Study On Characteristics Of Nitrogen Pollution Of Shallow Lakes At Plain River Network Area

This paper took shallow lakes in Yancheng-Dianmao region at Taihu area as research object. By means of monitoring and experiment analyse, the temporal and spatial distribution of total nitrogen(TN) and its species in the water and surface sediments of the lakes was analyzed, and the influence on the distribution of nitrogen was studied, and the function mechanism of algae and microbe in lakes of nitrogen pollution was discussed. The main study contents and results are as follows:(1) Study on characteristics of nitrogen pollution of water body in shallow lakes at plain river network area. The range of concentration of TN in the water of the lake was 1.16～10.50mg/L, the average value was 5.14mg/L.The characteristics of its temporal and spatial distribution was that nitrogen pollution of low flow period was more serious than high one in that area, the pollution in city was more serious than in country. The main one among the several species of the nitrogen was ammonium nitrogen(AN), ammonifying bacteria was more than other nitrite bacteria, the nitrification was blocked, and AN was cumulate. The correlation between AN and total phosphorus was better than others.(2) Study on characteristics of nitrogen pollution of surface sediment in shallow lakes at plain river network area. The range of concentration of Kelvin nitrogen in the surface sediment of the lake was 0.44～4.80mg/g. The organic nitrogen was 86 percent, the proportion of AN was 14 percent. In the surface sediment, ammonifying bacteria was more than other bacteria about nitrogen translation. The content of nitrogen of surface sediment was influenced greatly by DO, pH and the pollution degree in water.(3) Study on the zoology effect of nitrogen element in trophic lakes.The numbers of lakes which proportions of nitrogen and phosphorus was 20～30 were more than other types. In the winter, dominant species of algae was diatom, dominant species of 19 percent of lakes was blue algae, the other was diatom, the sort of dominant species was influenced by different proportions of nitrogen and phosphorus. Proportions of carbon and nitrogen in surface sediment was 7～20, nitrogen origin of surface sediment was the sedimentation of dead algae, its contribution from the exchange between rivers and lakes was small. TN in surface sediment of mass lakes was 0.550mg/g, its effect of zoology toxicity of trophic matters was serious, the surface sediment of the lake which contained nutrient matter such as nitrogen and pgosphorus abundantly had influenced the subsistence of meiobenthos seriously.