title: Fractionation of radiocesium in soil, sediments, and aquatic organisms in Lake Onuma of Mt. Akagi, Gunma Prefecture using sequential extraction.
abstract: The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has resulted in the contamination of the environment in Gunma Prefecture with radioisotope cesium (radio-Cs,134Cs and137Cs). Concentrations of radio-Cs >500Bqkg-1were found in wakasagi (Hypomesus nipponensis) in Lake Onuma at the top of Mount (Mt.) Akagi in August 2011. To explain the mechanism of this contamination, monitoring studies have been conducted around Lake Onuma by measuring radio-Cs concentrations in samples of fish, aquatic plants, plankton, lake water, lake sediments, and surrounding soil. The leachability of radio-Cs was evaluated using sequential extraction by Tessier et al. The total concentration of radio-Cs in Lake Onuma ecosystems decreased gradually with time. In the brown forest soil, radio-Cs concentrations of 2000 to 6000Bqkg-1were detected. The abundance ratio of the easy-elution form (exchangeable and carbonate forms) in the samples was <10%. The concentrations in phytoplankton samples were 3-6 times higher than those in wakasagi samples. The ratios of easy-elution forms increased by the rank in the food chain; 37% in phytoplankton, 78% in zooplankton, and 97% in wakasagi. It is likely that the lower ratio of the easy-elution form in phytoplankton is related to the adsorption of radio-Cs on suspended substances in the lake, as suggested by the analyses of aluminum and titanium in the phytoplankton, zooplankton, and wakasagi samples. The high concentrations of radio-Cs in wakasagi would be related also to the characteristics of closed mountain lakes.
authors.affiliation: Graduate School of Science and Technology, Gunma University, Japan. Electronic address: mori@gunma-u.ac.jp.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Mori
authors.affiliation: Graduate School of Science and Technology, Gunma University, Japan.
authors.forename: Kin-Ichi
authors.initials: KI
authors.lastname: Tsunoda
authors.affiliation: Graduate School of Science and Technology, Gunma University, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Aizawa
authors.affiliation: Graduate School of Science and Technology, Gunma University, Japan; Kiryu Bureau of Waterworks in Kiryu City, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Saito
authors.affiliation: Graduate School of Science and Technology, Gunma University, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Koike
authors.affiliation: Graduate School of Science and Technology, Gunma University, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Gonda
authors.affiliation: Graduate School of Science and Technology, Gunma University, Japan.
authors.forename: Shunji
authors.initials: S
authors.lastname: Abe
authors.affiliation: Gunma Prefectural Fisheries Experiment Station, Japan.
authors.forename: Kyuma
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Gunma Prefectural Fisheries Experiment Station, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Yuasa
authors.affiliation: Gunma Prefectural Fisheries Experiment Station, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kuge
authors.affiliation: Gunma Prefectural Fisheries Experiment Station, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: Gunma Prefectural Fisheries Experiment Station, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Arai
authors.affiliation: Gunma Prefectural Fisheries Experiment Station, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: National Institute for Environmental Studies, Japan.
authors.forename: Seiichi
authors.initials: S
authors.lastname: Nohara
authors.affiliation: Faculty of Humanities, Musashi University, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Minai
authors.affiliation: Atomic Energy Research Laboratory, Tokyo City University, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Okada
authors.affiliation: Low Level Radioactivity Laboratory, Kanazawa University, Japan.
authors.forename: Seiya
authors.initials: S
authors.lastname: Nagao
mesh_terms: D000818:Animals; D059001:Aquatic Organisms; D002588:Cesium Radioisotopes / Q000032:analysis*; D005591:Chemical Fractionation; D062406:Fukushima Nuclear Accident; D019015:Geologic Sediments / Q000032:analysis; D007564:Japan; D060106:Lakes / Q000032:analysis*; D011834:Radiation Monitoring; D012987:Soil / Q000737:chemistry; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D002588:Cesium Radioisotopes; D012987:Soil; D012990:Soil Pollutants, Radioactive; D014875:Water Pollutants, Radioactive
keywords: Easy-elution form; Gunma Prefecture; Mountain Lake; Radiocesium; Wakasagi