Physical Sciences and Mathematics Commons^™

Deconvolving Provenance Signatures Of Pliocene-Pleistocene Coastal Loess Deposits Along The Atlantic Margin Of Argentina, Will Robert Quanrud

Theses and Dissertations

Dust derived from southern South America provides critical nutrients for autotropic marine biota in the South Atlantic Ocean, such that fluxes of wind-blown sediment may ultimately affect the concentration of atmospheric CO2. Expansive sand, silt, and loess deposits are exposed in Central Argentina, recording millions of years of eolian processes; however, the provenance and transport pathways of this dust remains unclear. Coastal loess deposits ranging in age from Pliocene to upper Pleistocene are present along the Atlantic margin of Argentina and provide information on sediment transport pathways for the last 4 million years. Nine samples of loess were collected and …

Assessing Multi-Annual Phytoplankton Community Compositions And Biomass Across Tidal Creek And Open Water Estuarine Habitats In South Carolina, Shannon Elizabeth Powers

Theses and Dissertations

The urbanization of coastal environments in recent decades has caused an accelerating increase in nutrient-rich runoff from the landscape. The presence of these excess nutrients in the aquatic environment can result in degradation of water quality and harmful algal blooms. In South Carolina (SC), coastal development continues to threaten the resiliency of salt marsh estuaries, especially in combination with other stressors like climate change and sea level rise. Estuaries are important nurseries and habitats for fisheries and ecotourism. The South Carolina Estuarine and Coastal Assessment Program (SCECAP) is an ongoing monitoring program that assesses the habitat condition along the coast …

New Techniques For Studying Ocean Eddy Dynamics In The Arabian Sea And The Gulf Of Mexico, Paul Andrew Ernst

Theses and Dissertations

Coherent vortices known as eddies are ubiquitous throughout the world’s oceans and are responsible for modulating regional climates via the transfer of heat, momentum, and salt. Two regions where eddies are particularly prominent are the Arabian Sea (AS) and the Gulf of Mexico (GoM). This dissertation advances the study of eddies in these regions by developing and employing new techniques in conjunction with remotely sensed data and high-resolution ocean models. These models focus particularly on lesser-studied eddy components at the subsurface and the submesoscale (below 25 km in radius).

The first component of this dissertation focuses on the Lakshadweep High …

Investigating Arctic Ocean Freshwater Content And Circulation In A Changing Climate, Emma Louise Hoffman

Theses and Dissertations

The Arctic Ocean is unique among the world’s oceans, characterized by its cold temperatures, salinity-driven vertical structure, and shallow shelf seas. It has warmed intensely since the 1980s at rates exceeding the global average. This Arctic Amplification drives variability in sea ice and salinity, affecting local circulation and exchange with other basins, leading to global changes in oceanic and atmospheric circulation and the biosphere. This thesis explores changing dynamics in the Arctic Ocean, in particular connecting modeled changes in liquid freshwater content (FWC) and its pathways with major ocean circulation patterns, atmospheric drivers, and large-scale climatic changes.

This research combines …

Using Polonium-210 To Estimate Particulate Organic Carbon Consumption By Dreissenid Mussels In Lake Michigan, Rachel Ann Smith

Theses and Dissertations

In this study, I examine the potential of using the naturally occurring radionuclide Polonium-210 (half-life = 138.376 days) to estimate the in situ consumption of particulate organic carbon (POC) by dreissenid mussels in Lake Michigan. To estimate POC uptake, I measured the ratio of POC to particle-bound 210Po in the water column above the lakebed, as well as the inventory of 210Po being stored in mussel tissue on the lakebed at three sites with depths of 40, 50 and 80 meters. Additionally, I conducted lab incubation experiments to determine the biological half-life of 210Po in mussel tissue. These measurements were …

Using Lead-210, Bismuth-210, And Polonium-210 To Estimate Particulate Organic Carbon Flux To The Benthos Of Lake Michigan, Gage Justman Hunter

Theses and Dissertations

210Bi is a short-lived (t1/2: 5.01 days) naturally occurring radionuclide and a potential tracer of particle dynamics in high flux aquatic environments such as lakes, coastal oceans, and continental shelves. While its parent, 210Pb, and daughter, 210Po, have been used to estimate particle removal rates from the ocean, few studies have investigated the behavior of 210Bi in aquatic systems or its use as a tracer of particle export fluxes. In this study, a time series experiment was conducted where 210Pb, 210Bi, and 210Po activities were measured in rainwater and in the water column on the slope of southwestern Lake Michigan. …

