[M-IS14] 生物地球化学

[MIS14-09] Initial soil formation on fresh volcanic ash from the 2000 eruption of Miyake Island

*浅野 眞希¹、LI XINXIN¹、田村 憲司¹、上條 隆志¹、和穎 朗太²、武市 泰男³、小野 寛太³、高橋 嘉夫⁴ (1.筑波大学、2.農研機構、3.高エネ研、4.東大)

キーワード：初期土壌生成、一次遷移、有機無機相互作用、土壌有機物、火山灰土壌、三宅島

Mt. Oyama in Miyake Island erupted with large amounts of volcanic ash in 2000. Large areas of the island were severely damaged by the volcanic ash, debris flow and volcanic gas. The areas from the mountain top (new crater) to mountain side on western part of the Island (Igaya area) were buried by thick volcanic ash deposition followed by primary succession of plant-soil system. The research on the initial soil forming process on fresh volcanic ash under natural environment is important to understand the development of volcanic ash soil (Andosols) and ecosystem in volcanic region. Co-variation between vegetation growth and accumulation of organic matter is especially important. We conducted soil profile investigation and sampling in the vegetation monitoring sites at Igaya area in 2007, 2011, 2015 and 2017. We examined the changes in the soil profile morphology and soil physico-chemical properties in the time series. Organo-mineral particle was separated by the combination of density and particle size fractionation and the recovered fractions were observed by scanning transmission X-ray microscopy (STXM) and near-edge X-ray absorption fine structure (NEXAFS). We will discuss on the concurrent development of soil-vegetation system and the accumulation of soil organic matter in the initial soil formation.