Chlorine isotope analysis of groundwater was carried out to develop the method for determination of groundwater residence time in the Tono area, Gifu, Japan. Radiogenic chlorine isotope content in the groundwater is as well as that of natural generation rate by neutron flux in the granite. This fact indicates that the groundwater residence time of deep granite may be quite old.

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The Kanamaru area, near the boundary of Niigata and Yamagata Prefectures, has been surveyed again from 2001 in order to investigate the behavior of U in the environment, while this area was surveyed from 1950s for the U exploration. Several boreholls were drilled in the northeastern area of H-rotou (the outcrop of high U) and groundwaters were obtained from the well. In this study, the behaviors of uranium series nuclides are reported.

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A new type of high resolution phase shift interferometry was developed for study of mineral dissolution-precipitation phenomena. Using these instruments, dissolution/precipitation rates of minerals with very low solubility such as smectite, plagioclase and so on were experimentally determined in order to understand the mechanism of the reaction at the mineral-solution interface in nanometer scale. We advanced conventional interferometer with laser to a phase-shift interferometer with a white-light. Developments and evaluations were also made on the reaction cells at high temperature, high pressure and high pH conditions.

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