Thesis (Ph. D.)--University of Oklahoma, 1998. / Includes bibliographical references (leaves 215-221).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 90-103).

Thesis (Ph. D.)--Drexel University, 2003. / Includes abstract and vita. Includes bibliographical references (leaves 125-135).

abstract / Earth Sciences / Doctoral / Doctor of Philosophy

This thesis examines whether short term (one to three weeks) microbial sensitivity to temperature and carbon (C) inputs can be predicted from peat characteristics driven by nutrient gradients. The aim was to determine if relationships exist between peat macronutrient (C, nitrogen (N), phosphorus (P)) concentrations, microbial community composition and the microbial response to changes in temperature and C supply. The focus of this thesis was on using peat macronutrient concentrations as explanatory variables as this is a metric which is easy to define and measure consistently, unlike other factors such as peat C quality and availability of nutrients. It was observed that, over short timescales, microbial respiration rates in peat soils increased in response to warming, nutrient (N and P) additions and increased labile C supply. In the first two experimental chapters it was found that peat respiration was sensitive to temperature, with increases of 10°C shown to increase microbial CO2 production by factors of 2.8 to 4.4. In the final two experimental chapters priming effects in peat were examined with C additions found to stimulate microbial activity and increases in peat derived CO2 flux, which could be attributed to priming. Despite the wide variation in nutrient concentrations in the peat soils examined no clear relationships between peat nutrient properties (total and available concentrations) and the magnitude of the microbial responses were observed.

This project studies the relation between the amount of sediment deposited in the Nile Submarine Cone (NSC) and the influence exerted by external controls such as climate change. A detailed calculation of sediment volumes was performed as well as a detailed estimation between intervals in order to assess sedimentation rates and dry mass per Ma for the NSC from the Late Oligocene to Recent. In contrast to previous studies, this project presents for the first time detailed calculations for ten intervals from Late Oligocene to Re- cent, including calculations for Pre-Messinian deposits since they also play an important role in the evolution of the NSC and in the history of erosion and deposition processes in the Nile province. The results of this project evidenced a connection between climate change and the amount of sediment carried by rivers as well as its final fate. Sedimenta- tion rate values obtained for each interval showed an increase in sediment supply during the Late Pliocene-Early Pleistocene, coincident with the i) final uplift of the Ethiopian and Somalian plateaus, ii) the drop in temperatures that took in the northern hemisphere as a consequence of the growth of the ice sheets, and iii) the increase in rainfall in the Ethiopian Highlands as a consequence of the African and Indian Monsoon that produced sapropel deposits and eroded sediments in north-eastern Africa. Pre-Messinian intervals showed low sedimentation rates values compared to Post-Messinian associated probably with an elevated evapo-transpiration cycle reducing the rainfall in the Ethiopian Highlands, des- pite the humid conditions that were present during certain ages (e.g. Zeit Wet Phase Late Miocene).

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Unchecked climate change has the potential to have devastating effect on the Earth and its inhabitants. However, there is still time to avoid most of the worst impacts climate change will bring through massive mitigative actions. While state led governance mechanisms must be employed to effectively mitigate climate change, states seem unwilling or unable to effectuate the needed actions. How can states be pushed to take action aimed at mitigating climate change? This thesis utilises Securitisation Theory, as a starting point to test not only whether or not securitising climate change can induce state action on it, but also whether induced policies constitute ‘good’ or ‘bad’ actions. This thesis undertakes two case studies that focus on the executive level of governance of two sate: the United States and California. / Graduate

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No description available.