POLYCHLORINATED DIPHENYL ETHERS, DIBENZO-P-DIOXINS, DIBENZOFURANS ANDBIPHENYLS IN SEALS AND SEDIMENT FROM THE GULF-OF-FINLAND

Polychlorinated diphenyl ethers (PCDEs), 2,3,7,8-substituted polychlor inated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), and polych lorinated biphenyls (PCBs) were analyzed in seals from the Gulf of Fin land and in sediments from the Gulf of Finland and near Gotland. The s ediments included one surface core from both sampling sites. The seal material consisted of 14 ringed seals and 6 grey seals that all were f ound dead and examined for pathology. The main aims were to scrutinize levels and patterns of PCDEs for the first time in seals from the Bal tic Sea and to estimate whether chlorinated compounds mentioned have a n influence on an exceptional high mortality that occurred among ringe d seals in the Gulf of Finland in late 1991. The concentrations of 50 congeners of tetra-through deca-CDEs analyzed ranged from <0.3 to 62 n g/g lipid weight (lw) in seal blubber, but in the sediments PCDEs were non-detectable (tetra-through hepta-CDEs <0.1 ng/g dry weight (dw)). In ringed seals with good nutritional status, the concentrations of al most all PCDE congeners were greater in two adult females than in spec imens of younger age groups. The concentrations of PCDDs and PCDFs as TCDD-equivalents exceeded those of the coplanar (non-ortho) PCBs in se diments, whereas non-and mono-ortho PCBs constituted greater toxic loa ds as those calculated for PCDDs and PCDFs in seals. However, the leve ls revealed do not explain the high mortality of ringed seals. (C) 199 7 Elsevier Science Ltd.