Abstract
It is predictable from previous studies that radiocesium hardly migrates into surrounding soils and groundwater from soils contaminated by the accident at Fukushima Daiichi Nuclear Power Station if they are buried and covered with clean local soils. This study demonstrated the prediction by performing in-situ migration experiments over a year in a public park in Miho, Ibaraki prefecture and in two public parks in Misato, Saitama prefecture. Contaminated surface soils were gathered and buried at a depth range of 0.3 ～ 1.0 m or at 0.3 ～ 1.3 m and covered with clean local soil layer of 0.3 m, and were sprinkled with water to accelerate the radiocesium migration. Migration of radiocesium was not observed from radiometric analyses of boring cores and soil water samples. Laboratory column and sorption experiments revealed that the radiocesium hardly leaches out of the soil and even if it leaches out from the contaminated soil, radiocesium is sorbed on surrounding soils and hardly migrates through the soil layer. Simulation of Cs-137 migration for 100 years by an advection-diffusion model showed that Cs-137 migrates slightly and decays out in the contaminated soil.
