Heavy metal enrichment characteristics in different sedimentary environments: A case study of the Pearl River Estuary and adjacent coastal area

Estuarine and coastal sediments primarily function as repositories for heavy metals and other contaminants. This study investigates the enrichment characteristics of heavy metals in 65 surface sediment samples collected from the Pearl River Estuary (PRE) and its adjacent coastal areas. Both the enrichment factor and geo-accumulation index indicated low enrichment of heavy metals in the study area. Only a minor proportion of samples demonstrated slight to moderate contamination with Pb and Zn. Heavy metals primary originate from natural sources, with minor contribution from anthropogenic activities. The semi-enclosed nature of the PRE results in greater impacts from human activities, as reflected by the elevated concentrations of Cu, Zn, and Pb in its sediments. In contrast, coastal areas experience strong hydrodynamic forces , which lead to relatively low levels of heavy metal enrichment in their sediments. Sedimentary hydrodynamic conditions are the primary factor controlling the accumulation of heavy metals in these environments. • The sediments exhibited relatively low level of heavy metal enrichment. • Heavy metals primary originate from natural sources, while Cu, Pb, and Zn in sediments from local areas of the PRE exhibited obvious anthropogenic contributions. • The change in sedimentary hydrodynamic condition from the estuary to the coastal area is the primary factor controlling the accumulation of heavy metals in sediments.