PERSISTENT ORGANOCHLORINE RESIDUES IN FISH AND WATER BIRDS FROM THE BIOBIO RIVER, CHILE

Concentrations of polychlorinated biphenyls (PCBs), DDT and its metabo lites, HCH isomers and hexachlorobenzene (HCB) were determined in fish and birds from different locations in the Biobio river basin (central Chile). Samples collected near the mouth of the river contained high concentrations of PCBs, reflecting the massive use of these xenobiotic s in the urban and industrial areas of Concepcion and Talcauano. Sampl es collected in the central part of the basin contained very high conc entrations of lindane that coincide with the widespread use of lindane -based pesticides (purified gamma-HCH) in this area. DDT was distribut ed homogeneously throughout the basin, except at Laguna Icalma, the so urce of the river in the Andes. Most PCB residues in fish and birds co nsisted of congeners between penta- and hepta-chlorobiphenyls. In fish , the predominant congeners were the pentachlorobiphenyl 23'44'5 (IUPA C number 118) and the hexachlorobiphenyl 22'344'55' (PCB-153); in bird s 22'44'55' (PCB-180) prevailed.