title: Assessment of temporal and spatial differences of source apportionment of nitrate in an urban river in China, using δ(15)N and δ(18)O values and an isotope mixing model.
abstract: Nitrate contamination in surface water has become an environmental problem widespread concern. In this study, environmental isotopes (δ(15)N-NO3 (-) and δ(18)O-NO3 (-)) and the chemical compositions of water samples from an urban river in Chongqing, China, were analyzed to evaluate the primary sources of nitrate pollution. A Bayesian isotope mixing model was applied to estimate the relative contributions of five potential NO3 (-) sources to river pollution (sewage/manure, soil N, NH4 (+) in fertilizer and precipitation, NO3 (-) fertilizer, and NO3 (-) in precipitation). The results show that the urban river was affected by NO3 (-) pollution from multiple sources. The major sources of NO3 (-) pollution in the dry season were sewage/manure (38-50 %) and soil N (22-26 %); in the wet season, the major sources of NO3 (-) pollution were sewage/manure (30-37 %), soil N (16-25 %), and precipitation (14-24 %). The higher contribution of N to the river water by precipitation indicates that atmospheric N deposition has become an important source of pollution in surface water in China. We conclude that domestic sewage is still the main contributor to NO3 (-) pollution in urban rivers in China. The discharge of domestic sewage into rivers should be prohibited as a priority measure to prevent NO3 (-) contamination.
authors.affiliation: Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Science, Shijiazhuang, 050061, China.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China. wangxk@rcees.ac.cn.
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Wang
authors.affiliation: The Policy Research Center for Environment and Economy, Ministry of Environmental Protection, Beijing, 100029, China.
authors.forename: Feixiang
authors.initials: F
authors.lastname: Sun
authors.affiliation: Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Science, Shijiazhuang, 050061, China.
authors.forename: Jichao
authors.initials: J
authors.lastname: Sun
authors.affiliation: Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Science, Shijiazhuang, 050061, China.
authors.forename: Jingtao
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Ouyang
mesh_terms: D001499:Bayes Theorem; D002681:China; D016000:Cluster Analysis; D004784:Environmental Monitoring / Q000379:methods*; D005308:Fertilizers; D008372:Manure; D008962:Models, Theoretical; D009566:Nitrates / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis; D010103:Oxygen Isotopes / Q000032:analysis; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D012722:Sewage; D014507:Urbanization; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D005308:Fertilizers; D008372:Manure; D009566:Nitrates; D009587:Nitrogen Isotopes; D010103:Oxygen Isotopes; D012722:Sewage; D014874:Water Pollutants, Chemical
keywords: Bayesian isotope mixing model; Nitrate pollution; Nitrate sources; Sources apportionment; Stable isotope; Urban rivers