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.
Results
Showing 1 to 20 of 384 for “"Biogeochemistry."”.
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Investigation of Rhenium's Biogeochemistry
The form of the paleoredox indicator, rhenium, that is sequestered in reducing sediments is not known. To probe this question, I used Laser Ablation ICP-MS to look for correlations between Re signals and those of other elements. My results point to the possibility that Re is incorporated into …
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Floodplain Hydrology and Biogeochemistry
… between inundation hydrology and floodplain biogeochemistry, with an emphasis on analyzing variation experienced along the river continuum and the cumulative effects of river-floodplain connectivity at the basin scale. This was completed through four independent investigations. Field sites …
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The marine biogeochemistry of molybdenum
Prevailing wisdom holds that the vertical distribution of molybdenum (Mo) in the open ocean is conservative, despite Mo's important biological role and association with Mn oxides and anoxic sediments. Mo is used in both nitrogenase, the enzyme responsible for Nz fixation, and nitrate reductase, …
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The marine biogeochemistry of molybdenum
Prevailing wisdom holds that the vertical distribution of molybdenum (Mo) in the open ocean is conservative, despite Mo's important biological role and association with Mn oxides and anoxic sediments. Mo is used in both nitrogenase, the enzyme responsible for N2 fixation, and nitrate reductase, …
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The biogeochemistry of marine nitrous oxide
Atmospheric nitrous oxide N2O concentrations have been rising steadily for the past century as a result of human activities. In particular, human perturbation of the nitrogen cycle has increased the N2O production rates of the two major sources of this greenhouse gas, soil and the ocean. …
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The marine biogeochemistry of chromium isotopes
In the ocean, chromium (Cr) is a redox-sensitive trace metal. The reduction of Cr(VI) to Cr(III) occurs in oxygen deficient zones (ODZs), and Cr reduction in general has been identified as a significant Cr isotope fractionation mechanism. This thesis presents the first Cr isotope variations (d53Cr) …
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The marine biogeochemistry of zinc isotopes
Zinc (Zn) stable isotopes can record information about important oceanographic processes. This thesis presents data on Zn isotopes in anthropogenic materials, hydrothermal fluids and minerals, cultured marine phytoplankton, natural plankton, and seawater. By measuring Zn isotopes in a diverse array …
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Iron biogeochemistry in (sub-) Polar waters
… two decades. This<br/>work has focussed on the biogeochemistry of iron in two oceanic environments; the high<br/>latitude North Atlantic and the Scotia Sea in the Southern Ocean. The mechanisms of iron<br/>supply and the biological response of resident phytoplankton communities to iron …
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The Biogeochemistry of Iodine in Seawater
<p>Iodate and iodide are the two major species of iodine in seawater. In comparison to iodate, iodide is thermodynamically unstable in oxic seawater. The conversion (or reduction) of iodate to iodide may be mediated via biological activities. Since biological activities vary with the season, the …
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The biogeochemistry of marine nitrous oxide
Atmospheric nitrous oxide N₂O concentrations have been rising steadily for the past century as a result of human activities. In particular, human perturbation of the nitrogen cycle has increased the N₂O production rates of the two major sources of this greenhouse gas, soil and the ocean. …
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The marine biogeochemistry of zinc isotopes
Zinc (Zn) stable isotopes can record information about important oceanographic processes. This thesis presents data on Zn isotopes in anthropogenic materials, hydrothermal fluids and minerals, cultured marine phytoplankton, natural plankton, and seawater. By measuring Zn isotopes in a diverse array …
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The marine biogeochemistry of chromium isotopes
In the ocean, chromium (Cr) is a redox-sensitive trace metal. The reduction of Cr(VI) to Cr(III) occurs in oxygen deficient zones (ODZs), and Cr reduction in general has been identified as a significant Cr isotope fractionation mechanism. This thesis presents the first Cr isotope variations (653 …
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The biogeochemistry of marine particulate trace metals
Marine particles include living and non-living solid components of seawater, representing a dynamic and chemically diverse mixture of phases. Through a combination of method development, basin-scale particulate collection and analyses, modeling, and field experiments, this thesis examines both the …
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Biogeochemistry of Metals in Fish Farm Sediments
Salmon farming is a major industry in many Scottish sea lochs. Although the impact of salmon farming and pathways of several farm wastes have been studied extensively, there has been little research into the fate of metals originating from fish farms. This thesis investigates the influence of …
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The biogeochemistry of marine particulate trace metals
Marine particles include all living and non-living solid components of seawater, representing an extremely dynamic and chemically diverse mixture of phases. The distributions of these phases are poorly constrained and undersampled in the oceans, despite interactions between living organisms and …
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Biogeochemistry of a New England Sphagnum bog.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1977.
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Physical and Biological Drivers of Wetlandscape Biogeochemistry
Wetlands play a vital role in regional and global biogeochemistry by controlling the movement and cycling of nutrients and carbon. While individual wetlands may provide these ecosystem services, high density wetland landscapes, referred to as wetlandscapes, can have far reaching aggregate effects …
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Biogeochemistry of Carbon on Disturbed Forest Landscapes
Carbon accreditation of forest development projects is essential for sequestering atmospheric CO2 under the provisions of the Kyoto Protocol. The carbon sequestration potential of surface coal-mined lands is not well known. The purpose of this work was to determine how to measure carbon …
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The marine biogeochemistry of dissolved and colloidal Iron
Iron is a redox active trace metal micronutrient essential for primary production and nitrogen acquisition in the open ocean. Dissolved iron (dFe) has extremely low concentrations in marine waters that can drive phytoplankton to Fe limitation, effectively linking the Fe and carbon cycles. …
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The biogeochemistry of cobalt in the Sargasso Sea
… global carbon cycling. This thesis explored the biogeochemistry of cobalt using analytical chemistry and physiological experiments with the dominant phytoplankton species, Prochlorococcus. A high sensitivity method for Co speciation was developed using hanging mercury drop cathodic stripping …
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