Earth Sciences Commons^™

Quantifying The Controls Of Shear-Coupled P-Waves, Jackson Saftner

Theses and Dissertations

Shear-coupled P-waves have been shown to possess great utility in resolving crustal and upper mantle models, however these phases remain largely untapped due to their ephemeral nature. Shear-coupled P-waves are a type of seismic phase that undergo S-to-P conversion either at the free-surface or at the base of the crust. Under the proper conditions, it is possible for the converted crustal P phases to achieve total internal reflection, allowing these phases to remain large in amplitude and sample long segments of the crust. In this study, we use a combination of real-world observations collected from literature, and synthetic seismograms, to …

The Impact Of Framing On Natural Gas Pipeline Siting In Virginia, Ritvik Shukla

Theses and Dissertations

Natural gas has become a major share of energy consumption in the U.S. over the past two decades. This rise has resulted in considerable investment in the natural gas pipeline network so that the supply can be maximized. However, pipeline infrastructures, much like other fossil fuel energy infrastructures and activities, have an uneven distribution of benefits and costs across different regions. In regions where natural gas activities and infrastructure are being developed, local communities can become increasingly dependent on natural gas systems for stable revenue and employment. Such communities risk becoming “locked in” to carbon energy at a time when …

Hydrologic Profiles And Geospatial Trend Analysis Evaluating Recurrent Flooding At Coastal U.S. Air Force Installations, Dylan D. Bechen

Theses and Dissertations

Military installations are exposed to numerous threats, including a changing climate and the risk of recurrent flooding. The four components of recurrent flooding are sea-level rise, tidal fluctuations, storm surges, and precipitation. This research analyzed 40 years of historical precipitation and tidal data at 17 coastal U.S. Air Force installations using indicators of both peak and threshold exceedances to identify long-term temporal trends in the hydrologic components that make up recurrent flood risk, establishing an installation’s “hydrologic profile” which can be used to better inform decision makers when evaluating portfolio-wide adaptation strategies and prioritization of long-term infrastructure investments.

Biotic Characteristics Of Managed And Unmanaged Coastal Dunes In The Outer Banks, North Carolina, Andrew E. White

Theses and Dissertations

Under future climate change and sea level rise scenarios, Natural and Nature-Based Features (e.g., dunes) that protect coastal habitat and infrastructure will be exposed to increased wave energy and storm surge. Understanding how these forces will impact coastal dunes is necessary for their continued use as protective features. Coastal dunes develop through feedback between vegetation and sediment deposition, a process complicated by species-specific growth rates and responses to burial. Wave flume studies have tested the effects of dune vegetation on erosion and found multiple plant organs across several functional types to be important for resisting erosion. Although dune building and …

Identifying Biogeochemical Factors Responsible For The Cyclical Precipitation Of Sphalerite And Galena In Low Temperature Mississippi Valley Type Ore Deposits, Daniel John Makowsky

Theses and Dissertations

Mississippi Valley Type (MVT) lead and zinc deposits provide a significant source of sedimentary galena and sphalerite. However, geochemical characteristics and genesis including the source and production of hydrogen sulfide required for galena and sphalerite ore formation and the reasoning for quick, episodic mineralization is not fully understood. By simulating regional MVT brines, the input and effect of biological by-products during the development of these ores as well as the cause of cyclicity within MVT deposits have been observed. Experiments using compositions from MVT fluid inclusions were conducted over two-week periods. Variables during the experiments included temperature, CO2, hydrogen sulfide …

The Effects Of Cover Crops In An Integrated Livestock/Continuous Corn Cropping System In East-Central Mississippi, Ken Randolph Waddell

Theses and Dissertations

There is growing interest within the agricultural industry on how cover crop systems affect soil health and economic productivity in integrated crop-livestock systems. This study investigated the combined effects of cover crop species; no-till and conventional till; and grazed (G) and un-grazed (UG) in a continuous corn (Zea mays) production system in east-central Mississippi. Cover crops were established in the fall of 2019 and 2020 in two separate field studies. Corn yield was not affected by grazing or tillage but was affected by cover crop species. We then compared the difference in cover crop species treatments with their respective corn …

Chemical And Physical Weathering Rates Of Basaltic Volcanic Regions: Utilizing Space In Place Of Time In The Hawaiian Archipelago, Benjamin Clyde Barton

