Sources and geochemical background of potentially toxic metals in surface sediments from the Zhejiang coastal mud area of the East China Sea

• Potentially toxic metal concentrations were primarily controlled by grain size.
• Sources of metals could be identified by principal component analysis.
• Cu and Cd were of anthropogenic origin at many stations.
• The geochemical background function could be constructed by statistical methods.

The geochemical background concentration (GBC) of potentially toxic metals in coastal surface sediments is a useful reference to assess the extent of sediment contamination caused by human activities. Using surface sediments collected from the Zhejiang coastal mud area of the East China Sea, a regional GBC function (GBCF) for potentially toxic metals in sediments was constructed based on statistical techniques. Principal component analysis (PCA) was utilized to identify potentially toxic metal sources. For potentially toxic metals of natural origin, the GBCF was developed by directly fitting concentration with Al2O3 in a linear regression model. For potentially toxic metals of anthropogenic origin, concentration data were normalized with Al2O3 to eliminate the influences of grain size and mineral, and cleaned by the cumulative distribution function before linear regression analyses. At each sampling station, the enrichment factor (EF) was modified by the corresponding GBC calculated from the GBCF, and was then applied to identify metal sources. The EF results were consistent with those of the PCA and correlation analyses, indicating that the GBCs of potentially toxic metals at each station were applicable. The approach used in this study will be useful for assessing potentially toxic metal pollution in sediment and managing sediment quality.