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 130 for “"bottom water"”.
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Changes in Antarctic Bottom Water Formation During Interglacial Periods
… are observations that point to reduced Antarctic Bottom Water (AABW) formation. These reductions are believed to be driven by an increase in the strength of the Southern Ocean density stratification due to surface water freshening. Any reduction in AABW formation has important implications for …
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Antarctic Bottom Water in CMIP5 models : characteristics, formation, evolution
… suggest that the properties of Antarctic Bottom Water (AABW) are changing, causing significant steric sea level rise. Understanding the causes of these changes is critical for projections of future sea level, yet previous generations of climate models failed to represent AABW accurately. …
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Mechanisms and control of water inflow to wells in gas reservoirs with bottom water drive
Water inflow may cease production of gas wells, leaving a significant amount of gas in the reservoir. Conventional technologies of gas well dewatering remove water from inside the wellbore without controlling water at its source. This study addresses mechanisms of water inflow to gas wells and a …
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Analytical design method for cold production of heavy oil with bottom water using Bilateral Sink Wells
Few heavy oil reservoirs with strong bottom water drives have been developed successfully because of severe water coning. Water coning tends to cause low ultimate recovery, low well productivity, and high water production. Although thermal and gravity-assisted methods might improve recovery in oil …
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Oxygen dynamics in the bottom waters of lakes: Understanding the past to predict the future
… oxygen concentrations are declining in the bottom waters of many lakes around the world, posing critical water quality concerns. Throughout my dissertation, I assessed how bottom-water dissolved oxygen may mediate the effects of climate and land use change on water quality in lakes. First, I …
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A study of the remineralization of organic carbon in nearshore sediments using carbon isotopes
… inorganic carbon (ΣCO2) in sediment pore water. Six cores were collected seasonally over a period of two years. The following species were measured in the pore waters: ΣCO2, δ13C-ΣCO2, PO4, ΣH2S, Alk, DOC, and Ca. Measurements of pore water collected seasonally show large gradients with …
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A study of the remineralization of organic carbon in nearshore sediments using carbon isotopes
… inorganic carbon (XCO2) in sediment pore water. Six cores were collected seasonally over a period of two years. The following species were measured in the pore waters: JC02, &'3 C-2CO2, P04, JH 2S, Alk, DOC, and Ca. Measurements of pore water collected seasonally show large gradients with …
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Near-equatorial deep circulation in the Indian and Pacific oceans
… Pacific Oceans are reviewed. Flow of deep and bottom water in the near-equatorial Indian and Pacific oceans, the two oceans with only a southern source of bottom water, is described through analysis of recent CTD data. Zero-velocity surfaces are chosen through use of water-mass properties and …
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Ocean circulation and carbon cycle dynamics in the Pacific Southern Ocean during Late Pleistocene interglacials
… global ocean overturning circulation, enabling water mass exchange between ocean basins, driving Antarctic Bottom Water and Antarctic Intermediate Water formation and providing the major return path of Circumpolar Deep Water (CDW) to the ocean surface. The Pacific Ocean is the largest aquatic …
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Late quaternary sedimentation in the Eastern Angola Basin
… conditions, primary productivity, and near-bottom depositional environment during the late Quaternary. Sediments deposited during glacial intervals contain markedly lower carbonate, higher levels of organic carbon, and more abundant siliceous biogenic components, fecal pellets, and pyrite. …
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Habitat Selection and Movement of Pallid Sturgeon in Lake Sharpe, South Dakota
… sturgeon selected the 4-5 m depth interval of water (4.6 ± 0.08 m). They were not found in either backwaters or in submerged trees of former islands or riparian areas. Sixty-four percent of locations were in bottom water current velocities between 0.1 and 30 cm/s (25.7 ± 1.4 cm/s). Bottom water …
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Investigating the circulation of Southern Ocean deep water masses over the last 1.5 million years by geochemical fingerprinting of marine sediments
… as well as an important region of upwelling and water mass formation, it is thought to have played a key role in modulating Earth’s past climate. Changes in the circulation of SO deep and bottom waters over the last 1.5 million years are investigated using stable carbon isotope $δ^{13}C$ …
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Earth’s oceanic oxygen history from Phanerozoic to Pleistocene glacial cycles: insights from the carbonate iodine-to-calcium proxy
… (the top tens to a few hundred meters in the water column) where we see the oxygen minimum zones in the present oceans. This is a critical zone where animals have diversified most dramatically in Phanerozoic (542 million years ago (Ma) to present day) and where geologists have the best fossil …
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Late Paleogene (Eocene to Oligocene) paleoceanography of the northern North Atlantic
… circulating (Eocene) to vigorously circulating bottom water (early Oligocene). Sediment distribution patterns provide evidence for strong contour-following bottom water flow beginning at reflector R4 time; this suggests a northern source for this bottom water, probably from the Arctic via the …
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Geochemical Controls on Mercury Methylation in Backwaters of a Gulf Coastal Plain River System, Implications for Water Column Processes
… the potential for mercury methylation in the water column of backwaters off of the main channel. Results showed that filtered methyl mercury was positively correlated to dissolved organic carbon (r2=0.76) for water samples taken from the bottom 1 ft of the water column at three sites, …
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On-shelf nutrient trapping enhances the fertility of the southern Benguela upwelling system
… to support surface productivity and decreasing bottom water oxygen concentrations. The proposed mechanism for this “nutrient trapping” involves upwelled nutrients being removed from surface waters and converted into organic biomass that is sequestered and remineralized on the shelf while the now …
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Glaciomarine sedimentation at the continental margin of Prydz Bay, East Antarctica : implications on palaeoenvironmental changes during the Quaternary
… the Antarctic Ice Sheet is the largest freshwater reservoir on Earth. On the other hand, a major proportion of the global bottom-water formation takes place in Antarctic shelf regions, forcing the global thermohaline circulation. The main goal of this dissertation is to provide new insights …
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Zinc and cadmium in benthic foraminifera as tracers of ocean paleochemistry
… (LGM). A high-resolution Cd/Ca record from 965 m water depth suggests that Glacial North Atlantic Intermediate Water formation was strong during the LGM, weakened during the deglaciation, and strengthened again during the Younger Dryas cold period. Comparison of Cd/Ca and δ13C data reveals …
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