Determination of distribution and transfer coefficients of Sr-90 and Cs-137 based on the environmental monitoring data in Japan

Abstract

The pathway of farm product intake are very important for evaluating the human health risks caused by the long term global radioactive contamination. The main parameters contained in this pathway : the distribution coefficient (kd), the transfer coefficient by direct foliar absorption(K) and the transfer coefficient by root uptake (TF), were determined using the Sr-90 and Cs-137 environmental monitoring data in Japan. The major finding obtained in this study are as follows : (1) kd can be determined by the monitoring data of radionuclide concentration in soil, K by the concentration in farm products during larger fallout period, 1960's, and TF by the concentration in farm products during smaller fallout period, after 1970's. (2) The ranges of kd were determined as 10∼300 for Sr-90 and 10∼2,000(ml/g) for Cs-137. These ranges are smaller than the reported ranges, thus the accuracy for estimating kd were improved in this study. K are 0.03 ∼1 for Sr-90 and 0.4∼1(cm2·month/g) for Cs-137; TF are 0.001∼0.06 for Sr-90 and 0.0005∼0.001(-) for Cs-137.