Transport behavior of radioactive caesium from forests contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident through river water system

Iijima, Kazuki ; Funaki, Hironori ; Oyama, Takuya ; Niizato, Tadafumi ; Sato, Haruo*; Yui, Mikazu

Goal of the project is to develop mechanistic models to predict transport behavior of radioelements strongly adsorbed on soil particles from forests to sea through river systems, evaluate evolution of dose, and propose methods to constrain the transport. This study overviewed the behavior of radioactive caesium through one of the river systems in the coastal area of Fukushima. Concequently, caesium is considered to be strongly adsorbed on the soil particles in the transport through the river water system since more than 90% of caesium has still remained within 5 cm from the surface of topsoil in the forest, and the concentration of caesium in the lake water was extremely low. The difference of concentrations of caesium in the sediments in the river water system can be explained by the effect of particle size on the adsorption site density of caesium.