2001 Fiscal Year Final Research Report Summary
The relation of nitrate concentration of spring waters with the environment of catchment in the Imba-numa regional basin
| Project/Area Number |
12680529
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | Toho University |
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Principal Investigator |
IMAHASHI Masayuki Toho University, Faculty of Science, Professor, 理学部, 教授 (40120240)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Imba-numa / spring water / nitrate / source of nitrogen |
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| Research Abstract |
Lake Imba-numa is a former lagoon located about 40 km east of Tokyo. Many springs appear in the rivers feeding the lake. Chemical analyses and geological surveys at 29 points on springs in the Imbanuma basin were performed for the period March 2000 to December 2001. After considering differences in the geological horizons and drainage system, twenty-nine locations were selected covering most of the springs on the Hokuso plateau in Chiba Prefecture. Each spring-water was sampled once a month. The objectives of this research were to elucidate (1) the sources of nitrogen in the spring-water; (2) the relation of the sources of nitrogen with geological environment around the springs. The results obtained were as follows :
(1) Average nitrate levels ranged from a minimum of 0.0 mg/L to a maximum of 193 mg/L in the sample number of 311l(Tatsuzawa, Tomisato Town).
(2) Half of the springs complied with the Japan Drinking Water Standard of 45 mg/L.
(3) The sources of nitrogen in some springs were elucidated using the stable isotopic ratio of nitrogen (δ ^<15>N) and the identification of the catchment area. For example, the sources of nitrogen in the samples of 311 and 201(Kaga-shimizu, Sakura City) were decided as nitrogen-rich fertilizers and untreated domestic sewage, respectively.
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Research Products
(6 results)
