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 28 for “"oxygen minimum zone"”.
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The marine geochemistry of biogenic and redox sensitive elements in the oxygen minimum zone of western continental margin of India surface sediments
… durchgeführt, um den Einfluß der Sauerstoff-Minimum-Zone (OMZ) auf die Verteilung von Spurenmetallen zu verstehen. Die neuen Daten für organischen Kohlenstoff (OC) zeigen über weite Bereiche einen Zusammenhang mit der Produktivität am WCMI. Die hier ermittelte maximale OC Konzentration …
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Selenium Distribution and Cycling in the Eastern Equatorial Pacific Ocean
<p>Oxygen minimum zones in oceanic waters have become increasingly important to the marine environment and society. Low oxygen waters affect not only the distribution and abundance of marine organisms, but also impact the solubility and transport of trace elements that are of biological importance, …
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Sedimentary and ecosystem response to Late Cretaceous (Cenomanian - Turonian) paleoenvironmental events along the eastern margin of the Western Interior Seaway, Canada.
… including ashfalls and expansion of the oxygen minimum zone. Looking at both depositional and faunal responses to long- and short-term processes improves our understanding of the dynamics of the WIS during this enigmatic time.
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Natural variability in eastern tropical Pacific nitrous oxide emissions
… oxide (N2O) is a powerful greenhouse gas and ozone depleting substance, but its natural sources remain poorly constrained. Marine emissions are likely much higher than IPCC estimates predict, due to unusually high emissions from the oxygen minimum zones (OMZs) in the eastern tropical Pacific …
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Lipid profiles of deep-sea organisms
… vents and shrimp from below a permanent oxygen minimum zone. Lipid profiles of these organisms from extreme deep-sea environments are compared. Lipid profiles of adult Mid-Atlantic Ridge hydrothermal vent shrimp, Rimicaris exoculata. support a benthic existence and primarily …
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The marine geochemistry of iron and iron isotopes
… than]1 nmol/kg) were associated with an oxygen minimum zone in the tropical Atlantic at 100N, 45 degrees W. Fractionation of iron isotopes could be an effective tool to investigate the geochemistry of iron. Trace metal clean plankton tows, river samples, aerosol leachates, and porewater …
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Environmental controls on the distribution of bacterial membrane lipids
… gradients in the Eastern Tropical South Pacific oxygen minimum zone off the coast of northern Chile and in two ice-covered lakes of the McMurdo Dry Valleys, Antarctica. The results will enhance our ability to interpret the molecular fossil record, particularly those biomarkers that might preserve …
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Trace element signatures of Peruvian and Chilean upwelling sediments
… from particles settling through the Peruvian oxygen minimum zone (OMZ) implying a strongly reducing but non-sulfidic watercolumn. The sulfidic conditions within OMZ sediments are indicated by the extreme enrichments of e.g. Cd, Mo and Re. The suboxic conditions for sediments below the OMZ are …
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Biogeochemistry of dissolved free amino acids in marine sediments
… products. Surface sediments from the oxygen minimum zone of the Peru Upwelling Region, which consisted of a filamentous bacterial mat, were sampled at three locations. DFAA concentrations within the mat ranged from 5 to 220 μM, with the highest concentrations found in the upper 4 cm at …
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Investigating and modelling the body size structure of benthic communities
… Faroe-Shetland Channel and (iii) and a mid-slope oxygen minimum zone location on the Oman Margin, Arabian Sea. The construction of body size spectra formed a central component of this analysis and it served as a foundation for further investigations into the functioning and dynamics of these …
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Linking microbes and climate : insights into the marine oxygen and nitrogen cycles with microbial metabolic functional types
… 2, I use a simple model to predict the limiting oxygen concentration of aerobic microbial growth in an ecosystem. This limiting concentration is in the nanomolar range for much of the parameter space that describes microbial activity in marine environments, and so anticipates the recent …
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The marine geochemistry of iron and iron isotopes
… (>1 nmol/kg) were associated with an oxygen minimum zone in the tropical Atlantic at 10°N, 45°W. Fractionation of iron isotopes could be an effective tool to investigate the geochemistr of iron. Trace metal clean plankton tows, river samples, aerosol leachates, and porewater samples …
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Physical and biological forcings on the carbonate chemistry in the North Atlantic Ocean
… coastal upwelling and remineralization in an oxygen minimum zone. Although the physics appeared to be the main forcing on the carbonate system in this study, the role of biology in the seasonality of the carbonate system is highly important. However, physical forcings tend to set the level for …
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Marine Deoxygenation Predates the End-Triassic Mass Extinction Within the Equatorial Panthalassa and its Influence on Marine Ecosystems Before the Biotic Crisis
… data from Grotto Creek reflect a progressive deoxygenation of the upper water column with the expansion of the equatorial oxygen minimum zone (OMZ). Specifically, the δ15N excursion reflects a shift in the dominant processing of bioavailable nitrogen from uptake and nitrification under oxic …
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The marine biogeochemistry of dissolved and colloidal Iron
… (>1 nmol/kg) concentrations coincident with the oxygen minimum zone were determined to be caused by remineralization of a high Fe:C organic material (vertical flux), instead of a laterally advected low oxygen-high dFe plume from the African margin. In the South Pacific Ocean, dFe maxima near …
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Benthic protozoan community attributes in relation to environmental gradients in the Arabian Sea
… depth) across the Oman margin (Arabian Sea) oxygen minimum zone (OMZ). Very high abundances (2858 per 25.5 cm2), dominated by Uvigerina ex. gr. semiornata, were found in the upper 100 m. The 850 m site also had elevated abundances. These peaks probably represented upper and lower OMZ boundary …
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The marine biogeochemistry of dissolved and colloidal iron
… (>I nmol/kg) concentrations coincident with the oxygen minimum zone were determined to be caused by remineralization of a high Fe:C organic material (vertical flux), instead of a laterally advected low oxygen-high dFe plume from the African margin. In the South Pacific Ocean, dFe maxima near …
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Element cycling in organic rich sediments on the Pakistan margin
… determined at sites above, within, and below the oxygen minimum zone (OMZ) on the Pakistan margin of the Arabian Sea.<br/>Sampling was conducted before and during the late-to-post southwest monsoon, with the goal of assessing how low bottom-water O2 concentrations and high organic matter …
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Reconstructing Surface Water Carbonate Ion Concentration Changes in the Eastern Equatorial Pacific Across Glacial Transitions
… transitions coupled with an expansion of the oxygen minimum zone (OMZ) likely delivered CO<sub>2-</sub> and nutrient-rich water to the surface. However, this increase in nutrient concentrations coupled with dust fertilization across cold Heinrich events failed to stimulate biological …
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Community and trophic responses of benthic Foraminifera to oxygen gradients and organic enrichment
… (testate protists), that tolerate low-oxygen conditions and may lead to an overall decline in marine biodiversity. With this in mind, community and trophic responses of benthic Foraminifera were investigated at two contrasting sites in the upper boundary (140 m water depth; bottom-water …
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