Use Of Geomagnetic Paleointensity As A Correlation Tool In The Eastern Snake River Plain Lava Flows, Melissa Marie Sikes

Theses and Dissertations

The Snake River Plain volcanic province stretches 600 km from eastern Oregon across southern Idaho and into northwest Wyoming. Over the past ~14 million years, olivine tholeiitic lava flows have accumulated. To assess ongoing volcanic hazards, it is important to quantify the number, timing, and size of eruptive events. This assessment requires correlating lava flows across coreholes within the Eastern Snake River Plain. Previous paleomagnetic research applied paleomagnetic inclinations to correlate flows between coreholes. This study tests whether using geomagnetic paleointensity – in addition to inclination – can increase confidence in the correlation of these flows. Pilot samples were retrieved …

Paleoenvironmental Constraints On Pleistocene Ice Sheets From Glacio-Volcanic Deposits In Northeast Iceland, Cameron Essex

Theses and Dissertations

There are indications that the melt-back of glaciers due to climate change can trigger new eruptions for volcanoes and magma reservoirs that rest under ice sheets. The ideal locality on Earth to study volcano-ice interactions is Iceland, an active volcanic island that has been totally covered in previous ice ages. Eruptions under glaciers produce distinctive landforms called tuyas, or table mountains, which can provide an estimate of ice thickness at the time of eruption. One research tool used to investigate ice thickness is volcanic glass, which is formed from rapid cooling of magma, and thus is abundant in the majority …

High Temperature Alteration Conditions Within Lava Tubes: An Analogue For Venus Surface Geology, Dylan Alexander Childs

Theses and Dissertations

Scientific exploration of other planetary bodies comes with many limitations, and Venus is no exception. Average surface temperatures of ∼460°C and an atmospheric pressure of ∼96 bars has severely limited the longevity of any instruments sent to the surface of Venus. Furthermore, with an atmosphere composed of ∼96.5% CO2, there are only three wavelength windows in the near infrared region that can be used to measure the mineralogical composition of the surface. Due to these constraints, our understanding of Venus’ surface mineralogy is severely limited and to date direct measurements of its geologic composition are limited to a handful of …

Authigenic Minerals In Volcaniclastics From An Eastern African Paleolake: A Proxy For Paleoenvironment, Kaitlyn Truss

Theses and Dissertations

Olduvai Gorge exposes the stratigraphy of Paleolake Olduvai, an often saline-alkaline rift lake that records volcanism from the Ngorongoro Volcanic Highlands. In 2014, cores retrieved from the study area revealed new stratigraphy, including the lacustrine Naibor Soit Formation (Fm) and the volcaniclastic Ngorongoro Fm. In the Ngorongoro Fm part of the cores, mineralogy and geochemistry are the best paleoenvironmental proxies, since under saline-alkaline conditions, volcanic glass alters into specific authigenic minerals (e.g., zeolite, feldspar). This study employs X-Ray Diffraction, X-Ray Fluorescence, and Scanning Electron Microscopy to analyze authigenic mineralogy and geochemistry. The lower Ngorongoro Fm experienced the most alteration, with …

Examination Of Chemical Variations In Fossil Resin With Two-Photon Excitation Fluorescence And Paleobotanical Inventory Reports On National Park Service Units, Katherine Mae Maxine Bober

Theses and Dissertations

Fossil resin can be difficult to chemically characterize due to its complex chemistry which can be complicated by a unique chemistry for each fossil resin sample. Using two-photon excitation fluorescence micro-spectroscopy, we measured the wavelengths at peak emission intensity: we compared these fluorescence results to FTIR spectra. There are variations in fluorescence which indicate differences in botanic origin. This method may be used in future research to better understand botanic origin when more traditional analyses fail.There has been a need for a comprehensive paleobotanical inventory report for NPS units. Four teams consisting of graduate students and mentors are completing the …

Soil Carbon Sequestration Efforts In Arid And Semi-Arid Climates Under Conservation Agriculture And Reforestation, Samantha Lynn Colunga

Theses and Dissertations

Soil organic carbon (SOC) plays a vital role in the global carbon cycle and aids in climate change mitigation. However, deforestation and intensive agricultural practices threaten topsoil and carbon (C) pools through soil disturbances releasing vast amounts of carbon dioxide (CO2) by enhancing the decomposition of organic materials. Degraded soils typically lack stable aggregates, nutrient and water retention, and overall low fertility. In arid and semi-arid regions, soils are in an even more dire situation, as low precipitation and high temperatures slow down the accumulation of SOC. This thesis has two objectives: 1) to evaluate whether conservation tillage practices increase …

