Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

No description available.

by Jimmy Siu-hung Tsang. / Bibliography: leaves 124-148 / Thesis (M.Ph.)--Chinese University of Hong Kong

Two case studies are described where partially biodegraded petroleum residues were collected from the marine environment and analysed to investigate the changes in aromatic hydrocarbons with increasing biodegradation.The first of these studies, involved following the weathering of sea-floor residues from drilling discharges from an offshore petroleum exploration and production platform situated off the coast of North Western Australia. During operations, formation cuttings with adhering oil-based drilling muds were discharged into the ocean via a chute into approximately 125n1 of water, forming a substantial mound at the base of the platform. A suite of seabed sediments was collected from 16 sampling sites at various distances from the platform immediately following the cessation of drilling operations. The distribution of hydrocarbons in the sediment directly under tile cuttings chute was consistent with that found in drilling fluids formulated from a kerosene-like fluid. The samples from more remote sites exhibited the successive enhancement of an unresolved complex mixture relative to the n-alkanes, associated with tile presence of residues from petroleum biodegradation processes. In a subsequent sampling some three years later, a 10 cm core was retrieved from the cuttings pile and divided into 1 cm depth intervals. Samples within 6 cm of the surface of the cuttings pile contained biodegraded residues of the drilling mud, where the extent of biodegradation increased with decreasing proximity to the surface, most likely indicative of aerobic biodegradation. Biodegradation was less evident in the underlying sediments, where anaerobic conditions prevailed. / Analysis of the aromatic hydrocarbons in both sets of sediment extracts by using gas chromatography-mass spectrometry (GC-MS) revealed the successive depletion of alkylnaphthalenes, and due to the subtlety of changes in the extent of biodegradation, provided an excellent opportunity to examine the susceptibility of biodegradation towards the individual alkylnaphthalenes in the marine environment. Conventional GC-MS analysis of these mixtures is performed under chromatographic conditions where complete resolution of the mixture is not achieved and several isomers co-elute. The mass spectra of these co-eluting isomers may be so similar that one is unable to differentiate between them, and their abundance may therefore not be determined. Since each isomer has a unique infrared spectrum, however, the abundance of each individual isomer was determined by comparing the infrared spectrum of the co-eluting compounds with the spectrum of each of the isomers. To this end, techniques were developed for the application of direct-deposition gas chromatography - Fourier transform infrared spectroscopy (GCFTIR) to the analysis of the complex mixture of alkylnaphthalenes present in the petroleum. This technique was also extended to discriminate between individual alkylphenanthrene isomers, and to clarify the sorption behaviour of the dimethylphenanthrenes by mordenite molecular sieves. The identification of other compounds of geochemical significance in petroleum is also described. / Analyses of' the aromatic hydrocarbons in the contaminated sea-floor sediments using GC-FTIR enabled the unambiguous identification and quantification of each of the dimethylnaphthalene, trimethylnaphthalene and tetramethylnaphthalene isomers present in the samples, from which the relative extents of depletion of each with increasing extent of biodegradation were determined. It was apparent from the considerable differences in the observed susceptibility to biodegradation that a strong relationship exists between the compound structure and its susceptibility to biodegradation, with 1,6-disubstituted polymethylnaphthalenes being preferentially depleted relative to other isomers that lack this feature. The second case study involved tracking the fate (weathering) of hydrocarbons from an accidental release of condensate from a buried pipeline into intertidal coastal (mangrove) sediments in North Western Australia. Sediment samples were collected on nine occasions over a three-year period. Chemical analysis of the saturated and aromatic hydrocarbon components of the petroleum extracts revealed that both hydrocarbon fractions exhibited an increasingly biodegraded profile with increased residence time in the sediments. In a similar manner to the first case study, detailed analysis of the aromatic hydrocarbons using GC-FTIR techniques was performed to determine the depletion of individual alkylnaphthalene isomers with increasing extent of biodegradation. It was apparent that a relationship similar to that observed for the sea-floor sediments exists between the alkylnaphthalene structure and its susceptibility to biodegradation. / Changes in the distribution of methylphenanthrene and dimethylphenanthrene isomer mixtures were also studied and the susceptibility to biodegradation amongst these determined in a similar manner. These relative susceptibilities to biodegradation of the aromatic hydrocarbons were then related to the established hierarchy of susceptibilities of the saturated hydrocarbons, in effect providing a second parallel system for the assessment of the extent of biodegradation. Finally, a system of ratios calculated from the relative abundances of selected aromatic hydrocarbons was developed and used as indicators to differentiate between several crude oils that have been biodegraded to varying extents. These parameters also offer promise as indicators of multiple accumulation events in oil reservoirs where petroleum fluids biodegraded to differing extents are mixed.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

