Ten-year temporal changes in the supply source of 137Cs released by the Fukushima Daiichi Nuclear Power Plant to the coastal area
SATOH Shun (Completed Master’s Program in Environmental Radioactivity, 2023)
Research Overview
This study investigated the input of radioactive cesium (137Cs) to the coastal ocean off Fukushima from 2012 to 2021. Two pathways were compared: ongoing direct releases of 137Cs from the Fukushima Daiichi Nuclear Power Plant (FDNPP) and riverine 137Cs inputs. For the riverine input, both dissolved 137Cs and particulate 137Cs were quantified. The direct release from the FDNPP has been clearly decreased due to countermeasures implemented by Tokyo Electric Power Company. Currently, the dominant process is the desorption of particulate 137Cs transported by rivers, which becomes more pronounced during periods of high river discharge, such as typhoon events. The estimated concentrations of 137Cs in coastal seawater were generally consistent with trends observed in marine monitoring. Although, during periods of large river discharge, the estimated concentrations tended to be overestimated, indicating the need for further study of 137Cs behavior in coastal areas.
Significance of the Study
This study clarified the ten-year variation in 137Cs input from land to the coastal ocean off Fukushima. In the early post-accident period, direct release from the FDNPP was the dominant source, but it has since declined markedly due to countermeasures. Currently, riverine input during storm events represents the dominant source, with particulate 137Cs delivered by rivers undergoing desorption in seawater and contributing to dissolved 137Cs concentrations. These findings provide valuable insights into the long-term impact of 137Cs in coastal environments and support the development of future marine monitoring strategies.
Figures
(Right) Comparison of the total input during the initial three-year period (2012–2014) and the most recent three-year period (2019–2021).
Publication
This paper is made available online on September 11, 2025, on the website of the academic journal “Science of The Total Environment”, published by Elsevier.
| Journal | Science of The Total Environment |
|---|---|
| Title | Ten-year temporal changes in the supply source of 137Cs released by the Fukushima Daiichi Nuclear Power Plant to the coastal area |
| URL | https://doi.org/10.1016/j.scitotenv.2025.180380 |
| Authors | Shun Satoha,b*, Yoshifumi Wakiyamaa, Fumiaki Takahashib, Hyoe Takataa aInstitute of Environmental Radioactivity, Fukushima University, Fukushima, Japan bJapan Atomic Energy Agency, Ibaraki, Japan *Corresponding author |