Abstract
We investigated the effects of volcanic ash and gas (sulfur dioxide) on chemical properties of the mineral soil surface in Miyake Island. The pH(H2O) values of mineral soil increased from 4.0-4.4 in 2004 to 4.3-4.8 in 2006. Calcium and sulfate ion were washed out from the volcanic ash by acid rain water, so the mineral soil were protected by buffer effect of the ash. Though the sulfur dioxide concentrations were high (0.2-0.5 ppm), the vegetation were fast restorated because of the thick ash sedimentation (upper 10 cm) in east and north area of the Oyama volcano.
