Temporal change in depth profile of radiocaesium released by the Fukushima Daiichi Nuclear Power Plant accident in the Fukushima forest

Niizato, Tadafumi  ; Abe, Hironobu ; Ishii, Yasuo; Sasaki, Yoshito ; Mitachi, Katsuaki; Kitamura, Akihiro   ; Yamaguchi, Masaaki 

The depth profile of radiocaesium at the mountain forest of Abukuma Mountains, Fukushima Prefecture, shows the decreasing tendency of the radiocaesium inventory in the most upper part of the soil layer at ridge and valley bottom. A very slightly downward infiltration of the radiocaesium was found with decreasing of the inventory near the ground surface but most of the radiocaesium still exist in the upper part of the soil layer. Outflow of the radiocaesium from the mountain forest get to decrease due to the downward infiltration of the radiocaesium in the soil horizon by the application of the SACT model developed in JAEA.