Date of Award

8-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Committee Chair/Advisor

Cindy M Lee

Committee Member

Kevin T Finneran

Committee Member

Lisa Bain

Committee Member

William Bridges

Abstract

Polychlorinated biphenyls (PCBs) and trichloroethene (TCE) are ubiquitous contaminants and are recognized as persistent organic pollutants due to their extreme chemical stability. PCBs were manufactured by chlorinating biphenyls that created 209 congeners with various structures, of which 19 are chiral and can exist as a pair of stable atropisomers. PCBs have been known to cause developmental and neurological toxicity in humans and wildlife; they can act as endocrine disrupters, carcinogens, and teratogens. Sangamo Weston Inc. was an industrial plant located near Town Creek in Pickens Country, South Carolina, that manufactured capacitors and used Aroclors 1016 and 1254 as dialectic fluids for the capacitors. Before the plant’s closure in 1987, around 220 tons of PCBs were dispensed into Town Creek, which eventually feeds into Lake Hartwell, now recognized as a Superfund site.

My research was conducted with four chiral PCB congeners (149, 136, 95, and 91) found in the Aroclor 1254 mixture. They were selected due to their diverse enantiomeric concentrations measured in the sediment, water column, and organic matter present in the Lake Hartwell watershed. I used sediment from Town Creek in my microcosms due to the high concentrations of PCBs recorded in that area of the watershed. Town Creek is a unique natural system for PCB research since PCBs and chlorinated solvents (such as tetrachloroethene and TCE) are the main contaminants with no hazardous metal or pesticide influence, making it an excellent natural system to evaluate elevated concentrations of Zn2+ and Cu2+ and their effect on microbial dechlorination of PCBs.

My research objectives also involved using TCE as a halo-primer for sediment and enriched cultures to compare dechlorination rates and to determine the dechlorination products when exposing the sediment culture to single enantiomers of PCB 95, separated using HPLC methods.

My studies served to increase the scientific knowledge on halo-priming as an effective use for stimulating PCB dechlorination, how essential metals influence anaerobic PCB dechlorination, and how single PCB enantiomers biodegrade.

Author ORCID Identifier

0009-0006-6635-6300

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