Nitrogen transformation character from the Tiaoxi river to the estuary of the Qingshan Lake

Through the fixed-point sampling of the Qingshan lake and the estuary of Tiaoxi river, the temporal and spatial variation regularity of DCK COD_Mn, NH₄⁺-N and TN in the waterbody were analysed emphatically, and the preliminary analysis of its sources was carried out. The results showed that DO content decreased gradually from the Tiaoxi river to the estuary of the Qingshan Lake, but COD_Mn and NH₄⁺-N increased, and there was a significant relationship between DO and COD_Mn and NH₄⁺-N. The waterbody from the Tiaoxi river to the estuary of the Qingshan Lake has reached a certain degree of nitrogen pollution, and TN content was 2.64±0.38 mg L^-1, which is slight eutrophication, but the Qingshan Lake reached moderate eutrophication.