Abstract
Surface sediment samples were collected from a source water reservoir in Zhejiang Province, East of China to investigate pollution characteristics and potential ecological risk of heavy metals. The BCR sequential extraction method was used to determine the four chemical fractions of heavy metals such as acid soluble, easily reducible, easily oxidizable and residual fractions. The heavy metals pollution and potential ecological risk were evaluated systematically using geoaccumulation index (Igeo) and Hakanson potential ecological risk index (H′). The results showed that the sampling sites from the estuaries of tributary flowing through downtowns and heavy industrial parks showed significantly (p < 0.05) higher average concentrations of heavy metals in the surface sediments, as compared to the other sampling sites. Chemical fractionation showed that Mn existed mainly in acid extractable fraction, Cu and Pb were mainly in reducible fraction, and As existed mainly in residual fraction in the surface sediments despite sampling sites. The sampling sites from the estuary of tributary flowing through downtown showed significantly (p < 0.05) higher proportions of acid extractable and reducible fractions than the other sampling sites, which would pose a potential toxic risk to aquatic organisms as well as a potential threat to drinking water safety. As, Pb, Ni and Cu were at relatively high potential ecological risk with high Igeo values for some sampling locations. Hakanson potential ecological risk index (H′) showed the surface sediments from the tributary estuaries with high population density and rapid industrial development showed significantly (p < 0.05) higher heavy metal pollution levels and potential ecological risk in the surface sediments, as compared to the other sampling sites.
Highlights
Rapid population growth and economy development have resulted in serious pollution of water environment such as rivers and lakes or reservoir in many developing countries including China
The results showed that the sampling sites from the estuaries of tributary flowing through downtowns and heavy industrial parks showed significantly (p < 0.05) higher average concentrations of heavy metals in the surface sediments, as compared to the other sampling sites
The sampling sites from the estuaries of tributary flowing through downtowns and heavy industrial parks showed significantly (p < 0.05) higher concentrations of heavy metals in the surface sediments, as compared to the other sampling sites
Summary
[4] Heavy metals (HMs) are greatly harmful to organisms and ecological systems due to its degradation-resistance, bioaccumulation, and bio-amplification.[5,6,7] Sediments function as a sink for HMs from diverse sources, reflecting the natural soil composition of the surrounding areas, as well as human activities.[8] The heavy metals in the lakes or reservoirs are mostly concentrated in sediments by flocculation and sedimentation and thereby contaminated the sediments.[9] The lake sediments conserve valuable historic information on past and present water environment conditions and inputs of pollutants such as HMs.[10] the research on heavy metal pollution and environmental risk assessment of the sediments from lake or river affected by urbanization and industrialization is of great significance and attract many researchers all over the world.[11,12]
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