Distribution of polychlorinated biphenyls (PCBs), lead, and cadmium in Manko Tidal Flat, Okinawa

Concentrations of polychlorinated biphenyls (PCBs), Pb, and Cd in sediment samples from the Manko Tidal Flat, an important area for migratory birds in Okinawa, were analyzed. High concentrations of PCBs were detected in the sediment samples from sites under a bridge at the end of the Manko Flat, whereas Pb and Cd concentrations did not indicate specific pollution. The spatial distribution and homologue proportion of PCBs indicated that these PCBs are probably attributed to the residue of paints used on the bridge in the 1970s. PCBs were detected in tilapias from sites in the Manko Flat and in a river connecting to the flat without head constructions. PCBs were also detected in small invertebrates, tanaids, in the flat. The distribution of PCB concentrations in the fauna was parallel to that in the sediments. The average PCB homologue proportions in tilapias and tanaids were similar to those in sediments.