| In order to provide a scientific foundation for controlling non-point source pollution, we studied on output characteristics of non-point nitrogen under different land uses in a typical agricultural village in the Yangtze River Delta. The various species of nitrogen and output load under a typical individual rainfall runoff event were investigated. The results indicated that the event mean concentrations (EMC) of total nitrogen (TN) in monitoring sites ranged from 20.01 mg/L to 22.83 mg/L, and the main form was dissolved nitrogen (DN) in TN. The main form of the lost nitrogen in the studied area was DN which was mainly composed by dissolved organic nitrogen (DON). Coupled with the characteristics of nitrogen concentration and runoff, two peaks of non-point nitrogen output could be found, and appeared 4-55 min before the runoff peaks. The concentrations of TN, DN, and nitrate (NO-3-N) decreased with the rainfall time increasing. Nitrogen load was influenced by its concentration and runoff, and showed the same output characteristics of nitrogen concentration with a gentle variation. Form the cumulative load curve of nitrogen in a typical rainfall event, first-flush effect could be found for each nitrogen species in rural runoff. |
