Heavy Metals Quality Criteria And Assessment Research Of Sediments In Typical Tributary Of Three Gorges Reservoir During Its Operation

Three Gorges reservoir is a new eco-system, especially its storage level reached175meters, and its natural evolution was still in early stage, we did not know much about itsecology evolution principle and its environment problem. So Three Gorges reservoir wouldbe confronted with a lot of new ecological security problems in the future. We had gatheredsamples of Three Gorges reservoir from May to July, and studied heavy metals concentrationand their distribution in Three Gorges reservoir. Health risks associated with these heavymetals in Three Gorges reservoir were assessed by using US EPA health risk assessmentmodel. The Geoaccumulation index was used to study ecological risk of the heavy metals inthe sediments, and meanwhile we studied the source of the heavy metals. And we discussedthe form distribution of the heavy metals and their transformation rules. And at last we usedequilibrium partitioning approach to calculate the quality criteria of heavy metals in ThreeGorges reservoir. In this study we could get the conclusions as follows:①the concentrations of Cr、As、Cd、Cu、Zn and Pb in the tributaries(Zhuyi River,Caotang River, Meixi River) and the main stream in Three Gorges reservoir were lower thanthe Standard of National Drinking Water.②the order of the risk level of carcinogenic metals in Three Gorges reservoirwas Cr> As> Cd, the order of the risk level of non-carcinogenic metals was Cu> Pb> Zn.The risk level of Cr in all the sampling sites were beyond or similar to the accepted level of510-5a-1suggested by ICRP, the risk level of As was lower than the accepted levelsuggested by ICRP, but still higher than the level110-6a-1suggested by institution in manycountries of Europe.③The health risk level of carcinogenic metals was significantly higher than the level ofnon-carcinogenic metals, the risk level of carcinogenic metals was103~108times thannon-carcinogenic metals. ④The results of the Geoaccumulation index indicated the order of the heavy metalpollution was Sb>Li>Sn>Bi>V>B>Be≈Co≈Ga≈Tl. The Igeoresult indicated that ThreeGorges reservoir was middle polluted by Sb.⑤The result of principal component analysis and correlation analysis indicated Be、V、Co、Sn、Bi and Sb mainly originated from human activities, Li、B and Tl represented naturalsources, and Ga mixed sources of nature and human activities.⑥The order of danger of different metal forms was: acid extractable form> Fe-Mn oxideform> oxide form> residue form. The form of Pb was mainly in Fe-Mn oxide form, Cu、Zn、Cr and Ni was mainly in residue form, and Cd was mainly in acid extractable form.⑦We used equilibrium partitioning approach to calculate the quality criteria of heavymetals(Cu、Pb、Zn、Cd) in Three Gorges reservoir.