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Local Structure And Dynamic Studies Of Mixed Ch4-Co2 Gas Hydrates Via Computational Simulation And Neutron Scattering, Bernadette Rita Cladek

Doctoral Dissertations

Permeated throughout the ocean floor and arctic permafrost, natural gas hydrates contain an estimated 3000 trillion cubic meters, over three times that of traditional shale deposits, of CH₄ that is accessible for extraction. Gas hydrates are a crystal structure in which water molecules form a cage network, the host, through hydrogen bonds while trapping a guest molecule such as CH₄ in the cavities. These compounds form naturally where the appropriate low temperature and high pressure conditions occur. A promising and tested method of methane recovery is through exchange with CO₂, which energetically takes place of the …

Fire-Vegetation-Climate Interactions Across The Holocene On The U.S. Southeastern Coastal Plain, Mathew S. Boehm

Doctoral Dissertations

This dissertation research examined multiple proxy indicators in sediment cores from one lake and one wetland to reconstruct long-term relationships between fire, vegetation, and climate in the southeastern U.S.

At Lake Balboa (30.6992 N, 83.2031 W; 48 m elevation), a sinkhole pond located in southern Georgia, Bølling-Allerød conditions were sufficiently wet to maintain a shallow wetland at the site. Evidence for fire was minimal. Between 12,600 and 9200 cal yr BP, water availability declined, leading to a potential hiatus in sedimentation. During the early Holocene moisture availability increased, leading to greater primary productivity within and outside the lake, triggering an …

Exploration Of Mid To Late Paleozoic Tectonics Along The Cincinnati Arch Using Gis And Python To Automate Geologic Data Extraction From Disparate Sources, Kenneth Steven Boling

Doctoral Dissertations

Structure contour maps are one of the most common methods of visualizing geologic horizons as three-dimensional surfaces. In addition to their practical applications in the oil and gas and mining industries, these maps can be used to evaluate the relationships of different geologic units in order to unravel the tectonic history of an area. The construction of high-resolution regional structure contour maps of a particular geologic horizon requires a significant volume of data that must be compiled from all available surface and subsurface sources. Processing these data using conventional methods and even basic GIS tools can be tedious and very …

Late Paleozoic Ophiuroid Biodiversity Based On A Diverse Fauna From The Indian Springs Shale Member Of The Big Clifty Formation, Sulphur, Indiana, Usa, Nicholas Scott Smith

Masters Theses

Ophiuroids (brittle stars and basket stars) are a diverse echinoderm group (i.e. star fish, sea urchins, and sea lilies) found in almost all marine environments and often major components of seafloor communities. Originating in the early to middle Devonian, the group quickly diversified and is today the most species rich echinoderm clade. Unfortunately, our knowledge of their diversity and evolutionary pathways during the Late Paleozoic has been understudied leaving a large gap in our understanding of their true biodiversity. This can be attributed to study methods and a poor understanding of Paleozoic ophiuroid skeletal morphology. Ophiuroid skeletons are composed of …

Structure And Adsorption At The BastnäSite-Water Interface: Fundamental Investigations Toward Rare Earth Mineral Recovery, Anna Kristiina Wanhala

Doctoral Dissertations

This dissertation investigates the interfacial structure and reactivity of a rare earth mineral in the context of froth flotation. Bastnäsite [(Ce,La,Nd)FCO3], one of the primary mineral sources of rare earth elements, has been chosen for this investigation. Flotation separation relies on selective adsorption of collector ligands to the desired mineral surface in solution; fundamental understanding of these adsorption reactions will aid in the development of more effective separation technologies.

Chapter 1 presents an introduction to the significance of rare earth minerals and the process of froth flotation. Chapters 2 and 3 address the adsorption reactions of ligand molecules at the …

Conservation Agriculture As A Climate Change Mitigation Strategy In Zimbabwe, Deb O'Dell, Neal Eash, Bruce B. Hicks, Joel Oetting, Thomas J. Sauer, Dayton M. Lambert, Tarirai Muoni, Joanne Logan, James A. Zahn, John J. Goddard

Biosystems Engineering and Soil Science Publications and Other Works

There is a need to quantify agriculture’s potential to sequester carbon (C) to inform global approaches aimed at mitigating climate change effects. Many factors including climate, crop, soil management practices, and soil type can influence the contribution of agriculture to the global carbon cycle. The objective of this study was to investigate the C sequestration potential of conservation agriculture (CA) (defined by minimal soil disturbance, maintaining permanent soil cover, and crop rotations). This study used micrometeorological methods to measure carbon dioxide (CO₂) flux from several alternative CA practices in Harare, central Zimbabwe. Micrometeorological methods can detect differences in …