Heavy Metals in Surface Sediments Around Yangshan Port: Spatial Distribution, Sources, and Ecological Risks

Abstract

This study investigated the spatial distribution, pollution levels, probable sources, and overall ecological risks of heavy metals (Cu, Pb, Zn, Cd, and Hg) in surface sediments from a coastal area near Yangshan Port using 45 sediment samples. The mean CF values of heavy metals showed a decreasing order of Cd (2.07) > Cu (1.83) = Hg (1.83) > Zn (1.30) > Pb (1.19), revealing low to moderate contamination of Pb, Zn, Cu, Hg, and Cd. The mean mCd value was 1.65, showing an overall low contamination level. The mean value of RI was 153.17 and revealed a moderate ecological risk for heavy metals. Cd and Hg are the dominant contributors to ecological risks, while Cu, Pb, and Zn showed comparatively low individual ecological risks. According to mCd and RI, surface sediments around Yangshan Port, Donghai Bridge, and the coastal area south of Shanghai had higher contamination-index values and posed moderate ecological risk, potentially influenced by port activities and terrigenous input. Based on a positive matrix factorization model coupled with correlation analysis, four probable sources of pollution were quantitatively attributed: probable terrestrial land-based inputs from Hangzhou Bay with relatively high loading value for TOC, Cu, Pb, and Zn (26.78%), probable shipping-related source with high loadings of Cu, Pb, Zn, and Cd (38.91%), Hg-dominated inputs likely associated with atmospheric deposition (17.56%), and Cd-dominated loading with small amounts of Cu, Pb, Zn, and TOC probably associated with terrigenous inputs (16.75%). Among the four PMF-resolved factors, the probable shipping-related source showed the largest contribution to the measured heavy metal burden.