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 17 of 17 for “"Ocean biogeochemistry"”.
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Monthly variability in upper ocean biogeochemistry due to mesoscale eddy activity in the Saragasso Sea
A comparison of monthly biogeochemical measurements made from 1993 to 1995, combined with hydrography and satellite altimetry, was used to observe the impacts of nine eddy events on primary productivity and particle flux in the Sargasso Sea. Measurements of primary production, thorium-234 flux, …
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Monthly variability in upper ocean biogeochemistry due to mesoscale eddy activity in the Saragasso Sea
A comparison of monthly biogeochemical measurements made from 1993 to 1995, combined with hydrography and satellite altimetry, was used to observe the impacts of nine eddy events on primary productivity and particle flux in the Sargasso Sea. Measurements of primary production, thorium-234 flux, …
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Ocean biogeochemistry in the northern Gulf of Mexico, the East/Japan Sea, and the South Pacific with a focus on denitrification
Ocean nitrogen fixation and denitrification are crucial nitrogen source and sink mechanisms for the global ocean environment. While recent studies have reported that oceanic denitrification has increased over the last few decades, others have suggested that global ocean nitrogen fixation rates have …
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Understanding ocean iron dynamics and impacts on marine ecosystems
… nutrients for phytoplankton growth in the ocean, making it a crucial element in the regulation of the ocean carbon balance and biogeochemical cycles. Atmospheric deposition of dissolved Fe (dFe) to the ocean has increased over the last decades partly due to human activities, which can …
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Establishing geochemical constraints on mass accumulation rates across the Cretaceous-Paleogene boundary with extraterrestrial Helium-3
Records of ocean biogeochemistry in marine sediments show shifts across the Cretaceous-Paleogene boundary (K-Pg) that are simultaneous with the extinction event and onset of the boundary clay deposition. However, the timescale of these records is difficult to determine near the boundary because of …
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Mineralogy-based global anthropogenic combustion-iron emission inventory
Total and soluble iron modulate ocean biogeochemistry and global nitrogen and carbon cycle in over 40% of global ocean. The understanding of the current and future changes in oceanic productivity can be improved by understanding and constraining the atmospheric inputs of iron. Models generally …
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Fingerprints and Drivers of Recent Changes in Oceanic Oxygen: From Regional to Global Scales
… reduction in the oxygen inventory of the global ocean, termed ocean deoxygenation, is a likely consequence of on-going anthropogenic warming. The contribution of external forcing factors to observed changes in dissolved oxygen concentration ([O2]) relative to natural internal variability is …
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Relating Biological Rate Measurements and Microbial Processes Across Diverse Ocean Ecosystems
… including primary production across the global ocean. Despite the importance of such interactions between the marine microbial community and ocean biogeochemistry, oceanographers have yet to attain a deep understanding of the ecological mechanisms underlying these connections. Due to the vast …
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Time and process in sedimentary rocks at the dawn of animal life
… work provide an independent record of changes in ocean biogeochemistry before and during the rise of animals. Chapters 3, 4, and 5 focus on the sedimentary rock record of the Ediacaran Period (635-541 Ma). Chapter 3 describes new Re-Os age constraints on Earth's largest negative carbon isotope …
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The biogeochemistry of lipid derived infochemical signals in the ocean
The role of oxylipins in ocean biogeochemistry was investigated using microcosm amendment experiments, environmental lipidomics, and culture based studies. Oxylipins are a bioactive class of secondary metabolites produced by diatoms and other eukaryotic phytoplankton. Previous research has focused …
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The biogeochemistry of lipid derived infochemical signals in the ocean
The role of oxylipins in ocean biogeochemistry was investigated using microcosm amendment experiments, environmental lipidomics, and culture based studies. Oxylipins are a bioactive class of secondary metabolites produced by diatoms and other eukaryotic phytoplankton. Previous research has focused …
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Microbial responses to environmental forcing and implications for trophic transfer through the lens of lipidomics
… mesoscale eddies and their subsequent impact on ocean biogeochemistry. Lipidomic analysis of sediment trap material showed the export of particulate organic carbon (POC) enriched in the energy storage molecule, triacyglyceride (TAG), from the cyclonic eddy despite similar total fluxes of POC from …
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Development of low-cost in situ gas sensors for oceanographic applications
… and driving widespread environmental change. The ocean acts as a major sink. Accurate and scalable in situ monitoring of oceanic carbon chemistry is vital for understanding the impacts of climate change and informing marine carbon dioxide removal (mCDR) strategies. Many existing in situ …
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Development of Low-Cost In Situ Gas Sensors for Oceanographic Applications
… and driving widespread environmental change. The ocean acts as a major sink. Accurate and scalable in situ monitoring of oceanic carbon chemistry is vital for understanding the impacts of climate change and informing marine carbon dioxide removal (mCDR) strategies. Many existing in situ …
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Mechanismen und Ausmaß des indirekten Einflusses von anthropogenen Stoffeinträgen auf das Erdsystem
Komplexe Zusammenhänge bestimmen sowohl das Klimasystem der Erde als auch die Biogeochemie des Ozeans. Obwohl die obere Troposphäre und der tiefe Ozean räumlich weit entfernt vom direkten Wirken menschlicher Aktivitäten sind, gibt es eine zunehmende Anzahl von Hinweisen darauf, dass auch diese …
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The Role of the Ocean in MIS 4 Climatic Changes and Atmospheric CO₂ Variability: a Geochemical Fingerprinting Approach
… the hydroclimate, sea surface temperature (SST), ocean circulation and ocean biogeochemistry. The ocean is thought to have played a key role in controlling and modulating these changes through its impacts on both heat transport and the carbon cycle. High resolution marine sediment cores can be …
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Physical Control of Biological Processes in the Central Equatorial Pacific: A Data Assimilative Modeling Study
… <p>When actual EqPac cruise data and SeaWiFS ocean color data are assimilated, one can objectively determine whether or not a given model structure is consistent with specific sets of observations. For instance, a brief period of macro-nutrient limitation during the 1997–98 El Niño, as well as …