title: Urban rivers as hotspots of regional nitrogen pollution.
abstract: Excess nitrogen inputs to terrestrial ecosystems via human activities have deteriorated water qualities on regional scales. Urban areas as settlements of over half global population, however, were usually not considered in the analysis of regional water pollution. Here, we used a 72-month monitoring data of water qualities in Hangzhou, China to test the role of urban rives in regional nitrogen pollution and how they response to the changes of human activities. Concentrations of ammonium nitrogen in urban rivers were 3-5 times higher than that in regional rivers. Urban rivers have become pools of reactive nitrogen and hotspots of regional pollution. Moreover, this river pollution is not being measured by current surface water monitoring networks that are designed to measure broader regional patterns, resulting in an underestimation of regional pollution. This is crucial to urban environment not only in China, but also in other countries, where urban rivers are seriously polluted.
authors.affiliation: Urban River Monitoring and Administration Center of Hangzhou, Hangzhou 10008, PR China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Policy Simulation Laboratory, Zhejiang University, Hangzhou 310058, PR China.
authors.forename: Yiyun
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Policy Simulation Laboratory, Zhejiang University, Hangzhou 310058, PR China. Electronic address: bjgu@zju.edu.cn.
authors.forename: Baojing
authors.initials: B
authors.lastname: Gu
mesh_terms: D002681:China; D002947:Cities; D017753:Ecosystem; D004784:Environmental Monitoring; D006801:Humans; D009584:Nitrogen / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D014876:Water Pollution / Q000032:analysis*; D060753:Water Quality
chemical_list: D009584:Nitrogen
keywords: Human activities; Mitigation; Pollution source; Regional pollution