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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Environmental risk management of contamination of marine biota by hydrocarbons specifically those arising following an oil spill

Enwere, Rita January 2009 (has links)
Marine pollution resulting from oil spillage has received much attention mostly due to the damaging effects it has on fisheries and aquacultures. One component of oil that is widely studied due to its toxic and carcinogenic properties is the polycyclic aromatic hydrocarbons. The physical and chemical properties of these compounds control their distribution into the various phases of the environment. The rates of elimination of these compounds from impacted organisms were investigated in laboratory and field experiments using selected marine organisms (Mytilus edulis and Salmo salar). The elimination of individual PAH compounds followed first order kinetics. Elimination rate varied among compounds and generally decreased with increase in molecular weight and degree of alkylation. Elimination rate constants (k2) and biological half-lives (t1/2) evaluated from chronically exposed mussels (collected from Aberdeen harbour) in separate laboratory and field studies were comparable but differed from those evaluated from acutely exposed mussels. Shorter t1/2 were obtained from acutely exposed mussels. The t1/2 ranged between 0.5- 22 d (acute exposure) and 3.8- 31.5 d (chronic exposure).The longer apparent t1/2 calculated for the chronically impacted mussels was attributed to the retention of the compounds in a stable compartment due to long period of exposure that limited exchange with the surrounding water. Contrary to expectation, t1/2 for similar compounds was higher in salmon than in mussels. The reason for this was unknown but attributed to the route of elimination. A good correlation (r2 > 0.72) was found between PAHs tissue concentration and taint intensity in salmon. Comparison of the results from this study with literature data showed that tank water replacement time and exposure duration affects rate of PAHs elimination. The data generated in this study and some of the reviewed studies will find application in different oil spill scenarios. The usefulness and limitations of the n-alkanes profile, PAH distribution and concentration ratios, and specific biomarker ratios from organisms in oil spill source identification was also demonstrated.
42

Towards a novel methodology for the environmental remediation of oil-polluted aqueous systems

Lawson, Jeffrey January 2010 (has links)
Aromatic hydrocarbons are a prevalent constituent of crude oil. The refined products of crude oil such as petroleum and diesel can find their way into groundwater though oil-spillages and are also present in the oil and gas industry’s produced water. These aromatics are biorecalcitrant, however upon ingestion with water, may be metabolised to toxic intermediates that are carcinogenic or mutagenic in nature. Although some treatment technologies are available most of these are under development and are yet to be proven in the field. This illustrates the need for novel, economical and environmentally friendly technologies to be developed with a view to remediating aqueous systems that have been polluted with aromatics hydrocarbons. The supramolecular cyclodextrin molecule, with its hydrophobic interior and hydrophobic exterior seems to be an excellent molecule for the trapping of the pollutant molecules, however the inclusion complexes with this cyclic sugar are water-soluble therefore there is a need for the cyclodextrin to be rendered waterinsoluble. A study of the aqueous solubilities of some aromatic hydrocarbons that may be present in crude oil has been carried out and shows that the majority of these molecules have a degree of water solubility that may increase upon environmental weathering. The successful reaction between a solid-phase resin and the β-cyclodextrin molecule has been achieved, with the total dryness of the system being required including Soxhlet extraction of the resin with anhydrous acetone before the reaction. The reaction between β-cyclodextrin and a range of isocyanates proved unsuccessful, but a range of symmetrical aryl ureas were synthesised from their isocyanates with the influence that different activating or deactivating groups on the ring have on the propensity to form the ureas being shown. The successful alkylation between β-cyclodextrin and a series of haloalkanes has shown the effect of increasing chain length on the degree of alkylation. This reaction involved the deprotonation of the cyclodextrin by sodium hydride in anhydrous dimethyl sulphoxide followed by reaction with the alkyl iodide. Increasing the equivalents of hydride or iodide, or the reaction time did not have a noticeable effect on the degree of reaction indicating that steric constraints were limiting the degree of reaction. Testing several of these alkyl iodides gave an indication as to their tendency to uptake and remove several model pollutants that had been dissolved in water with the propylated β-cyclodextrin displaying potential for the remediation of aqueous systems that had been polluted. Several of these results were very promising leading to the conclusion that further derivatives of these alkylated sugars may be even more suitable for future research into the remediation of organically polluted aqueous systems.
43

