Impact of radiocesium contamination in flood sediment deposited after the 2019 typhoon on decontaminated fields of Fukushima Prefecture, Japan

International audience; Sediment that has deposited after the flood generated by the 2019 typhoon (referred to as Flood Sediment, FS) was collected along two rivers in eastern Fukushima Prefecture, Japan to determine the total and exchangeable radiocesium (137 Cs), and acid-extractable potassium (K) contents. Then, these FS parameters were compared with those of decontaminated soils (DS) in nearby agricultural fields to discuss the potential transfer risk of 137 Cs from rivers to nearby remediated soils. While FS had about four times higher total 137 Cs content, it showed a three-times lower exchangeable 137 Cs content than DS. Furthermore, acid-extractable K referred to as non-exchangeable K (Nex-K) content was high enough to restrict 137 Cs transfer from soil to crops for both FS and DS. From these comparisons, we concluded that deposition of FS onto DS may not increase the transfer of 137 Cs from soil to crops.