Transfer of Cs-137 and stable trace elements from soil to plants and mushrooms in forests

This study aimed to investigate the distributions and transfers of radioactive Cs and various trace elements in forests and elucidate the nuclide transfer through analysis of soil and plants including mushroom. As the subjects, soils, plants and mushrooms were collected in a pine grove near seaside in Ibaraki Prefecture. The concentrations of alkali and alkaline elements along with Cs were determined. The transfer coefficients of Co, Ba, La, Ce, Pb. Th and U were low (<0.1) for plants and mushrooms, but those of Cu, Zn, Rb and Cd were comparatively high. When compared with plants, the concentrations of Rb and Cs in mushrooms were high and those of Ca and Sr were low, showing coincidence with the previous results that 90Sr is difficult to be absorbed into mushrooms. There was a close correlation between 137Cs and stable Cs in mushrooms in the pine groove (r=0.99) and the 137Cs/Cs ratio was 134±36 (Bq/mg), higher than the ratio (2.3-27 Bq/mg) in the soil. In plants, positive correlations were found among K, Rb, Cs and Mg as well as between Cs and Sr. These results suggest that the transfers of radioactive Cs and Sr are estimatable with stable alkali and alkaline elements. (M.N.)