Distribution and ecological risk assessment of sediment PCBs in Songhua River.

In this study, the concentrations and seasonal changes of sediment PCBs from 14 site points were characterized. 57 PCBs homologs were detected totally. The concentrations of Σ PCBs ranged from 1.0 x 10¹⁰ to 1.15 x 10 and the average percentage was 1.91 x 10^-9, which showed a little seasonal changes. The ecological risk assessment was carried out and the same risk results were obtained with two methods: Ha- kanson ecological risk index and Canadian sediment quality guidelines (SQG). It is found that the ecological risk ranks in all target sites are all below the high ecological hazard. The risk value of Songyuan belongs to the middle ecological hazard in spring and the risk of the rest of the target sites belongs to the light ecological hazard in different seasons. The order of the top five risk sites is as follows : Songyuan > downriver Jiamusi > Fujin > downriver Harbin > upriver Harbin. [ABSTRACT FROM AUTHOR]