title: Spatio-temporal variations of nitrogen in an agricultural watershed in eastern China: catchment export, stream attenuation and discharge.
abstract: Using the monthly hydrogeochemical data of ChangLe River system from 2004 to 2008, total nitrogen (TN) export load (S(n)) from nonpoint sources (NPS) to stream and in-stream attenuation load (A(L)) was estimated by the inverse and forward format of an existing in-stream nutrient transport equation, respectively. Estimated S(n) contributed 96 ± 2% of TN entering the river system, while A(L) reduced the input TN by 23 ± 14% in average. In-stream TN attenuation efficiency in high flow periods (10 ± 5% in average for the entire river system) was much lower than that in low flow periods (39 ± 17%). TN attenuation efficiency in tributaries (28 ± 16% in average) was much higher than that in mainstream (11 ± 8%). Hydrological conditions are important in determining the spatio-temporal distributions of NPS TN export, stream attenuation and discharge. Increasing the water residence time might be a practical method for mitigating stream TN.
authors.affiliation: College of Environmental Science and Natural Resources, Zhejiang University, Yuhangtang Rd, 388#, Hangzhou City, Zhejiang Province, Hangzhou 310058, China.
authors.forename: Dingjiang
authors.initials: D
authors.lastname: Chen
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.forename: Yena
authors.initials: Y
authors.lastname: Shen
authors.forename: Dongqin
authors.initials: D
authors.lastname: Gong
authors.forename: Ouping
authors.initials: O
authors.lastname: Deng
mesh_terms: D000383:Agriculture / Q000706:statistics & numerical data*; D002681:China; D004784:Environmental Monitoring; D009584:Nitrogen / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data*; D014881:Water Supply / Q000032:analysis* / Q000706:statistics & numerical data
chemical_list: D014874:Water Pollutants, Chemical; D009584:Nitrogen