Elucidation of specific poise function of Andisol for arsenic reduction in paddy rice; Application of 57Fe tracer

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06335
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41050:Environmental agriculture-related
• Research Institution: Tohoku University
• Principal Investigator: Makino Tomoyuki 東北大学, 農学研究科, 教授 (60354106)
• Co-Investigator(Kenkyū-buntansha): 菅野 均志 東北大学, 農学研究科, 准教授 (30250731) ; 濱本 亨 東北大学, 農学研究科, 助教 (80877100)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 土壌 / 鉄酸化物 / ヒ素 / 安定同位体

Outline of Final Research Achievements

The soil Fe elution was compared by adding 57Fe oxide to Andisol and non- Andisol and incubating them in water using 57Fe as a tracer. The soil Fe release from the non- Andisol was reduced by the addition of 57Fe, and the As release was also reduced. The Andisol did not reduce soil Fe leaching after the same addition. The electrons supplied by waterlogged incubation test were equally distributed between soil Fe and material Fe in the non- Andisol, suggesting that soil Fe is less electron-accepting in the Andisol.
Mixing of Andisol with alluvial soil resulted in a decrease in As concentration in the soil solution and an increase in the Si/As ratio, and the total As concentration in brown rice decreased. Under reducing conditions, Andisol has a high adsorption capacity for As(III), suggesting that amorphous iron and large amounts of silicate increase the relative amount of As and contribute to the reduction of As in brown rice.

Free Research Field

土壌環境

Academic Significance and Societal Importance of the Research Achievements

黒ボク土は、非黒ボク土に比べて、湛水培養における土壌鉄の溶解性が特異的に低いが、その詳細なメカニズムは十分に解明されていなかった．本研究では、安定同位体57Feをトレーサーとして含有する57Fe鉱物の利用により、「湛水条件下の黒ボク土における土壌鉄の低溶解性のメカニズムを解明した。この点が、既存の研究にはない、本研究の学術的独自性と創造性の中核となるものである．
また、本研究により、黒ボク土と非黒ボク土の鉄およびヒ素の挙動が解明されることで、農業や土壌管理における合理的な手法の確立、さらには玄米中のAs低減を通じた食品の安全性向上への貢献が期待される．