Abstract
Cesium (Cs) adsorption and desorption properties of soils in southern Ibaraki prefecture of Japan and selected clay minerals were examined using a stable isotope 133Cs. When 27 mL of 1 mg L-1 Cs was added to 1.0 g of soil, bottom mud of Lake Kasumigaura adsorbed 97 %, and Andisol topsoil adsorbed 88 % of the Cs. When the Cs adsorbed soils were washed 3 times with water, the Cs adsorption percentage of Andisol topsoil decreased to 82 %. Further washing of the soil with 3 times1 M KCl decreased it to 75 %. Considering that the K concentration used was thousand times high compared with that of an agricultural field, the effect of K fertilization on Cs elution from soils was suggested to be negligible. The distribution coefficient (Kd) of Cs in Andisols and bottom mud of Lake Kasumigaura increased with decreasing initial concentration of Cs within the range of 0.01~10 mg L-1. Because the actual concentrations of 137Cs in contaminated soils were several orders lower than those tested in this experiment, it was clear that the radioactive cesium would be adsorbed on such soils more firmly than the data found in this experiment.