Towards Machine Learning-Based Control Of Autonomous Vehicles In Solar Panel Cleaning Systems, Farima Hajiahmadi

Theses and Dissertations

This thesis presents a machine learning (ML)-based approach for the intelligent control of Autonomous Vehicles (AVs) utilized in solar panel cleaning systems, aiming to mitigate challenges arising from uncertainties, disturbances, and dynamic environments. Solar panels, predominantly situated in dedicated lands for solar energy production (e.g., agricultural solar farms), are susceptible to dust and debris accumulation, leading to diminished energy absorption. Instead of labor-intensive manual cleaning, robotic cleaners offer a viable solution. AVs equipped to transport and precisely position these cleaning robots are indispensable for efficient navigation among solar panel arrays. However, environmental obstacles (e.g., rough terrain), variations in solar panel …

Toward A Greater Comprehension Of The Paraná Epicontinental Sea During The Late Paleozoic Ice Age: The Glacial And Postglacial Record In The Western Paraná Basin (Brazil) And The Kaokoveld Fjord Network (Namibia), Eduardo Luiz Menozzo Da Rosa

Theses and Dissertations

The late Paleozoic Ice Age (LPIA; 362 to 255 Ma) was an icehouse interval that drove substantial changes in Earth’s surficial systems. Numerous paradigms regarding aspects of the LPIA were established throughout ~150 years of research based primarily on the evolving state of knowledge in sedimentology. The near-field lithological evidence for widespread glaciation across sedimentary basins of Gondwana are the building blocks for comprehensive paleoclimatic, biologic, paleogeographic, and ice volume models. Nevertheless, the embodied glacial record from several late Paleozoic Gondwanan depocenters still rely on insufficient and/or outdated sedimentologic and stratigraphic studies, which can lead to misinterpretations in models built …

Understanding The Role Of The Jet Streams And Gulf Stream Eddies On The Northwest Atlantic Marine Heatwaves, Lydia Rose Duncan Sims

Theses and Dissertations

The Northwest (NW) Atlantic is one of the fastest warming regions in the global ocean and in the recent decade has experienced several extreme temperature events. These extreme anomalous temperature events are known as Marine Heatwaves (MHWs), which are forced by a variety of physical processes that affect the heat source and sink of the water column. These MHWs have been increasing globally in duration and frequency due to anthropogenic warming, and have increased ecological damage seen in mass mortality events of economically viable species. Within the NW Atlantic, several key processes encourage the formation of MHWs, such as the …

Trace Metal Analysis Of Pond Sediments To Measure Deposition From A Coal-Fired Power Plant In Ackerman Mississippi, Charles Bills

Theses and Dissertations

Trace element sediment pollution due to coal power plants have been reported in many countries. In this study, pond sediment samples collected from locations around a coal fired power plant in Ackerman, MS, were evaluated for their trace element concentration and pollution status. The samples were collected at two depths to study changes in element accumulation over time. The samples were digested and the elements, As, Cd, Cr, Cu, Pb, Hg, and Zn were analyzed using ICP-MS. Results were then compared to known background concentrations as well as sediment quality guidelines and pollution thresholds. The sample locations downwind of the …

Nutrient Dynamics Of Freshwater Estuarine Sediments Disturbed By Dredging, Ryan Allan John Roekle

Theses and Dissertations

This study examined the nutrient environment of sediments in the Milwaukee River estuary and the dynamics of those nutrients during simulated disturbance experiments within the context of large-scale dredging remediation. Surface sediments were collected from throughout the Milwaukee estuary (including river, harbor, and nearshore stations) by PONAR, centrifuged to separate porewater (interstitial water) from solid material, and filtered to further isolate and stabilize dissolved material. Porewaters were analyzed for dissolved nutrients including ammoniacal nitrogen (AN), nitrate, nitrite, and soluble reactive phosphorus (SRP). Surface sediment porewaters within the estuary were often highly enriched in AN and SRP, which were often 10-2000x …

Groundwater Flow And Salt Marsh Migration: The Forest/Marsh Boundary, Camille Rossiello

Theses and Dissertations

Salt marshes migrate landward in response to sea level rise, but the rate of this migration is not constant and can be influenced by pulse disturbances. Long term observations at Sapelo Island, Georgia, show that salt marsh migration has occurred during droughts, but the mechanism for this migration is unclear. Drought is thought to influence salt marsh migration by reducing fresh groundwater discharge from the upland. Rising sea level also encroaches on the upland, which could cause movement of the freshwater lens inland. A two-dimensional numerical model was built to simulate groundwater flow and solute transport based on the Marsh …

