Micromorphological characteristics of soils under the abandoned fields of mines, Ningyo-toge, Japan

人形峠鉱山の鉱山跡地における土壌微細形態

Jiang, Q.*; 田村 憲治*; 浅野 眞希*; 福山 賢仁; 高橋 純子*; 山路 恵子*

Jiang, Q.*; Tamura, Kenji*; Asano, Maki*; Fukuyama, Kenjin; Takahashi, Junko*; Yamaji, Keiko*

人形峠鉱山露天採掘場跡地の植生はススキが優占し、約20年間遷移が進んでいない。本研究の目的はこの特異的な場所の土壌微細形態を把握することである。露天採掘場跡地に2箇所の調査地点siteAとsiteBを設定した。SiteAはススキが優占し、SiteBはカヤツリグサが優占する。化学分析に供するため、各地点の土壌断面の各層から土壌サンプルを採取した。各地点の深さ0-5cm, 10-15cm, 30-35cmのコアから薄層サンプルを作成した。SiteBのBC層はEhが低く、それより下層が空隙が少ないために水を貯めていることが原因であると考えられた。コアの薄層観察から0-5cm層は良好な土壌構造を示したが、それより下層では構造が未熟で塊状構造を形成していた。固相5形態の鉄、マンガンの含有量は、残渣酸化結合態有機結合態炭酸結合態交換態の順であった。

In the former open-pit mining area of Ningyo-toge mine, is the dominant in its vegetation and the vegetation succession has been suspended for 2 decades. The present work was conducted to understand the soil micromorphological characteristics on this unusual area. We set two sampling sites (site A and site B) at the former open-pit mining area. Site A is in dominant vegetation, and site B is in dominant vegetation. Soil samples were taken from each horizon of the soil profiles for chemical analysis at the sites, and thin sections were obtained from the soil core samples (0-5 cm, 10-15 cm, 30-35 cm depth of site A and Site B, respectively). The BC horizon of site B has a lower Eh, which may be due to the less voids in the underlying soil, which results in seasonal accumulation of water. And the soil thin section observation showed that the 0-5cm of soil is in good structure, but the lower layer is not fully developed and forms a block structure. The content of the five forms of Fe and Mn are residual form oxide-bound form organic-bound form carbonate-bound form exchangeable form in this study site.