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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.
11

Characterisation of unresolved complex mixtures of hydrocarbons

Gough, Mark Adrian January 1989 (has links)
The hydrocarbons of recent polluted sediments, in-reservoir and laboratory biodegraded crude oils, and certain petroleum products (e.g. lubricating oils) often display 'humps' or Unresolved Complex Mixtures (UCMs) when analysed by gas chromatography (GC). Although widespread and often abundant, to date little is known of their detailed molecular composition. Standard chromatographic methods of isolation of model aliphatic and aromatic hydrocarbon UCMs from lubricating oils followed by conventional methods of analysis provided little compositional detail. Thus GC and GC-electron impact mass spectrometry (GC-EIMS) was limited to an estimate of carbon number ranges and to the identification of certain series of 'biological marker' compounds. However, these were well resolved and were estimated to account for <10% of the total detector response. Further analyses were performed by chemical ionisation-MS (CI-MS), probe distillation EI-MS, field ionisation-MS (FIMS), and elemental analysis; yet the information provided by each was limited to a few 'average' molecular types. In view of the limitations of conventional methods of analysis, alternative methods were adopted. These utilised novel chemical and pyrolytic degradations of the UCM hydrocarbons. Chemical oxidation with Cr03 in glacial acetic acid produced reasonable yields of total recoverable material (40-80%). Furthermore, a high proportion were functionalised (>90%), and many resolved, which allowed their identification by EI and CI GC-MS. Surprisingly, the most abundant products of oxidation of hydrocarbon UCMs were straight chain monocarboxylic acids. This appeared to contradict literature consensus on UCM composition, namely a predominance of highly branched and/or cyclic hydrocarbons. However, from literature reported CrO oxidations of hydrocarbons, potential precursor compounds were proposed. These were monoalkyl substituted 'TO-branched acyclic and monocyclic alkanes for the aliphatic UCM and alkyl 'TO-branched monoaromatic hydrocarbons for the aromatic UCM. Proposed precursor UCM hydrocarbons were confirmed by synthesis and chemical oxidation under the same conditions. Thus each of the synthetic candidate UCM hydrocarbons [7-n-hexylnonadecane, 9-(2-phenylethyl)-heptadecane and 9-(2- cyc 1 ohexyl ethyl j--hep tade cane] produced n-acids on oxidation with Cr03- Further correlations were found for products of other synthetic alkanes and less abundant UCM oxidation products. For example, n-alkan-2-ones. iso alkan-2- ones, and 7-methyl--y-lactones could all be correlated with methyl substituted acyclic alkyl linkages on UCM hydrocarbons. The application of chemical oxidation to aliphatic UCMS of varied origin showed the technique has great potential for fingerprinting such samples. GC-MS analysis of a selected series of resolved product compounds (alkyl ketones, -y-methyl--y-lactones) showed good correlations for samples of the sane origin, yet distinct differences for UCHs from different sources. Biodegradation of the three candidate UCM hydrocarbons alongside acyclic isoprenoid alkanes and normal and monomethyl alkanea showed the UCM hydrocarbons were at least as resistant to microbial degradation as the isoprenoid alkanes. In this context it is therefore concluded that the candidate UCM compounds serve as good molecular models for hydrocarbon UCMs.
12

Studies of the synthesis, environmental occurrence and toxicity of unresolved complex mixtures (UCMs) of hydrocarbons

