Spatio-temporal variations of nitrogen in an agricultural watershed in eastern China: Catchment export, stream attenuation and discharge

Chen, Dingjiang; Lu, Jun; Shen, Yena; Gong, Dongqin; Deng, Ouping

Spatio-temporal variations of nitrogen in an agricultural watershed in eastern China: Catchment export, stream attenuation and discharge

2011

Chen, Dingjiang | Lu, Jun | Shen, Yena | Gong, Dongqin | Deng, Ouping

Using the monthly hydrogeochemical data of ChangLe River system from 2004 to 2008, total nitrogen (TN) export load (Sₙ) from nonpoint sources (NPS) to stream and in-stream attenuation load (AL) was estimated by the inverse and forward format of an existing in-stream nutrient transport equation, respectively. Estimated Sₙ contributed 96±2% of TN entering the river system, while AL 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.

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