Abstract
This study investigated the concentrations of polychlorinated biphenyls (PCBs) and the specific compositional characteristics in the tidal flat sediments collected from the Ariake Sea. In general, the residue levels were several ten ng/g (dry wt.), which is comparable to those to Japanese coastal waters and lower than those of other Asian countries. In contrast, maximum concentrations of PCBs were found in river sediments (3, 900 ng/g dry wt.), indicating that the large amounts of PCBs discharge occurred. The principal component analysis (PCA) applied to PCB congener compositions in all sediments provided the construction of three different groups. The result implies that the profile of PCBs sources is different among sampling sites. Isomer compositions of PCBs in several sediment samples were compared with those of technical PCBs products, such as Kanechlor (KC) -300, 400, 500 and 600 by using the fingerprint method. The PCB isomer patterns in river sediment was resembled with those in the KC-400, which is indicator of greater di-, tri-, tetra- and pentachloro biphenyls. The Biota-Sediment Accumulation Factors (BSAFs) were calculated from the concentrations of PCBs in oysters and sediments from the heavily contaminated river. The relationship between BSAFs and log Kow suggested that higher chlorinated congeners were likely to retain in the sediment through the river systems.