Wraige, Emma Jane January 1997 (has links)
The occurrence of unresolved complex mixtures of hydrocarbons (UCMs) in the aliphatic fraction of marine sediments and organisms from areas impacted by petroleum hydrocarbons is well documented and widely accepted as an indication of fossil fuel contamination. In contrast, the presence of an aromatic UCM is often ignored and environmental concentrations of aromatic UCM hydrocarbons in marine biota and sediments are rarely reported. The aims of this study were to establish the quantitative significance of aromatic UCMs in environmental samples and to assess the toxicological significance of both aliphatic and aromatic UCMs. A reproducible method was developed and validated for the analysis and quantification of petroleum hydrocarbons in mussel (Mytilus edulis) tissue. Emphasis was placed upon development of a method which minimized losses of more volatile, lower molecular weight, toxicologically significant hydrocarbons, without compromising recovery of higher molecular weight compounds which are useful for source identification in environmental monitoring schemes. Analysis of mussels from a small number of U. K. coastal locations indicated that aromatic hydrocarbon UCMs may form a significant proportion (ca 20 %) of the total hydrocarbon body burden of mussels from areas contaminated with petroleum hydrocarbons. Aromatic UCM hydrocarbons were not observed in mussels from relatively uncontaminated areas but concentrations of 430 μg g'' (dry wt tissue) were measured in mussels from heavily impacted areas. Aliphatic UCM concentrations ranged from 7- 3445 μg gg' (dry wt tissue). For the purposes of toxicological studies, a low molecular weight model aliphatic UCM hydrocarbon, 4-propyloctane (4-PO) was synthesised. Two low molecular weight model aromatic hydrocarbons 7- cyclohexyltetralin and 7-cyclohexyl-l-propyltetralin were also synthesised using a modification of the Haworth synthesis. All three target compounds and synthetic intermediates were characterised by NMR, MSandIR. Exposure of M. edulis to 4-PO caused a significant reduction in mussel ciliary feeding activity indicating that 4-PO was indeed toxic as measured by this bioassay. The demonstrable narcotic activity of 4-PO is presumably related to the greater aqueous solubility of branched hydrocarbons compared with similar straight chain hydrocarbons. Further experiments investigating the effect of 4- PO over exposure periods up to 120h provided a unique and detailed insight into the relationship between concentration of toxicant in the gills of M. edulis and observed feeding rate. The established method of mussel feeding rate determination was modified in light of this relationship to produce an " improved rapid and reproducible screening technique. Both of the model aromatic UCM hydrocarbons were also found to be toxic to mussel ciliary feeding activity. This appears to be the first report of investigations into the toxicity of the aromatic UCM and suggests that previous studies have ignored an environmental burden of toxicological significance. Estimates of the tissue effective concentration (TEC50) for the model UCM hydrocarbons gave comparable values with those reported for the effect of other narcotic hydrocarbons upon mussel feeding rate, providing support for the theory that non-specific narcosis occurs at a relatively constant tissue concentration of toxicant. The demonstrated narcotic activity of each of the three model UCM hydrocarbons has extended the molecular weight range of narcotic hydrocarbons studied to date. The results presented herein suggest that a small proportion of low molecular weight aliphatic UCMs and perhaps a greater proportion of aromatic UCMs are of toxicological significance.
13

Tradable permit markets for the control of point and nonpoint sources of water pollution technology-based collective performance-based approaches /

Taylor, Michael A., January 2003 (has links)
Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xi, 465 p.; also includes graphics. Includes abstract and vita. Advisor: Allan Randall, Interdisciplinary Program. Includes bibliographical references (p. 161-165).
14

Public participation : principles and practice : the legal regulation of water pollution

Burton, Timothy Paul January 1990 (has links)
The main body of the thesis is a detailed study of the practice of the legal regulation of water pollution, primarily between the period of 1 October 1983 and 31 August 1989, although reference is made to events preceding that period where necessary to provide a full assessment.
15

The development of an in house greywater and roof water reclamation system for large institutions during 1994 to 1998

