¹³⁷Cs Soil to Rice Transfer Factor and Soil Properties: Fukushima and Kawauchi Case Study

Abstract

 The long-term migration of ¹³⁷Cs in the environment is mainly through the ¹³⁷Cs adsorbed on the dispersed soil particles of various sizes. However, the transfer of ¹³⁷Cs from soil to plant, especially rice plant, remains questionable. The objective of this study is to determine the relation among soil characteristics, ¹³⁷Cs distribution and transfer factor (TF) of ¹³⁷Cs from soil to rice. In this study paddy fields in Kawauchi and Fukushima were chosen. This is because more studies have focused only on one sampling field and there have not been much discussion comparing various fields as envisaged in this study. The results have shown that TF for Kawauchi is 5-fold higher than that of Fukushima. Physicochemical properties of the soils showed that Fukushima soil has less percentage of exchangeable ¹³⁷Cs and high percentage of exchangeable K in contrast to Kawauchi soil. These factors likely disturbed the transfer of ¹³⁷Cs from soil into the rice plant. Powder X-ray diffraction has shown that Fukushima soil is rich in micaceous minerals which also release a lot of K⁺ to distract the ¹³⁷Cs transfer. This study suggests that the presence of micaceous minerals in the soil would be a good amendment for radiocesium-contaminated rice paddy fields in enhancing adsorption of ¹³⁷Cs in the soil. However, there is still a need to investigate adsorption kinetics of ¹³⁷Cs to ascertain higher values of TF in Kawauchi soil.