Distribution, Sources, and Ecological Risk Assessment of Potentially Toxic Elements in Surface Sediments of Dongzhai Harbor, Hainan Island, China

The mangrove wetland ecosystem functions as a natural purifier and a significant repository for pollutants, effectively facilitating the transfer and transformation of contaminants into sediments. This study focuses on the Dongzhai Harbor wetland on Hainan Island, aiming to investigate the spatial distribution patterns, pollution status, potential sources, and ecological risk levels of potentially toxic elements (PTEs) (Cu, Pb, Zn, Cr, Cd, Ni, and As) in the surface sediments of the region. The sediment quality in the study area generally complies with Marine Sediment Quality Standards. Results from the contamination factor (CF), pollution load index (PLI), geoaccumulation index (Igeo), and potential ecological risk index (RI) indicate that Zn, Cr, Ni, Pb, and Cu are primarily derived from natural sources. In contrast, Cd and As exhibit mild to moderate pollution levels, likely influenced by natural and anthropogenic activities. Cd is identified as the primary potentially toxic element pollutant and ecological risk factor in the study area, presenting a low ecological risk level. The mean range of effects-median quotient (M-ERM-Q) and hazard quotient (HQ) of the sediment toxicological profiles indicate that there is some risk of toxicity from PTEs in the sediments of the study area. This research provides valuable references for pollution prevention and control in the Dongzhai Harbor mangrove wetland.