[Water quality comparison between Lake Taihu and contribute river during high water-level period]

Thirty-two main rivers around Lake Taihu were sampled during high water period in 2008 to investigate river's vital impact on Lake water quality. Different forms of nitrogen and phosphorus were analyzed for the 32 river water samples according to nutrients function to algae. The aim of this study is to provide the basic information for river rehabilitation. Based on the results, the nutrients and suspended substance (SS) concentrations of Wangyu River were the highest, its water quality was below the V grade (Chinese water quality criterion). Water quality of northern rivers was also below the V grade, organic matter and enzymatically hydrolysable phosphate (EHP) concentration were the highest. The EHP concentration was 0.240 mg/L, and accounted for 62.4% of total phosphorus (TP). Nitrite nitrogen (NO2(-) -N) concentration was exceptionally high in western rivers and the average concentration was 0.270 mg/L, it was 2-3 times higher than that of other rivers. The northern rivers' nitrogen, phosphorus and organic concentration were markedly higher than those in the north Lake region, while the western rivers' nitrogen was markedly higher than that in the west Lake region. It can also be concluded that algae and suspended sediment were able to bring more phosphorus to water by comparing the ratio of total nitrogen(TN) and TP in these rivers and Lake Taihu.