Clarify of origin and migration of substances in subsurface environment using stable isotope

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Chemical composition, hydrogen and oxygen isotopes were studied for analyzing the origin and migration behavior or groundwater and surface water in the small forested basin near the Kinokawa. Also rain water was sampled at both Osaka and Wakayama cities and was analyzed. River water chemistry depended on the runoff of soil water in rainy period, however it did on the runoff of groundwater excluding the rainy period. Ionic concentrations of rain water were low as compared with those of river water, stream water and groundwater. Stream water chemistry was almost the same as river water chemistry. Groundwater chemistry, however, was different from river water chemistry due to the weathering and chemical reaction of the sedimentary rocks and soils. It was clarified that stable isotopic ratios or river waters depended on the runoff of groundwater of which isotopic ratios were determined by the height of mountains in the basins, and the differences of the isotopic ratios between rainwater and river water showed whether the surface runoff exists or not. Cl^- in precipitation sampled at Wakayama, Osaka and Tondabayashi cities were mainly derived from sea. Concentrations of nitrate and sulfate derived from productions accompanied with city activities in Osaka and Tondabayashi cities were higher than those in Wakayama city. The average pH values, 5.2 in Osaka and Tondabayashi cities were lower than 5.8 in Wakayama city. Oxygen and hydrogen isotopic ratios in precipitation were very variable with times. In spite of the variation widely, time series of Oxygen and hydrogen isotopic ratios showed almost the same values in the wide areas from Wakayama to Osaka prefecture. Therefore, Oxygen and hydrogen isotopic ratios in precipitation were thought to depend on the change or Oxygen and hydrogen isotopic ratios in air.