STUDY OF HEAVY METALS IN BOTTOM SEDIMENTS OF THE EAST CHINA SEAS (Bohai, Huanghai and the East China Sea):A REVIEW OF CURRENT STATUS

A great amount of heavy metals is discharged from large and small rivers into the Eastern China Seas, which include the Bohai, Huanghai and the East China Sea in total, and eventually preserved in the bottom sediments, which makes the marine environment faced with the serious heavy metal pollution. These heavy metals come from various sources, which may be generally put into natural and anthropogenic groups. The natural sources mainly include the eroded soils from the Yangtze River Basin and the Yellow River Basin and the desert dust from West China. The anthropogenic sources mainly include the pollution caused by human activities dominated by combustion of fossil fuels and smelting of steel and non-ferrous metals. These heavy metal contaminants are mainly discharged into the Chinese Eastern Seas through rivers. Various methods have been adopted to identify the sources of heavy metals in marine sediments, and the stable isotope of Pb is believed the most successful indicator. Although huge amounts of heavy metals have been discharged into the Chinese Eastern Seas, the marine sediment offshore remain in good quality, except the Jinzhou Bay which is faced with the serious heavy metal pollution.