title: Biological thresholds of nitrogen and phosphorus in a typical urban river system of the Yangtz delta, China.
abstract: River health and associated risks are fundamentally dependent on the levels of the primary productivities, i.e., sestonic and benthic chlorophyll-a. We selected a typical urban river system of the Yangtz delta to investigate nutrient and non-nutrient responses of chlorophyll-a contents and to determine biological thresholds of N and P. Results showed the mean contents of sestonic and benthic chlorophyll-a across all sampling points reached 10.2 μg L(-1) and 149.3 mg m(-2). The self-organized mapping analysis suggested both chlorophyll-a contents clearly responded to measurements of N, P, and water temperature. Based on the chlorophyll-a criteria for fresh water and measured variables, we recommend the biological thresholds of N and P for our river system be set at 2.4 mg N L(-1) and 0.2 mg P L(-1), and these be used as initial nutrient reference values for local river managers to implement appropriate strategies to alleviate nutrient loads and trophic status.
authors.affiliation: Zhejiang University, College of Environmental and Resources Sciences, Hangzhou, Zhejiang 310058, China. Electronic address: liang410@zju.edu.cn.
authors.forename: Xinqiang
authors.initials: X
authors.lastname: Liang
authors.affiliation: Zhejiang University, College of Environmental and Resources Sciences, Hangzhou, Zhejiang 310058, China.
authors.forename: Sirui
authors.initials: S
authors.lastname: Zhu
authors.affiliation: University of California Davis, Department of Land, Air, and Water Resources, Davis, CA 95616, USA.
authors.forename: Rongzhong
authors.initials: R
authors.lastname: Ye
authors.affiliation: Zhejiang University, College of Environmental and Resources Sciences, Hangzhou, Zhejiang 310058, China.
authors.forename: Ru
authors.initials: R
authors.lastname: Guo
authors.affiliation: Zhejiang University, College of Environmental and Resources Sciences, Hangzhou, Zhejiang 310058, China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Zhejiang University, College of Environmental and Resources Sciences, Hangzhou, Zhejiang 310058, China.
authors.forename: Chaodong
authors.initials: C
authors.lastname: Fu
authors.affiliation: Zhejiang University, College of Environmental and Resources Sciences, Hangzhou, Zhejiang 310058, China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Tian
authors.affiliation: Zhejiang University, College of Environmental and Resources Sciences, Hangzhou, Zhejiang 310058, China.
authors.forename: Yingxu
authors.initials: Y
authors.lastname: Chen
mesh_terms: D002681:China; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D002947:Cities; D004784:Environmental Monitoring; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D010758:Phosphorus; D009584:Nitrogen; D000077194:Chlorophyll A
keywords: Biological threshold; Chlorophyll-a; Nitrogen; Phosphorus; SOM; Urban river