Doctor of Philosophy (Ph.D.)
Virginia Institute of Marine Science
Robert C. Hale
Peter A. Van Veld
Aroclor 5432, a mixture of polychlorinated terphenyls (PCT), was detected in sediment and several biological compartments including: saltmarsh cordgrass (Spartina alterniflora), American oysters (Crassostrea virginica), red-jointed fiddler crabs (Uca minax), wharf crabs (Sesarma reticulatum) and mummichogs (Fundulus heteroclitus) collected from Tabbs Creek. This tidal creek is located in the southern Chesapeake Bay region. Species from several phyla were selected in order to examine PCT accumulation in physiologically and ecologically different organisms. In general, PCT concentrations in sediment and biota decreased with distance downstream from the PCT outfall. The organism with the highest mean concentration (18,300 &\mu&g/kg dry weight) was the native oyster, a benthic filter feeder. A second study examined the dose-response effects of PCT mixtures on levels of hepatic cytochrome P4501A (CYP1A) and associated EROD activity in the mummichog, relative to a polychlorinated biphenyl (PCB) mixture Aroclor 1254. Fish were injected intraperitoneally with PCT formulations Aroclor 5432, Aroclor 5460, or the PCB magnitude as that caused by equivalent doses of the PCB mixture Aroclor 1254. Treatment with Aroclor 5460 did not result in significant induction. This work represents the first report of hepatic CYP1A induction caused by Aroclor 5432 in teleosts and, similar to work in mammalian systems, suggests that the effects of this mixture may be mediated through Ah receptor binding. PCT mixtures contain small amounts of PCB. Therefore, PCB may have contributed to the induction observed following Aroclor 5432 injection. The planar PCB congener 3,3',4,4'-tetrachlorobiphenyl was identified in Aroclor 5432 by GC-MS operating in negative chemical ionization mode. Environmental induction was observed in mummichogs collected from Tabbs Creek. This study revealed CYP1A induction at the two most contaminated sites along the PCT gradient. Fish at the upper creek site exhibited inhibition of EROD activity. Definitive environmental induction by PCT could not be established due to the presence of other inducing pollutants in the creek.
© The Author
Gallagher, Kathryn, "Occurrence, fate and effects of polychlorinated terphenyls in an estuarine environment" (1995). Dissertations, Theses, and Masters Projects. Paper 1539616654.