Ecological Remediation Effect Of The Waterbody And Eutrophication Assessment In The Lakeside Zone Of Wuli Lake

With the increase exploitation of the natural resources, especially the water resources, more pollution containing nitrogen and phosphorus has been discharged into lakes, reservoirs and rivers continuously. It increases the quantity of nutriment substance and accelerates the speed of eutrophication in waterbody. The traditional process flow of water treatment is already mature. But for some open water area such as rivers and lakes, the process flow has large limitation. As to this condition, ecological remediation has been international research focus in resent years. And the microorganisms related to the removal of nitrogen and phosphorus from eutrophicated water have attracted more attention.(1) By contrast with the water quality indices in the Lihu Park from Feb. 2007 to Jan. 2008, such indices as TP, TN, CODMn and NH4+-N in the restoration center were much better than those in the restoration area and the lakeside zone. Artificial wetland system could promote elimination of pollutant in the water. It also stabilized the concentration of DO in the water and could obviously restore the lakeside zone.(2) The lakeside zone of Wuli Lake was separated into the three parts the restoration area, the water quality area and the tourism areas. Annual analysis of the lakeside zone shows that such indices as TP, TN, CODMn and NH4+-N in the restoration area were much better than those in the other two. It indicates that the lakeside zone of Wuli Lake was remediate evidently. The Person Correlation Analysis shows that there was the positive correlation among the four water quality indices including TP,CODMn,TN and NH4+-N. Of them, TP, TN and CODMn were the most distinct while the temperature and the total number of bacteria was obviously positive. By using the Cluster Analysis, the water indices were separated into the three sorts. The first was TP, CODMn, TN and NH4+-N, the second was temperature and the total number of bacteria; and the third was DO and SD. In a word, the most important pollution of Wuli Lake was the nonpoint sources and the eutrophication in Wuli Lake was developing.(3) Through the Principal Component Analysis by SPSS, TP, TN, CODMn, NH4+-N, DO were the five most important indices and could be clustering indices. Eutrophication degree is divided into four levels (four gray classifications) according to the eutrophication standard of lake. The measured data of those clustering indices and the value of gray classifications were disposed with non-dimension data to evaluate eutrophication of Wuli Lake in four seasons by use of grey clustering method. The results show that the trophic level of annual mean and four seasons in the lakeside zone of Wuli lake was at eutrophic level.