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| Spatiotemporal characteristics and sources of dissolved inorganic nitrogen in the Dagu River, Jiaodong Peninsula， China |
| Received:July 22, 2019 |
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| KeyWord:dissolved inorganic nitrogen;spatiotemporal characteristics;influencing factors;pollution sources;Dagu River |
| Author Name | Affiliation | E-mail | | XIA Yun | College of Chemical Science and Engineering, Qingdao University, Qingdao 266071, China
Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China | | | ZHANG Bo-tao | College of Chemical Science and Engineering, Qingdao University, Qingdao 266071, China | | | JIANG De-juan | Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China | djjiang@yic.ac.cn |
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| Abstract: |
| Rivers discharge large amounts of nitrogen into the oceans, which has caused increasing concern worldwide. The Dagu River is the largest river in the Jiaodong Peninsula, and the estuary has higher inorganic nitrogen and reactive phosphate concentrations than the environmental standard for long period. As such, the estuary is a critical zone to control the land-based sources of pollutants into the ocean. River water and possible pollutant sources were collected three times considering seasonal differences in 2018 and 2019 to determine the dissolved inorganic nitrogen(DIN) concentration. The spatiotemporal variation, controlling factors, and possible sources of DIN were analyzed using non-parametric test, cluster analysis, and Pearson correlation analysis. The DIN concentration exhibited a significant seasonal difference(P<0.05), which was high in the dry season and low in the wet season. The seasonal variations in DIN were mainly affected by precipitation, temperature, and dissolved oxygen(DO). Spatially, the upstream NO3--N concentration was higher because of the potential non-point source emissions from fertilizer application and rural domestic wastewater discharge. The NH + 4-N concentration was higher in the tributaries than in the main stream, which was attributed to the possible discharge of domestic sewage, industrial wastewater, and livestock wastewater. The DIN concentration was low in the middle and lower reaches owing to the interception and retention by cascade dams. |
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