[Concentration characteristics and ecological risk of persistent organic pollutants in the surface sediments of Tianjin coastal area].
Surface sediments were sampled from various surface water bodies in Tianjin coastal area, and four types of persistent organic pollutants including polycyclic aromatic hydrocarbons (PAHs), organic pesticides (OCPs), polychlorinated biphenyl (PCBs) and polybrominated diphenyl ethers (PBDEs) were measured. The purposes were to investigate the concentration characteristics of the four types of pollutants and to assess their ecological risks. The results showed that all the 16 priority PAHs were detected from the 10 sediments sampled from the Tianjin coastal area. The total concentrations of the 16 PAHs ranged from 274.06 microg x kg(-1) to 2656.65 microg x kg(-1), with the average being 1 198.51 microg x kg(-1). Combustion of fossil fuel such as coal and gasoline was the major source of PAHs in the surface sediments, while input of petroleum products might occur in some locations. In the Dagu discharging river, the total concentration of 22 OCPs was 3 103.36 microg x kg(-1), the total concentration of 35 PCBs and the total concentration of 14 PBDEs were 87.31 microg x kg(-1) and 13.88 microg x kg(-1), respectively. The concentrations of OCPs, PCBs and PBDEs in other sampling locations were low. The total organic carbon in the surface sediments had good correlation with PAHs but not with OCPs, PCBs and PBDEs, and this might be due to the fact that PAHs mainly came from area pollution while the other compounds mainly came from point pollution. In the sediments, PAHs (particularly low molecular weight PAHs) had high ecological risk; in multiple locations, the concentrations of naphthalene and/or acenaphthene exceeded their probable effect concentrations, indicating that they were most likely causing adverse effects to benthonic organisms. In the Dagu discharging river, the concentrations of heptachlor epoxide and lindane (gamma-BHC) exceeded their probable effect concentrations and were most likely causing adverse effects to benthonic organisms. The OCPs in other sampling locations had low ecological risk. Overall, PCBs and PBDEs had low ecological risk.