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| Source Apportionment of Non-point Source Nitrogen Pollution in Ashi River Basin Using δ15N Technique |
| Received:June 20, 2015 |
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| KeyWord:non-point source pollution;δ15N-NO3- isotope tracers;nitrogen pollution |
| Author Name | Affiliation | E-mail | | HU Yu | College of Water Sciences, Beijing Normal University, Beijing 100875, China
Chinese Research Academy of Environmental Science, Beijing 100012, China | | | WANG Ye-yao | China National Environmental Monitoring Centre, Beijing 100012, China | yeyaowang@163.com | | TENG Yan-guo | College of Water Sciences, Beijing Normal University, Beijing 100875, China | | | XIANG Bao | Chinese Research Academy of Environmental Science, Beijing 100012, China | | | MA Guang-wen | China National Environmental Monitoring Centre, Beijing 100012, China | | | FANG Guang-ling | Chinese Research Academy of Environmental Science, Beijing 100012, China | |
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| Abstract: |
| Crop farming activities along river have significantly affected the quality of river water. In this paper, nitrogen pollution in river water basin, nitrogen characteristics in crop farming soil and nitrogen pollution origins were investigated in the Ashi River basin, using water quality and soil monitoring techniques as well as 15N stable isotope. Results showed that there were high nitrogen concentrations in Ashi River water. The water quality was relatively good in the upstream section of the river, but gradually became worse in the midstream and downstream sections. This pattern is closely related to the land use types and human activities. The impacts of crop farming on water nitrogen pollution were dependent on river water seasonal periods and farming cycles. During the normal water period, non-point nitrogen pollution by crop farming occurred mainly in the midstream and downstream sections, with δ15N value ranging from 0.46% to 0.77%. The pollution sources were primarily artificial chemical fertilizers and farmland water recession. During the high water period, the pollution from non-point nitrogen extended to the upstream area, with δ15N range of 0.19%~0.4%. The main pollution source was artificial chemical fertilizers in the upstream area, while it was soil organic nitrogen via soil erosion caused by rainfall and irrigation in the midstream and downstream. During the low water period, however, artificial chemical fertilizers were still the main contributor of non-point nitrogen pollution, with δ15N values of 0.11% to 0.39%. This was resulted from the feedback of the nitrite-nitrogen from artificial chemical fertilizers that were applied and infiltrated in the ground during the monsoon. |
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