| Project/Area Number |
06650578
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
水工水理学
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| Research Institution | Wakayama University (1995)
National Institute for Environmental Studies (1994) |
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Principal Investigator |
HIRATA Tatemasa Wakayama University, Faculty of Systems Engineering, Department of Environmental Systems, システム工学部, 教授 (30093454)
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| Co-Investigator(Kenkyū-buntansha) |
TERAO Hiroshi Health and Environmental Institute of Gifu Pre.Senior Researcher, 環境科学部, 専門研究員
西川 雅高 国立環境研究所, 地域環境研究グループ, 主任研究員 (80228171)
中杉 修身 国立環境研究所, 地域環境研究グループ, 上席研究官 (50109899)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1995: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1994: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Groundwater pollution / Nitrate nitrogen / Chemical fertilizer / Sewage water / Land treatment / Stable nitrogen isotope / Land use / Groundwater use / 硝酸性窒素 / 酸素安定同位体 |
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| Research Abstract |
The nitrate nitrogen was detected widely in the regional gound water of Japan, and has been becoming a great environmental issue in many developed nations. The nitrate in ground water is considered to originate mainly from agricultural practice of fertilizer application to arable land and land application of industrial and domestic sewage.
The research program was designed to reveal the effect of land use like forest, arable land and urbanization on the groundwater chemical features in cooperation with several environmental institutes belonging to local governments. The nitrate nitrogen in regional groundwater was analyzed with other chemicals to calculate the nitrogen load from human activities such as the agricultural practice and land application of sewage etc. In order to do that, seven investigation wells to sample groundwaters at different depth were constructed in a study basin of arable land in Yamagata Prefecture. In particular, the nitrogen isotope values of nitrate delta ^<15
… More
>N were measured for discriminating the origin of the nitrate discovered in regional groundwater. The results indicated that the concentrations of nitrate nitrogen and SO4^<2-> ion reduce with groundwater depth, while the nitrogen isotope ratio delta^<15>N increases. Such behavior of nitrogen in subsurface environment implies that the shallow groundwater is clearly affected by the inorganic fertilizer application and its leachate to groundwater. In addition to Yamagata basin, the isotope value delta ^<15>N was also measured in the groundwater of Miyakojima Isle in Okinawa Prefecture. The delta^<15> N values classified into the land use showed that they tends to slightly reduce with groundwater passing through arable land, for example, from 7.28 to 5.76 % and that they take higher values in urban area such as about 12% than those in arable land. The behavior of nitrogen isotope ratio has a possibility to identify the origin of nitrogen in groundwater and to calculate nitrogen load with use of other dissolved chemicals, separating individual nitrogen source. Less
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