The Pollution Status of Heavy Metals in the Surface Seawater and Sediments of the Tianjin Coastal Area, North China

Heavy metal pollution has become a great concern due to its adverse effects on the ecological system and human health. The present study investigated the concentrations of six common heavy metals (Cr, Cu, Zn, As, Cd, and Pb) in the Tianjin coastal area to understand their distribution, enrichment, sources, and potential ecological risk levels, focusing on the main contributors. The results showed that the concentration of Cu was high in the surface seawater (6.89 µg/L for the average), while Cd was the main contaminating metal in the sediments, with an average concentration of 0.77 mg/kg. The potential ecological risk index (RI) implied that the heavy metals in the sediments could cause considerable ecological risk, and Cd was the major contributor to ecological risk in this area. In particular, the field investigation showed that Cd contamination occurred as a result of anthropogenic activities, including port transportation, mariculture, and metal fabrication along the coastal area. Therefore, it is necessary to control Cd contamination in the future to improve the quality of the marine environment in Bohai Bay.