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| Fraction Distribution and Risk Assessment of Heavy Metal in Sediments of Miyun Reservoir |
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| KeyWord:Miyun Reservoir; sediments; heavy metals; speciation; risk assessment code（RAC） |
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| Abstract: |
| Contents and spatial distribution of heavy metals in the sediments of Miyun Reservoir in Beijing were researched in this article， and the degree of pollution was analyzed by the method of Enrichment Factor and Risk Assessment Code（RAC）. The results showed that the average contents of all heavy metals were higher than the background values of Beijing soils， and heavy metals appeared certain enrichment. Correlation analysis showed that significant correlations existed among Zn， V， Cu， Mn， Pb， Ni（P＜0.01）， and it indicated that these elements have the same man-made and natural sources of pollution. The analysis of chemical speciation showed that the residual fraction for Cu and Ni accounted for 71%， 72% of the total contents， respectively. And then the organic matter fraction was 17%， 14%. The residual form for Mn accounted for 45%， Fe-Mn oxides fraction was 22%， and bound to carbonates fraction was 18%. Other heavy metals were dominated by Fe-Mn oxides fraction and residual fraction， they accounted for more than 80% of the total contents. The RAC showed that Mn（except the sampling point 18） posed a medium ecological risk or high ecological risk， and the potential ecological risk of heavy metals（Pb， Zn， Cu） was from low risk to a medium ecological risk level， whereas Ni， V， Cr and Ti posed low risk. The results of the study will provide a scientific basis for the protection of Miyun Reservoir and the estabilishment of measures for people′s health and security. |
