Temperature dependence on soil-soil solution distribution coefficient of radiocaesium in Japanese agricultural soils

Radiocaesium mobility in 40 agricultural soil samples at different temperature conditions (4–30 °C) was studied by measuring the soil-soil solution distribution coefficient, K_d (L/kg). Comparison of K_d values obtained at 10 °C and at 30 °C indicated significant differences for 36 soil samples by the one-way ANOVA test (p < 0.05) with decreases in K_d values under the higher temperature condition. The K_d measurement at 4 °C was intended to minimize the soil microbial activity effect; the results were almost the same as those observed at 10 °C. From this result, it was difficult to identify the effect of microbial activity on the radiocaesium absorbability to the soil solid phase. The obtained data imply a possible seasonal change of K_d values in many types of soils, and the K_d change likely affects the radiocaesium release rate change from soil to river water during a year.