ORCID ID

0000-0002-3702-9419

Date of Award

5-2025

Degree Type

Dissertation

Degree Name

Ph.D.

Degree Program

Chemistry

Department

Chemistry

Major Professor

Matthew A Tarr

Abstract

This dissertation investigates the photochemical transformation of different crude oil types in marine environments, focusing on the time and temperature dependency of the formation of oxygenated photoproducts and their potential genotoxic effects. Using electrospray ionization tandem mass spectrometry (ESI-MS/MS), we examined the time and temperature dependence of aldehyde and ketone oxocarboxylic acid photoproduct generation from crude oil-seawater systems under simulated solar irradiation. The study revealed a near-linear increase in photoproduct concentration over an 18-hour irradiation period, with production rates ranging from 0.6 to 69 µmol/hm² of oil surface. Temperature effects on photoproduct formation were complex, but generally showed increased total organic carbon (TOC) in the aqueous phase with rising temperatures (12°C, 25°C, and 35°C).

Furthermore, we assessed the genotoxicity of these photoproducts using the Ames test with two strains of S. Typhimurium to detect frameshift and base-pair substitution mutations. The mutagenicity response showed a positive correlation with irradiation time for all three oils tested (Maya crude, NIST residual fuel, and Alaskan crude). Maya crude oil induced the most pronounced frameshift mutations, while NIST residual fuel oil exhibited the highest base pair mutations after 48 hours of irradiation. Temperature effects on genotoxicity were complex and did not present a clear trend.

These findings enhance our understanding of photochemical product formation in oil spills and their potential ecological impacts, contributing to the development of more effective pollution mitigation strategies and improved protection of marine ecosystems.

Rights

The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

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