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 104 for “"Biogeochemical processes"”.
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Nitrate isotope anomaly as a tracer of biogeochemical processes
… fractionation) signature as a tracer of biogeochemical processes. Nitrate δ15N, δ17O and δ18O of water samples collected at the Marano lagoon (Italy) have been analysed, by combining the denitrifier method with the N2O thermal decomposition in a gold furnace. No clear correlation between …
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Organic geochemistry and stable isotope constraints on Precambrian biogeochemical processes
Details of the biogeochemical cycles and the dominant mechanisms present in Precambrian remain heavily debated topics. The events of the Late Proterozoic onset to glaciations and what types of early life existed in the Archean are two of the many provoking topics within the Precambrian. We set out …
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CHARACTERIZATION OF OYSTER-ASSOCIATED BIOGEOCHEMICAL PROCESSES IN OYSTER RESTORATION AND AQUACULTURE
… of oysters relative to sediments on oyster reef biogeochemical fluxes. Next, I compared in situ and ex situ methods for the determination of biogeochemical fluxes associated with oysters. Finally, I conducted field sampling and experiments to characterize how on-bottom oyster aquaculture impacts …
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Temporal and spatial scaling of coupled hydrological and biogeochemical processes in river basins
… dissertation is to understand nutrient delivery processes in river networks, including the processes and factors controlling both the flow generation and nutrient retention mechanisms. An analysis framework that synthesizes the bottom-up and top-down approaches is implemented in this dissertation …
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Tree community assembly and biogeochemical processes along an elevational gradient in western Panama
… interactions in plant community assembly and biogeochemical processes. Changes in environmental and biotic conditions are expected to influence tree diversity, floristic composition, nutrient and C cycling. My dissertation evaluates how edaphic factors, climate, and mycorrhizal associations …
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Carbon and sulfur isotopic constraints on Ediacaran biogeochemical processes, Huqf supergroups, Sultanate of Oman
The link between environmental and evolutionary change is investigated in the Ediacaran Period (- 635 - 541 million years ago (Ma), an interval where we see the emergence of macroscopic animals along with large perturbations to the carbon and sulfur cycles. Paleoenvironmental reconstruction used …
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The Flow Regime of Function: Influence of flow changes on biogeochemical processes in streams
… flow. Elevated flow can both stimulate ecosystem processes and impede them. Consequently, flow plays a critical role in shifting the dominant stream function between biological transformation and physical transportation of materials. To garner further insight into the complex interactions of …
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Shewanella oneidensis MR-1 cell-to-cell signaling and its influences on biogeochemical processes
The goal of this project is to decipher the quorum sensing (cell-to-cell signaling) abilities of Shewanella oneidensis MR-1, a Gram-negative bacterium well known for its ability to use geologic substrates, such as Fe and Mn oxides, for respiratory purposes. Overall our results show that S. …
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Protein regulation in Trichodesmium and other marine bacteria: observational and interpretive biomarkers of biogeochemical processes
Marine microbes play key roles in global biogeochemistry by mediating chemical transformations and linking nutrient cycles to one another. A major goal in oceanography is to predict the activity of marine microbes across disparate ocean ecosystems. Towards this end, molecular biomarkers are …
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Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective
… it an excellent location for understanding biogeochemical cycling of sediments and terrigenous organic carbon in a relatively pristine, large, temperate watershed. Sediments delivered by all tributaries have the potential to reach the ocean due to a lack of main stem lakes or impoundments, a …
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Spatial and temporal dynamics of biogeochemical processes in the Fraser River, Canada : a coupled organic-inorganic perspective
… it an excellent location for understanding biogeochemical cycling of sediments and terrigenous organic carbon in a relatively pristine, large, temperate watershed. Sediments delivered by all tributaries have the potential to reach the ocean due to a lack of main stem lakes or impoundments, a …
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Modeling the Effects of Physical and Biogeochemical Processes on Phytoplankton Species and Carbon Production in the Equatorial Pacific Ocean
… to variations in physical forcing and biological processes in the Cold Tongue region of the equatorial Pacific Ocean at 0°N, 140°W. This research objective was addressed using a one-dimensional multi-component lower trophic level ecosystem model that includes detailed algal physiology, such as …
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The Distribution of Dissolved Barium Along the U.S. Geotraces North Atlantic Transect: Impact of Biogeochemical Processes, Circulation and Phase Association
… there has been a growing interest in the biogeochemical cycle of barium (Ba) due to its potential as a proxy for interpreting the geologic record. The typical barium distribution exhibits removal in the upper water column and regeneration at depth, consistent with its classification as a …
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Effects of land-use changes on the properties of a Nitisol and hydrological and biogeochemical processes in different forest ecosystems at Munesa, south-eastern Ethiopia
The effects of conversion of natural forest into different exotic tree species plantations and crop cultivation were investigated at Munesa, south-eastern Ethiopia with the objectives of (i) determining changes on soil physical and chemical properties, (ii) quantifying water and nutrient fluxes …
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The Biogeochemistry of Carbon Isotopes in Local Lakes
… the carbon-bearing species in the systems. These biogeochemical processes also fractionate the carbon isotope composition, which results in changes to the carbon isotope composition of the dissolved inorganic carbon (DIC) pool. This thesis presents two separate, but related studies regarding the …
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Compartmental Process-based Model for Estimating Ammonia Emission from Stored Scraped Liquid Dairy Manure
The biogeochemical processes responsible for production and emission of ammonia from stored liquid dairy manure are governed by environmental factors (e.g. manure temperature, moisture) and manure characteristics (e.g. total ammoniacal nitrogen concentration, pH). These environmental factors and …
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Exploring the distribution and physiological roles of bacterial membrane lipids in the marine environment
… organisms that carry out specific biochemical processes or that are demonstrated to have unique physiological roles can be used to trace the biogeochemical influence of bacteria in modern and ancient environments. In this thesis I explore the application of two classes of bacterial membrane …
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Exploring the distribution and physiological roles of bacterial membrane lipids in the marine environment
… organisms that carry out specific biochemical processes or that are demonstrated to have unique physiological roles can be used to trace the biogeochemical influence of bacteria in modern and ancient environments. In this thesis I explore the application of two classes of bacterial membrane …
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