Assessment of water quality and the main pollutions of Taihu Lake.

The analysis samples of water chemistry and aquatic biology were collected quarterly in Taihu Lake from November 2007 to August 2008.We evaluate the actual condition of water quality and the main pollution sources of Taihu Lake by ways of water pollution index and comprehensive analysis of eutrophication.Evaluation of water pollution index analysis revealed that the main pollutants in Taihu Lake were nitrogen(N),phosphorus(P) and organic oxygen consumption(COD Mn).Total phosphorus(TP) shared the largest pollution load index(34.34%-54.34%),with the average pollution index of 48.36%.TN,TP and COD Mn had a significant positive correlations with Chlorophyll a(Chl-a),Pearson correlation coefficients were 0.715(P0.01),0.666(P0.01) and 0.740(P0.01) respectively.According to comprehensive analysis of nutritional status indicators,it also showed that TLI(Σ) values of Taihu Lake were between 60 and 70 in four seasons,with a mean value of 65.54.The seasonal changes of water quality were small.In a word,Taihu Lake was in a moderately eutrophication,and some of the region had shown a serious eutrophication.