EVIDENCE FOR ATMOSPHERIC TRANSPORT AND DEPOSITION OF POLYCHLORINATED-BIPHENYLS TO THE LAKE TAHOE BASIN, CALIFORNIA - NEVADA

PCB congener concentrations in air, water, fish, and snow were determi ned in the lake Tahoe basin and in the water and fish of an adjacent b ut more remote rural comparison lake, Marlette lake, to examine whethe r atmospheric transport and deposition are primary sources of contamin ation to this alpine region of the Sierra Nevada Mountains. Profiles o f 97 congeners analyzed by capillary GC-ECD from surface waters of Lak e Tahoe and Marlette Lake were closely matched, with total dissolved P CB (t-PCB) concentrations of 0.37 ng/L in Lake Tahoe and 0.67 ng/L in Marlette Lake. Gas-phase t-PCB concentrations measured in air samples from the Lake Tahoe basin averaged 72 pg/m(3), and t-PCB (dissolved an d particulate) concentrations in snow were 4.8-5.1 ng/L. Rainbow trout from Marlette Lake and lake trout from Lake Tahoe had similar distrib utions of congeners, with t-PCB tissue levels varying from 3 to 14 ng/ g wet weight. The finding of PCBs in all sampled compartments, particu larly snow and air, and the similar pattern of congeners in surface wa ters and in fish from Lake Tahoe and Marlette Lake indicate an atmosph eric source of contamination.