CHARACTERIZATION OF 2 MAJOR TOXAPHENE COMPONENTS IN TREATED LAKE SEDIMENT

The structures of two environmentally significant toxaphene congeners, namely, a hexachlorobornane (Hx-Sed) and a heptachlorobornane (Hp-Sed ), from the sediment of two lakes located in Alberta, Canada, have bee n characterized by H-1 NMR and mass spectrometries. Both lakes were tr eated in the early 1960s by the addition of toxaphene, as a pesticide, to the water column at low microgram per liter concentrations. Highes t toxaphene concentrations were found in sediments of both lakes in sl ices dated to the early 1960s. In these slices, the chromatographic pa ttern resembled that of the toxaphene standard while, in more recent s lices, the number of chlorinated bornane (CHB) peaks was greatly reduc ed, with the two most prominent peaks corresponding to 2-exo,3-endo,6- exo,8c,9b(or 8b, 9c),10a-hexachlorobornane and 2-exo,3-endo,5-exo,6-en do,8c,9b(or 8b, 9c),10a-heptachlorobornane. Hx-Sed has previously been identified as one of the major reductive dechlorination metabolites o f toxicant B (2-exo,3-endo,6,6,8c,9b,-10a-heptachlorobornane), one of the most toxic components of the technical mixture. Never before, howe ver, has it been identified as a persistent contaminant in the environ ment.