Cadmium soil sorption at low concentrations: V. Evidence of competition by other heavy metals

Abstract

Sorption of Cd at low concentrations onto 12 Danish soils (coarse sands to sandy loams) was studied with respect to competitive effects of other heavy metals by means of laboratory batch experiments. Both a mixture of Ni, Co, and Zn and of Cr, Cu, and Pb effectively reduced the sorption of Cd onto the soils. The employed mixtures of competing heavy metals were considered to resemble moderately polluted conditions. Cadmium distribution coefficients were reduced 2 to 14 times due to competition, but at constant concentrations of competing heavy metals the shape of Cd isotherms was not affected. The effect of Ni, Co, and Zn, which like Cd is primarily governed in soil environments by sorption, was also studied individually. Apparently Zn, which is present in relatively higher concentrations than Ni and Co, accounts for most of the observed competition with Cd.