Theses and Dissertations

With large populations living in tropical regions of the world with volcanic substrates, understanding basalt weathering processes is vital. The Hawaiian Islands are an excellent natural analogue to study chemical weathering rates due to a uniform bedrock (basalt), large variations in rainfall, and varying ages across the islands. Laterite weathering profiles (LWP) develop over time through chemical weathering, where LWP thickness is influenced by many factors, including precipitation and time. Using the rapid, non-invasive horizontal-to-vertical spectral ratio (HVSR) method, LWP thicknesses can be estimated to constrain chemical weathering rates. Studying the laterite weathering profiles developed from basaltic bedrock of varying …

Snook (Centropomus Undecimalis) Behavior And Accelerometer Telemetry In The Bahia Grande Of Texas, Jonathan Truett Cawlfield

Theses and Dissertations

There has been very little study of the Texas population of snook. No studies have have looked at behavior in the Texas snook population. In this study we look at behavioral patterns and activity level in Lower Laguna Madre snook utilizing accelerometer telemetry tags. Twenty-one common snook were surgically implanted with tags and monitored from summer and fall of 2019 until September 2020. The accelerometer tags which sum acceleration over the x, y, and z planes calculated (ODBA) which was used to estimate behavior. This behavior was then compared with environmental data like diel period, tidal period, water temperature, and …

Assessment And Monitoring Of Deltaic Wetlands And Fluvial Systems: Refining And Validating A Multimetric Index Of Resaca Ecosystem Health, David Lecusay Jr.

Theses and Dissertations

Resacas are ancient distributary channels of the lower Rio Grande River historically serving as floodwater drainage pathways onto the Laguna Madre, Texas. Resacas provide numerous ecosystem services and critical habitat for many species. Mainly influenced by urbanization, integrating a multimetric index for assessing and monitoring resaca ecosystem health is required for adaptive management. The Resaca Health Index (RHI) integrates structural and functional components: (1) nonredundant metrics describing fish communities (Fish Community Index); (2) Trophic State Index derived from Secchi depth; (3) decay constant from riparian vegetation leaf litter decomposing in the water column; and (4) a riparian quality index based …

Managing Water Resource And Land Use In Lower Rio Grande Valley Of South Texas Using A Groundwater Vulnerability Model, Leslie Soto Sanchez

Theses and Dissertations

The Lower Rio Grande Valley (LRGV) has three Metropolitan Statistical Areas. These are Brownsville-Harlingen, Laredo, and McAllen-Edinburg-Mission, the latter with a population of around 1 million people and had an estimated growth of 62% from the period of 2010-2018 (Texas State Data Center, 2020). Low precipitations, intensive agricultures as well as growth in the manufacturing and tourism industries have resulted in an increasing concern of scarce water supply especially the region relies primarily on a single water source, the Rio Grande River. These circumstances could potentially disrupt economic development, negatively affecting the local manufacturing industry, agriculture, and the community. With …

Land, Racial Formations, And Power: Exploring The Network Of Power Relationships During Climate Change Planning In Coastal South Carolina, Teresa Norman

Theses and Dissertations

Climate change projections for the coastline of South Carolina predict that by mid-century there will be around 1.2 feet of sea level rise, and potentially up to 4 feet of rise by 2100. Additionally, climate change is linked to intensified hurricanes, a hazard for the South Carolina coastline every year. Both of these scenarios result in increases in the regularity and severity of coastal flooding, making the threat of permanent or temporary displacement (relocation) from coastal lands a reality. This is a particularly pressing matter for African American communities already made vulnerable by the long history of racial discrimination in …

Assessing The Anthropogenic Footprint On The Channel Sinuosity Of The Rio Grande The Delta, Edoardo Davila

Theses and Dissertations

The Rio Grande has been an emblematic feature and a source of life for the Rio Grande Valley. Since Pre-Historic times, it has provided the resources that allowed communities to thrive in a land where water is scarce. Large scale anthropogenic activities including, primarily in the form of river diversions and dam construction, have negatively impacted the river. Twenty-three major dams, and many small ones built on the main channel and many of its tributaries in the last century, have drastically reduced water discharge and virtually eliminated sediment delivery to the delta. This study explores how the channel sinuosity …

