Résumé
Objective To investigate the contamination of Cd,Pb,Cu and Cr in the sediment of Guangzhou reach in Pearl River.Methods The sediments were collected in Yagang spot in April,2006.The content of heavy metals were determined,the heavy metals in the sediment were extracted with Tessier five stage sequential extraction procedure,and AAS was applied to determine the concentration of heavy metals in the sediment and extracts.Results The level of Cd,Pb,Cu,Cr were 2.29 mg/kg,217.97 mg/kg,320.60 mg/kg and 124.44 mg/kg respectively in the sediment in Yagang spot.They were higher than the background values of soil of Guangdong,and different heavy metals had different values of five forms.Cd existed as exchanged form mainly,and Cr,Pb existed as stable form mainly,so,Cd was easy to be resolved into water,Cr,Pb were relatively stable in the sediment.Conclusion The ecological risk of the four heavy metals is assessed with Hakanson potential ecological harmful index,the ecological risk of Cd is high,Cr,Pb is lower,Cu is moderate.