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Browsing by Author "Bojan, Olivia, author"

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    Exposing new compositional coverage of weathered petroleum hydrocarbons through a tiered analytical approach
    (Colorado State University. Libraries, 2019) Bojan, Olivia, author; Blotevogel, Jens, advisor; Sale, Tom, advisor; Denef, Karolien, committee member
    Petroleum hydrocarbon spills are a widespread source of contamination that may threaten ecosystem services and human health, especially due to modern society's dependence on petroleum-based fuels. Remediation mainly relies on natural source zone depletion (NSZD) processes, which may generate partially oxidized transformation products of the spilled hydrocarbons through weathering or biodegradation processes. These byproducts containing one or more heteroatoms (N, S or O) – referred to as "polar hydrocarbons" – have increased water solubility and mobility in the environment. The unknown fate and toxicity of these complex mixtures of polar metabolites are causing growing concern. The objectives of this thesis were (1) to use a tiered analytical approach to investigate polar transformation products from various sources and (2) to identify common marker compounds that can be used for a more focused characterization of weathering processes at petroleum-contaminated sites. Previous studies have shown that the majority of weathered petroleum hydrocarbon compounds could not be detected by the GC-based analyses currently required by the United States Environmental Protection Agency due to their low volatility and high molecular weight. Therefore, standard methods may yield misleading characterizations of plumes and impede effective risk management. Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), an emerging analytical technique in the field of "petroleomics" (the characterization of petroleum at the molecular level) offers unrivaled resolving power and mass accuracy; here it was used to determine the elemental composition of highly complex petroleum mixtures present in hydrocarbon-impacted sediment samples collected from field sites with varying redox and hydrogeological conditions. The tiered analysis revealed that GC-based techniques could only detect select nonpolar, low-molecular weight species (