China is experiencing rapid urbanization,which has changed the water quality of rivers,especially the load of nutrient.In this study,a typical urban river located in the karst area,Chengguan River,was chosen to explore the influence of urbanization on river ecosystem.Water chemistry and nutrient concentration showed monthly variability.Nutrient concentration in two tributaries and mainstream showed significant spatial variability with heavy pollution of N and P in one tributary near the suburban area.Measurements of nitrate dual isotopes suggested that volatilization,assimilation,nitrification and denitrification all occurred in the polluted river.Water chemistry and nitrate isotope measurement showed that the major nitrogen sources included domestic waste,agricultural input such as chemical fertilizer and manure.Our results point to the need to manage point sources of sewage effluents to improve the water quality of urban rivers in Southwestern China.
Urbanization Urban river Nitrate isotopes Southwestern China
Zhongjun Wang Fujun Yue Jie zeng Siliang Li Faxiang Tao
State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Scie State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Scie Key Laboratory of Karst Environment and Geohazard,Ministry of Land and Resources,Guizhou University, Institute of Surface-Earth System Science,Tianjin University,Tianjin 300072,China;State Key laborato State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Scie