Geochemistry and bioremediation of oiled Louisiana salt marshes amended with clay minerals

Ghelerter, Jill 12 June 2014 (has links)
Salt marshes are one of the most difficult environments to remediate due to their sensitive and important ecosystems. Traditional cleanup methods can do more harm to the marsh than the oil itself. Bioremediation is the preferred cleanup approach for these delicate environments. Typically bioremediation has been carried out by the addition of nutrients but the results have been inconsistent. Previous laboratory studies conducted in oiled seawater demonstrated that clay minerals enhanced microbial growth and hence oil degradation. However, this had not been tested at field sites or on oiled marine sediments where oil is known to persist. The main objectives of this research were to test clay minerals as a bioremediation alternative for enhancing degradation of oiled salt marsh sediments and evaluate the geochemistry of sediment profiles for heavy metal enrichment. Laboratory experiments were carried out to evaluate the application of montmorillonite or kaolinite clay minerals on salt marsh sediments impacted by diesel oil. Oil biodegradation in control experiments was significantly more successful than in clay amended experiments. Clay minerals may have caused an increase in pH which inhibited enzyme-catalyzed processes required for metabolism. Field experiments were carried out in control and clay treatment plots in Louisiana salt marshes impacted by the Deepwater Horizon oil spill. In this research it was demonstrated for the first time that biodegradation of n-alkanes and PAHs was significantly enhanced by the addition of montmorillonite compared to controls. Vegetated treatment plots were slightly more effective than non-vegetative treatment areas. It is suggested that bivalent cations adsorbed to montmroillonite’s surface suppressed the diffuse double layer. This allowed the oil along the clay’s surface to be accessible to the bacteria where oil could be readily consumed. Clay minerals may serve as a new and unique bioremediation strategy for oiled salt marsh sediments. Geochemical sediment profiles from Louisiana salt marshes showed elevated concentrations of selected heavy metals (Zn > Cu > Pb > V > Cr > Fe > Ni). The Deepwater Horizon oil spill is a likely source of metal enrichment as many of these same metals are also constituents of the Deepwater Horizon oil.
44

An assessment of the impacts of spilt crude oil and dispersants on an intertidal wetlands community (mangroves) /

Wardrop, John A. January 1983 (has links) (PDF)
Thesis (M. Env. St.)--University of Adelaide, 1984. / Includes bibliographical references (leaves 273-308).
45

A knowledge-based spatial decision support system (SDSS) for coastal zone oil spill response in Anaktalak Bay, Labrador /

Russell, Karen, January 2004 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 2004. / Restricted until October 2005. Bibliography: leaves 127-136.
46

[en] THE USE OF THERMAL DESORPTION FOR CLEANING OILED DEBRIS / [pt] APLICAÇÃO DA DESORÇÃO TÉRMICA NA REMEDIAÇÃO DOS RESÍDUOS DA LIMPEZA DE PRAIAS ATINGIDAS POR DERRAMES DE ÓLEO

VANIA LUCIA DE OLIVEIRA PORTES 27 August 2002 (has links)
[pt] Notícias ambientais no Brasil foram dominadas através de derramamentos de óleo nos últimos anos. Esta dissertação apresenta os resultados de um programa experimental para estudar a capacidade de desorção térmica em limpar as costas afetadas.A temperatura ambiente, os resíduos oleosos emitem metano e amônia e estas emissões tendem a aumentar com a elevação das temperaturas. Por outro lado, o teor de óleo e graxa dos resíduos oleosos cai com o aumento da temperatura e exposição prolongada.Um cobertor térmico foi construído e avaliado. Os resultados mostraram que sua eficiência é restringida a poucos décimos de centímetros abaixo da superfície do solo devido à condutividade térmica de areias. Porém, esta desvantagem poderia ser contornada colocando o termopar de controle do sistema na profundidade desejada.Finalmente, a desorção térmica in situ parece ser um sistema único para a limpeza de resíduos oleosos. É simples, rápido e evita todo o incômodo associado à escavação de solo para disposição ou limpeza. / [en] Environmental news in Brazil has been dominated by oil spills in the past years. This dissertation presents the results of a comprehensive experimental programme on studying the ability of thermal desorption on cleaning up the affected shores.At ambient temperature, oiled debris emit methane and ammonia and these emissions tend to increase with rising temperatures. On the other hand, oil&grease content from oiled debris falls with rising temperature and prolonged exposure.A thermal blanket was designed, built and evaluated herein. Results have shown that its efficiency is restricted to few tenths of centimetres below the ground surface due to the thermal conductivity of sands. However, this drawback could be overcome is the control thermocouple of the system is positioned at the desired depth.Finally, in situ thermal desorption seem to be an unique system for cleaning debris from oil spills. It is simple, fast and avoids all the harassment associated to digging up the soil for disposal or cleanup.
47

