9:15 AM - 9:30 AM
[HTT15-02] Relation between 87Sr/86Sr ratio of groundwater and spring water and groundwater flow in Oshino, Yamanashi
Keywords:Oshino Village, groundwater, spring water, 87Sr/86Sr, water quality, groundwater flow
Oshino-Hakkai springs, which consist of eight springs, are located in Oshino Village, and they are one of the world cultural heritage. Additionally, there is a lot of wells, e.g., municipal wells and private wells. And many residents in Oshino Village are using the groundwater of private wells for drinking water and agricultural, etc. Groundwater is one of the most precious resources, and for sustainable water use, it is important to grasp the groundwater storage and groundwater flow.
As a result of observation of groundwater flow at Oshino village, the following was obviously; there is are two major groundwater flow, one is flows from south to north at the western part of village, and other is flows from east to west at the central to eastern part of village. The former corresponds to flows from Mt. Fuji to Oshino-Hakkai springs, and the latter correspond to flows from Doshi mountains to western part of village (Yabusaki et al, 2023). These groundwater flows were consistent with the characteristics of water quality and water stable isotopes. In addition, strontium isotope ratio (87Sr/86Sr) is useful to understand the recharge area of groundwater and spring water. The objectives of this study are to analyze the 87Sr/86Sr of groundwater, spring water, river water, etc. of Oshino Village, and to grasp the recharge area of these water samples.
Water samples, which include shallow groundwater, deep groundwater, spring water, artesian well water, lake water, and hot spring water, were sampled on January, 2017 and on August, 2017 at Oshino Village. In this observation, the shallow groundwater was defined as the well depth is below 30 m deep, and the deep groundwater is defined as the depth is above 30 m deep. The 87Sr/86Sr were analyzed for all water samples. Additionally, 87Sr/86Sr of basaltic rock which was taken near the Oshino-Hakkai springs was also analyzed. After preprocessing for analysis of water samples and soil/rock samples, measuring 87Sr/86Sr ratios with MC-ICP-MS (NEPTUNE PLUS) was carried out. Incidentally, the dissolved ions, stable isotopes of oxygen and hydrogen, and trace elements have already been analyzed.
As a result of strontium isotope analysis, it was grasp that the range of 87Sr/86Sr ratio of water samples in Oshino Village was from 0.7035 to 0.7061. These isotope ratios were relatively low in the western part of village and relatively high in the central to eastern part of village, and it was consistent with the groundwater flow which was indicated by previous study. And 87Sr/86Sr were showing a tendency to relatively high at the site where the Shinnasho river and Katsura river flow into each other. The 87Sr/86Sr ratios of water which was recharged at Mt. Fuji indicated approximately 0.7035, and these values were relatively low of this study area. As a result of distribution map of 87Sr/86Sr ratios of water samples at large area, that the isotope ratios of Lake water (e.g., Kawaguchiko, Saiko, Shojiko, Motosuko) and groundwater near the lake indicated above 0.7039; therefore, these isotope ratios was different from those of water recharged at Mt. Fuji. Vanadium concentration of water recharged at Mt. Fuji was relatively high (approximately 40–160 μg/L); however, that of lake water and groundwater near the lake was relatively low (several μg/L). Therefore, it was suggested that the source of these lake water and groundwater near the lake is not Mt. Fuji but might possibility Misaka mountains. In future, 87Sr/86Sr ratios of water and soil/rock samples at Misaka mountains will be analyzed and will discuss about the recharge area of water in detail.
REFERENCE
Yabusaki, S., Taniguchi, M., Tayasu, I., Akimichi, T., Ohmori, N., Gotou, K., Watanabe, H., Watanabe, S., and Furuya, S. (2023): Water quality characteristics and dynamics of groundwater and spring water revealed by multi-tracers in Oshino, Yamanashi, Japan. Geochemical Journal. (in press) https://doi.org/10.2343/geochemj.GJ23003.
As a result of observation of groundwater flow at Oshino village, the following was obviously; there is are two major groundwater flow, one is flows from south to north at the western part of village, and other is flows from east to west at the central to eastern part of village. The former corresponds to flows from Mt. Fuji to Oshino-Hakkai springs, and the latter correspond to flows from Doshi mountains to western part of village (Yabusaki et al, 2023). These groundwater flows were consistent with the characteristics of water quality and water stable isotopes. In addition, strontium isotope ratio (87Sr/86Sr) is useful to understand the recharge area of groundwater and spring water. The objectives of this study are to analyze the 87Sr/86Sr of groundwater, spring water, river water, etc. of Oshino Village, and to grasp the recharge area of these water samples.
Water samples, which include shallow groundwater, deep groundwater, spring water, artesian well water, lake water, and hot spring water, were sampled on January, 2017 and on August, 2017 at Oshino Village. In this observation, the shallow groundwater was defined as the well depth is below 30 m deep, and the deep groundwater is defined as the depth is above 30 m deep. The 87Sr/86Sr were analyzed for all water samples. Additionally, 87Sr/86Sr of basaltic rock which was taken near the Oshino-Hakkai springs was also analyzed. After preprocessing for analysis of water samples and soil/rock samples, measuring 87Sr/86Sr ratios with MC-ICP-MS (NEPTUNE PLUS) was carried out. Incidentally, the dissolved ions, stable isotopes of oxygen and hydrogen, and trace elements have already been analyzed.
As a result of strontium isotope analysis, it was grasp that the range of 87Sr/86Sr ratio of water samples in Oshino Village was from 0.7035 to 0.7061. These isotope ratios were relatively low in the western part of village and relatively high in the central to eastern part of village, and it was consistent with the groundwater flow which was indicated by previous study. And 87Sr/86Sr were showing a tendency to relatively high at the site where the Shinnasho river and Katsura river flow into each other. The 87Sr/86Sr ratios of water which was recharged at Mt. Fuji indicated approximately 0.7035, and these values were relatively low of this study area. As a result of distribution map of 87Sr/86Sr ratios of water samples at large area, that the isotope ratios of Lake water (e.g., Kawaguchiko, Saiko, Shojiko, Motosuko) and groundwater near the lake indicated above 0.7039; therefore, these isotope ratios was different from those of water recharged at Mt. Fuji. Vanadium concentration of water recharged at Mt. Fuji was relatively high (approximately 40–160 μg/L); however, that of lake water and groundwater near the lake was relatively low (several μg/L). Therefore, it was suggested that the source of these lake water and groundwater near the lake is not Mt. Fuji but might possibility Misaka mountains. In future, 87Sr/86Sr ratios of water and soil/rock samples at Misaka mountains will be analyzed and will discuss about the recharge area of water in detail.
REFERENCE
Yabusaki, S., Taniguchi, M., Tayasu, I., Akimichi, T., Ohmori, N., Gotou, K., Watanabe, H., Watanabe, S., and Furuya, S. (2023): Water quality characteristics and dynamics of groundwater and spring water revealed by multi-tracers in Oshino, Yamanashi, Japan. Geochemical Journal. (in press) https://doi.org/10.2343/geochemj.GJ23003.