Poster Presentations
- Day 2, May 12（Tue.） Poster (1008/09)
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2P-16 PDF
Application of 234U/238U isotopic proxy to a highly reductive groundwater system
234U/238U ratios were examined from a groundwater system which flows in a Tertiary sedimentary rock in the Horonobe area in Hokkaido to estimate the degrees of U-series isotopic disequilibrium. About 10 L groundwater samples (less than 1 ppt U) and carbonate samples precipitated from the groundwater were collected in the area. After the conventional chemical separation, their 234U/238U isotope ratios were determined by double-focusing sector field ICPMS. Various 234U/238U ratios were observed for the groundwater samples, but those for carbonate samples were nearly in secular equilibrium. Isotope ratios of 234U/238U detected precisely by mass spectrometry will become a useful isotopic proxy in groundwater hydrological studies to trace their origin, flow direction, and water mixing.