Section 8: The influence of groundwater chemistry on arsenic concentrations and speciation in a quartz sand and gravel aquifera)

Geochemical Transactions, Vol. 5, No. 1, pp. 1–12, March 2004
©2004 American Institute of Physics. All rights reserved.

Previous section: APPENDIX1: EXTRACTABLE Al, Fe, AND Mn ON SEDIMENTS
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APPENDIX 2: PARAMETERVALUES USED IN SURFACE COMPLEXATION MODEL CALCULATIONS IN FIG. 4

Table X.
Parameter Value
Ionic Strength 0.003
m²/l^a 1240
Surface species equilibriumexpressions and log K values^b
>FeOH = >FeO^– + H⁺ –8.93
>FeOH + H⁺ = >FeOH 2+ 7.29
>FeOH + H₃AsO₃ = >FeH₂AsO₃ + H₂O 5.41
>FeOH + AsO 43– + 3H⁺ = >FeH₂AsO₄ + H₂O 29.31
>FeOH + AsO + 2H⁺ = >FeHAsO 4– + H₂O 23.51
>FeOH + AsO = >FeAsO 10.58
>FeOH + PO + 3H⁺ = >FeH₂PO₄ + H₂O 31.29
>FeOH + PO + 2H⁺ = >FeHPO + H₂O 25.39
>FeOH + PO + H⁺ = >FePO 42– + H₂O 17.72
Solution species equilibrium expressions and log K values^b
H⁺ + H₂AsO 3– = H₃AsO₃ 9.29
H⁺ + AsO 43– = HAsO 11.50
2H⁺ + AsO = H₂AsO 4– 18.46
3H⁺ + AsO = H₃AsO₄ 20.70
H⁺ + PO = HPO 42– 12.35
2H⁺ = PO = H₂PO 19.55
3H⁺ + PO = H₃PO₄ 21.70
^a Surface area-to-volume ratio.
^b All log K values fromDzombak and Morel (Ref. 58). Activity coefficients for aqueous speciescalculated using Davies equation.

Previous section: APPENDIX 1: EXTRACTABLE Al, Fe, AND MnON SEDIMENTS
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Title Page

Table X.
Parameter	Value
Ionic Strength	0.003
m²/l^a	1240
Surface species equilibriumexpressions and log K values^b
>FeOH = >FeO^– + H⁺	–8.93
>FeOH + H⁺ = >FeOH	7.29
>FeOH + H₃AsO₃ = >FeH₂AsO₃ + H₂O	5.41
>FeOH + AsO + 3H⁺ = >FeH₂AsO₄ + H₂O	29.31
>FeOH + AsO + 2H⁺ = >FeHAsO + H₂O	23.51
>FeOH + AsO = >FeAsO	10.58
>FeOH + PO + 3H⁺ = >FeH₂PO₄ + H₂O	31.29
>FeOH + PO + 2H⁺ = >FeHPO + H₂O	25.39
>FeOH + PO + H⁺ = >FePO + H₂O	17.72
Solution species equilibrium expressions and log K values^b
H⁺ + H₂AsO = H₃AsO₃	9.29
H⁺ + AsO = HAsO	11.50
2H⁺ + AsO = H₂AsO	18.46
3H⁺ + AsO = H₃AsO₄	20.70
H⁺ + PO = HPO	12.35
2H⁺ = PO = H₂PO	19.55
3H⁺ + PO = H₃PO₄	21.70
^a Surface area-to-volume ratio.
^b All log K values fromDzombak and Morel (Ref. 58). Activity coefficients for aqueous speciescalculated using Davies equation.

APPENDIX 2: PARAMETER VALUES USED IN SURFACE COMPLEXATION MODEL CALCULATIONS IN FIG. 4

APPENDIX 2: PARAMETERVALUES USED IN SURFACE COMPLEXATION MODEL CALCULATIONS IN FIG. 4