Study On The Amount Of Pollutants Into The Lake Yangcheng Lake Water Quality And Phytoplankton

Yangcheng Lake locates in Taihu Plain of the Yangtze River Delta, and the northeastern city of Suzhou. As the second largest lake in Suzhou, this lake has a very important role in the household water, industrial, and agricultural production of Suzhou. With the rapid socio-economic development, the sewage from industrial, agricultural production, and people’s lives increased significantly. Large amounts of sewage discharged into the Yangcheng Lake, which has been having a serious impact on the water quality and aquatic plankton of the lake.This paper studies the effects of pollutants into the Yangcheng Lake to the lake’s water quality and quantity of phytoplankton through calculating the CODMn, TN, and TP of the watercourse around the lake flowing into the Yangcheng Lake monthly, and the simultaneous monitoring of the water quality and the community structure of phytoplankton in the Yangcheng Lake’s three regions. The results indicate that:1.The amount of pollutants into the Yangcheng Lake’s three regions is listed from greatest to least as following: the west region, the middle region, and the east region. The amount of pollutants into the west region is significantly larger than the pollutants into the other two regions. The west region is the main polluted area in the Yangchang Lake.2.Diatoms and green algae are the dominant phytoplankton in the Yangcheng Lake. The biological density and biomass of phytoplankton in summer and autumn are higher than in winter and spring. The index of biodiversity is between 2.06 and 2.34, and evenness index is between 0.69 and 0.78.3.The amount of pollution into the Yangcheng Lake’s three regions is positively correlated with the level of water eutrophication. The phytoplankton diversity is also positively correlated with the level of water eutrophication, yet the correlation is not significant. However, there is a significantly positive linear correlation between the eutrophication index and phytoplankton diversity index in the west region of the Yangcheng Lake. There is a significant negative correlation between the phytoplankton diversity index and the total phosphorus into the east region of the Yangcheng Lake.