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Many pesticides, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers
(PBDEs), and polycyclic aromatic hydrocarbons are persistent, bio-accumulative, and
toxic. These semi-volatile organic compounds (SOCs) can undergo atmospheric
transport and deposition in cold, remote ecosystems. A better understanding of their
accumulation in the fish of these ecosystems is important to better predict the human
and ecosystem health risks of these and other SOCs. This dissertation describes the
development of analytical methods to measure 91 of these SOCs at concentrations <1
ng/g in fish tissues, and determination of fish and ecosystem characteristics affecting
their distributions throughout western US lakes. To measure PBDEs in extracts, a gas
chromatography low resolution mass spectrometric method was developed for the
selective and quantitative isotope dilution analysis of 39 PBDEs. PBDE specific high
mass ion production was optimized, selectivity enhanced, and accuracy was improved
with the use of ¹³C surrogates. An analytical method was developed and validated to
measure 91 target compounds at <1 ng/g in fish. The method was sensitive (0.2-990
pg/g detection limits), efficient (61 % recovery), reproducible (4.1 %RSD), and
accurate (8 % deviation, NIST SRM #1946). SOC concentrations in 136 fish from 14
remote lakes were compared to human health contaminant screening values. Most fish
concentrations were 1-6 orders of magnitude below screening values, however average
fish concentrations of dieldrin and/or p,p’-DDE in 8 lakes exceeded lifetime cancer
screening values for subsistence fishers. Because fish SOC concentrations varied
several orders of magnitude within and between lakes, statistical models were
developed to explain the influence of 7 fish and 12 ecosystem characteristics on fish
SOC concentrations. Fish characteristics that best explained SOC concentrations were
fish age and lipid concentration. Average air temperature, measured winter SOC
deposition, and lake elevation were ecosystem characteristics that best explained fish
concentrations of historic use pesticides, current use pesticides, and PCBs and PBDEs,
respectively. This suggests that human health impacts are possible from some
atmospherically deposited SOCs, and that fish SOC concentrations in western US
lakes can be explained by combinations of fish lipid concentration and/or age, and air
temperatures, elevations, proximity to sources, and/or winter SOC deposition. |
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