Assessing Long-Term Coral Coverage At East And West Flower Garden Banks, Rebekah Alicia Hernandez

Theses and Dissertations

Coral reefs provide critical habitat for diverse benthic communities; however, more than 10% of existing reefs have been lost as a result of natural and anthropogenic stressors. While there has been a decline in reefs around the world, East and West Flower Garden Banks (FGBs), part of Flower Garden Banks National Marine Sanctuary (FGBNMS), have maintained > 50% live coral cover for over 27 years as revealed by the FGBNMS long-term monitoring (LTM) program. In the 1980’s, the LTM program at East and West FGBs was developed in response to the expansion of oil and gas exploration, anchoring, and fishing impacts …

Biochar Applications To The Remediation Of Lead And Polychlorinated Biphenyl Contaminated Water, Victory Itua Igberase

Theses and Dissertations

This study investigated the performance of biochar materials as adsorbents to remove Pb and polychlorinated biphenyl (PCB) in aqueous solutions. Batch adsorption and column experiment packed with biochar and geomaterials (pumice) in 1:1 volume ratio was evaluated to address the efficacy of biochar in removing Pb while only batch adsorption was employed for PCB removal with biochar materials. Overall, PT biochars performed the best (42–53 mg g−1) followed by BE biochars (10–32 mg g−1) and AB biochars (17–27 mg g−1) while high temperature biochars were favored in terms of maximum Pb adsorption capacity. Column Pb breakthrough showed similar results, with …

Soil Chemistry Modification By Guinea Grass In Semi-Arid Soils: A Litter Mediated Positive Feedback, Vanessa Elizabeth Thomas

Theses and Dissertations

Nutrients are a key component of healthy soils. Their composition plays an important role in plant growth through nutrient cycling and directly influences the functioning of plant communities in both agricultural and natural ecosystems. Shifts in macronutrients such as phosphorus and nitrogen may be initiated by invasive growth as a driver for competition with native plants. The goal of this study is to explore the plant soil feedback in an exotic invasive plant, Guinea grass (Pancium maximum), an invasive bunch grass originally from Africa, across different habitat types in the Lower Rio Grande Valley (LRGV). To determine a positive plant …

Groundwater Discharge From Passive Continental Margins: Rethinking Marine Chemical Budgets, Andrew William Osborne

Theses and Dissertations

Geothermal convection and sediment compaction drive large-scale flow in continental shelves. We suggest that this flow is an overlooked control on the major ion chemistry of the ocean. Conventional ocean chemical budgets are constructed using river discharge, axial mid-ocean ridge (MOR) convection and CaCO3 production, but these budgets are still poorly quantified. We synthesized data from 17 passive continental margin basins to calculate a range of estimated groundwater and chemical fluxes from continental shelves, considering five major ions (Ca2+, Na+, K+, Mg2+, and Cl-). When extrapolated globally, volumetric groundwater flux estimates were comparable to those for MOR axial circulation, and …

Carbon Storage Via Mineral Bonding In Subsoils A Review Of Soil Processes, Kiele Goins

Theses and Dissertations

Soil is an important but often poorly understood portion of the carbon cycle. Soil can store more carbon than twice today’s atmosphere, but the factors that control carbon storage are often unclear. Carbon enters the soil through input of organic matter, erosion, and aerosol deposition and is lost mostly via microbial decomposition. Carbon loss in soil is impacted by the chemical composition of organic compounds, environmental factors, and human activities. Furthermore, as climate changes soil, carbon storage may be vulnerable. Although carbon can be stored throughout soil, carbon storage varies with depth. In topsoil, carbon is stored for short periods …

Groundwater Flow And Transport At The Forest-Marsh Boundary: A Modeling Study, Sophia Chason Sanders

Theses and Dissertations

The forest-marsh boundary, where tidally influenced salt marshes meet a forested upland, is hydrologically complex due to its multiple water inputs. Groundwater flow and salinity transport at this boundary are not well understood. In order to make predictions about salinity at this boundary as it responds to climatic factors, a two-dimensional model was built to simulate groundwater flow and solute transport at a salt marsh on Sapelo Island, Georgia. After calibration based on observed data from wells at the study site, the model can be used to identify patterns in groundwater movement and solute transport that may influence the vegetation …

