Chemical speciation and availability of phosphorus in soil colloids for the prediction of eutrophication

2019 Fiscal Year Final Research Report

• Project/Area Number: 15H04467
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Plant nutrition/Soil science
• Research Institution: Tokyo University of Agriculture and Technology
• Principal Investigator: Hashimoto Yohey 東京農工大学, (連合)農学研究科(研究院), 准教授 (80436899)
• Co-Investigator(Kenkyū-buntansha): 豊田 剛己 東京農工大学, (連合)農学研究科(研究院), 教授 (30262893) ; 山口 紀子 国立研究開発法人農業・食品産業技術総合研究機構, 農業環境変動研究センター, ユニット長 (80345090)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: コロイド / リン / 土壌

Outline of Final Research Achievements

Phosphorus is one of the important elements involved in eutrophication of water bodies and algae growth. Phosphorus is supplied to lakes and marshes from land such as farmlands in the form of adhering to soil particles. It has been pointed out that soil colloidal particles (1 nm to 1 μm) play an important role in long-range transport of phosphorus. In this study, we focused on the colloidal particles of soils and clarified the concentration and chemical form of phosphorus contained in the soils to obtain the knowledge that leads to the eutrophication of water system. This study confirmed that phosphorus was accumulated in the colloidal particles of soils and that it was mainly retained by iron minerals such as ferrihydrite.

Free Research Field

環境化学

Academic Significance and Societal Importance of the Research Achievements

土壌のコロイド粒子中の鉄は，フェリハイドライトやゲーサイトのような(水)酸化鉄鉱物が主体である(60～70%)ことが明らかになった．一方，バルク土壌においては，イライトのような層状ケイ酸塩鉱物に含まれる鉄が主体であった．この結果は，コロイド粒子には，(水)酸化鉄鉱物が選択的に含まれることを示しており，土壌からリンを吸着した(水)酸化鉄鉱物がコロイドに含まれる形で，水田土壌から河川へ流出する可能性を示唆している．