Abstract:

Lake Taihu is a large lake in the Yangtze Delta plain,on the border of Jiangsu and Zhejiang provinces Eastern China.In recent years,Lake Taihu has been plagued by pollution as a result of rapid economic growth in the surrounding region.LandUse and LandCover Change (LUCC) is of intriguing interest in international research.And a lot of researches show that land use and land management practices have a major impact on nature resources especially water.To explore water quality characteristics in response to land use change in basin is helpful to controll water pollution from the source.Two kinds of representative areas,one is urban area in Jiangsu province with high population density beside the north of Lake Taihu,the other is cultivated land and water conservation forest in Zhejiang province,were selected for study areas in Lake Taihu watershed.Different forms of nutrients,such as TN,DTN,PN,NH+4N,NO-3N,TP,DTP,PP,CODMn,were monthly monitored from June 2009 to May 2010.In order to explore typical characteristics of the river water pollution in the Taihu lake basin,the regional and seasonal multivariate analysis were used.The results showed as follows. (1) High concentration levels of TN in HX and XM was 623 mg/L and 608 mg/L.DTN,PN,NO-3N and NH+4N in HX were 471 mg/L,152 mg/L,231 mg/L and 171 mg/L  respectively.DTN,PN,NO-3N,NH+4N in XM were 297 mg/L,312 mg/L,168 mg/L,080 mg/L respectively.The concentrations was 033 mg/L and 011 mg/L for TP in HX and XM.DTP and PP in HX were 012 mg/L,021 mg/L respectively ,while DTP and PP in XM were 003 mg/L,009 mg/L respectively.The concentrations was 617 mg/L and 421 mg/L for CODMn in HX and XM.(2) Generally,water quality of the river Huishuikou (HS) was worse than that of Xiaomeigang`s (XM).DTN was the main nitrogen form in HS,while DTN and PN were two main nitrogen forms in XM.TN concentrations were high in both two study areas.Therefore,controlling of TN pollution was important in two rivers area.(3) Based on the Oneway multivariate analysis of variance between HS and XM,it was found that land use pattern,land watercycle model and proportion of water conservation forests in the two study areas were significantly different.There were significant difference of DTN,NH+4N,TP,DTP,PP,CODMn between this two study ares.(4) HS area displayed the strong point source pollution based on Seasonal Multivariate Analysis of water quality parameters and the Pearson Correlation Analysis between water pollution and rainfall.Meanwhile,the main pollutants in XM including TN,PN,NH+4N showed the characters of nonpoint source pollution.Finally,the methods of water pollution controlling were the most important to improving water quality.Because the sources of water pollution were different,a variety of pollution prevention and control measures were needed.Therefore,in order to mitigation eutrophication of Lake Taihu,point source pollution,such as industrial pollution source and domestic pollution source,should be controlled in HS,while nonpoint source pollution,especially agricultural nonpoint source pollution,should be controlled in XM.〖HJ1〗〖HJ〗