A COMPARISON OF DISTRIBUTIONS OF PCB CONGENERS AND OTHER CHLORINATED COMPOUNDS IN FISHES FROM COASTAL AREAS AND REMOTE LAKES

A total of 28 PCB congeners, p,p'-DDE, pp'-DDD, pp'-DDT, HCB and gamma-HCH were determined in lake trouts (Salmo trutta) from two isolated lakes in the Pyrenees and in red mullets (Mullus barbatus) from the Mediterranean coast. The lower concentrations, in the range of 1.9-6.0 ng g-1 (wet wt) for pp'-DDE and 0. 1-0.8 ng g-1 (wet wt) for the other individual compounds (2.6-7.2 ng g-1 for the sum of PCB congeners), were found in the remote lake samples, where the atmosphere was the only source for these anthropogenic compounds. These samples were also relatively enriched in gamma-HCH, consistently with the predominant atmospheric transport pathway of this compound. The PCB congener patterns exhibited substantial differences between both sets of samples. The trouts were enriched in the tri- to pentachlorobiphenyl congeners whereas the mullets were dominated by the hexachlorobiphenyl isomers, reflecting the predominance of atmospheric and aquatic point-source inputs, respectively. On the other hand, the congeners with adjacent unsubstituted positions were clearly depleted in the marine fishes, indicating a relatively enhanced metabolic activity of these chronically exposed organisms. All these features illustrate the advantage of the analysis of individual PCBs for a better understanding of their environmental transport and fate.