Heavy metal pollution in Tianjin Bohai Bay, China.

The contamination levels and distribution characters of heavy metals in coastal waters and sediments from Tianjin Bohai Bay, China were examined. Pb and Zn were found as the main heavy metal pollutants in the coastal waters of the bay. High levels of Pb and Zn appeared especially near the estuary, indicating that river discharge was the main pollution source. Moreover, atmospheric deposition resulted in Pb contamination in the middle of the embayment. Analysis of data for the period 1987-2004 indicated that Pb pollution in coastal waters of Tianjin Bohai Bay originated primarily from river discharge before 2001. Pb levels did not decrease after 2001 when annual runoff levels declined; indicating that Pb pollution by atmospheric deposition had increased due to the use of leaded petrol in motorcars. Pb, Zn, and Cd were the dominant polluting elements in surficial sediments from Tianjin Bohai Bay, with levels in excess of the corresponding upper limits of environmental background values. High concentrations of polluting elements were found in tidal sediments near water bodies such as Qihe and Dagu estuaries.