2020 Fiscal Year Final Research Report
Dynamics of radioactive cesium in Lake Onuma of Mt. Akagi by speciation analysis.
| Project/Area Number |
18K04995
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 31010:Nuclear engineering-related
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| Research Institution | Tokyo City University |
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Principal Investigator |
Okada Yukiko 東京都市大学, 理工学部, 准教授 (60287860)
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| Co-Investigator(Kenkyū-buntansha) |
薬袋 佳孝 武蔵大学, 人文学部, 教授 (10157563)
長尾 誠也 金沢大学, 環日本海域環境研究センター, 教授 (20343014)
角田 欣一 群馬大学, 大学院理工学府, 教授 (30175468)
木川田 喜一 上智大学, 理工学部, 教授 (30286760)
渡辺 峻 群馬県水産試験場, その他部局等, 研究員 (30739024)
松浦 治明 東京都市大学, 理工学部, 准教授 (70262326)
森 勝伸 高知大学, 教育研究部総合科学系複合領域科学部門, 教授 (70400786)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | 放射性Cs / 内陸湖沼 / 赤城大沼 / 放射性Csの再溶出 / スペシエーション分析 / 放射性Csの吸着 / 逐次抽出法 / 無酸素状態 |
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| Outline of Final Research Achievements |
In order to investigate the cause of the prolonged contamination of the lake water of Lake Onuma on Mt. Akagi with radioactive Cs, and to understand the actual situation of radioactive Cs contamination and to predict its future, we continued our multifaceted researches focusing on the sequential extraction method using radioactive Cs and stable Cs, adsorption experiments, speciation analysis using XAFS analysis, XRD analysis, SEM observation, ICP-MS analysis, and high-density field monitoring.
The results showed that the adsorption rate of radioactive Cs in the bottom sediment was lower and the desorption rate was higher than that in other lakes in Gunma Prefecture. It was found that the retention period of the lake water in summer, which is a characteristic of Lake Onuma, may cause anoxic conditions in the deep water, triggering the re-leaching of radioactive Cs. Because Lake Onuma is a natural lake and is strongly closed, the leaching of radioactive Cs was remarkably observed.
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| Free Research Field |
放射化学、分析化学
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| Academic Significance and Societal Importance of the Research Achievements |
内陸湖沼の放射性物質動態に関する知見は,決定的に不足している．内陸湖の汚染が遷延を考えるうえで，底質からの放射性Csの再溶解の寄与を考えざるを得ない．この寄与を考える上で，赤城大沼のような閉鎖的火山性湖沼は，攪乱が少なく比較的安定した生態系を維持していると考えられ，放射性Csの汚染機構の解明と将来予測のために適した対象である．従って，本研究の成果は，多くの陸水生態系の放射性Cs汚染の研究者の学際的な基礎となる情報を与えうるものである．
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