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Microbe-Mineral Relationships And Biogenic Mineral Transformations In Actively Venting Deep-Sea Hydrothermal Sulfide Chimneys, Tzihsuan J. Lin

Doctoral Dissertations

This dissertation uses a combination of microbiology, mineralogy, and geochemistry to understand dissimilatory iron reduction in hyperthermophilic archaea and the role and potential impact of these and other vent microorganisms within active deep-sea hydrothermal vent chimneys. The central objective of the dissertation is to determine if mineral composition and chimney type are among the primary determinants of microbial community composition and hyperthermophilic, dissimilatory iron reducer growth, in addition to other environmental factors such as nutrient availability, temperature, pH, and chlorinity. This is done using samples and organisms collected from the Endeavour Segment of the Juan de Fuca Ridge in the …

Exploring Martian Magmas: From The Mantle To The Regolith, Arya Sigrid Waltraud Udry

Doctoral Dissertations

The planet Mars is geologically more similar to Earth than to other planets of the solar system. For the past 50 years, new rovers, orbital spacecraft, and new martian meteorites have helped us to understand the geological processes that occurred on Mars. In this dissertation, I investigate a wide range of martian igneous compositions, such as shergottite and nakhlite meteorites, Gusev and Gale surface basalts, and the Northwest Africa (NWA) 7034 breccia. I attempt to better understand magmatic processes that occurred in the martian mantle and crust as well as surficial processes using various petrologic and geochemical tools.

As shown …

An Examination Of Radionuclide Transport In The Vadose Zone Using Field Lysimeters, Michael Witmer

All Theses

Understanding how radionuclides interact in the subsurface is important for the remediation of contaminated sites, assessment of risk due to radioactive waste disposal, and designing new radioactive waste management strategies. The current understanding of the geochemical behavior of radionuclides in the subsurface and more specifically the vadose zone has been developed through reactive transport modeling supplemented by laboratory experiments. Interactions between radionuclides with the mineral particles and organic matter in the vadose zone can be very complex and while laboratory experiments produce valuable data, few controlled, intermediate scale transport studies have been performed. In order to accurately predict vadose zone …

Geochemistry And Stable Isotopes Of Surface Water And Groundwater In The Continental Pit In Butte, Montana, Usa, Amber Mcgivern

Graduate Theses & Non-Theses

The Continental porphyry Cu‐Mo mine, located 2 km east of the famous Berkeley Pit lake of Butte, Montana, contains two small lakes that vary in size depending on mining activity. In contrast to the acidic Berkeley Pit lake, the Continental Pit waters have near-neutral pH and relatively low metal concentrations. The main reason is geological: whereas the Berkeley Pit mined highly‐altered granite rich in pyrite with no neutralizing potential, the Continental Pit is mining weakly‐altered granite with lower pyrite concentrations and up to 1‐2% hydrothermal calcite. The purpose of this study was to gather and interpret information that bears on …

Contact Zone Mineralogy And Geochemistry Of The Mt. Mica Pegmatite, Oxford County, Maine, Kimberly T. Clark

University of New Orleans Theses and Dissertations

This study focuses on exocontact mineral assemblages to determine composition, thermal signatures, and the extent of exomorphism that occurred between the Mt. Mica pegmatite and the migmatite host rock at the contact. Biotite-garnet thermometry of country rock samples resulted in an average temperature estimate of 630 °C. Measured biotite Fe/(Fe+Mg) ratios were used to calculate an fO2 of -18. The results indicate that the country rock and pegmatite formed under similar oxidizing conditions near the quartz-fayalite-magnetite (QFM) equilibria buffer. Whole rock (REE) analysis indicates an interaction trend between the country rock and pegmatite. Exomorphism does not appear to have …

Gastrointestinal Microbial Diversity And Diagenetic Alteration Of Bone From The American Alligator (Alligator Mississippiensis), Sarah Wheeler Keenan

Doctoral Dissertations

One of the most challenging questions in paleobiology is how bone transforms from a living tissue into a fossil. In life, the gastrointestinal tract microbiome of an animal promotes host health. But, in death, these microbial communities, as well as soil communities, begin to degrade tissue, including bones. Using the American alligator from coastal wetland habitats as a model system, the gastrointestinal tract microbiome was found to contain microbial communities consisting of Fusobacteria, Proteobacteria, Bacteroidetes, and Firmicutes, with variations based on tissue type along the length of the digestive tract. The overall dominance of Fusobacteria is distinct from any other …

Isotopic Fingerprinting Of Shallow And Deep Groundwaters In Southwestern Ontario And Its Applications To Abandoned Well Remediation, Mitchell E. Skuce

Electronic Thesis and Dissertation Repository

Abandoned hydrocarbon wells in southwestern Ontario can act as conduits for Sulphur water, brines, and hydrocarbons from deep Paleozoic bedrock aquifers. Such leakage may pose a threat to shallow groundwater and the environment. Cost-effective plugging of these wells requires knowledge of the sources of the leaking fluids. This study characterizes the isotopic compositions (δ18OH2O, δ2HH2O, δ34SSO4, δ18OSO4, δ13CDIC, 87Sr/86Sr) of groundwaters in the region, which are distinct in different bedrock formations. A Bayesian mixing model was applied to these data to develop a tool for identifying the source(s) of leaking fluids. The geochemical data also improve our understanding of groundwater …

Exploring The Hydrogeologic Controls On Brackish Water And Its Suitability For Use In Hydraulic Fracturing: The Dockum Aquifer, Midland Basin Texas, Francisco Ruben Reyes

Open Access Theses & Dissertations

Water scarcity in arid regions can limit or impede certain hydrocarbon production activities, such as hydraulic fracturing and well drilling. The Midland Basin, a major oil-producing area in semi-arid far west Texas and the eastern sub-basin of the Permian Basin, is already impacted by limited freshwater availability. A typical tight oil well in the Midland Basin requires ~3.8-11.4 x 103 m3 of water per fracture treatment (Nicot et al., 2012). Despite draught conditions and limited resources, data for 2011 indicate freshwater comprises ~70% of the water used in hydraulic fracturing in the Midland basin. Thus, the Midland Basin represents an …

Surface Complexation Of Monosubstituted Organoarsenicals On Hematite: Atr-Ftir Investigations, Md Abdus Sabur

Theses and Dissertations (Comprehensive)

Little is known about the surface chemistry of organoarsenic compounds with iron-containing materials commonly found in geosorbents and arsenic removal technologies. In this thesis, these organoarsenicals include aliphatic and aromatic arsenicals that historically have been used as herbicides, pesticides and in the poultry feed industry, respectively. Attenuated total internal reflectance Fourier transform infrared spectroscopy has been used to study the surface interactions of organoarsenicals at the molecular level under various environmentally-relevant conditions. Kinetic and thermodynamic parameters extracted from these molecular level experiments provide trends that are not observed in any published bulk experiments. Apparent initial rates of adsorption and desorption …