Toxic metal pollution in the Yellow Sea and Bohai Sea, China: distribution, controlling factors and potential risk

The Bohai Sea (BS) and Yellow Sea (YS), which are adjacent to the most urbanized and industrialized areas in China, are facing a variety of environmental problems. Two cruises were conducted to investigate the pollution status of toxic metals in BS and YS sediments. They generally presented a decreasing trend from near shore to offshore. In addition, two high concentration areas were observed in the central south YS and north of the Shandong Peninsula. The results of multiple regression analyses suggest that Hg is mainly controlled by anthropogenic loading, whereas for Cr, Cu, Ni, Pb and Zn, sediment properties, especially the Fe oxides content, play a more important role. For As and Cd, the contribution of anthropogenic loading and sediment properties are comparable. The risk assessment indicates that Hg, As, Cd and Ni should be listed as the primary contaminant metals in the BS and YS.