Bioremediation of unresolved complex mixtures in marine oil spills : an analytical perspective

THESIS 5340Unresolved complex mixture (UCM) is the fraction of some petroleums that cannot be resolved by conventional gas chromatography and is characteristic of biodegraded petroleum oils and some refined products such as lubricating oils. This study aimed to investigate the effects of environmental biodegradation, and more specifically shoreline bioremediation, on the chemistry of UCM. A number of wet chemical and instrumental analytical methodologies, including gravimetry, urea adduction, spectroscopy, chrom atography and mass spectrometry, were evaluated for their suitability to monitor UCM compositional changes during the course of biodegradation trials. Six UCM rich oils were also characterised using these methods, three crude oils and three lubricating oils. In parallel, an investigation of microbial degradation of UCM in solution was carried out in the laboratory. Using respirometry trials, undefined consortia of natural marine micro-organisms enriched on UCM demonstrated an enhanced ability to metabolise UCM. The pooled crude enriched consortium also performed considerably better at metabolising UCM when compared with a cocktail derived from the apparently dominant individual colonies (not identified) isolated from the crude consortium using standard techniques. Initial investigations of UCM biodegradation using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were carried out at this stage. An inoculum based on the undefined consortium was prepared for testing in microcosm trials