When each term on the right side of this equation is expressed in terms of its
equilibrium constant given in Table 14.1, Eq. 14.6 can be rearranged to give:
[Cum r ]
C 2+ _ log g
( u ) 1 + 1O2?36(S02_) + 10-13.78 + 10-11.43CO2(g)
vw 4 2 2
Thus the activity of Cuz + can be estimated from this equation with measure-
ments of (1) total inorganic copper in solution, (2) pH, (3) ionic strength,
(4) the activity of so;-, and (5) the partial pressure of CO2(g). lf conditions
are such that other inorganic copper complexes contribute signiiicantly
to soluble copper, they must also be included in Eq. 14.5 and reflected in
Eq. 14.7. _
Copper is normally present in soil solution as both organic and inorganic
complexes (Hodgson et al., 1966). For this reason total soluble copper IS
expressed as
[Total soluble copper] = [Cuinmg] -1- [Cum] (14-8)