Distribution coefficients of 137Cs, 85Sr, 141Ce, 103Ru, 131I and 95mTc in the various horizons of cultivated soils in Germany

Distribution coefficients Kd for Cs-137, Sr-85, Ce-141, Ru-103, I-131, and Tc-95m were determined in the six horizons of a cultivated Parabrown earth soil and an Auenrendzina, in order to obtain some information on the vertical rate of migration of radionuclides in these soils. In general batch methods were applied, but in the Ap-horizons of the soils, column methods, using undisturbed soil monolithes (30 cm diam., 1 m length) were used as well for comparison. The effect of the concentration of K+ and Ca++ ions in the soil solution was investigated as well and the results are compared with distribution coefficients obtained for other soil types. In general Cs-137 and Ce-141 are sorbed most strongly by the soil and thus retarded considerably with respect to the vertical pore water velocity. Tc-95m exhibits the lowest Kd-values under the aerobic conditions of the batch experiments. Under the partially unaerobic conditions in the soil columns, the pertechnetate ions are, however, to some extent reduced to a much slower migrating species. (orig.)