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 degrees C) was studied by measuring the soil-soil solution distribution coefficient, K-d (L/kg). Comparison of K-d values obtained at 10 degrees C and at 30 degrees 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 degrees C was intended to minimize the soil microbial activity effect; the results were almost the same as those observed at 10 degrees 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.