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 54 for “"Chemical oceanography"”.
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thesis in the field of Chemical Oceanography: Marine iodine biogeochemistry: inorganic speciation, redox dynamics and organic complexation
Iodine holds significant importance across various disciplines, including medicine, industrial processes, organic synthesis, paleoclimatology, atmospheric chemistry and modern climate science. The ocean, as a major surficial iodine reservoir and the primary source of this element to the atmosphere, …
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Protein regulation in Trichodesmium and other marine bacteria: observational and interpretive biomarkers of biogeochemical processes
… key roles in global biogeochemistry by mediating chemical transformations and linking nutrient cycles to one another. A major goal in oceanography is to predict the activity of marine microbes across disparate ocean ecosystems. Towards this end, molecular biomarkers are important tools in chemical …
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Insight into chemical, biological, and physical processes in coastal waters from dissolved oxygen and inert gas tracers
… O2 and inert gases to provide insight into the chemical, biological, and physical processes that impact the oceanic cycles of carbon and dissolved gases. Dissolved O2 concentration and triple isotopic composition trace net and gross biological productivity. The saturation states of inert gases …
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Marine thorium and protactinium distributions: Tools for past and present chemical flux
… scavenging behavior can be utilized to trace chemical flux in the modern and the past ocean. While 230Th and 231Pa are produced by the radioactive decay of uranium dissolved in seawater, 232Th is added to the ocean via the input of continental material. Removal of Th by scavenging should be …
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Temporal variability in chemical cycling of the subterranean estuary and associated chemical loading to the coastal ocean
… estuary, which can play host to dynamic biogeochemical cycling of nutrients, trace metals and radionuclides. This chemically altered groundwater enters the ocean through submarine groundwater discharge (SGD), a process that is driven by a number of physical processes acting on aquifers and the …
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Variations in coral reef net community calcification and aragonite saturation state on local and global scales
Predicting the response of net community calcification (NCC) to ocean acidification (OA) and declining aragonite saturation state (Ωa) requires a thorough understanding of controls on NCC. The diurnal control of light and net community production (NCP) on NCC confounds the underlying control of Ωa …
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Using passive samplers to assess bioavailability, toxicity, and reactivity of hydrophobic organic chemicals (HOCs)
Hydrophobic organic chemicals (HOCs) are a class of environmental contaminants responsible for numerous acute and chronic health effects in humans and wildlife. This thesis illustrates three applications of polyethylene (PE) passive sampling, which enhance our toolbox for estimating environmental …
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Evolution of anthropogenic Pb and Pb isotopes in the deep North Atlantic Ocean and the Indian Ocean
Pb and Pb isotopes in the ocean have varied on decadal to centennial time scales due to anthropogenic Pb inputs. Thus, tracing the temporal variation of Pb and Pb isotopes in the ocean provides information on the major sources of Pb and the transport of Pb from sources to the ocean surface and into …
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Stability of Methane-Ethane-Propane Mixed Gas Hydrates under Deep Water Conditions
Methane hydrates are globally distributed in sediments along the continental margins and potentially contain more energy than all fossil fuel reserves. However, methane is also a potential greenhouse gas which could play a major role in global climate change. Understanding the stability of gas …
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Halogenated 1'-methyl-1,2'-bipyrroles (MBPs) in the northwestern Atlantic
Halogenated 1’-methyl-1,2’-bipyrroles (MBPs) are a distinctive class of marine organic compounds. They are naturally produced, they have a unique carbon structure, they are highly halogenated, and they bioaccumulate in upper trophic levels. MBPs share many characteristics with persistent organic …
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The Biogeochemistry of Iodine in Seawater
… the Chesapeake Bay might act as a geochemical reactor which reduces iodate in the Bay and transports iodide to the oceans.</p> <p>The reaction between H<sub>2</sub>0<sub>2</sub> and iodide was investigated by adding them in artificial seawater and monitoring the variations in the …
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The interaction of metal ions at the hydrous manganese dioxide-solution interface
An experimental study of the interaction of metal ions with the surface of hydrous manganese dioxide has been completed. The results of these experiments have greatly improved our qualitative understanding of the adsorption mechanism and have also provided a means of testing quantitatively the …
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High-Resolution In Situ Oxygen-Argon Studies of Surface Biological and Physical Processes in the Polar Oceans
<p>The Arctic Ocean and Western Antarctic Peninsula (WAP) are the fastest warming regions on the planet and are undergoing rapid climate and ecosystem changes. Until we can fully resolve the coupling between biological and physical processes we cannot predict how warming will influence carbon …
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Exploring the distribution and physiological roles of bacterial membrane lipids in the marine environment
… of certain organisms that carry out specific biochemical processes or that are demonstrated to have unique physiological roles can be used to trace the biogeochemical influence of bacteria in modern and ancient environments. In this thesis I explore the application of two classes of bacterial …
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Geochemistry of hydrothermal vent fluids from the northern Juan de Fuca Ridge
… matter has the potential to influence a range of chemical processes in hydrothermal vent environments. For example, hydrothermal alteration experiments indicate that alteration of organic-rich sediments leads to up to an order of magnitude more metals in solution than alteration of organic-poor …
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Abyssal benthonic foraminifera and the carbonate saturation of sea water and a benthonic foraminferal carbonate saturation history for the Cape Verde Basin for the last 550,000 years
The distribution of certain Atlantic Ocean benthonic foraminifera is most consistently correlated with the degree of saturation of seawater with respect to calcium carbonate. The relative abundance of cibicidids, miliolids, Uvigerina and Globocassidulina subglobosa increases in saturate water and …
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The marine geochemistry of trace metals
The marine geochemical cycles of iron, copper, nickel, and cadmium were studied in order to provide a basis for oceanographic models for trace metals. Copper, nickel, and cadmium can be determined in a 100 ml seawater sample using cobalt pyrrolidine dithioacarbamate chelate coprecipitation and …
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Geochemistry of deep-sea hydrothermal vent fluids from the Mid-Cayman Rise, Caribbean Sea
… Chapters 3 and 4 present in-depth studies of the chemical and isotopic compositions of aqueous species in vent fluids at Von Damm and Piccard to elucidate the role of reaction temperature, pressure, substrate composition, and water/rock mass ratios during the chemical evolution of hydrothermal …
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The biogeochemistry of marine particulate trace metals
… seawater, representing an extremely dynamic and chemically diverse mixture of phases. The distributions of these phases are poorly constrained and undersampled in the oceans, despite interactions between living organisms and non-living minerals having central roles within many globally relevant …
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The marine biogeochemistry of dissolved and colloidal iron
… carbon cycles. Understanding the marine biogeochemical cycling and composition of dFe was the focus of this thesis, with an emphasis on the role of the size partitioning of dFe (<0.2 jm) into soluble (sFe<0.02 jm) and colloidal (0.02ptm<cFe<0.2 m) size fractions. This was accomplished through …
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