Accumulated Characteristics and Pollution Assessment of Heavy Metals in Shenzhen River Sediments

Spatial and temporal distribution of heavy metals including Cu,As,Cd,Cr,Hg,Pb and Zn in Shenzhen River,Buji River,Longgang River and Maozhou River sediments from 1996 to 2007 were investigated and studied in order to understand heavy metal pollution and degree.Based on analysis,a comprehensive assessment on heavy metals in Shenzhen urban river sediments was presented using index of geo-accumulation and potential ecological risks index.Results showed that the four rivers were polluted by heavy metals and contents increased with the year,with the pollution degree followed the order as river of Longgang,Buji,Shenzhen and Maozhou,with the most serious polluted heavy metals as Cu,Cd,Cr and Zn.Potential ecological risks and pollution degree of Longgang and Buji were very severe,with average geo-accumulation and potential ecological risks index of Longgang as 6.36 and 2333.2 respectively.River of Shenzhen was in middle degree or severe potential ecological risks.Maozhou was under relatively well sate and most metals were under low or middle potential ecological risks except for Cd and Hg,with average geo-accumulation index as 274.1.