Abstract
In order to estimate influences on the environment of the Miyake Island by sulfur compounds emitted by volcanic activity in 2000, volcanic ash of Mt. Oyama was washed with Mill-Q water. The contents and chemical forms of the sulfur, mainly originating in sulfur dioxide adsorbed on the ash, in the washed water were determined by ion chromatography and the turbidimetry using the precipitation of barium sulfate. Ion chromatography showed that the washed water contained only sulfate and chloride anions. The concentration of the sulfate ion dissolved in the washed water maintained the same value after hydrogen peroxide was added to it. By turbidimetry, sulfate ion was identified in the water. These results suggest that only the sulfate ion existed in the washed water. Most of the sulfate ion was extracted to the water immediately when the volcanic ash and the water were contacted. The pH values of the water also decreased immediately upon contact. Then, the concentrations of sulfate ion and proton, together, were slightly increased according to the contact time. By washing volcanic ashes with Milli-Q water, more than 23% of the total sulfur in the volcanic ash was quickly extracted out as the sulfate ion. This result suggested a possibility that the volcanic ash may result in serious problems involving the reconstruction of daily lives on the Miyake Island, e.g. to get the city water.