Hf Radar: Shining A Light On Ocean Currents, Douglas Cahl

Theses and Dissertations

High Frequency (HF) radar systems are commonly used to estimate surface ocean currents over the coastal ocean. Their range depends on their operational frequency and low frequency systems (≤ 10 MHz) can reach distances up to 200 km from the coastline. These systems are used to estimate surface currents by measuring the phase speed of wind-driven waves and comparing the measured speed with that expected theoretically; deviations from the theoretical still-water phase speed are attributed to ocean surface currents. Although HF radar systems are considered a mature technology and the accuracy of the radar-derived surface current estimates is well studied, …

Evaluating The Relationship Between Methane Seeps And Seafloor Geomorphology On The Northern Us Atlantic Margin, Gabriel Hernandez

Theses and Dissertations

Methane seeps are a transport pathway for carbon from seafloor sediments to the marine environment with important implications for global biogeochemical cycling. Accordingly, there is substantial interest in better understanding the processes that control seep location and predicting the distribution of seeps with existing seafloor datasets. Visual evaluation of methane seeps, in multibeam sonar water column data, suggests a spatial relationship between seeps and specific seafloor morphologic features such as ridge crests. In this thesis, seafloor geomorphology at 1996 seep detection sites on the US Atlantic margin was quantitatively characterized by geomorphologic phonotype, bathymetric position index, slope, rugosity, and aspect …

Testing The Use Of Anisotropy Of Magnetic Susceptibility (Ams) In Determining Genetic Origins Of Paleoproterozoic Diamictites, Miles A. Harbury

Theses and Dissertations

The Huronian Supergroup (2.4-2.1 Ga) in Ontario, Canada is widely accepted as an important stratigraphic interval for interpreting Paleoproterozoic climate. This is because it contains some of the oldest glaciogenic rocks on the planet. However, massive and poorly-stratified diamictites in the Gowganda Formation of the Huronian Supergroup have varying depositional interpretations among sedimentologists (subglacial, rainout, sediment gravity flow etc.). Diamictites can occur from a variety of processes and, therefore, proper depositional interpretation is essential for unraveling detailed environmental conditions at the time of deposition. Anisotropy of magnetic susceptibility (AMS) looks at the orientation of magnetic particles within a rock and …

Entangled Conquest: A Study Of Cultural Hybridization And Change In Norman Ireland, Sean Mcconnel

Theses and Dissertations

This thesis employs entanglement theory and new geophysical macro-analytical methods to

examine the spread of Norman culture in late medieval Ireland. The traditional theories of

Anglo-Norman conquest by mass migration, by military conquest, and by political conquest are

reviewed and compared to a more nuanced theory of Normanization, which suggests that

genetically Irish people, who spoke Irish, practiced Irish law, and pursued Irish interests were

primarily responsible for what is considered "Norman" material culture on the Island. This

dissertation presents the idea that adherence to the English king was a necessary and expedient

action on the part of Irish lords …

Elucidating Unique Sources And Persistent Hydrologic Pathways Of Chloride To Perennial Freshwater Streams: Root River Analog In A Cold-Weather Environment, Leah Elizabeth Dechant

Theses and Dissertations

Chloride in freshwater streams is increasing in concentration, persisting throughout the year, and contributing to the salinization of water resources. The primary source and pathway of chloride in cold-weather environments are thought to be road salt and runoff. However, mounting evidence displays that other sources and pathways of chloride play an important role yet studies to elucidate them at a high resolution, both temporally and spatially, and across diverse land use are lacking. In this study, chloride was quantified continuously for an urban and rural stream year-round in a watershed thought to be heavily impacted by road salt. Bivariate mixing …

Relative Eruption Chronology And Tephra-Vent Correlations Of The Sand Mountain Volcanic Field, Oregon High Cascades, Adam S. Chumley

Theses and Dissertations

Tephra stratigraphy east of the SMVF was sampled to characterize the major and trace element geochemistry, along with olivine and plagioclase mineral chemistry, in attempts to correlate the tephra with specific cones and cone groups in the SMVF chain. Three geochemical groups are represented in the tephra stratigraphy, defined by relative proportions of SiO2, TiO2, Sr, Cr, and Ni, and determined by SAHN Clustering analysis. These three groups are defined in the basal, middle, and upper portions of the stratigraphy and generally correlate with the three major geochemical groups defined in the SMVF lava flows. Correlation between the tephra and …

Long-Term Spatial And Temporal Assessment Of Criteria Air Pollutants Concentration Trends In The Lower Rio Grande Valley Region Of Texas, Usa, Md Salahuddin Majumder

