Changes in the Soil to Brown Rice Concentration Ratio of Radiocaesium before and after the Fukushima Daiichi Nuclear Power Plant Accident in 2011.

Radiocaesium (Cs) mobility in soil is initially relatively high when the nuclide first comes into contact with soil, after which the mobile fraction decreases with time due to Cs fixation to soil particles (aging effect). Consequently, the Cs activity concentration in plants grown in soil was expected to decrease with time after the Fukushima Daiichi nuclear power plant accident in 2011. In this study, we collated data on concentration ratios (CR) of Cs between brown rice grain and paddy soil and compared CR values reported for periods before and after the accident.