Spatial distribution, source identification, and risk assessment of heavy metals in seawater and sediments from Meishan Bay, Zhejiang coast, China

The aim of this study is to determine the spatial distribution, potential sources, and ecological risks of 8 heavy metals (Zn, Cu, Cr, Ni, As, Cd, Hg, and Pb) in Meishan Bay, Zhejiang coast, China. Surface water (n = 31), bottom water (n = 31), and surface sediments (n = 31) were collected. Water physicochemical properties and sediment resuspension were important factors affecting spatial distributions of heavy metals. The spatial distributions of Cr, Ni, Pb, As, Cu, and Zn were consistent with the clay distribution. Atmospheric deposition was the main source of Cd and Pb, mainly from industrial and transportation exhausts, while Zn was mainly from ship transportation. Agriculture pesticides and sewage wastewater were considered as the main sources for Hg. The geo-accumulation index results indicated that there was limited pollution of Cu, Zn, Cr, Pb, and As, and mild to moderate pollution of Cd and Hg. The potential ecological risk assessment suggested a high ecological risk of Hg in Meishan Bay.