Date of Award
The degradation of petroleum-derived organic pollutants in aquatic systems occurs through lengthened exposure to UV and visible light. In this thesis, organic pollutants include crude oil, refined fuels, and plastic particles or films. The photo-oxidation of these pollutants are monitored over natural waters. To characterize the molecular signatures of photo-oxidized petroleum, bench-scale spills of refined fuels and crude oil were irradiated over Alaskan waters. A 4-component fluorescence PARAFAC model revealed a unique feature associated with photo-oxidized refined fuel unlike traditional “microbial”- or “terrestrial-like” components. In contrast, crude oil photolytically decomposed into humic-like components and oxidized aliphatics. FT-ICR MS data corroborated the optical data. Overall, refined fuels produce a significantly higher mass of photoproducts than crude oil and carry a unique chemical signature.
To characterize degradation pathways of plastic particles mediated by reactive oxygen species (ROS), chemical probes were added to solutions of plastic in water to react with reactive transients produced from plastic irradiation. ROS examined were hydroxyl radical and singlet oxygen. A higher ROS production rate was observed in nanosized particles versus microsized particles, and higher in plastics with backbones containing ester bonds than that of backbones made of carbon-carbon bonds. Cloud point extraction was successfully used to separate plastic particles from water, and surface chemistry changes on shopping bags show early signs of degradation from UV light. Results in this thesis give encouraging precedent to future methods of studying photodegradation of environmentally relevant organic pollutants.
Whisenhant, Elizabeth, "Photoproducts and Transformations of Organic Pollutants in Aquatic Environments" (2022). University of New Orleans Theses and Dissertations. 3040.
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