title: Assessment of the caesium-137 flux adsorbed to suspended sediment in a reservoir in the contaminated Fukushima region in Japan.
abstract: We estimated the flux of caesium-137 adsorbed to suspended sediment in the Kusaki Dam reservoir in the Fukushima region of eastern Japan, which was contaminated by the Fukushima Nuclear Power Plant accident. The amount and rate of reservoir sedimentation and the caesium-137 concentration were validated based on the mixed-particle distribution and a sediment transport equation. The caesium-137 and sediment flux data suggested that wash load, suspended load sediment, and caesium-137 were deposited and the discharge and transport processes generated acute pollution, especially during extreme rainfall-runoff events. Additionally, we qualitatively assessed future changes in caesium-137 and sediment fluxes in the reservoir. The higher deposition and discharge at the start of the projection compared to the 2090s are most likely explained by the radioactive decay of caesium-137 and the effects of reservoir sedimentation. Predictions of the impacts of future climate on sediment and caesium-137 fluxes are crucial for environmental planning and management.
authors.affiliation: Institute of Industrial Science (IIS), The University of Tokyo, Be505, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan. Electronic address: mouri@rainbow.iis.u-tokyo.ac.jp.
authors.forename: Goro
authors.initials: G
authors.lastname: Mouri
authors.affiliation: Faculty of Geography, Lomonosov Moscow State University, 119991 Russia, Moscow, GSP-1, Vorob'evy Gory, MSU, Moscow, Russia.
authors.forename: Valentin
authors.initials: V
authors.lastname: Golosov
authors.affiliation: Department of Urban and Environmental Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Michiharu
authors.initials: M
authors.lastname: Shiiba
authors.affiliation: Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
authors.forename: Tomoharu
authors.initials: T
authors.lastname: Hori
mesh_terms: D000327:Adsorption; D002588:Cesium Radioisotopes / Q000032:analysis*; D062406:Fukushima Nuclear Accident; D019015:Geologic Sediments / Q000737:chemistry*; D007564:Japan; D055848:Nuclear Power Plants; D011834:Radiation Monitoring; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D002588:Cesium Radioisotopes; D014875:Water Pollutants, Radioactive
keywords: Caesium-137; Fukushima accident; Kusaki Dam basin; Numerical hydrodynamic model; Reservoir sedimentation; Suspended sediment