Development Of A Cyberinfrastructure For Assessment Of The Lower Rio Grande Valley North And Central Watersheds Characteristics, Linda Isabel Navarro Navarro

Theses and Dissertations

Due to an increase in urbanization in the Lower Rio Grande Valley (LRGV), there have been substantial modifications to hydrology causing a decline in water quality to the Laguna Madre watershed. The major concern is the inflow of freshwater from the North and Central waterways released to the Lower Laguna Madre which is designated as an impaired watershed for high concentrations of bacteria and low dissolved oxygen. The objective of this study is to perform a watershed characterization to determine potential pollution sources of each watershed by developing a cyberinfrastructure and collect a wide inventory of data. The objective will …

Unravelling The Role Of Pgpr "Pseudomonas Fluorescens" In Semi- Arid Soils Of The Rio Grande Valley, Mandip Tamang

Theses and Dissertations

Chapter 1: In this chapter, we have provided a review on the components of rhizosphere engineering and the potential use of PGPR and its challenges to serve as an efficient component for sustainable agriculture.

Chapter 2: In this chapter, we isolated 35 different strains of a PGPR, Pseudmonas fluorescens and characterized various plant growth promoting traits such as production of ammonia, protease, Indole acitic acid (IAA), 1-aminocyclopropane-1-carboxylate deaminase (ACC) deaminase, ammonia, hydrogen cyanide (HCN), and souliblization of zinc and phosphate.

Chapter 3: In this chapter, we tested the influence of plant beneficial soil microbe, P. fluorescens, on the growth and …

Terrestrial Lidar Scanning And Gaming Engines: Using Unity3d To Visualize High-Resolution Point Clouds From Big Bat Cave, Kentucky, Jeffrey Aaron Baggett

Theses and Dissertations

Terrestrial LiDAR scanning has become a staple of modern speleological research and mapping due to its increasing availability, rapid deployment, and ability to collect large quantities of spatial data in a short period of time. In addition to spatial data, LiDAR scanners’ ability to record reflection intensity is of interest in the geoscience community as a proxy for surface reflectivity and as a means of aiding in visualizations when a lack of lighting prevents the use of photography at a useful scale. In this study, a methodology for rendering a stereoscopic, real-time rendering of a 10 scan, 425-million point portion …

Radium At The Lost City And Mid-Cayman Rise Hydrothermal Fields, Jessica D. Frankle

Theses and Dissertations

Fluid residence times of deep-sea hydrothermal circulation influence chemical cycling in the ocean. While fluid residence time estimates exist for many basalt-hosted systems, no estimates exist for serpentinite hosted systems that emit fluids with inherently different chemistry. We measured short- and long-lived radium (Ra) nuclides in fluids from two hydrothermal systems on the Mid-Cayman Rise to constrain their residence times: the Von Damm Vent Field, a mixed ultramafic-mafic system, and the Piccard Vent Field, a mafic, neovolcanic system. Von Damm fluids contain remarkably elevated 223Ra activities (half-life = 11.4 days), surpassing those from basalt-hosted hydrothermal systems by one to two …

Monitoring Of Carbon Dioxide Injection In The Southeastern United States, Adil Murad Awad Alshammari

Theses and Dissertations

Over the past few decades, measured levels of atmospheric carbon dioxide have substantially increased. One way to limit the adverse impacts of increased carbon dioxide concentrations is to capture and store it inside Earth's subsurface, a process known as CO2 sequestration. This method's success is critically dependent on the ability to confine injected CO2 for up to thousands of years. Establishing effective maintenance of sealing systems of reservoirs is of importance to prevent CO2 leakage. Understanding the nature and rate of potential CO2 leakage related to this injection process is essential to evaluating seal effectiveness and ultimately mitigating global warming. …

Carbonatite Metasomatism And Water Systematics Of Peridotite Xenoliths From Lanzarote, Canaries, Sierra N. Patterson

Theses and Dissertations

Water in Earth’s mantle, present as structurally bound hydrogen in minerals, influences large scale processes like mantle deformation, plate tectonics, and melting. To better understand the processes controlling water concentrations in the Earth’s upper mantle, we analyzed hydrogen (calculated as ppm wt. H₂O), major, and trace element concentrations in minerals from peridotite mantle xenoliths of Lanzarote, Canaries. The Canaries Islands are thought to be the surface expression of a deep-seated mantle plume erupting through the Atlantic Ocean lithosphere. Carbonatite magmas have erupted in the Canaries and previous studies have shown evidence for carbonatite metasomatism in Lanzarote peridotites. Thus, …

