Application of Diffusive Gradients in Thin Films (DGT) for the Dynamic Speciation of Radioactive Cesium in Fukushima Prefecture, Japan

• Published in: ACS ES&T water 2024-08, Vol.4 (8), p.3579-3586
• Main Authors: Tanaka, Takuro, Fukuoka, Masafumi, Toda, Kanako, Nakanishi, Takahiro, Terashima, Motoki, Fujiwara, Kenso, Niwano, Yuma, Kato, Hiroaki, Kobayashi, Natsuko I., Tanoi, Keitaro, Saito, Takumi
• Format: Article
• Language: English
• ISSN: 2690-0637; 2690-0637
• DOI: 10.1021/acsestwater.4c00453

Radioactive cesium released by the Fukushima Daiichi Nuclear Power Plant accident in March 2011 remains in the forest environment and is being transported to the ocean via residential areas by runoff into river systems. Most of the 137Cs in river water exists as suspended forms, being strongly fixed by micaceous clay minerals. If this fraction can change its form to dissolved forms, this results in additional input of bioavailable 137Cs. In this study, in situ sampling of 137Cs at multiple rivers in Fukushima Prefecture was conducted using diffusive gradient in thin film (DGT) devices to investigate the dynamics of radioactive cesium in river environments. At almost all sampling points, the DGT 137Cs concentrations exceeded the dissolved 137Cs concentrations, revealing the existence of a flux from the suspended to the dissolved forms. This additional input was found to have higher 137Cs/133Cs ratios than those of Cs in the dissolved form. This study demonstrates that the bioavailability of 137Cs can be underestimated by assessing only the dissolved form due to the flux of 137Cs from the suspended particles likely caused by their dissolution.