Distribution coefficients of tin (Sn) in Japanese agricultural soils

From the viewpoint of nuclear waste management, environmental mobility of tin (Sn) is important because 126Sn (half life: 105 y) and 121mSn (half life: 55.5 y) are fission products of 235U and are found in nuclear wastes. In soil environments, Sn mobility can be affected by its sorption onto the soil solid phase. Thus, in this study, we studied sorption behavior of Sn in Japanese agricultural soils using radiotracer experiments with 113Sn tracer. Soil-soil solution distribution coefficient (Kd) of Sn (Kd-Sn) was measured for 110 soil samples from 4 Japanese soil types as an index of the sorption levels. Kd is defined as the concentration of an element in or on the soil solid phase divided by the concentration of the element in the soil solution. Since the Sn solubility is highly pH dependent, the pH effect on Sn mobility in soil-solution system was also investigated. Moreover, we evaluated the soil-sorbed Sn fractions in each type pf soil colloidusing selective extraction because metal sorption in soil is generally controlled by the soil colloids such as clay minerals and soil organic matters.18th World Congress of Soil Scienc