Abstract
The contents, speciation, source factors and potential ecological risks of the selected metals (Cr, Ni, Cu, Pb, Zn, Cd and As) were analyzed in surface sediments from Daya Bay (DYB). The results show that, with the exception of Pb, metal concentrations have decreased at all sites over the past decade. The distribution features of these concentrations represent a ring shape that descends from shore to bay by varying degrees. Speciation analysis showed that Cr, Ni, Cu, Zn and As exist mainly in the residual fraction and, thus, are of low bioavailability, while Cd and Pb were found to be abundant in the non-residual fraction and, thus, have high potential mobility. The ratio of heavy metals in non-residual form in descending order is Pb (78.83%), Cd (78.65%), Cu (48.54%), Zn (48.10%), Ni (38.31%), Cr (28.43%) and As (27.76%). The ratio of Pb content is the highest, meaning the highest mobility of Pb. The metals’ potential ecological risks to the environment were also assessed using the methods of the mean effect range-median quotient and the criteria of risk assessment code. The results showed that Cd presents the highest risk, and Pb and Cu are generally considered to be medium risks in the sub-basins of Daya Bay. The principal component analysis (PCA) revealed that natural coastal weathering and erosion of rock caused the highest input, followed by mariculture and industrial wastewater and, finally, domestic sewage discharge.
Highlights
In recent decades, environmental and ecological problems have been widely reported due to the presence of different contaminants from anthropogenic activity in terrestrial and aquatic ecosystems, which can pose a serious hazard to the environment and to human health [1,2,3,4]
According to Shepard’s sediment granularity classification, clay-like silt accounted for 71.2% of the surface sediments in Daya Bay (DYB) and sandy silt accounted for 11.2%
This study has shown that using a combination of sequential extraction data, multivariate statistical analyses and the ecological risk indexes, an effective assessment of environmental quality in the studied areas affected by several sources of anthropogenic pollution can be produced
Summary
Environmental and ecological problems have been widely reported due to the presence of different contaminants from anthropogenic activity in terrestrial and aquatic ecosystems, which can pose a serious hazard to the environment and to human health [1,2,3,4]. Considerable research has been focused on the environmental and ecological problems caused by various contaminants in terrestrial and aquatic ecosystems [5,6,7]. The health status of sediments is a crucial criterion to assess the state of the environment; the determination of heavy metals in sediments is a significant measure to understand the possible environmental changes caused by human activities
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