Na-montmorillonite, MINSORB code (2-site protolysis no electrostatics surface complexation and cation exchange model developed and incorporated into MINEQL); citation in [BB99a]; fixed parameters: selectivity coefficient (I=0) for cation exchange Na-Ni=3.1, Zn inventory 1E-3mol/kg; Mn inventory 4E-4mol/kg, logK(Ni) on strong sites=-0.1; logK for first weak site