Identification of Nitrate Sources in Rivers in a Complex Catchment Using a Dual Isotopic Approach
| Autor: | Qiqi Yuan, Hong Yang, Yuhua Li, Chun-Fa Zhao, Jiaxun Guo, Yunyun Xu, Lachun Wang, Xiaoxue Ma |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
inorganic chemicals
lcsh:Hydraulic engineering Geography Planning and Development Drainage basin Sewage Aquatic Science Biochemistry chemistry.chemical_compound lcsh:Water supply for domestic and industrial purposes Nitrate lcsh:TC1-978 Tributary nitrate isotope Water Science and Technology Hydrology lcsh:TD201-500 geography geography.geographical_feature_category business.industry food and beverages source identification eutrophication chemistry Nutrient pollution Environmental science Bayesian isotope mixing model Sewage treatment business Eutrophication Surface water |
| Zdroj: | Water, Vol 13, Iss 83, p 83 (2021) Water Volume 13 Issue 1 |
| ISSN: | 2073-4441 |
| DOI: | 10.3390/w13010083 |
| Popis: | Excessive nutrient input to surface water, including nitrate, exacerbates water eutrophication. Clarifying the proportions of different nitrate sources in the aquatic environment is critical for improving the polluted water. However, nitrate sources in river basins are very complex and not clearly understood. In this study, nitrogen concentrations and nitrate isotopic compositions were determined to estimate the spatiotemporal variation in nitrate sources in the Yuntaishan River basin, Nanjing, East China, from March 2019 to January 2020. The results showed that the concentrations of total nitrogen (TN), ammonium (NH4+-N), and nitrate (NO3&minus N) changed in the ranges of 0.53&ndash 18.0 mg/L, 0.01&ndash 15.4 mg/L, and 0.06&ndash 9.3 mg/L, respectively, wherein NO3&minus N was the main nitrogen form. Higher nitrogen concentrations appeared in winter and in the downstream parts of the river. In the entire river basin, the NO3&minus N mainly originated from sewage (67%) and soil (26%), with clear spatial variations. NO3&minus N in the Yunba sub-watershed was mainly derived from sewage (78%), which was higher than that in other tributaries, i.e., Shengli River (44%) and Yangshan River (49%). This was due to the fact that that Shengli and Yangshan sub-watersheds were covered by urban areas and were equipped with a complete sewage treatment system. In addition, the contributions of sewage to NO3&minus N rose from 60% upstream to 86% downstream, suggesting the increasing influence of the point source of sewage. The results showed that 53% of NO3&minus N in the basin outlet originated from the point source of sewage near the M4 site. Sewage contributed 75% of NO3&minus N in the rainy season and 67% of NO3&minus N in the dry season, suggesting the weakly temporal variation. Our results highlight the spatiotemporal variations in sources of NO3&minus N. These results will aid in the development of measures needed to control nitrogen pollution in river basins. |
| Databáze: | OpenAIRE |
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