Isotopic and chemical compositions of volcanic gases from Satsuma-Iwojima, Japan

Abstract

D/H and ¹⁸O/¹⁶O ratios of fumarolic condensate, hot spring water and surface water collected from a volcanic island, Satsuma-Iwojima were determined together with some of chemical components. δD and δ¹⁸O of fumarolic condensates range from -27 to -17‰ (SMOW) and from +7.3 to +9.5‰ (SMOW), respectively. The high value of δ¹⁸O was concluded to be the result of thorough oxygen isotope exchange with ambient andesitic rocks. δD values are also higher than that of the local surface water, but we could not find a positive evidence that supports the assumption of mixing of the local surface water and sea water. On the basis of the relationship between the concentration of chemical components and isotope ratios of fumarolic condensates, it was concluded that water vapor and chemical components behave independently in an individual fumarole.