERI's Bioavailability Conference, December 3-4 1998, Washinton, DC)
References
Sauvé S., A. Dumestre, M.B. McBride and W.H. Hendershot Derivation of soil quality criteria using predicted chemical speciation of Pb2+ and Cu2+. Environmental Toxicology and Chemistry 17:
Sauvé S., M.B. McBride and W.H. Hendershot Speciation of lead in contaminated soils. Environmental Pollution. 98:
Sauvé S., M.B. McBride, W.A. Norvell and W.H. Hendershot Copper solubility and speciation of in situ contaminated soils: Effects of copper level, pH and organic matter. Water, Air and Soil Pollution. 100:
Sauvé S., M.B. McBride and W.H. Hendershot Soil solution speciation of Pb2+: Effects of organic matter and pH. Soil Science Society of America Journal 62:
Sauvé S., M. McBride and W. Hendershot Lead phosphate solubility in water and soil suspensions. Environmental Science and Technology 32:
McBride M.B., Sauvé S. and W.H. Hendershot Solubility control of Cu, Zn, Cd and Pb in contaminated soils. European Journal of Soil Science 48:
Sauvé S., M.B. McBride and W.H. Hendershot Ion-selective electrode measurements of copper(II) activity in contaminated soils. Archives of Environmental Contamination and Toxicology. 29: