Background values and contamination of heavy metals in sediments from the Pearl River Estuary

By using statistical methods,the background values of heavy metals in sediments of the Pearl River Estuary(PRE) were estimated based on the heavy metals date of 348 surface sediments and 2 sediments cores from the PRE. The background values of Cu,Pb,Zn,Cr and Ni are derived as 16. 1,21. 9,94. 3,69. 3 and 30. 3 μg·g- 1,respectively,which is believed more representative by sediment core tests and comparison with other studies. In addition,the contamination levels of heavy metals in sediments of PRE were assessed. The results showed that both of the single heavy metal pollution and overall pollution were in moderate- and low-level in surface sediments from most regions of the PRE,and the heavily polluted area were mainly distributed near the eight outlets of the Pearl River,especially in the West Beach of the east four outlets. The results of core ZY1 indicated that the heavy metal content increased quickly from 1997 to 2003,and then increased quickly from 2005 again after a slight growth from 2003 to 2005. The history of heavy metal pollution can better reflect the impact of the socio-economic development and human activities in the Pearl River Delta.