Spatial distribution of polychlorinated biphenyls (PCBs) contaminants in the tidal-flat sediments of Yangtze Estuary

PCBs pollutants are measured on tidal-flat sediments of Yangtze estuary by a high-resolution capillary column gas chromatography (HP6890) equipped with a super(63)Ni electron capture detector (ECD). The concentration tendency of PCBs is Phragmites zone > Scirpus zone > bare mudflats. There are linear relations between PCBs and TOC and > 63 mu m grain size percentage (in volume). The low chlorinated congeners may be more important than the high chlorinated congeners in this area. PCBs prefer to accumulate in the sediments near sewage outlets and Phragmites zone. The sediments' PCBs pollution (10.7-28.6 ng/g, dry weight) in the Yangtze estuary tidal-flat is less serious than that of the most of other areas in the world. But the detected ratio is 100%, even the Jiuduansha shoal has detected PCBs, so much attention should be paid to this area for PCBs.