CHEMICAL SPECIATION OF ENVIRONMENTALLY SIGNIFICANT METALS WITH INORGANIC LIGANDS PART 2:THE Cu2+ -OH-,Cl-(CO3)2-,(SO4)2-,AND(PO4)3- SYSTEMS

摘要

Complex formation between Cu~(II)and the common environmental lig-ands Cl-,OH-,(CO3)2-,(SO4)2-,and(PO4)3- can have a significant effect on Cu~(II)spe-ciation in natural waters with low concentrations of organic matter.Copper(II)complexes are labile,so the Cu~(II)distribution amongst these inorganic ligands can be estimated by numerical modeling if reliable values for the relevant stability(formation)constants are available.This paper provides a critical review of such constants and related thermodynamic data.It recommends values of log_(10)beta_(p,q,r)° valid at I_m = 0 mol kg~(-1)and 25 °C(298.15 K),along with the equations and specific ion interaction coefficients required to calculate log_(10)beta_(p,q,r)values at higher ionic strengths.Some values for reaction enthalpies,DELTA_rH_m,are also reported where available.In weakly acidic fresh water systems,in the absence of organic ligands,Cu~(II)speciation is dominated by the species Cu2+(aq),with CuSO4(aq)as a minor species.In seawater,it is dominated by CuCO3(aq),with Cu(OH)+,Cu2+(aq),CuCl+,Cu(CO3)OH- Cu(OH)2(aq),and Cu((CO3)2)2- as minor species.In weakly acidic saline systems,it is dominated by Cu2+(aq)and CuCl+,with CuSO4(aq)and CuCl2(aq)as minor species.