Table 2

Complexation reactions with the constants used in the model
Aqueous and surface reactions	log K (I = 0 M, 25°C)	Reference

H₃AsO₄° = H₂AsO₄^-+ H⁺	-2.25	[32]
H₂AsO₄^-= HAsO₄^2-+ H⁺	-6.96	[32]
HAsO₄^2-= AsO₄^3-+ H⁺	-11.5	[32]
FeH₂AsO₄⁺= H₂AsO₄^-+ Fe²⁺	-2.86	[32]
FeHAsO₄° + H⁺= H₂AsO₄^-+ Fe²⁺	3.42	[32]
FeAsO₄^-+ 2H⁺= H₂AsO₄^-+ Fe²⁺	11.04	[32]
H₃AsO₃° = H₂AsO₃^-+ H⁺	-9.22	[33]
H₂AsO₃^-= HAsO₃^2-+ H⁺	-12.11	[33]
HAsO₃^2-= AsO₃^3-+ H⁺	-13.41	[33]
≡(w)FeOH + H⁺= ≡(w)FeOH₂⁺	7.29	[27]
≡(w)FeOH = ≡(w)FeO^-+ H⁺	-8.93	[27]
≡(s)FeOH + H⁺= ≡(s)FeOH₂⁺	7.29	[27]
≡(s)FeOH = ≡(s)FeO^-+ H⁺	-8.93	[27]
≡(w)FeOH + AsO₄^3-+ 3H⁺= ≡(w)FeH₂AsO₄+ H₂O	29.88	[28]
≡(w)FeOH + AsO₄^3-+ 2H⁺= ≡(w)FeHAsO₄^-+ H₂O	24.43	[28]
≡(w)FeOH + AsO₄^3-+ H⁺= ≡(w)FeAsO₄^2-+ H₂O	18.10	[28]
≡(w)FeOH + AsO₃^3-+ 3H⁺= ≡(w)FeH₂AsO₃+ H₂O	38.76	[28]
≡(w)FeOH + AsO₃^3-+ 2H⁺= ≡(w)FeHAsO₃^-+ H₂O	31.87	[28]
≡(w)FeOH + CO₃^2-+ H⁺= ≡(w)FeOCO₂^-+ H₂O	12.78	[34]
≡(w)FeOH + CO₃^2-+ 2H⁺= ≡(w)FeOCO₂H + H₂O	20.37	[34]
≡(w)FeOH + Fe²⁺= ≡(w)FeOFe⁺+ H⁺	-2.98	[34]
≡(s)FeOH + Fe²⁺= ≡(s)FeOFe⁺+ H⁺	-0.95	[34]

Burnol et al. Geochemical Transactions 2007 8:12 doi:10.1186/1467-4866-8-12