Characterizing the Fate of Petroleum Biomarkers and Polycyclic Aromatic Hydrocarbons in Oil Spill Residues
The oil industry is one of the most important industries that support the energy demands of the modern world. Oil can enter the environment from different sources such as transportation, natural oil seeps, and accidental oil spills. Oil compounds are toxic (to varying extents) to coastal environments, and one of the main concerns of oil spills is releasing polycyclic aromatic hydrocarbons (PAHs) into the environment. PAHs are considered hazardous pollutants due to their toxicity, mutagenicity, and carcinogenicity and are classified as compounds with significant human health risks in the priority list of pollutants by USEPA. Thus, much attention has been focused on the source and fate of oil spill contamination in the environment and the natural processes by which the spilled oil is degraded, including photodegradation mediated by sunlight. The most common method for identifying an oil spill source is the chemical characterization of the spilled oil using petroleum biomarker fingerprints, which are geochemical organic compounds present in crude oils that can be related to their unique biological precursors. This dissertation focuses on three general research goals surrounding petroleum biomarkers and PAHs in oil spills. The first goal is to use petroleum biomarkers as oil spill fingerprinting methods and to complete an assessment of PAHs in the residues (tarmats) collected from the Persian Gulf shoreline remaining from the largest oil spill in history, the 1991 Gulf War oil spill. After an introduction in Chapter 1, Chapter 2 presents the results of a detailed field survey on the western shores of the Persian Gulf in Qatar and the chemical characterization dataset developed to investigate the source of the tarmats found in this area. The second goal is to characterize the fate of petroleum biomarkers over a 10-year period to validate their use for fingerprinting purposes in the residues (tarballs) of the 2010 Deepwater Horizon (DWH) oil spill in the Gulf of Mexico. For this purpose, Chapter 3 discusses the fate of three groups of petroleum biomarkers including terpanes, steranes, and triaromatic steranes in the DWH oil spill tarballs that have weathered in the Alabama coastal environment for over 10 years. The third goal is to characterize the efficiency of two types of low-cost LED light sources (full-spectrum and UV-A lights) for conducting laboratory-scale PAH photodegradation investigations, and Chapter 4 presents the results of this investigation. Finally, Chapter 5 summarizes the main findings of the studies conducted for this dissertation and discusses future research areas that are worth exploring in the context of oil spill pollution.