Theses and Dissertations

Air pollution is a substantial environmental challenge all over the world. This study investigated the long-term air pollution levels in the Lower Rio Grande Valley region, by utilizing data collected from five continuous ambient monitoring stations in two counties over 23 years, from January 2000 to December 2022, to analyze daily, monthly, and seasonal variations of different pollutants, including ground-level ozone, particulate matter, and carbon monoxide. This study also identified distinct daily and seasonal patterns for O3, PM2.5, PM10, and CO at each monitoring site, influenced by factors such as traffic emissions, temperature, solar radiation, indoor heating, and weather conditions. …

Flow Monitoring And Tidal Exchange Ratio Estimation For The Bahia Grande After Widening Of The Carl Joe Gayman Pilot Channel: Bahia Grande, Cameron County, Tx, Sabas Lopez Iii

Theses and Dissertations

The Bahia Grande (BG) is an 8,500-acre set of coastal bays and wetlands located between Brownsville and Port Isabel, Tx, near the Gulf of Mexico (GOM) coastline. In 2005, the Carl Joe Gayman Pilot Channel was constructed to address hypersalinity concerns that resulted from natural and anthropogenically-caused tidal isolation since the early 1940’s. In 2022, the Texas General Land Office (GLO) increased the channel’s width and depth in anticipation of increasing tidal exchange ratios by a factor of two to three. Once the channel widening was complete, two SL-1500-3G side-looking acoustic doppler current profilers (ADCPs) were periodically deployed beneath the …

Exploring The Current Training Of Undergraduate Geology Students And Teaching Spatial Skills To Improve Student Outcomes, Ann Marie Klyce

Theses and Dissertations

Spatial skills, which represent the ability to mentally manipulate objects (Schneider & McGrew, 2012; Atit et al., 2020) have been shown to be correlated with entrance, persistence and success in STEM (Shea et al., 2001; Wai et al., 2009). Specifically, these skills have been shown to be necessary to geologists and geoscientists (Hegarty, 2014; Gagnier et al., 2016). While we recognize the importance of these skills, explicit training in them is rarely offered (NRC 2006). Consequently, cognitive scientists and discipline based education researchers have begun concerted efforts to offer training in spatial skills to improve student outcomes (e.g. Uttal et …

Dust Production And Transport In A Long-Lived Fluvial-Eolian System In The Pampas Of South America, Blake Marcus Stubbins

Theses and Dissertations

Wind-blown dust from southern South America links the terrestrial, marine, atmospheric, and biologic components of Earth’s climate system. The Pampas of central Argentina (~33-40° S) contain an extensive upper Miocene to Holocene eolian record that spans the relatively warm conditions of the Late Miocene to cooler climates of the Plio-Pleistocene and Holocene. We collected 13 loess, paleosol, and fluvial samples from the upper Miocene Cerro Azul and Rio Negro Formations which resulted in n = 5129 new detrital zircon U-Pb ages. Late Miocene rivers conveyed sediment from northern Patagonia, the Andes adjacent to the Pampas, and the Sierras Pampeanas to …

Surficial Geologic Mapping Of The Starkville 7.5-Minute United States Geological Survey Quadrangle 33088d-7 In Oktibbeha County, Mississippi, Jonathan Leard

Theses and Dissertations

The Starkville Quadrangle is a hotspot for geological research. The Late Cretaceous is represented by the Demopolis Formation in the northeast corner of the quadrangle, followed by the Ripley Formation, and the Prairie Bluff Formation. The K-Pg boundary is exposed in the quadrangle, and the remarkable paleontology is of global importance. The Clayton Formation is the first Paleocene unit. Where the Clayton Formation channel sands are in contact with the underlying Prairie Bluff Formation, springs occur. Springs were a rare source of water in the Black Prairie and spurred the settlement of the area over 10,000 years ago. The Paleocene …

Geologic Mapping Of The Sparta 7.5-Minute Quadrangle In Northern Mississippi Via Remote Sensing, Traditional Geologic Survey, And Applied Geospatial Information Systems Methods, Rayford Dean Parnell

Theses and Dissertations

Traditional geologic mapping involves substantial time and labor in the field as geologic contacts are manually examined and interpreted. The processes of mapping geologic contacts can be condensed into a quicker and less laborious process using advances in remote sensing and GIS (geospatial information systems), including increased resolution and computerized data management and interpretation. Application of these advances reduces the costs and time of geologic mapping. The Sparta 7.5-minute quadrangle provides a mostly unaltered view of regional Paleocene and Upper Cretaceous geology due to its rural locale, lack of development, and stream topography. Recently LiDAR (Light Detection And Ranging) survey …