Adsorption of Cs and U(VI) on soils of the Australian arid zone

Distribution coefficients (K-d values) for Cs and U(VI) on soils from an ar id region of Australia were measured under a range of conditions. The K-d v alues for trace Cs-137 in, 0.02 M NaCl were typically around 10(4) mL/g, an d were not affected by the pH. However, the K-d decreased with increasing i onic strength, and was strongly dependent on the total Cs concentration. Mu ch lower K-d values (around 10(2) mL/g) were measured in systems containing total Cs of 1 mmol/L in a background electrolyte of 0.10 M NaCl. The main factor determining the sorption behaviour of U(VI) in systems equilibrated with air was the pH, with the K-d decreasing from above 10(3) mL/g at pH 7 to around 10 mL/g at pH 9.