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| Spatial characteristics of nitrogen and phosphorus retention and loading in typical agricultural areas of the Jiuqu River basin |
| Received:January 13, 2025 |
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| KeyWord:non-point source pollution;nitrogen and phosphorus retention;nitrogen and phosphorus load;spatial differentiation;Jiuqu River |
| Author Name | Affiliation | E-mail | | SU Weihua | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China
University of the Chinese Academy of Sciences, Beijing 100049, China | | | WANG Haixiang | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China | | | CHEN Hao | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China | | | YAN Xing | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China | | | XIA Yongqiu | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China
University of the Chinese Academy of Sciences, Beijing 100049, China | | | GUAN Ruixue | Zhenjiang Ecological Environment Bureau, Jiangsu Province, Zhenjiang 212050, China | | | WANG Shenqiang | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China
University of the Chinese Academy of Sciences, Beijing 100049, China | | | WANG Yu | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China
University of the Chinese Academy of Sciences, Beijing 100049, China | wangyu@issas.ac.cn |
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| Abstract: |
| In order to explore the spatial characteristics of nitrogen（N）and phosphorus（P）absorption and load in the typical agricultural area of Jiuqu River, this study, based on the systematic sampling and analysis during the period from 2022 to 2023, combined with the water quality response model（NutriShed）of "farmland loss-along-the-way absorption-water body load", comprehensively discussed the spatial distribution of nitrogen and phosphorus loss, absorption and load in the watershed. The results showed that the monthly average total phosphorus（TP）concentration in the main stream of the Jiuqu River ranged from 0.02 to 0.12 mg · L-1, generally maintaining Class Ⅱ water quality standards（0.1 mg·L-1）. In contrast, TP concentrations in tributaries fluctuated more widely, ranging from 0.03 to 0.23 mg·L-1, with some periods exceeding Class Ⅲ standards（0.2 mg·L-1）, especially during spring and summer when pollution was more severe. The monthly average total nitrogen（TN）concentrations in both the main stream and tributaries exceeded 2.00 mg · L-1. The average TN concentration in tributaries was 20.4% higher than in the main stream, with ammonium nitrogen being the primary nitrogen pollution form. The transition from winter to spring and the summer season were identified as peak periods for nitrogen pollution, with tributaries such as the Nongyan River and Yongsheng River serving as pollution hotspots. Spatially, the highest N and P loads were observed in upstream areas with intensive agricultural activities and densely populated residential zones. Simulations using the NutriShed model further revealed that the annual TN loss in the basin amounted to 404 t, with 147 t attenuated along the way, accounting for 36.4%, and a remaining load of 257 t from 2022 to 2023. The total annual loss of P loss was 57.2 t, with 33.6 （t 58.7%）attenuated and a remaining load of 23.6 t from 2022 to 2023. The model analysis highlighted that tributaries with higher N and P concentrations, such as the Nongyan River, are priority areas for targeted remediation. Based on the study results, it is recommended to enhance comprehensive management of non-point source pollution through measures such as optimizing fertilizer application, rationally planning riparian ecological buffer zones, and implementing targeted remediation for highly polluted tributaries. |
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