title: Size-dependent distribution of radiocesium in riverbed sediments and its relevance to the migration of radiocesium in river systems after the Fukushima Daiichi Nuclear Power Plant accident.
abstract: We investigated the particle size distribution of radiocesium in riverbed sediments after the Fukushima Daiichi Nuclear Power Plant accident. Riverbed sediments were collected in the Abukuma River system in Fukushima and Miyagi Prefectures. The collected sediments were separated into 11 fractions, ranging from granular size (>2000 μm) to clay size (<2 μm) fractions. Cesium-137 concentrations were higher in the smaller particle size fractions, possibly reflecting specific surface areas and the mineralogy, in particular the clay mineral content. A gap in (137)Cs concentration was observed between the silt size and sand size fractions of riverbed sediments at downstream sites, whereas riverbed sediments at an upstream site did not show such a concentration gap. It is likely that selective transport of small particles in suspended state from upstream areas resulted in an accumulation of radiocesium in downstream areas.
authors.affiliation: Institute for Sustainable Sciences and Development, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan. Electronic address: kt0830@hiroshima-u.ac.jp.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Hokuto
authors.initials: H
authors.lastname: Iwatani
authors.affiliation: Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Sakaguchi
authors.affiliation: Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Qiaohui
authors.initials: Q
authors.lastname: Fan
authors.affiliation: Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takahashi
mesh_terms: D002586:Cesium / Q000032:analysis*; D002588:Cesium Radioisotopes / Q000032:analysis*; D062406:Fukushima Nuclear Accident; D019015:Geologic Sediments / Q000032:analysis*; D007564:Japan; D055848:Nuclear Power Plants; D011834:Radiation Monitoring; D011847:Radioactive Fallout / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D012990:Soil Pollutants, Radioactive / Q000032:analysis; D014875:Water Pollutants, Radioactive / Q000032:analysis
chemical_list: D002588:Cesium Radioisotopes; D011847:Radioactive Fallout; D012990:Soil Pollutants, Radioactive; D014875:Water Pollutants, Radioactive; D002586:Cesium
keywords: Fukushima; Particle size; Radiocesium; Riverbed sediment