The aerobic transformation of TCE and cis-DCE by a tetrabutoxysilane-grown microorganism (Vancheeswaran et al., 1999) led to the investigation of novel substrates, including benzyl alcohol, for promoting cometabolism. The culture grew on carboxylic compounds and alcohols, but did not grow on formate, methanol, methane, propane, butane, ethylene, benzene, toluene, or p-xylene. Cis-DCE transformation was observed when the culture grew on butyrate, glucose, 1-propanol, 1-butanol, ethanol, benzyl alcohol, and phenol, and effectively transformed TCE, cis-DCE, and vinyl chloride when grown on phenol or benzyl alcohol. Several cycles of growth on benzyl alcohol led to increases in TCE transformation rates and transformation capacities. Products of benzyl alcohol degradation shifted from benzaldehyde to 2-hydroxy benzyl alcohol (2HBA) during the several cycles of growth. In resting cells studies, 2HBA production rates were highly correlated with TCE transformation rates. TCE transformation and 2HBA production rates doubled when the culture was grown on phenol and rates of TCE transformation were correlated with 2HBA production rates. Benzyl alcohol- and phenol-grown cells oxidized toluene to o-cresol, which indicated the similarity between benzyl alcohol ortho-monooxygenase, phenol hydroxylase, and toluene ortho-monooxygenase. 2-Butyne and 1-hexyne (but not acetylene) inhibited benzyl alcohol- and phenol-grown cells similarly, indicating the same ortho-monooxygenase was responsible for TCE cometabolism. Resting cell kinetic studies were performed with cells grown on phenol or benzyl alcohol. Benzyl alcohol degradation followed a Monod kinetics while phenol degradation followed a Haldane kinetics. The maximum transformation rates (k[subscript max]) of TCE, cis-DCE, and VC achieved by phenol-grown cells were about a factor of two higher than achieved with benzyl alcohol-grown cells, while the half-saturation constants (K[subscript s]) were in a similar range. Transformation capacities (Tc) for TCE, cis-DCE, and VC were about a factor of two to four higher with phenol-grown cells. The modeling of TCE, cis-DCE, and VC transformation using independently measured k[subscript max] and K[subscript s] values matched well with observed data from batch tests. Benzyl alcohol was shown to be an effective novel substrate for the aerobic cometabolism of TCE, cis-DCE, and vinyl chloride. Being a non-regulated compound, it might have applications for in-situ bioremediation. / Graduation date: 2004

Plant-based remediation techniques that can address mixtures of heavy metals and organic contaminants in soil warrant investigation due to their cost effectiveness and public acceptability. The potential of phytoremediation to remediate mixtures of heavy metals and hydrocarbons in soil is presented in two papers. A hydropic screening of twenty-seven forage grasses, grown in a solution containing 100 muM Zn, 5 muM Cu and 1 muM Cd, provided six species that were exceptionally metal tolerant. These six species were examined for their growth response and root phenolic secretion at five levels of hydroponic heavy metal contamination. Phenolic secretion, an indicator of a plant's capacity to promote polycyclic aromatic hydrocarbon (PAH) degradation, increased with heavy metal contamination, however, the values were low (<30 mug/g root). Two high biomass producing, metal-tolerant grasses, Bromus riparius and Arrhenatherum elatius, were combined with M2Rhizo4, a strain of plant growth-promoting rhizobacteria. The plant-bacterial combinations were established in artificial and genuine soils contaminated with heavy metals and PAHs at a range of concentrations. In contaminant-free artificial soil, inoculation promoted B. riparius growth by 25% compared to non-inoculated plants. In artificial soil, contaminated with 495 mg/kg Zn, 263 mg/kg Cu and 23 mg/kg Cd, M2Rhizo4 promoted B. riparius growth by 22%. In chromated-copper-arsenate (CCA) and creosote contaminated soil, M2Rhizo4 inoculated A. elatius had 15% more biomass and greater survival rates than non-inoculated A. elatius. A phytoremediation system composed of metal-tolerant plants inoculated with hydrocarbon-degrading or plant growth promoting bacteria may be suitable for sites contaminated with a mixtures of hydrocarbons and heavy metals.

