Spatial and temporal variations of heavy metals in marine sediments from Liaodong Bay, Bohai Sea in China

An integrated analysis has been carried out using surface sediment monitoring data in order to characterize the spatial distributions and temporal trends of heavy metals within ten years from 2004 to 2013 in the entire Liaodong Bay. Hg, Cd and As were predominant contaminants with their median concentrations of 0.04-0.15, 0.01-0.65, and 1.80-30.3 mg/kg respectively. Both areas and levels of Cu and Pb contamination were low. Cd contents exhibited an obvious decreasing trend and As presented a similar law during these 10 years. Further, emissions from different sources were analyzed to identify the possible reasons contributing to the metal pollution. Dramatic descending of waste water might be the top reason for Cd and As variations. Local flue gases and smoke emissions might not be the main sources contributing to Hg pollution, whereas atmospheric deposition at a larger scale was supposed to be the leading factor.