Evaluation of heavy metal accumulation and sources in surface sediments of the Pearl River Estuary (China)

The Pearl River Estuary (PRE) has experienced an influx of metals and nutrients, predominantly from the Pearl River, which has led to a potential threat to the estuarine ecosystem. In this study, sediment samples were densely collected to clarify the accumulation, and source contributions of heavy metals (namely Hg, Zn, Cu, As, Pb, Cd, and Cr) in the PRE. The spatial distributions of these metals exhibited significant differences, with higher values detected in the offshore areas and lower values further away. The metal values along the western coast tended to be significantly elevated compared to that of the eastern seaboard, which may relate to anthropogenic pollution, the discharge of industrial and domestic effluents in the region. The geological accumulation index (I_geo) was utilized to evaluate the pollution status, categorized as ranging from light to moderate pollution levels. The homology of metal elements was determined through Pearson correlation analysis and principal component analysis (PCA). A receptor model of positive matrix factorization (PMF) was developed to quantify the contributions of various sources to the accumulation of metal elements in the PRE. Industrial sources contributed the most to sediment metals (37.07%), followed by agricultural and natural sources, with transportation sources contributing the least (11.17%).