Relationship between the radiocesium interception potential and the transfer of radiocesium from soil to soybean cultivated in 2011 in Fukushima Prefecture, Japan

The concentration of radiocesium (134Cs and 137Cs) in agricultural fields around Fukushima Dai-ichi Nuclear Power Plant (FDNPP) was elevated after the accident in March 2011. Evaluation of soil properties that influence phytoavailability of radiocesium is important for optimal soil management to minimize radiocesium transfer to crops. In this study, soybean grain and soil samples (0-15 cm) were collected from 46 locations in Fukushima Prefecture in 2011, and 137Cs concentrations were measured. 137Cs concentration ranges were 11-329 Bq kg−1-dry in soybean grain samples, and 0.29-2.49 kBq kg−1-dry in soil samples. The radiocesium interception potential (RIP) values in the soil samples ranged from 0.30 to 8.61 mol kg−1. RIP negatively correlated with total carbon content and oxalate-extractable Si and Al + 1/2 Fe in the soils, suggesting that soils rich in organic matter and poorly crystalline clays tended to have lower RIP in this region. The soil-to-plant transfer factor for 137Cs, analyzed in relation with various soil characteristics, varied by two orders of magnitude and was significantly negatively correlated with RIP and exchangeable K concentration in soil. The results show that RIP is useful for evaluating the efficiency of radiocesium transfer from soil to plants in this region.