A method for the bioremediation of insulating oil contaminated soil

Du Plooy, A. D. 04 February 2014 (has links)
M.Tech. (Operations Management) / The field of study is of a multi-disciplinary nature relating to chemistry, microbiology, electrical engineering, soil technology and legislation dealing with different aspects of soil, water and environmental contamination in South Africa The relevant basic principles involved as applicable to the problem being researched are discussed in the dissertation. The reader is introduced to the statement ofthe problem in Chapter 1. A study was carried out of research projects which were conducted elsewhere in the world with regard to oil pollution and the remediation procedures followed. This research project has focused on a problem which revolved around the pollution of soil from insulating oil spillages. Insulating oil is used in electrical equipment, such as transformers, tap changers and other items in the distribution of electricity throughout South Africa. Insulating oils perform three functions namely, a cooling function, acts as an insulator and as an indicator ofthe condition ofa transformer. The aim ofthe research was to develop methods and techniques, under the South African climatic conditions, to clean insulating oil polluted soil cost effectively. Oil in its various forms and derivatives is part of our modem society. Scientists are continuously designing new applications for various types of lubricants without the knowledge of the impact the product might have on the environment. When a pollution problem becomes intolerable, then a solution is investigated. Then man, with its superior brain power, goes to the simplest life on earth to solve his pollution problem. Various products and applications were investigated theoretically and also in practice. Case studies were investigated to determine the success rate of different products and applications. Laboratory tests were carried out to determine the true results of some of the products. The laboratory results were tested in practice on two test sites to confirm the results. The consequence of the research project has indicated that excellent results have been achieved. The results have indicated that insulating oil polluted soil can be cleaned in a...
48

The effect of weathering processes on the vertical turbulent dispersion characteristics of crude oil spilled on the sea

Boyé, Donald J. 29 July 1994 (has links)
Since the Exxon Valdez accident in 1987, renewed interest has come forth to better understand and predict the fate and transport of crude oil lost to marine environments. The short-term fate of an Arabian Crude oil was simulated in laboratory experiments using artificial seawater. The time-dependent changes in the rheological and chemical properties of the oil under the influence of natural weathering processes were characterized, including dispersion behavior of the oil under simulated ocean turbulence. Methodology included monitoring the changes in the chemical composition of the oil by Gas Chromatography/Mass Spectrometry (GCMS), toxicity evaluations for the oil dispersions by Microtox analysis, and quantification of dispersed soluble aromatics by fluorescence spectrometry. Results for this oil show a sharp initial increase in viscosity, due to evaporative losses of lower molecular weight hydrocarbons, with the formation of stable water-in-oil emulsions occurring within one week. Toxicity evaluations indicate a decreased EC-50 value (higher toxicity) occurring after the oil has weathered eight hours, with maximum toxicity being observed after weathering seven days. Particle charge distributions, determined by electrophoretic techniques using a Coulter DELSA 440, reveal that an unstable oil dispersion exists within the size range of 1.5 to 2.5 um, with recombination processes being observed between sequential laser runs of a single sample.
49

