[SVC39-P03] Determination on the stable isotopic compositions of H2O in a volcanic plume
Keywords:Volcanic gases, Stable isotopic compositions, Cavity Ring-Down Sectroscopy
In this study, we determined the isotopic ratios of H2O in a volcanic plume that had been ejected from accessible fumaroles to confirm whether the isotopic ratios (δD and δ18O) estimated from plume H2O is consistent with those of fumarolic H2O or not.
The samples were taken in Hakone volcano from 2014 to 2018. We collected around 20 volcanic plume samples into pre-evacuated glass bottle (ca. 1000 ml) during each sampling, while changing the distances from the fumarole. Besides, we also collected the fumarolic H2O through condensation using a cold trap.
The isotopic ratios (δD and δ18O) of plume H2O showed strong linear correlation (R2 = 0.9 or more) with the reciprocal of H2O concentration. The isotopic ratios (δD and δ18O) estimated as the intercept of the linear correlation found in the plume H2O was consistent with fumarolic H2O. We concluded that we can estimate the stable isotopic ratios of fumarolic H2O remotely using those in plume H2O.
This study was supported by MEXT Scientific Research Program grants “Integrated Program for Next Generation Volcano Research and Human Resource Development”.