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 18 of 18 for “"sedimentary organic matter"”.
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Liberation of low molecular weight organic acids from sedimentary organic matter and their role on microbial activity
Low molecular weight organic acids (LMWOAs) are important nutrients for microbes. However, most LMWOAs do not exist freely in the environment but are bound to macromolecular organic matter, e.g. kerogen, lignite and coal. During burial and geological maturation of sedimentary macromolecular organic …
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Effects of anthropogenic and natural disturbance on sedimentary organic matter quantity, nutritional quality and degradation in river, lagoon, and coastal marine ecosystems
… anthropogenic and natural disturbances on sedimentary organic matter (OM) quantity, biochemical composition, nutritional quality, and C degradation rates, with the aim of exploring the magnitude and direction of changes in the benthic trophic status of river, lagoon, and coastal marine …
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Marine sedimentary organic matter : delineation of marine and terrestrial sources through radiocarbon dating; and the role of organic sulfur in early petroleum generation
… project. All of the projects are related to the organic geochemistry of marine sediments, however, this is a fairly encompassing area of study. Chapters 1 and 2 stem from the same experimental study -the use of hydrous-pyrolysis to investigate mechanisms leading to the production of …
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Marine sedimentary organic matter: delineation of marine and terrestrial sources through radiocarbon dating; and the role of organic sulfur in early petroleum generation
… project. All of the projects are related to the organic geochemistry of marine sediments, however, this is a fairly encompassing area of study. Chapters 1 and 2 stem from the same experimental study -- the use of hydrous-pyrolysis to investigate mechanisms leading to the production of …
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Vulnerability analysis and new tools for climate change adaptation of marine and lagoon systems
… quantity, composition and degradation rates of sedimentary organic matter in a Mediterranean coastal lagoon (Santa Gilla). Through simulation in benthocosms of marine heat waves of different intensities, I was able to highlight their impact on sedimentary organic matter of coastal lagoons, …
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Organic Sulfur-Bearing Species as Subsurface Carbon Storage Vectors
… Natural sulfurization processes in sedimentary organic matter are investigated as mechanisms to generate biologically refractory water-soluble organic molecules. Such molecular vectors could be sequestered in shallow, saline, contaminated aquifers through solubility trapping. …
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Re-Os dating of algal laminites : reduction-enrichment of metals in the sedimentary environment and evidence for new geoporphyrins
… low concentrations of Re and Os in these organic-rich rocks. The unexpectedly low metal concentrations require an oxic interpretation of the kukersite depositional environment. Kukersites were likely rapid, shallow water deposits protected from grazing and burrowing by hypersalinity, …
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Geochemistry of hydrothermal vent fluids from the northern Juan De Fuca Ridge
The presence of aqueous organic compounds derived from sedimentary organic 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 …
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Assessment of Estuarine Respiration and Benthic Nutrient Fluxes in Mississippi Sound
… with porewater nutrient concentrations and sedimentary organic matter. These findings illustrate that benthic respiration can contribute to water column hypoxia and that sediments serve as a source of nutrients to the water column. Overall, these findings provide us with valuable insight …
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An organic geochemical approach to problems of glacial-interglacial climatic variability
… and carbon isotopic composition (δ13C) of sedimentary organic carbon (Corg), N/C ratios, and terrigenous and marine δ13C-Corg end-members form a basis from which to address problems of Late Quaternary glacial-interglacial climatic variability in a 208.7 m hydraulic piston core (DSDP 619) …
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Surface-water groundwater interaction and arsenic mobilization in south and southeast Asia
… iron-oxides coupled to the oxidation of organic carbon. However, it is unclear why dissolved arsenic concentrations have reached the high levels currently observed in aquifers throughout the region. In particular, the influence of surface water recharge on arsenic contamination remains …
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Influence of increased sediment exposure on suspension-feeder assemblages in a temperate seagrass meadow
… ecosystems through their active transfers of organic and inorganic between the water column and the seabed (i.e. benthic-pelagic coupling), increased sediment exposure generated by anthropogenic activities may negatively impact these organisms. This study set out to evaluate the influence of …
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Sedimentary lipids as indicators of depositional conditions in the coastal Peruvian upwelling regime
This thesis assesses the utility of various sedimentary lipids as indicators of short-term changes in depositional conditions and sedimentary organic matter sources in the coastal upwelling regime off of Peru. A variety of lipids (n-alkanes, n-alkanols, C37 alkenones, hopanoids, keto-ols, lycopane, …
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Iron inputs from sediments to the oceans
… to the water column during the oxidation of<br/>sedimentary organic matter. Deep-sea and volcanogenic sediments however, are<br/>important reservoirs of Fe, which have not yet been investigated as sources of Fe to<br/>seawater. Furthermore knowledge of the nature of Fe phases involved in …
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Geochemistry of hydrothermal vent fluids from the northern Juan de Fuca Ridge
The presence of aqueous organic compounds derived from sedimentary organic 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 …
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Sedimentary molecular and isotopic markers of intertidal vegetation - a tool for coastal monitoring
Los humedales costeros que albergan ecosistemas de manglares y marismas se clasifican como uno de los ecosistemas más productivos de la Tierra. Han sido reconocidos como sitios de producción de materia orgánica (MO), reciclaje y sumideros de carbono a largo plazo para el CO2 atmosférico.Los …
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Carbon storage and preservation in seagrass meadows
… questions remain unaddressed in regards to the organic carbon (OC) sequestration capacity and processes leading to retention and persistence of OC in seagrass sediments. The research summarised in this dissertation examined 37 sediment cores from twelve Australian seagrass meadows (Posidonia …
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GEOCHEMISTRY OF THERMALLY ALTERED COALS AND ORGANIC-RICH SHALES: THE IMPACT OF RAPID HEATING ON PHYSICAL AND CHEMICAL PROPERTIES OF ORGANIC MATTER
… the geochemical and petrographic properties of sedimentary organic matter (such as coals and organic-rich clays or shales) including vitrinite reflectance, maceral petrographic composition, mineralogy, stable isotope composition, trace element composition, and bulk geochemistry. Igneous …