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 15 of 15 for “"iron cycling"”.
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Exploring candidate genes and rhizosphere microbiome in relation to iron cycling in Andean potatoes
… interaction in potato Fe nutrient cycling. From the analysis of the high-throughput Illumina sequences of 16S and ITS region of ribosomal RNA gene, we found that both potato landraces with low and high Fe content in tubers and a landrace on which low or high Fe content fertilizer …
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From the atmosphere to the abyss: tracing organic carbon deposition, cadmium isotopes, and iron cycling using marine
… than 4 % of the OC is buried in low-oxygen environments. However, in order to understand how the efficiency of the biological pump may have changed over time, it is necessary to use proxies. In Chapter 3, I examine cadmium isotopes as a potential paleonutrient proxy. I suggest that in addition …
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From the atmosphere to the abyss: Tracing organic carbon deposition, cadmium isotopes, and iron cycling using marine sediments
… than 4 % of the OC is buried in low-oxygen environments. However, in order to understand how the efficiency of the biological pump may have changed over time, it is necessary to use proxies. In Chapter 3, I examine cadmium isotopes as a potential paleonutrient proxy. I suggest that in addition …
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Dynamics of soil processes under extreme meteorological boundary conditions - response of below-ground carbon, sulfur, and iron cycling in fen soils
… however, investigated changes in average environmental conditions in the long term, while the impact of extreme weather on peatland elemental cycles is still uncertain. Moreover, most studies do not provide a mechanistic understanding of the redox processes underlying the response of …
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Understanding Formation and Transport of Amorphous Iron Oxyhydroxides in Porous Media using Microfluidic Flow Cells- a Novel Method to Study Freshwater Iron Cycling
… which in turn has deep impact on the iron cycling and thus the fate of contaminants in the water column. We constructed an experimental micromodel that to observe key processes that affect biogeochemical iron cycling in the fresh water interface zones where the oxic surface water mixes …
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Microbial Iron Geochemistry of a Pristine Glaciofluvial Groundwater System
The biogeochemical cycling of iron by microorganisms has a strong impact on groundwater resources due to their influence on aqueous geochemistry, including contaminant mobility. This thesis expands on knowledge of groundwater-surface transitions through the characterization of an iron cycling …
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Geobiology of marine magnetotactic bacteria
… suboxic to anoxic zones of stratified marine environments worldwide. Their population densities (up to 105 cells ml-1) and high intracellular iron content suggest a potentially significant role in iron cycling, but very little is known about their population dynamics and regulation by …
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Trace Element Cycling during Iron(II)-activated Recrystallization of Iron(III) Oxide Minerals
Biogeochemical iron cycling initiates secondary abiotic reactions between aqueous Fe(II) and Fe(III) oxide minerals, which results in dynamic recrystallization via simultaneous Fe(II) oxidative adsorption and Fe(III) reductive dissolution. Fe(III) oxide minerals are abundant in soils, sediments, …
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Organic matter remineralization in the sediment of two acid mine drainage lakes
Acid mine drainage is a significant environmental problem throughout the world. At Rocky Forks Conservation Area near Columbia, MO numerous lakes have formed from old coal mining pits. Most of these lakes have a pH near 7, presumably buffered by the limestone bedrock except one, nicknamed Red Lake, …
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Decoupling of iron and phosphate in the global ocean
Iron (Fe) is an essential micronutrient for marine phytoplankton often limiting phytoplankton growth due to its low concentration in the ocean and thus playing a role in modulating the ocean's biological pump. In order to understand controls on global Fe distribution, the decoupling between Fe and …
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Geobiology of marine magnetotactic bacteria
… suboxic to anoxic zones of stratified marine environments worldwide. Their population densities (up to 105 cells ml−1) and high intracellular iron content suggest a potentially significant role in iron cycling, but very little is known about their population dynamics and regulation by …
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Not all models are created equal: assessing parameterisations of iron dynamics in ocean biogeochemical models
Iron is one of the most commonly studied trace metals as it exerts a significant influence on ocean productivity, carbon sequestration as well as modulating atmospheric CO2 concentrations. As iron is such a vital nutrient for biogeochemical processes it is often included as a variable in ocean …
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Observations and assessment of iron oxide nanoparticles in metal-polluted mine drainage within a steep redox gradient, and a comparison to synthetic analogs
… of minerals, microbes, and metals drive the cycling of iron and the fate and transport of metal(loid)s in contaminated systems. The former uranium mine near Ronneburg, Germany is one such system, where slightly acidic mine drainage crossing a steep redox gradient (groundwater outflow into a …
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Understanding ocean iron dynamics and impacts on marine ecosystems
… comprehensive understanding of how the ocean Fe cycling operates and how it will respond to human perturbations is urgently needed. In this work, I first significantly improve the Fe parameterization in a global ocean biogeochemistry model, constrained by new high-quality ocean Fe datasets. Then, …
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Biogeochemical controls on arsenic cycling in a hydrocarbon plume
… water sources. This dissertation investigates As cycling in an aquifer contaminated by petroleum hydrocarbons near Bemidji, Minnesota, where As is mobilized into groundwater due to biodegradation of hydrocarbons coupled to reduction of ferric oxides. The first project describes how aquifer …