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 273 for “"carbon cycle"”.
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Heterogeneous reservoirs in the marine carbon cycle
… between the distinct reservoirs of organic carbon in the ocean and their underlying complexity. First, we show how the heterogeneity of portions of the carbon cycle can be packaged in terms of age structured models and their accompanying age and rate distributions. We further relate the …
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Characterizing uncertainty for regional carbon cycle modeling
The discrepancy between current estimates of carbon dioxide emissions from natural processes, disturbance of the land surface and fossil fuel combustion, and the magnitude of accumulated CO2 in the atmosphere as measured by the global flask network indicates that there must be a terrestrial and/or …
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Heterogeneous reservoirs in the marine carbon cycle
… between the distinct reservoirs of organic carbon in the ocean and their underlying complexity. First, we show how the heterogeneity of portions of the carbon cycle can be packaged in terms of age structured models and their accompanying age and rate distributions. We further relate the …
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Feedback mechanism in the oceanic carbon cycle
… implemented a simple atmosphere-ocean coupled carbon cycle model which can be used as a tool to uncover the mechanisms of the interaction between the dynamics of the atmosphere-ocean system and the oceanic reservoir of CO 2 on the 101 to 103 years time scale. The atmosphere-ocean coupled model …
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Tracing the global carbon cycle with bomb radiocarbon
Bomb radiocarbon (14C) emitted to the atmosphere by nuclear explosion tests has not yet reached equilibrium within the Earth carbon system. In the present thesis this fate of radiocarbon is investigated using coarse-grid models to trace high-precision 14CO2 observations available in the atmosphere …
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Calcium isotope insight into the global carbon cycle
… was understanding the sedimentary sink for carbon. The formation of authigenic carbonate in marine sediments is caused by the microbial degradation of organic matter. I used pore fluid measurements and a numerical model to identify zones of authigenic carbonate precipitation. This knowledge …
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Nonlinear Amplification of Extreme Climate-Carbon Cycle Events
The geological records of carbon cycle change present significant disruptions at intermittent times, which are often associated with events of abrupt climate change. Despite the variety of mechanisms driving these fluctuations, different disruptions present common characteristics. Through this …
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Middle Miocene carbon cycle dynamics: A multi-proxy approach
… Ice Sheet are major perturbations in the global carbon system, represented by some of the largest fluctuations in marine carbonate δ<sup>13</sup>C values in the Cenozoic (Flower and Kennett, 1995; Zachos et al., 2001). A broad positive carbon isotope excursion; the “Monterey Excursion” (Vincent …
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The role of diatoms in the global carbon cycle
… Types (PFTs), each playing a specific role in carbon and nutrient cycling and in the trophic chain. The growth parameters for each PFT are now being derived in order to represent their dependence on environmental conditions, including climate change. Here we present our work on diatoms, a …
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Coordinated regulation of glycolysis and the folate one-carbon cycle
… glycolytic intermediates. This diverts one-carbon units into the folate pool to generate nucleotides via phosphoserine inhibition of SHMT1-mediated serine synthesis and one-carbon "wasting" in some cancer cells. We will also consider the reciprocal question of how folate one-carbon pool …
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Urbanised territories as a specific component of the global carbon cycle
Wir betrachten folgende Teile: die zusätzlichen Kohlenstoff(C)-emissionen, welche aus der Umwandlung von natürlichem Umland durch Stadtwachstum resultieren, und die Änderung des C-Flusses durch 'urbanisierte' Ökosysteme, soweit atmosphärisches C durch diese in umliegende natürliche Ökosysteme …
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Studies of genera cytophaga-flavobacterium in context of the soil carbon cycle
There is a great need to understand the global carbon cycle; with specific interest in the cycling of soil carbon. This need is two-fold and interconnected. The global climate change is in-part due to the loss of soil organic carbon and the reduced ability of soils to sequester carbon. Also, to …
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Idenfitying and Understanding North American Carbon Cycle Perturbations from Natural and Anthropogenic Disturbances
Carbon dioxide accumulating in our atmosphere is one of the most important environmental threats of our time. Humans and changing climate, separately or in concert, have affected global vegetation, biogeochemical cycles, biophysical processes, and primary production. Recent studies have found …
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Carbon cycle changes during the end-Marjuman (Cambrian) extinction in the Southern Appalachians
… thought to coincide with the Steptoean Positive Carbon Isotope Excursion or SPICE, a large and rapid excursion in the marine carbon isotope record. This excursion, which is expressed in sedimentary successions globally, is thought to represent a large perturbation to the carbon cycle during this …
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Novel analytical strategies for tracing the organic carbon cycle in marine and riverine particles
Particulate organic carbon (POC) in the ocean and mobilized by rivers on land transfers ~0.1% of global primary productivity to the deep ocean sediments. This small fraction regulates the long-term carbon cycle by removing carbon dioxide from the atmosphere for centuries to millennia. This thesis …
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The terrestrial carbon cycle in transition: tracking changes using novel tracers on multiple timescales
Soils store more carbon than the atmosphere and terrestrial vegetation combined, therefore, changes in soil carbon storage can affect the global carbon budget. One of the forms in which carbon is exported from soil is as dissolved organic carbon (DOC). Upon release from soil, components of DOC can …
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Adsorption–Desorption Reactions in the Weathering Zone: Implications for Silicate Weathering & the Carbon Cycle
The carbonic acid-driven chemical weathering of silicate minerals removes carbon dioxide (CO2) from Earth's atmosphere. The tectonic processes of uplift, exhumation, and erosion modulate the negative feedback relationship between climate, silicate weathering rates, and atmospheric CO2 removal rates …
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