Reconstruction of bioavailable Cs-137 activity concentration just after the FDNPP accident using hard tissues memory as a proxy

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H03383
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 63040:Environmental impact assessment-related
• Research Institution: Hirosaki University
• Principal Investigator: Tazoe Hirofumi 弘前大学, 被ばく医療総合研究所, 准教授 (60447381)
• Co-Investigator(Kenkyū-buntansha): 永井 尚生 日本大学, 文理学部, 教授 (10155905) ; 三浦 富智 弘前大学, 被ばく医療総合研究所, 教授 (20261456) ; 白井 厚太朗 東京大学, 大気海洋研究所, 准教授 (70463908)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: セシウム / 河川 / ストロンチウムー９０ / ヨウ素－１２９

Outline of Final Research Achievements

During the transitional period immediately after the Fukushima Daiichi Nuclear Power Plant accident, the transfer process of radionuclides to the river ecosystem is orders of magnitude larger than the subsequent state, and has a tremendous impact on biota. In order to clarify how the highly bioavailable dissolved and mobile particle-form Cs-137 changed in the river environment during the first month immediately after the accident, we attempted to reconstruct the river environment using the shells of the Japanese mussel. The results showed that within one month after the earthquake, the concentrations of both Sr-90 and I-129 increased more than 500-fold compared to the pre-earthquake levels. The results also indicate that a large amount of radioactive Cs flowed into the river as water-soluble and organic components during the transitional period immediately after the accident.

Free Research Field

分析化学

Academic Significance and Societal Importance of the Research Achievements

河川環境下で生息する生物にとって，河川水から溶存態として直接的に，あるいは移行性の高い有機態から食物網を通じて間接的に生体内へ取り込まれる放射性セシウムの動態に関する事故直後の情報が欠損している．事故直後の放射性セシウムの変遷は，詳細観測開始後の数か月から数年単位の変動から遡って予測されたものであり，過渡的な特性を反映させることは困難である．事故直後の動態を解明することで，今後，原子力関連施設での事故が再発してしまった際にも，河川環境に生息する生物への影響評価，さらには災害時の飲用水確保の対策としても有益な知見を与える．