No description available.

Batch microcosms utilizing indigenous microorganisms were used to examine the effect of soil pH on the biodegradation of benzene, toluene, ethylbenzene, and m-xylene in subsurface soils. The biodegradation potential of both denitrifying and aerobic respiring microorganisms were assessed. Uncontaminated soil from five different soil depths was utilized. The pH of each soil was adjusted, such that a range of soil pH values existed at each soil depth. In this way, degradation rates of each of the aromatic compounds were determined at different soil pH values. Soil from each depth was characterized on the basis of: (1) soil particle size, (2) natural soil pH, (3) moisture content. It was suspected that the physical and chemical characteristics of a soil affected the microbial populations and the subsequent biodegradation potential of that soil. At each soil depth, microcosms under aerobic conditions experienced a higher cumulative degradation rate of the BTEX compounds than did microcosms under denitrifying conditions. The results from this study suggest that the natural soil pH did not provide an optimum environment for those aerobic respiring microorganisms which degrade BTEX. But rather, each depth in the soil profile had an optimum soil pH existing somewhere within the pH 5.4 to 6.6 range. Thus, the maximum combined degradation rate of BTEX was not found in soils at the natural soil pH. The 15 ft soil experienced the highest maximum combined degradation rate of BTEX. This soil had the highest moisture content, and relatively high sand and silt contents, which may have provided optimum conditions for microbial growth and subsequent biodegradation. / Master of Science

Increased production of petroleum based products to keep pace with technological advances has taken its toll on the environment. Hydrocarbon contamination of the subsoil and groundwater has become a major problem facing scientists and environmentalists in the 20th century. Initial treatment of contamination sites include the removal of the contaminant from the subsurface for subsequent above ground remediation. Once these methods are exhausted, some type of <i>in-situ</i> remediation, particularly aerobic biodegradation, is sought. Although considered the preferred treatment method, <i>in-situ</i> biodegradation's usefulness is currently limited by oxygen delivery and retention techniques. A novel method of delivering supplemental oxygen to the subsoil, colloidal gas aphrons, has been studied. In addition, this method was compared to the current technique of sparged air injection. The methods and equipment for conducting experimentation on the aeration of an unconfined aquifer, as a vertical slice of soil, have been developed. A specific number of parameters including dissolved oxygen concentration, hydraulic conductivity and tracer dye concentration were measured in order to determine the state of aeration of the saturated soil. Colloidal gas aphrons, CGA, were generated using both NaDBS (sodium dodecylebenzenesulfonate) and Tergitol 15-S-12 surfactants. These dispersions were injected into a 7ft by 7ft by 5in wide two-dimensional vertical slice test cell, which contained about 1600lbs of soil. Continuous dissolved oxygen measurements were conducted using an in-line analysis chamber. Samples were removed through the back of the cell via double-ended shutoff valves and a peristaltic pump. Hydraulic conductivities were monitored to observe variations in fluid flow following the injection of CGA/sparged air. The main conclusions of this work are: l. Both CGA and sparged air introduce dramatic increases in groundwater dissolved oxygen concentrations after injection into the saturated soil. 2. CGA, unlike sparged air/air saturated water, provide supplemental oxygen which forms an "oxygen wall". CGA accumulate near the injection tube forming a stationary front which enhances the dissolved oxygen concentrations of groundwater flowing through the cell. 3. Air sparging does not appear to be as efficient a means of oxygen enhancement of the subsoil as CGA delivery. / Master of Science