Pollution characteristics of heavy metals in sediment from Heizhu River in Tianjin Binhai New Development Area and selection of regional heavy metal pollution indicators.

The concentrations of eight heavy metals(Cu,Cd,As,Pb,Cr,Zn,Ni and Hg) were determined in the sediments of the Heizhu River in Binhai New Development Area,Tianjin,China.Enrichment factors and potential ecological risk indices were calculated to evaluate the environmental risk of these contaminants.Results showed that the concentrations of Hg and Cd were relatively high and posed greater ecological risk,while minimal risks were found for the other six heavy metals in the surface sediments of the Heizhu River.Correlation analysis and Principal Component Analysis were applied to identify the common sources of the heavy metals.Results indicated that Zn,Cr and Ni were mainly controlled by natural factors,and were associated with parent rock erosion.As and Cu were mainly released from agricultural activities.Wastewater irrigation,fossil fuel burning and domestic waste emissions were identified as the sources of Hg and Cd.Pb originated from both natural sources and human activities,although the anthropogenic load was predominant.Additionally,a systematic comparison was made for the data of heavy metal pollution degree in various sediments and soils in the Tianjin area from the literature,and their correlation with the pollution levels in vegetables and fish was made.The results showed that the enrichment factors of Cd and Hg in the sediments and soils were significantly high.Therefore,Cd and Hg may be selected as the regional indicators of heavy metal pollution.