Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 351 for “"Marine environment"”.
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Alpha-radioactive isotopes in the marine environment.
Various marine organisms collected from southern hemisphere waters around Cape Town were analysed by radiochemistry and alpha-spectrometry for Pu-239, 240. Many of these organisms were also analysed for Pu-238, Po-210 and - those isotopes of thorium and uranium that are alpha-emitters. In some …
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Rare-earth distributions in the marine environment.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Geology and Geophysics, 1966.
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Concrete ecological enhancement in the temperate marine environment
… may have on a concrete substrate in the marine environment. Firstly, the bioreceptivity of concrete in the coastal environment is reviewed, discussing the various methods by which bioreceptivity may be enhanced. The chemical bioreceptivity of concrete remains somewhat unclear, and …
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Studies of alpha-radioactivity in the marine environment
… deals with the alpha-radioactivity in the marine environment around South Africa, and the published literature relating to alpha-emitting nuclides in sea water and in marine organisms is surveyed in Chapter 1. As a first step in the investigation, the total alpha-activity of some 400 …
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The production of biogenic gases in the marine environment
… and methane is an important greenhouse gas. The marine environment is an important source of both DMS and methane and this thesis investigated the interactions between methylated sulphur compounds and methanogenesis within micro-environments in the upper-water column.<br/>The production of DMS is …
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Predictions of reinforced concrete durability in the marine environment
… of reinforced concrete structures in the marine environment. The objective was to identify reliable means of characterizing early-age properties of concrete which affect durability and relate these to the durability performance of the material under marine conditions. Establishing a …
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Molecular characterization of organically bound copper in the marine environment
Marine microbes require copper (Cu) for a variety of key enzymes and can therefore experience limitation when concentrations are low. However, when Cu concentrations are too high, it becomes toxic causing decreased cell growth and even cell death. Laboratory culture experiments have shown that a …
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Patterns and causes of population subdivision in the marine environment
… decisions for the management and conservation of marine resources. However, obtaining a precise assessment is particularly challenging since population subdivision results from the interaction of many biological and environmental variables. Here, the patterns of population subdivision that can be …
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Molecular Characterization of Organically Bound Copper in the Marine Environment
Marine microbes require copper (Cu) for a variety of key enzymes and can therefore experience limitation when concentrations are low. However, when Cu concentrations are too high, it becomes toxic causing decreased cell growth and even cell death. Laboratory culture experiments have shown that a …
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Characterizing bacterial antibiotic resistance, prevalence, and persistence in the Marine Environment
… the ocean as an understudied region of the environment for antibiotic resistance. The ocean represents an area of human activity with recreation and food consumption and it is an enormous region of the planet that is affected by both land and sea activities. In Chapter 2, I explore the …
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Characterizing bacterial antibiotic resistance, prevalence, and persistence in the marine environment
… the ocean as an understudied region of the environment for antibiotic resistance. The ocean represents an area of human activity with recreation and food consumption and it is an enormous region of the planet that is affected by both land and sea activities.
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Mechanisms of terrestrial organic carbon export and preservation in the marine environment
… carbon export and preservation in the marine environment. The thesis focuses on two globally important river systems that collectively deliver 25% of the total terrestrial carbon flux to the ocean, the Ganges-Brahmaputra (G-B) Rivers and the Amazon River. The first two chapters focus on …
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Interactions of Trace Metals with Plastic Production Pellets in the Marine Environment
… metal affinities for pellets collected from the environment (beached) and those obtained directly from a plastics processing facility (virgin) were also identified. Adsorption maxima for virgin pellets ranged from < 1 ng g-1 (Cd) to 300 ng g-1 (Cr) with corresponding, respective Langmuir …
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THE STUDY OF THE DISSOLVED NITROGEN CONTAINING MACROMOLECULES IN THE MARINE ENVIRONMENT
A method was developed for the direct determination of the dissolved combined amino acid (DCAA) content of seawater involving the acid hydrolysis of seawater under specified conditions, followed by the determination of the amino acids by reverse phase liquid chromatography (RPLC). No …
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Nitrate Reductase Activity, Nitrate Uptake and Iodine Speciation in the Marine Environment
<p>The present method for the determination of new production (NP) by measuring the uptake of added <sup>15</sup>NO<sub>3</sub><sup>–</sup> suffers from a number of limitations. In an attempt to improve this situation, this research examined the possibility of estimating …
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Measurement and behaviour of heavy metals in the marine environment of Singapore
… characteristics in Singaporea??s coastal environment. To evaluate relative mobility and bioavailability, a further study on the chemical speciation of heavy metals in the marine sediments from the two sampling sites was determined using a modified BCR-sequential extraction procedure. In …
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Numerical Modelling of Sediment Delivery from Tidewater Glaciers to the Marine Environment
Glaciated fjords are dynamic sedimentary environments with high deposition rates, thus providing high-resolution sedimentary records of deglaciation. This thesis introduces two numerical models, SedBerg and SedPlume, developed to simulate marine sedimentation from tidewater glaciers for the …
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Mechanisms of terrestrial organic carbon export and preservation in the marine environment
… carbon export and preservation in the marine environment. The thesis focuses on two globally important river systems that collectively deliver 25% of the total terrestrial carbon flux to the ocean, the Ganges-Brahmaputra (G-B) Rivers and the Amazon River. The first two chapters focus on …
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The determination and environmental significance of planar aromatic compounds in the marine environment.
… three groups of planar aromatic compounds to the marine environment. The groups comprised chlorobiphenyls (CBs), polychlorinated dioxins and -furans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs). Previous studies on toxicity, occurrence, origins and methods of analysis were reviewed, and …
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