2022 Fiscal Year Final Research Report

Study on arsenic accumulation mechanism in surface layer of paddy soils using advanced X-ray spectroscopy and its application to soil remediation technique

Research Project

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Project/Area Number	19H03087
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 41050:Environmental agriculture-related
Research Institution	Ehime University
Principal Investigator	Mitsunobu Satoshi 愛媛大学, 農学研究科, 准教授 (70537951)
Co-Investigator(Kenkyū-buntansha)	松本真悟島根大学, 学術研究院農生命科学系, 教授 (00346371) 白石史人広島大学, 先進理工系科学研究科(理), 准教授 (30626908) 加藤真悟国立研究開発法人理化学研究所, バイオリソース研究センター, 上級研究員 (40554548) 濱村奈津子九州大学, 理学研究院, 教授 (50554466) SHUKLA ELVIS.ANUP 愛媛大学, 防災情報研究センター, 准教授 (70833721)
Project Period (FY)	2019-04-01 – 2022-03-31
Keywords	水田土壌 / ヒ素 / スペシエーション / 微生物
Outline of Final Research Achievements	In this study, we investigated the behavior of inorganic arsenic (As), which is currently the most serious pollutant of rice paddies in the world paddy soils. In particular, we investigated the factors related to the As accumulation in the surface soil layer that occurs specifically in waterlogged paddy soils. The experimental results showed that As is reduced in the deep layer and diffused/re-oxidized to the oxidized surface layer due to the depth-differentiation of the redox state caused by waterlogging, and that As is easily adsorbed on soil minerals. The obtained findings can be applied to new soil remediation methods for efficient removal of As from pollutant paddy fields, as well as to elucidate the regional As behavior at pollutant paddy field sites in Asian countries and Japan.
Free Research Field	土壌化学
Academic Significance and Societal Importance of the Research Achievements	ヒ素は水田土壌のみならず最も深刻な土壌・水質汚染を引き起こしている有害元素の一つである。土壌中で特異的に起きる濃集現象の本質的な要因を分子レベルで明らかにした本研究はヒ素の環境中における拡散濃集メカニズムを考察する上でも重要な知見となる。将来的には、表層土壌へのヒ素濃集現象を応用することで、汚染水田からAsを高効率、低コスト、低環境負荷で除去する新たな土壌修復法へ応用できると考えており、今後も更なる研究を進めていく。