Distribution, reserves and pollution evaluation of nitrogen and phosphorus in surface sediments of Baiyangdian Lake

Baiyangdian Lake is the main ecological function area of Xiong'an New Area.In order to find out the distribution characteristics of nitrogen and phosphorus in the surface sediments of Baiyangdian Lake and evaluate the pollution degree of nitrogen and phosphorus, we carried out the investigation and pollution assessment of nitrogen and phosphorus in Baiyangdian Lake.The results indicate that the total nitrogen(TN)content of sludge layer of surface sediments are 528.5~10566.5 mg/kg, and the average is 2859.91 mg/kg.The total phosphorus(TP)content of sludge layer is 425.7~2446.0 mg/kg, and the average is 789.22 mg/kg.The TN content of transition layer is 318.5~4662.0 mg/kg, and the average is 1706.7 mg/kg.The TP content of transition layer is 315.05~976.30 mg/kg, and the average is 598.97 mg/kg.The total TN reserves of surface sediments are 15.86×10⁴ t, among which the TN reserves of sludge layer are 3.76×10⁴ t and the TN reserves of transition layer are 12.10×10⁴ t.The total TP reserves of surface sediments are 5.54×10⁴ t, among which the TP reserves of sludge layer are 1.02×10⁴t and that of transition layer are 4.52×10⁴ t.According to the evaluation result of comprehensive pollution index method, the sludge layer of surface sediments in Baiyangdian Lake have been heavily polluted.As for the transition layer, except Shaoche Lake, which is severely polluted, the other lakes are all moderately polluted or slightly polluted.