Evidence for organochlorine contamination in tissues of salmonids in Lake Tahoe

To evaluate the extent of organochlorine pollution in the Sierra Nevada eco system, residues of certain organochlorines in lake trout and Kokanee fish from Lake Tahoe, an alpine lake located between the Sierra Nevada Mountain Range and the Carson Range of California and Nevada, were analyzed. Multire sidue analysis in fish muscle revealed wet weight concentrations of total p olychlorinated biphenyls (PCBs) in the range 18 to 430 ppb and of p,p'-DDE in the range 5 to 85 ppb in the two fish species studied. In one large lake trout sample (6.6 kg), which was studied in more detail as compared with o thers, residue levels of PCB (267 ppb), toxaphene (154 ppb), a chlordane mi xture (78 ppb), and a DDT mixture (154 ppb) were found in muscle. Full spec tra of specific PCB congeners and p,p'-DDE were obtained from fish fat tiss ues and their identities were confirmed using gas chromatography/mass spect rometry (GC-MS). The results of total PCB analysis indicated that residues found in fish consisted mostly of moderately (tri- to tetrachloro-) to high ly (penta- to heptachloro-) chlorinated biphenyls, For all fish residues an alyzed, the best match to PCB residue profiles was with Aroclor 1260 or 126 2. (C) 1999 Academic Press.