Contaminants Removal Research And Aquatic Vegetation Restoration Preliminary Design For Shaping Bay Aquatic Ecosystems

Erhai lake is the mother river of Dali,Yunnan, and an increasingly serious pollution of Erhai lake has been paid much attention by the society. With the effective controlling and treatment of point source pollution, the water pollution situation has improved, but the trend of eutrophication is still very severe. Shaping Bay in the northern Erhai lake, has a good aquatic ecosystem, but a study on the removal capacity of pollutants is still absent. In this paper, we set sections to inspect water quality, analyze the yearly changes of water pollutants. We analyzed the correlation between nitrogen and environmental factors, found the favor conditions for nitration and denitrification occurring. At the same time, we proposed the preliminary design of aquatic vegetation restoration for the Bay.According to the monitoring datas, we did a general analysis on the Bay's water temperature, pH value, dissolved oxygen, and studied the yearly variation characteristics on the total nitrogen, ammonia nitrogen and nitrate nitrogen, phosphorus and potassium permanganate index, Chl-a, and calculated the Shaping Bay's pollutant capacity. Research results show that: from January 2010 to January 2011,bay water temperature and dissolved oxygen showed a significant seasonal variation, pH value, no significant change during the year; in lake the water total nitrogen, ammonia nitrogen, nitrate , Dissolved total nitrogen concentration respectively ranges of 0.28~1.08mg/L, 0.017~ 0.368mg/L, 0.02~0.58mg/L, 0.124~0.71mg/L; ammonia was positively correlated with temperature, negatively correlated with the dissolved oxygen ,and the correlations were not significant; nitrate nitrogen was negatively correlated with temperature, positively correlated with the dissolved oxygen, and the correlations were more significant; total nitrogen as the same correlations as nitrate nitrogen, with temperature and dissolved oxygen, but the relationship was not significant; dissolved total nitrogen as the same correlations as nitrate nitrogen, too. The Bay's pollutant carrying capacity of total nitrogen is 183.45t/a; pollutant carrying capacity of phosphorus is 2.58t/a; pollutant carrying capacity of ammonia is 387.56t/a; pollutant carrying capacity of potassium permanganate index is 1020.03t/a. The Shaping Bay's pollutant carrying capacity can satisfy bear the load of present pollutants. To improve its pollutant carrying capacity, the Bay needs to be raised its comprehensive environmental functions. Based on the above contents and results, this paper proposed a preliminary restoration programs to the bay's aquatic vegetation restoration,such as planting suitable plants in different part of the Bay, cleaning up sediment ,harvesting the plants in time to prevent secondary pollution.