Modeling watershed-scale137Cs transport in a forested catchment affected by the Fukushima Dai-ichi Nuclear Power Plant accident.
The Fukushima nuclear accident in 2011 resulted in137Cs contamination of large areas in northeast Japan. A watershed-scale137Cs transport model was developed and applied to a forested catchment in Fukushima area. This model considers137Cs wash-off from vegetation, movement through soils, and transport of dissolved and particulate137Cs adsorbed to clay, silt and sand. Comparisons between measurements and simulations demonstrated that the model well reproduced137Cs concentrations in the stream fed from the catchment. Simulations estimated that 0.57 TBq of137Cs was exported from the catchment between June, 2011 and December, 2014. Transport largely occurred with eroded sediment particles at a ratio of 17:70:13 of clay, silt, and sand. The overall137Cs reduction ratio by rainfall-runoff wash-off was about 1.6%. Appreciable137Cs remained in the catchment at the end of 2014. The largest rate of137Cs reduction by wash-off was simulated to occur in subwatersheds of the upper catchment. However, despite relatively low initial deposition, middle portions of the watershed exported proportionately more137Cs by rainfall-runoff processes. Simulations indicated that much of the transported137Cs originates from erosion over hillsides and river banks. These results suggested that areas where137Cs accumulates with redeposited sediments can be targeted for decontamination and also provided insight into137Cs transport at the watershed scale to assess risk management and decontamination planning efforts.
Department of Environmental Science and Technology, Tokyo Institute of Technology, Japan; Linköping University, Guangzhou University Research Center on Urban Sustainable Development, Guangzhou University, China. Electronic address: bjyq_2006@126.com.
Lezhang
L
Wei
Department of Environmental Science and Technology, Tokyo Institute of Technology, Japan.
Tsuyoshi
T
Kinouchi
Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Japan.
Kazuya
K
Yoshimura
HDR, USA.
Mark L
ML
Velleux
D002588:Cesium Radioisotopes / Q000032:analysis*; D065928:Forests; D062406:Fukushima Nuclear Accident; D007564:Japan; D011834:Radiation Monitoring; D011847:Radioactive Fallout / Q000032:analysis; D012990:Soil Pollutants, Radioactive / Q000032:analysis; D014875:Water Pollutants, Radioactive / Q000032:analysis*
D002588:Cesium Radioisotopes; D011847:Radioactive Fallout; D012990:Soil Pollutants, Radioactive; D014875:Water Pollutants, Radioactive
(137)Cs transport; Forested catchment; Fukushima nuclear accident