Comprehensive Investigation and Assessment of Nutrient and Heavy Metal Contamination in the Surface Water of Coastal Bohai Sea in China

With the rapid development of industrialization and urbanization of coastal regions, eutrophication and metal pollution have caused serious environmental problems in China. To better understand the potential environmental risks associated with nutrients and heavy metals, the surface water was comprehensively investigated in the coastal Bohai Sea. A total of 150 sites were sampled from seven coastal regions, and the concentrations of nutrients (DIN and DIP) and metals (Cd, Pb, Zn, Cu, Cr, As and Hg) in the surface seawater were measured. The results showed that the DIN concentration of about 50% sites exceeded the Grade-I of Seawater Quality Standard of China. Due to high concentrations of DIN, the status of eutrophication was serious in the Bohai Bay and Shuangtaizi Estuary. According to Seawater Quality Standard of China, Pb, Zn, Hg and Cu were the main metal pollutants in the coastal Bohai Sea. There was generally low ecological risk caused by heavy metals, but certain hotspots existed near Shuangtaizi Estuary and Changxingdao Island.