Samples of two New York soils, an acid and a neutral silt loam, were equilibrated with Cu 2+ and Cd 2+ solutions in concentrations ranging from 10 −5 to 10 −4 M in distilled water and in 0.01 M CaCl 2 . The extent of complexation and adsorption of the heavy metals was measured using specific ion electrodes and atomic absorption. The data were found to fit the Langmuir adsorption model, and the Cu 2+ adsorption maxima were greater than those of Cd 2+ for both soils. Acid soils demonstrated much less ability to retain the heavy metals than neutral soils. In the presence of 0.01 M CaCl 2 , adsorption of the metals was much reduced, suggesting Ca 2+ competition for adsorption sites. A considerable amount of Cu 2+ was complexed in the soil solutions, but Cd 2+ complexation was much less evident. The results support an ion exchange mechanism of adsorption in the surface soils, and suggest that precipitation occurs in calcareous subsoils.
No takes yet. Share an insight, caveat, or question.
Cavallaro et al. (1978) studied this question.