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| Influence of anthropogenic nitrogen input on river nitrate nitrogen flux in the Chaohe River watershed |
| Received:March 31, 2022 |
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| KeyWord:net anthropogenic nitrogen input;nitrate nitrogen flux;detained nitrogen;Chaohe River watershed |
| Author Name | Affiliation | E-mail | | WANG Jun | College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China | | | HUANG Jieyu | College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China | | | LI Fangyuan | College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China | | | WANG Xiaoyan | College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China
Water Soil Conservation Station of Beijing, Capital Normal University, Beijing 100048, China | wangxy@cnu.edu.cn |
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| Abstract: |
| In order to effectively evaluate the nitrogen input of human activities in the catchment and determine their effects on the fluxex of stream nitrate nitrogen. In this paper, the net nitrogen input from human activities was divided into two parts：anthropogenic point source and non-point source. By estimating the variation of anthropogenic nitrogen input from point sources and non-point sources from 1995 to 2014, a multivariate regression model of nitrate flux between them and the river（R2=0.73）was established. The influencing factors of nitrogen export and retention in the watershed were analyzed. The results showed that the average net nitrogen input of human activities in the Chaohe River watershed during the past 20 years was 5 569.27 kg · km-2 · a-1. The non-point and point source inputs accounted for 76.87% and 23.13% of the net nitrogen inputs, respectively, from human activities. Among non-point source inputs, fertilizer nitrogen input accounted for the largest proportion of the total net nitrogen input from human activities（35.92%）, followed by food and feed nitrogen input（21.12%）, atmospheric nitrogen deposition（15.05%）, seed nitrogen input（4.35%）, and agricultural nitrogen fixation（0.43%）. The average nitrate input to the Chaohe River watershed was 115.94 kg · km-2 · a-1 during the 20-year period. The nitrogen input caused by human activities accounted for 96.65% of nitrate flux in the river basin. Human input significantly influences the river nitrogen flux. Point source N input, fertilizer N input, and seed N input were the main sources of river flux. Affected by hydrometeorology and underlying surface factors, the contribution rate of retained nitrogen to nitrate flux was 11.01%. |
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