Derivation of Soil Quality Criteria Based on Chemical Speciation of Pb2 and Cu2

1
Derivation of Soil Quality Criteria Based on
Chemical Speciation of Pb2 and Cu2

• S. Sauvé1,2, A. Dumestre1, M. McBride1 and W.
  Hendershot2

1Cornell University-Soil Crop and Atmospheric
Sciences (NY) 2McGill University-Macdonald Campus
(QC, Canada) (e-mail sebastien.sauve_at_umontreal.c
a)
2
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
Pb Distribution
Sauvé S, Dumestre A, McBride M, Hendershot W.
1998. Derivation of soil quality criteria using
predicted chemical speciation of Pb2 and Cu 2 
Environmental Toxicology and Chemistry
171481-1489.
4
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
Pb2 and Cu2 Solubility
Sauvé S. 1999. 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
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 S, Dumestre A, McBride M, Hendershot W.
1998. Derivation of soil quality criteria using
predicted chemical speciation of Pb2 and Cu 2 
Environmental Toxicology and Chemistry
171481-1489.
8
Pb2, pH and Total Pb
Sauvé S, McBride M, Hendershot W. 1997.
Speciation of lead in contaminated soils 
Environmental Pollution 98149-155.
9
Cu2, pH and Total Cu
Sauvé S. 1999. 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
Inhibition
Sauvé S, Dumestre A, McBride M, Hendershot W.
1998. Derivation of soil quality criteria using
predicted chemical speciation of Pb2 and Cu 2 
Environmental Toxicology and Chemistry
171481-1489.
13
Inhibition
Sauvé S, Dumestre A, McBride M, Hendershot W.
1998. Derivation of soil quality criteria using
predicted chemical speciation of Pb2 and Cu 2 
Environmental Toxicology and Chemistry
171481-1489.
14
Inhibition
Sauvé S, Dumestre A, McBride M, Hendershot W.
1998. Derivation of soil quality criteria using
predicted chemical speciation of Pb2 and Cu 2 
Environmental Toxicology and Chemistry
171481-1489.
15
Soil Criteria
Sauvé S, Dumestre A, McBride M, Hendershot W.
1998. Derivation of soil quality criteria using
predicted chemical speciation of Pb2 and Cu 2 
Environmental Toxicology and Chemistry
171481-1489.
16
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
References

• Sauvé S., A. Dumestre, M.B. McBride and W.H.
  Hendershot. 1998. Derivation of soil quality
  criteria using predicted chemical speciation of
  Pb2 and Cu2. Environmental Toxicology and
  Chemistry 171481-1489.
• Sauvé S., M.B. McBride and W.H. Hendershot. 1997.
  Speciation of lead in contaminated soils.
  Environmental Pollution. 98149-155.
• Sauvé S., M.B. McBride, W.A. Norvell and W.H.
  Hendershot. 1997. Copper solubility and
  speciation of in situ contaminated soils Effects
  of copper level, pH and organic matter. Water,
  Air and Soil Pollution. 100133-149.
• Sauvé S., M.B. McBride and W.H. Hendershot. 1998.
  Soil solution speciation of Pb2 Effects of
  organic matter and pH. Soil Science Society of
  America Journal 62618-621.
• Sauvé S., M. McBride and W. Hendershot. 1998.
  Lead phosphate solubility in water and soil
  suspensions. Environmental Science and Technology
  32388-393.
• McBride M.B., Sauvé S. and W.H. Hendershot. 1997.
  Solubility control of Cu, Zn, Cd and Pb in
  contaminated soils. European Journal of Soil
  Science 48337-346.
• Sauvé S., M.B. McBride and W.H. Hendershot. 1995.
  Ion-selective electrode measurements of
  copper(II) activity in contaminated soils.
  Archives of Environmental Contamination and
  Toxicology. 29373-379.