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 52 for “"Euphotic zone"”.
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Phytoplankton production in Agulhas bank waters (South Africa)
… the mixed layer extended deeper than the euphotic zone, with nitrate and phytoplankton biomass being evenly distributed through the euphotic zone. Production maxima occurred at the 40 - 90 % surface irradiance light depths, with some evidence of surface photoinhibition. All surveys during …
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Shear enhanced nutrient supply at the Mesoscale
… almost exclusively in the sunlit waters of the euphotic zone. However, in addition to sunlight, phytoplankton require a regular supply of nutrients to grow. In the open ocean such nutrients are abundant in the dark waters below the euphotic zone. Hence, to a large extent it is the physical …
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Mixed Layer Dynamics Along the Seward Line in the Northern Gulf of Alaska
… by which nutrients are brought to the euphotic zone are not known. One mechanism that might bring nutrients into the euphotic zone is the deepening of mixed layers. This dissertation is the first study of mixed layer depths (MLDs) across the continental shelf of the northern Gulf of …
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Biogeochemical applications of compound-specific radiocarbon analysis
… source for most of the biomarkers is marine euphotic zone primary production or subsequent heterotrophic consumption of this biomass. Two lipid classes represent exceptions to this finding. Δ14C values for the n-alkanes are consistent with mixed fossil and contemporary terrestrial plant …
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Biogeochemical applications of compound-specific radiocarbon analysis
… source for most of the biomarkers is marine euphotic zone primary production or subsequent heterotrophic consumption of this biomass. Two lipid classes represent exceptions to this finding. A14C values for the n-alkanes are consistent with mixed fossil and contemporary terrestrial plant …
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Variations of Physical and Chemical Parameters Within a Shallow Wind Influenced Lake
… level of plant nutrients, clear water, and large euphotic zone. Recommendations. A year long study of physical and chemical parameters would be useful as would a study of the productivity in view of the high nutrient levels and large euphotic zone. The source of pollutants should be studied. A …
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Chemical controls on the cycling and reactivity of marine dissolved organic matter
… compounds with a direct C-P bond, in the lower euphotic zone using a newly developed fluorescent assay, which measures the activity of carbon-phosphorus lyase. C-P lyase activity (CLA) profiles from the North Pacific Subtropical Gyre (NPSG) showed a sharp activity maximum near the …
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Chemical Controls on the Cycling and Reactivity of Marine Dissolved Organic Matter
… compounds with a direct C-P bond, in the lower euphotic zone using a newly developed fluorescent assay, which measures the activity of carbon-phosphorus lyase. C-P lyase activity (CLA) profiles from the North Pacific Subtropical Gyre (NPSG) showed a sharp activity maximum near the …
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Quantifying the Role of Mesoscale-Driven Processes of Nitrate Supply Within an Iceland Basin Eddy Dipole
… contribution to vertical nutrient flux to the euphotic layer.<br/><br/>Data were collected during a multi?disciplinary research cruise aboard the NERC research ship RRS Discovery to the Iceland Basin in July/August 2007. Three quasi?synoptic spatial surveys show a southeastward flowing jet with …
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Rates of vertical mixing, gas exchange, and new production : estimates from seasonal gas cycles in the upper ocean near Bermuda
… is responsible for excess 3He and nitrate in the euphotic zone observed at a July, 1986 occupation of the Station S site. Hydrographic profiles are consistent with a type of eddy observed by Brundage & Dugan (1986), characterized by an unusually thick lens of subtropical mode (18°C) water. …
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INVESTIGATING THE CONTRIBUTION OF MARINE VIRUSES TO OPTICAL BACKSCATTER IN THE <0.2 µM FRACTION OF SEAWATER
… transect from 15°N to 35°N at 26°W from the euphotic zone and in three areas of the Gulf of Mexico (Petit Bois, Horn Island, Cat Island). Samples were subjected to two size fractionations (0.2 µm, and 30 kDa) where marine viruses are assumed present in thefor 0.2 µm – 30 kDa) of seawater. …
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Physical Controls on Low and Mid-Latitude Marine Primary Productivity
… upward entrainment of deep nutrients into the euphotic zone. Herein, we examine the local stratification control of productivity over the subtropical and equatorial Pacific by directly comparing a wide range of contemporaneous metrics, drawn from the modern observational record, for interannual …
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Phytoplankton production studies in the coastal waters off the Cape Peninsula, South Africa
… rates of production near the bottom of the euphotic zone particularly below a thermocline. Simulated in situ rates of oxygen production were only slightly higher than in situ rates. When ships time is limited, the simulated in situ method can safely be used in local waters. Definite diel …
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A determination of air-sea gas exchange and upper ocean biological production from five noble gases and tritiugenic helium-3
… were used to quantify export production, and euphotic zone seasonal cycles of oxygen and argon were used to determine net community production. The concurrent use of these three methods allows examination of the relationship between the types of production and begins to address a number of …
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A determination of air-sea gas exchange and upper ocean biological production from five noble gasses and tritiugenic helium-3
… were used to quantify export production, and euphotic zone seasonal cycles of oxygen and argon were used to determine net community production. The concurrent use of these three methods allows examination of the relationship between the types of production and begins to address a number of …
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Copper-Phytoplankton reciprocal interaction: Biogeochemical cycling of copper and its isotopes
… increases in pCu concentration [pCu]. Below the euphotic zone, decreases in the [pCu] are coupled with a heavier pCu isotope value and a lighter dCu isotope signature. This distribution was largely attributed to the biological uptake of the lighter isotope at the surface and remineralisation of …
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Copper-Phytoplankton reciprocal interaction: Biogeochemical cycling of copper and its isotopes
… increases in pCu concentration [pCu]. Below the euphotic zone, decreases in the [pCu] are coupled with a heavier pCu isotope value and a lighter dCu isotope signature. This distribution was largely attributed to the biological uptake of the lighter isotope at the surface and remineralisation of …
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A model of the temporal and spatial distribution of carbon monoxide in the mixed layer
… indicate that [CO] does not vanish below the euphotic zone as expected. This may be due to a possible blank correction to the measurements, low destruction rate at depth, or a small dark production rate. The CO consumption e-folding was optimized by numeric experiment and calculated to be …
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Assessing the potential for Zn limitation of marine primary production: proteomic characterization of the low Zn stress response in marine diatoms
… scarce dissolved concentrations in the upper euphotic zone reflecting high biological demand. In this thesis, I investigated the response of marine diatoms to Zn scarcity to characterize metabolic mechanisms used to combat Zn stress. I began by assaying the ability to metabolically substitute …
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Carbon flow and food web structure in the mesopelagic zone of the North Atlantic Ocean
… ecosystems are vital habitats that link the euphotic zone and the deep ocean through food web interactions and carbon flow pathways. In this dissertation, I use carbon compound-specific stable carbon isotope analysis of amino acids (CSIA-AA) and DNA gut metabarcoding methodologies to provide …
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