1999 Fiscal Year Final Research Report Summary
Analysis of nitrate in surface water using environmental isotopes
| Project/Area Number |
09680508
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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 | Wakayama University |
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Principal Investigator |
LI Hiroyuki Wakayama University, Systems Engineering, Professor, システム工学部, 教授 (60283959)
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| Co-Investigator(Kenkyū-buntansha) |
YABUKI Sadayo RIKEN, Surface research laboratory, Senior research, 表面解析室, 先任研究員
UEDA Akira Mitsubishi material, Central research institute, Senior research, 中央研究所, 室長
YABU Shinobu Wakayama University, Systems Engineering, Professor, システム工学部, 教授 (00200569)
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| Project Period (FY) |
1997 – 1999
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| Keywords | ISOTOPE / NITRATE / LAND USE / WATER QUALITY |
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| Research Abstract |
To investigate the influence of chemical fertilizers on groundwater and surface water neighboring tea plantations in central Shizuoka prefecture, a time series of chemical compositions and nitrogen isotopic ratios within local wells, springs, rivers and ponds were studied. The pH of spring and pond water in some areas maintained basic acidity with neither any noticeable changes in nitrogen isotopic ratios nor any disappearance of nitrate within the ponds and low concentrations of chlorophyll and phosphorus. Therefore, the activities of photosynthesis in the ponds of this area were very low due to low concentrations of phosphorus. However, the pH of spring water in the other areas maintained basic neutrality to alkali with high concentrations of CaィイD12+ィエD1 and SOィイD24ィエD2ィイD12-ィエD1 and low concentrations of NOィイD23ィエD2ィイD1-ィエD1 because of soil and fertilizer improvement. Concentrations of Al, Co, Ni, Zn and Mn ions in the groundwater and surface water increased with the decrease of pH
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values. Then, soil and fertilizer improvement is important.
Sources of water and soluble substances in the Ishi river basin were studied. As the δD and δィイD118ィエD1O values of river and groundwater in the Ishi basin were on the meteoric line and these values varied with sampling altitudes, these waters were thought to have arisen from precipitation. COィイD22ィエD2 pressure in river and groundwater were estimated to be high from pH values and HCOィイD23ィエD2ィイD1-ィエD1 and were equilibrated with COィイD22ィエD2 pressure in soil. The δィイD113ィエD1C values of river and groundwater were in agreement with that of soil. High COィイD22ィエD2 pressure derived from soil was thought to cause weathering of feldspar in rock and to increase HCOィイD23ィエD2ィイD1-ィエD1 and CaィイD12+ィエD1 concentration in waters. As the δィイD115ィエD1N values of NOィイD23ィエD2ィイD1-ィエD1 in river water varied with land use of sampling pints, the source of nitrogen contamination could be estimated from δィイD115ィエD1N values of NOィイD23ィエD2ィイD1-ィエD1 in waters. Less
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