title: Variation in nitrate isotopic signatures in sewage for source apportionment with urbanization: a case study in Beijing, China.
abstract: Nitrate (NO3-) pollution is a severe problem in urban aquatic systems especially within megacity undergoing rapid urbanization, and mostly, sewage is supposed as the prevailing NO3-source. A dual isotope approach (δ15N-NO3-and δ18O-NO3-) was applied to explore the variation in NO3-isotopic signatures in sewage processed by wastewater treatment plants (WWTPs) in Beijing from 2014 to 2015. We found that the raw and treated sewage owned the different NO3-isotopic signatures, including δ15N from 1.1 to 24.7 ‰ and δ18O from 1.6 to 22.8 ‰ in raw sewage, as well as δ15N from 6.1 to 22.8 ‰ and δ18O from 1.6 to 13.2 ‰ in treated effluents. The WWTP processing would result in the enrichment of NO3-isotopic compositions in discharged effluents with NO3-concentrations increasing. Besides, advanced sewage treatment technology with more pollutant N reduction may raise the heavier NO3-isotopic compositions further. The NO3-isotope value ranges of urban sewage and manure should be separated, and the seasonal and tighter NO3-isotope value ranges are supposed to improve the accuracy of source apportionment. The NO3-isotope value ranges conducted in this study might provide useful information for tracing NO3-sources towards the implementation of efficient water pollution control in Beijing.
authors: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors: Chaofan
authors: C
authors: Xian
authors: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China. zyouyang@rcees.ac.cn.
authors: Zhiyun
authors: Z
authors: Ouyang
authors: School of Geographical Sciences, Southwest University, Chongqing, 400715, China.
authors: Yanmin
authors: Y
authors: Li
authors: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
authors: Yang
authors: Y
authors: Xiao
authors: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
authors: Yufen
authors: Y
authors: Ren
mesh_terms: D000068476:Beijing; D004784:Environmental Monitoring / Q000379:methods*; D008372:Manure; D009566:Nitrates / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D012722:Sewage / Q000737:chemistry*; D014507:Urbanization; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008372:Manure; D009566:Nitrates; D009587:Nitrogen Isotopes; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Beijing; Dual isotope; Nitrate; Sewage treatment; Source apportionment