CHLOROBORNANES IN SEDIMENTS AND FISH 30 YEARS AFTER TOXAPHENE TREATMENT OF LAKES

Chlorobornanes (CHBs) were isolated from recent and older sediments as well as from rainbow trout muscle in two prairie lakes that were trea ted with toxaphene as a pesticide in the early 1960s. Gored sediments representing the years of treatment(1961/1962) contained high concentr ations of hepta-, octa-, and nonachlorobornanes (Sigma CHBs, 1602 and 500 ng g(-1)) with a similar gas chromatographic peak pattern to techn ical toxaphene. In contrast, negative ion mass spectrometry confirmed that the near-surface sediments contained hexa- and heptachlorobornane s at levels not normally observed in environmental samples. This sugge sts that some of the original toxaphene mixture had been dechlorinated and was redistributed by porewater diffusion and/or sediment focusing . Analyses of fish revealed a toxaphene ''fingerprint'' similar to tha t of the dechlorinated material in sediments, suggesting that the chem ical was both water soluble and bioavailable. Significant residual CHB s in surface sediments and in fish indicate that other toxaphene-treat ed lakes should be reexamined.