Background Values,Contamination Assessment and Zoning of Heavy Metals in Sediments of the Pearl River Estuary

Background values of heavy metals in sediments at the Pear river estuary were estimated through division of background sedimentation zones in combination with statistical methods,then the contamination of heavy metals in surface sediments at the Pear river estuary was assessed and zoned in terms of these background values through potential ecological risk indexing. The background values (μg/g) of Cu,Zn,Pb,Cr,As,Cd and Hg are 38.6,100.7,44.0,81.1,22.9,0.20 and 0.170,respectively. Assessment results revealed that the degree of total heavy metal contamination in surface sediments at the Pear River estuary is mainly moderate; the degree of total potential ecological risk is light for most of the study area. However,the degree of total heavy metal contamination and potential ecological risk is heavy for the entrance of Hongqimen,Hengmen and the sea area extends southeastward to the south of Wanqinsha,in which the sediment contamination of Cd and Hg requires special concern.