REDOX ENVIRONMENT CONTROLS ON THE DEGRADATION OF HARMFUL ORGANIC CONTAMINANTS IN MARINE SEDIMENT

Unknown Date (has links)
Harmful organic contaminants, such as petroleum hydrocarbons, are ubiquitous in coastal marine ecosystems around the world, a problem that will only be exacerbated with rising sea level and increased inundation of coastal urban areas. Therefore, it is necessary to understand the fate of these contaminants following their deposition on marine sediment, where they can potentially persist for long periods of time. As organic carbon remineralization rates depend on the respiration process employed by the bacteria in the sediment, it was the goal of this study to determine how the sediment redox environment, with an emphasis on Fe redox chemistry, affects the biodegradation of recalcitrant petroleum hydrocarbon compounds. While amendment of natural sediment with Fe minerals that are commonly transported to coastal areas following erosion from continental crust did successfully catalyze Fe reduction and inhibit sulfate reduction, the effect on the hydrocarbon biodegradation rate was negligible. However, inoculation of the sediment with Shewanella oneidensis, an exoelectrogenic, Fe reducing bacteria known to catalyze the degradation of hydrocarbon compounds found in crude oil, did significantly affect the redox environment and sediment microbial communities and alter the pattern of hydrocarbon loss in the sediment over time. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection
50

Beyond the wound and oblivion: the voz memoriosa and its narrative in two Radio Ucamara documentaries / Mais além da ferida e do esquecimento: a voz memoriosa e sua narrativa em dois documentários da Radio Ucamara / Más allá de la herida y el olvido: la voz memoriosa y su narrativa en dos documentales de Radio Ucamara

García, Andrea Cabel 01 January 2022 (has links)
In this research, we use an interdisciplinary approach to analyze the narrative of Radio Ucamara in order to render visible the material and spiritual consequences of the largest oil spill of the first decade of the 2000s in Peru. To do so, I analyze two documentaries: Consuelen a mi pueblo. Cuninico, dos años después (14' 37"), and Daños a la espiritualidad kukama (11' 40"). They show their forms of resistance and denunciation through what we call a voz memoriosa. This conceptual metaphor is characterized by intersecting their own social practices (songs, icaros, and stories) with official narratives (the chronology of the spill, the tallying of material damage, and extracts from trials). Thus, their way of presenting the consequences of the spill and of representing themselves in relation to them is not only cross-cultural, but also highly metaphorical. I chose to apply a qualitative approach based on ten extensive, in-depth, semi-structured telephone interviews and by instant messaging with Leonardo Tello, director of Radio Ucamara, from May 2020 to June 2021. The analysis and the theoretical concept reveal that documentaries are part of their social practices insofar as they involve community members and the non-human subjectivities with whom they relate. Thus, they, on their own terms, manage to interweave Western perspectives of linear (cause-consequence) remembrance with their polyphonic remembrance of organic aesthetics. The concept that I propose allows us to broaden Ginsburg’s use and understanding of organic aesthetics. The study also offers an analysis of the way in which those affected describe the consequences that environmental pollution brings directly upon their spirituality. / La presente investigación analiza desde un enfoque interdisciplinario la narrativa de Radio Ucamara para visibilizar las consecuencias materiales y espirituales del derrame de crudo de petróleo más grande de la primera década de los 2000 en el Perú. Para ello, analizo dos documentales: Consuelen a mi pueblo. Cuninico, dos años después (14' 37") y Daños a la espiritualidad kukama (11' 40"). Estos muestran sus formas de resistir y denunciar a partir de lo que llamamos una voz memoriosa. Esta metáfora conceptual se caracteriza por intersecar prácticas sociales propias (cantos, icaros e historias) con narrativas oficiales (la cronología del derrame, la contabilización de los daños materiales, extractos de juicios). De ese modo, su forma de presentar las consecuencias del derrame y de representarse frente a ellas no solo es intercultural, sino que es altamente metafórica. Se optó por aplicar un enfoque cualitativo sostenido en diez entrevistas extensas, a profundidad y semiestructuradas vía telefónica y a través de mensajería instantánea con Leonardo Tello, director de Radio Ucamara, desde mayo del año 2020 hasta junio de 2021. Los análisis y concepto teórico hechos permiten entender que los documentales forman parte de las prácticas sociales del territorio en tanto envuelven a los miembros de la comunidad y a las subjetividades no humanas con quienes se relacionan. Así las cosas, ellos, desde sus propios términos, logran entramar las perspectivas occidentales de recuerdo lineal (causa-consecuencia), con su recuerdo polifónico de estética orgánica. El concepto propuesto permite ampliar el uso y la forma de entender la estética orgánica de Ginsburg. Asimismo, el estudio propone un análisis de la forma en la que los afectados narran las consecuencias que la contaminación ambiental trae directamente a su espiritualidad.

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