Relation between heavy metal properties in sclerotia grains and soil environment

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07700
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Plant nutrition/Soil science
• Research Institution: Tokyo Metropolitan University
• Principal Investigator: Watanabe Makiko 首都大学東京, 都市環境科学研究科, 教授 (10175119)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 菌核粒子 / 重金属 / 放射性炭素年代測定 / 金属移行係数 / 森林土壌 / 土壌環境

Outline of Final Research Achievements

Melanic sclerotia formed by ectomycorrhizal fungi such as Cenococcum geophilum are essential component of the interface between the soil and roots of many arborescent species under adverse conditions and can be visually detected in forest soil. In this study, the concentration of heavy metal contained in melanin sclerotium grains were collected from forest soils in Japan and overseas to obtain metal concentration in the grains and to elucidate the mechanism of metal enrichment in sclerotia grains. As a result of ICP-OES, ICP-MS, SEM-EDS, XRF, and AMS14C dating analyses, the characteristics of elemental composition of sclerotia grains collected from a wide range of soil pH 4-8 became clear. Time and soil environment were pointed out as regulating factors of transfer factor of specific metallic elements from soil to sclerotia grain.

Free Research Field

土壌学

Academic Significance and Societal Importance of the Research Achievements

わが国の森林土壌（低pH領域）については，土壌から菌核への金属元素移行係数のバックグランド値に関して信頼性の高いデータが得られた。また，放射性炭素年代測定によって得られた菌核の土壌残留期間の推定値から，菌核内部の金属元素の濃縮機構に関する新たな知見が得られた。半乾燥地域（高pH領域）の土壌からメラニン質菌核を検出し、その特性について明らかにすることが世界で初めてできた。菌体由来の構造物で土壌に長く残留する土壌菌核粒子が，重金属汚染等の過去の環境負荷推定や腐植金属複合体の形成メカニズム等に関する情報を保持する環境試料であることを示した点で，本研究で得られた知見は学術への貢献が大きい。