Transport and Adsorption-Desorption of Cd in Soils: Influence of Phosphate.

The focus of this study was to quantify Cd affinity (adsorption-desorption) and transport in soils having distinctly different properties.  A second objective was to test assess the influence of phosphate on Cd mobility and retention in soils. We tested the hypothesis that phosphate additions to soils increases adsorption and consequently reduces Cd transport in the soil profile.  To achieve these goals, time dependent retention of Cd adsorption and desorption was measured using kinetic batch methods.  Zinc adsorption isotherms were obtained for three soils in the presence of different concentrations of phosphate solutions. To quantify Cd transport in soils, miscible displacement methods was used where steady flow in soil columns was maintained.  Effluent breakthrough results for Cd from individual soil columns were obtained in the presence or absence of different in applied P solutions.