Thesis (Ph. D.)--University of Wisconsin--Madison, 1973. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Subsurface oil and surface seep samples from the Niger Delta Nigeria, Tano and Cape Three Points Basins in Ghana, and the Orcadian Basin in Scotland were analysed using an organic geochemistry approach. Source organofacies, oil thermal maturity and the effect of alteration processes were evaluated, with the aim of developing a better understanding of the origin, nature and type of petroleum present. Biomarker analyses suggested that undegraded oils are found with biodegraded oils with a range of levels of biodegradation in the Niger Delta. On the commonly used Peters and Moldowan scale of biodegradation, the samples rank between PM level 0 and 7. The Ghanaian and Scottish oils and seeps showed a range of biodegradation levels between PM level 2 and 7. Biodegradation appeared to be the major control on the composition and physical properties of the oils and seeps from Niger Delta and Ghana while there is evidence that a stage of water washing was important for the Scottish seeps. Key aspects of the biodegradation process were reflected in the variable occurrence of hopanoids and other biomarkers. 25-Norhopanes were detected in all samples biodegraded in subsurface reservoirs but absent in seeps degraded at surface conditions. This was observed for both the Ghanaian and Nigeria samples. The inverse relationship of hopane to 25- norhopanes in the Niger Delta is presented for the first time. This evidence supports the hypothesis that 25-norhopanes are a product of hopane demethylation. Furthermore a pathway for the formation of 25-norhopane from 25-norhopanoic acid by decarboxylation is evidence by nature of the covariation in relative concentration of these compounds. Seeps from Scotland show that only moderate levels of biodegradation (PM 3) have significantly reduced monoaromatic and triaromatic steroids abundances. The most likely cause for this is by water washing at surface conditions. Reservoir temperature and oil charge histories appeared to have had a significant influence on the extent of biodegradation in the Niger Delta. The late migration of oil from deeper hotter subsurface regions to shallow reservoirs accounts for the presence of undegraded oils amidst the biodegraded oils in the Niger Delta.

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In 1970 the Arrow oil spill off Cape Breton contaminated 305 kilometres of shoreline. Aerial and land surveys have demonstrated that natural weathering has occurred throughout this period, but it was relatively slow, especially in sheltered areas like Black Duck Cove lagoon. This study analyzed the microbial hydrocarbon degradation potential in the lagoon sediments using direct and culture-based techniques. Mineralization of hydrocarbon substrates (hexadecane, octacosane and naphthalene) indicated the presence of an active degradative microbial community, however, genes from known bacterial hydrocarbon degradation pathways (alkB, ndoB, phnAc) were not detected by direct extraction of sediment DNA and PCR amplification. Sediment enrichment cultures had increased mineralization rates for naphthalene and hexadecane, and a hexadecane-degrading pure culture, Rhodococcus sp. BDC14, with a typical alkB gene was isolated. PCR analysis of total community DNA extracted directly from the enrichments indicated the presence of the Alcanivorax borkumensis alkB1 genotype. The results demonstrated that there were notable differences between culture-based and direct molecular analytical techniques in characterizing the contaminated sediments.

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