Surendran, Sundaralingam S. January 2001 (has links)
For sustainable water management, here is a necessity to consider alternatives, in addition to conventional systems. The aim of this research is to develop and demonstrate a sustainables, from and greywater reclamation system for WC flushing and it was started in 1994. In the UK there are no water quality standards for WC flushing water use. There were no design guidelines for greywater water reclamation and no published study on the supply-dernandb alance, in detail, for water recycling in institutions such as universities. The research has shown the feasibility of planned direct grey and storm water reclamation and recycling system to manage growing water and wastewater problems. This thesis is based on the information gathered from 4 universities, 3 hotels and 3 recreational centres, and experiences gained at Loughborough University during the development and demonstration of the full scale "in-house grey and roof water" reclamation and recycling systems. The water use, greywater quality and roof water characteristics were studied in detail and this information was used for the development of the reclamation and recycling system. The studies showed that the water usage at the university halls were not similar to usage in households. Unlike large water supply schemes, small in-house systems generate a large peak factor for water use. To avoid deficit, in addition to personal washing waters, a top-up of laundry wastewater or roof water, and a well-designed balancing tank is necessary. The demonstration study shows that there was no standby mains' water used, which means that the water reclaimed was sufficient for reuse. The quality characterisation study shows that the greywater and first flush storm water roof runoff were polluted. The characteristics of combined grey and roof water are suitable for biological treatment. Based on the infomation, a lab-scale unit was developed; the reactor characteristics and performance such as head losses and removal efficiency were monitored; and the unit was refined. Two novel multi-barrier reclamation systems were developed to achieve sufficient quantity and near potable quality of water with minimum maintenance and cost. During 1997 the grey and roof water recycling system with laboratory tested physical and biological reclamation processes without the use of coagulants and disinfection were installed. The performance of the treatment system was closely monitored until 1998. This provided benefits in near potable quality of reclaimed water, low head loss, reliability, failure free operation and simple maintenance. The reclaimed effluent from Project I and 2 met the UK/EU bathing water standards and was also able to meet the US EPA standards for WC flushing. The microbial (using coliform as an indicators) quality of reclaimed water without disinfection is acceptable for controlled recycling systems (carefully monitored and fully informed). There were no odour problems in the treated water or sludge blockages. Comparatively, Project I was more efficient at removing coliform, turbidity, solids (suspended, dissolved, volatile), and Project 2 better at removing carbon (organic and inorganic). A simple cost benefit analysis done for the recycling system at Royce Hall of Residence showed 10 years pay back. More detailed cost-benefit analysis including comparisons of new built and retrofit recycling system and fife cycle analysis are recommended. This study shows that most of the people questioned were accepted and were willing to consider using the recycling system for toilet flushing, if the water was clear, colourless, odour free, carried no risk and gave cost-benefits. During the demonstration stage the users willingly accepted non-potable grey water reuse.
16

Stream water quality studies in a recreational area

Hurpaul, Leckrazsingh, January 1971 (has links) (PDF)
Thesis (M.S. - Civil Engineering and Engineering Mechanics)--University of Arizona. / Includes bibliographical references.
17

A strategic response to water crises : examining the application of integrated water resource management in Afghanistan /

Najibullah Yamin, Kanchana Nakhapakorn, January 2008 (has links) (PDF)
Thesis (M.Sc. (Natural Resource Management))--Mahidol University, 2008.
18

Stream pollution study, Wichita Drainage Canal, Wichita, Kansas comprehensive report submitted for the degree--Master of Science, Public Health Engineering /

Cherry, R. Paul. January 1900 (has links)
Thesis equivalent (M.P.H.E.)--University of Michigan, 1947.
19

Stream pollution study, Wichita Drainage Canal, Wichita, Kansas comprehensive report submitted for the degree--Master of Science, Public Health Engineering /

Cherry, R. Paul. January 1900 (has links)
Thesis equivalent (M.P.H.E.)--University of Michigan, 1947.
20

Examining the presence and prevalence of key human enteric viruses in environmental samples using cultivation, molecular and array-based tools for detection

Wong, Mark Vee-Meng. January 2008 (has links)
Thesis (Ph. D.)--Michigan State University. Dept. of Crops and Soil Sciences, 2008. / Title from PDF t.p. (viewed Aug. 18, 2009). Includes bibliographical references (p. 147-171). Also issued in print.

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