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Nohara, Tsuyoshi; Takesue, Norito; Matsumura, Toshihiro*; Nakagiri, Toshio; Takeuchi, Shinji*
no journal, ,
It was reported that traces of high and low permeable zones formed by the supercritical fluid flow through granite have been observed in Japan. These traces directly related to current permeability. In this study, we will improve the investigation methods and evaluation technologies considering the influence of supercritical fluids through case studies in the Ningyo-toge area. In this presentation, we will introduce the research plan and the preliminary results.
Takesue, Norito; Nohara, Tsuyoshi
no journal, ,
no abstracts in English
Takesue, Norito; Nohara, Tsuyoshi; Endo, Kaito*; Takeuchi, Shinji*
no journal, ,
Analysis of groundwater flowing through granitic mountains is generally difficult because of complex topography and geology, small-scale aquifer. The groundwater flowing through granitic mountains is controlled by hydrothermal alteration and weathering, displacement of fracture. Groundwater level between adjacent In-situ could be also changed by rugged topography, but detailed research example is poorly known. Therefore, this study clarifies characteristics of groundwater flowing, aim to application and improvement of field research in southwest Japan. In the result, we identified high pervious aquifer with decomposed granite and sand-gravel layer, infer continuous distributions of aquifer. We report research program and result of field research in this session.
Takesue, Norito; Nohara, Tsuyoshi; Endo, Kaito*; Takeuchi, Shinji*
no journal, ,
no abstracts in English
Takesue, Norito; Nohara, Tsuyoshi; Endo, Kaito*; Izumi, Masahiro*; Takeuchi, Shinji*
no journal, ,
no abstracts in English
Nohara, Tsuyoshi; Takesue, Norito; Endo, Kaito*; Sato, Haruo*
no journal, ,
In order to understand the characteristics and evolution of groundwater flow and uranium behavior in the granitic mountains, existing information was organized, and a field survey was conducted on the Ningyo-toge uranium deposits. Existing borehole data for the main aquifers were organized and divided into high permeable layers and low permeable layers. Field investigations revealed that the high permeable layers were continuously distributed from the north side of the southern slope to the basin where the uranium deposits were distributed, and the low permeable layers were distributed immediately below the high permeable layer. Uranium was estimated to be transported by groundwater from the granitic rocks, and then reduced by carbon materials in the basin, resulting in the accumulation of uranium. Based on these findings, a conceptual model of groundwater flow is discussed that considers the heterogeneity of regional groundwater flow and topographic evolution.
Takesue, Norito; Nohara, Tsuyoshi; Endo, Kaito*; Takeuchi, Shinji*
no journal, ,
no abstracts in English
Nohara, Tsuyoshi; Takesue, Norito; Sakoda, Akihiro
no journal, ,
Radon is a radioactive gas that is exhaled from rocks and soils, and is generated over a time scale of tens of thousands of years by the radioactive decay of uranium and radium. Smoking and radon are the main causes of lung cancer, and based on the WHO recommendation in 2009, the natural conditions of the geogenic radon potential and the artificial conditions related to indoor radon, which are the main factors of radon exposure, have been examined in Europe. Although indoor radon concentration in Japan is low in the world, and it has been reported that indoor radon concentration increases due to the use of well water, and it is necessary to prioritize investigations on high geogenic radon potential points considering radon concentration in groundwater. The purpose of this study is to confirm the uneven distribution of high radon potential points in the radon spring area, and to investigate the possibility that groundwater flow increases the underground radon potential. Results of field measurements of ambient gamma-ray dose rate, radon exhalation rate and underground radon concentration are reported in some radon spring areas.
Nohara, Tsuyoshi; Takesue, Norito; Sakoda, Akihiro; Sakaguchi, Chie*; Kobayashi, Katsura*
no journal, ,
no abstracts in English