1. Nanjing University of Science & Technology, Nanjing 210094, China;
2. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
In this study, a total of 103-surface sediments were collected from lakes and rivers in Taihu watershed on the basis of different ecological zones. A total of 103 surface sediments were collected from lakes and rivers of Taihu watershed. The nutrients and heavy metals in sediments were analysed and the assessment of the ecological risk were carried out. The results showed that the concentration of total nitrogen descended as Ⅱ11 zone (hill zone of west lake) > Ⅱ21 zone (agricultural zone of Wuxiyu) > Ⅱ12 zone (mountain zone of Zhexi) > Ⅱ23 zone (agricultural zone of Husujia) > Ⅱ12 zone (wetland zone of Taihu Lake) with the value in the range of 550 to 3450mg/kg. The concentration of total phosphorus descended as Ⅱ23 zone > Ⅱ21 zone > Ⅱ22 zone > Ⅱ11 zone > Ⅱ12 zone with the value ranging from 320 to 2481mg/kg. The results of heavy metals in surface sediment of Taihu watershed indicated that the value of heavy metal concentrations were highest in zones of Ⅱ23 and Ⅱ21. While it was the lowest in zones of Ⅱ12, Ⅱ11 and Ⅱ22. The results of comprehensive pollution index (FF) indicated that the contamination of nutrients in sediment of Taihu watershed were very serious and a grading of pollution has been formed. The value of RI indicated that metals in Ⅱ21 zone rank the highest and then was zones of Ⅱ23,Ⅱ12 and Ⅱ22 and Ⅱ11 zone rank the lowest. The results of Igeo indicated that metals including As、Cu、Zn、Pb、Ni、Cr were not polluted while the value of Er indicated that Hg and Cd were the most polluted elements and which contribute a lot to the pollution status of metal in sediments of Taihu watershed.
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