Application Of The Revised Universal Soil Loss Equation To Develop A Management Plan In The Chittagong Hill Tracts Region Of Bangladesh, Nira Rahman

Theses and Dissertations

Land degradation from soil erosion is a major issue in hilly areas of tropical regions such as the Chittagong Hill Tracts (CHT) of Bangladesh. The combination of an elevated topography, high-intensity storms that are further exacerbated by the impacts of climate change, and farming practices increase the susceptibility of the region to soil erosion. The Revised Universal Soil Loss Equation (RUSLE) was developed in the mid-latitude dry climate zone of the United States during the 1990s to assist soil conservationists in implementing farming strategies that would address soil loss. Since then, researchers employed remote sensing and geographic information systems (GIS) …

Modeling Vegetation Effects On Barrier Island Evolution, Eric W. Schoen

Theses and Dissertations

Barrier islands play a significant role in protecting coastlines and harboring coastal habitats. In an effort to study and better understand the evolution of barrier island systems, a cellular model capturing various meteorological and environmental processes is proposed. Erosion due to wind, gravity, and marine processes are coupled with plant population effects. We demonstrate the inhibition of plant cover on sediment mobility, island migration, and erosion in the presence of sea level rise.

Paleoseismic Studies Using Geophysical Techniques: Sand Blow Features In Eastern Arkansas, Rauf R. Hussein

Theses and Dissertations

Damaging earthquakes including pre-historical, historical and recent demand paleoseismic studies to improve seismic risk assessment of future destructive earthquakes. Such large earthquakes could damage many structures, kill scores of people and leave others homeless, and devastate the economy. In this study, extensive research efforts are described to investigate the feasibility and effectiveness of using Ground Penetrating Radar (GPR) in detecting and identifying specific geological features that are related to historic and prehistoric earthquakes. These features are preserved in the near surface soil and manifested as sand blows, buried paleo-surfaces, venting dikes, and structural faults. They are related to severe cyclic …

Impacts Of Land-Use Change On The Menominee River In Jo Daviess County, Illinois, Preston J. Konop

Theses and Dissertations

This study addresses land-use changes in Jo Daviess County, Illinois, and their effects on the Menominee River. The Menominee River flows north to south through Jo Daviess County, and southern Grant County, Wisconsin. Many of the surrounding properties are agricultural and have undergone developmental and land-use changes that may affect the flood flashiness of the Menominee River. The concern with increasing flood flashiness of the Menominee River include more frequent flooding events, undercutting of riverbanks, and increased amounts of sediment transport from upstream locations into the Mississippi River. Increases in impermeable surfaces have led to greater amounts of runoff during …

Snow-Albedo Feedback In Northern Alaska: How Vegetation Influences Snowmelt, Lucas C. Reckhaus

Theses and Dissertations

This paper investigates how the snow-albedo feedback mechanism of the arctic is changing in response to rising climate temperatures. Specifically, the interplay of vegetation and snowmelt, and how these two variables can be correlated. This has the potential to refine climate modelling of the spring transition season. Research was conducted at the ecoregion scale in northern Alaska from 2000 to 2020. Each ecoregion is defined by distinct topographic and ecological conditions, allowing for meaningful contrast between the patterns of spring albedo transition across surface conditions and vegetation types. The five most northerly ecoregions of Alaska are chosen as they encompass …

Predicting Patterns Of Heavy Metal Contamination In Rio Grande Valley Agricultural Soils, Joy Z. Youwakim

Theses and Dissertations

The Rio Grande Valley of Texas is the statewide leader in the production of produce and grains and is irrigated by the Rio Grande River, in which heavy metal contaminants have been documented by both the International Boundary Water Commission and the United States Geological Survey. This work attempts to observe and document patterns of heavy metal pooling in order to mitigate the increased risk of contamination due to urbanization. We hypothesize that relationships exist between heavy metal content and proximity to roads, land use, and soil type. This research tests these relationships through soil sampling and atomic absorption spectrometry …