Physical Sciences and Mathematics Commons^™

Exploring The Potential Impacts Of Climate Change On North America's Laurentian Great Lakes Tourism Sector, Natalie Chin

Open Access Dissertations

Climate change is one of the major challenges facing the global hospitality and tourism sector in the coming century and, given the important role that weather and climate play in all aspects of the tourism experience, tourism businesses owners need to start thinking about and enacting climate change adaptation strategies now. This work has utilized a combination of social science and physical science methods to (1) understand how the Great Lakes tourism sector could be impacted by climate change and (2) provide some insights into how researchers can help business owners prepare for these potential impacts. Overall, the results of …

Hydrocode Modeling Of Oblique Impacts Into Terrestrial Planets, Jordan D. Kendall

Open Access Dissertations

The abundance of moderately siderophile elements (“iron-loving”; e.g., Co, Ni) in the Earth’s mantle is 10 to 100 times larger than predicted by chemical equilibrium between silicate melt and iron at low pressure, but it does match expectation for equilibrium at high pressure and temperature. Recent studies of differentiated planetesimal impacts assume that planetesimal cores survive the impact intact as concentrated masses that passively settle from a zero initial velocity and undergo turbulent entrainment in a global magma ocean; under these conditions, cores greater than 10 km in diameter do not fully mix without a sufficiently deep magma ocean. I …

Policy Design Tool For Managing Indoor Residential Water Demand In Water-Scarce Regions, Mujahed M. Thneibat

Open Access Dissertations

In view of population growth; climate change; and economic evolution, water resources in numerous parts of the world have reached their natural capacities. Consequently, the ability of many countries to grow; meet the basic needs of inhabitants; and protect the environment will be endangered like never before unless water resources are smartly handled and managed. ^ In the past few decades, many developed and developing countries have suffered from water scarcity, and more are certain to follow. The water security dilemma is much more challenging in developing countries. Water utilities have had to follow regulatory plans to manage demand on …

Miocene-Pliocene Strike-Slip Basin Development Along The Denali Fault System In The Eastern Alaska Range: Chronostratigraphy And Provenance Of The Mccallum Formation And Implications For Displacement, Wai Kehadeezbah Allen

Open Access Theses

The Denali fault system represents one of the major strike-slip faults in North America but very little is known about the amount and timing of displacement on this 2000-km-long structure. The 7.9 M 2002 Denali Earthquake emphasized the importance of this fault system for understanding the deformational record of the upper plate of the southern Alaska convergent margin. Our analysis of the Miocene-Pliocene McCallum Formation located along the east-central part of the Denali fault provides one of the few records for Neogene displacement as well as changes in surface and basin processes related to tectonic transport. We have established a …

The Cloud-Radiative Forcing Of The U.S. Landfalling Atmospheric Rivers, Qianwen Luo

Open Access Dissertations

Atmospheric rivers (ARs) are narrow channels in the atmosphere that transport an enormous amount of moisture from the tropics to the higher latitudes. Streaks of highly reflective clouds are observed along with the ARs in satellite imagery. These clouds both influence the moisture transport of ARs, as well as modify the Earth-Atmospheric energy budget through pathways such as cloud-radiative forcing (CRF). This dissertation studies the CRF of the U.S. Landfalling ARs in weather and climate scales. Three crucial questions are addressed. First, how do clouds produced by the ARs modulate the moisture and heat balance of the Earth-Atmospheric system? Even …

Modeling The Impact Of Land Surface Feedbacks On Post Landfall Tropical Cyclones, Subashini Subramanian

Open Access Dissertations

The land surface is an important component of numerical models. The land surface models are modules that control energy partitioning, compute surface exchange coefficients and form the only physical boundary in a regional scale numerical model. Thus, an accurate representation of land surface is critical to compute surface fluxes, represent the boundary layer evolution and affect changes in weather systems. Land surface can affect landfalling tropical cyclones in two ways: (i) when the cyclone is offshore and land can influence cyclones by introducing dry (or moist) air that can weaken (or strengthen) the organized convective structure of cyclones, and (ii) …

Unraveling The Fingerprints Of Nox Using Stable Isotopes: Implications For Nox Source Partitioning And Oxidation Chemistry, Wendell William Walters

Open Access Dissertations

The nitrogen (N) and oxygen (O) stable isotope composition (δ15N & δ18O) of nitrogen oxides (NOx )may be a useful tool for constraining NOx emission sources as well as for understanding the atmospheric oxidation pathways responsible for its removal if various NOx sources and sink processes exhibit characteristic isotopic compositions (“fingerprints”). However, this requires (1) an accurate and complete inventory of δ15N(NOx) values from major emission sources, (2) an assessment of the kinetic and equilibrium isotope effects that can impact δ15N and δ18O values of NOx, (3) and test these assumptions by conducting accurate in situ δ15N and δ18O measurements …

An Examination Of Geographic Patterns Of Soil Climate And Its Classification In The U.S. System Of Soil Taxonomy, Hans Edwin Winzeler

Open Access Dissertations

Soil climate, the record of temporal patterns of soil moisture and temperature, is an important component of the structure of U.S. Soil Taxonomy. The U.S. Soil Survey has used the Newhall Simulation Model (NSM) for estimating soil climate from atmospheric climate records at weather stations since the 1970s. The current soil climate map of the U.S. was published in 1994 by using NSM runs from selected weather stations along with knowledge-based hand-drawn mapping procedures. We developed a revised soil climate mapping methodology using the NSM and digital soil mapping techniques.

The new methodology is called Grid Element Newhall Simulation Model …

Investigation Of Ambient Seismic Noise Using Seismic Interferometry In The Midwestern United States, Joshua Dakota Boschelli

Open Access Theses

The portion of the North American craton occupied by the Midwestern United States is a cratonic platform, where a veneer of Phanerozoic sedimentary strata buries the Precambrian basement up to 7 km. Due to the sediment cover and low topographic relief, the at depth structure of the region remains poorly understood. This region is of particular interest because over the past half-billion years tectonic forces have resulted in the formation of epeirogenic provinces in a stable cratonic interior. Using the OIINK flexible seismic array and the Earthscope Transportable Array, Ambient Seismic Noise Tomography was applied to investigate the crustal structure …

Willingness To Pay For Irrigation Water Under Scarcity Conditions, Tyler Robert Knapp

Graduate Theses and Dissertations

Reliance of Arkansas agricultural producers on groundwater for irrigation has led to depletion of the Mississippi River Valley alluvial aquifer. Without intervention, consequences include insufficient groundwater to meet irrigation demand as well as drawdown of the deeper Sparta Aquifer, upon which communities in eastern Arkansas rely for non-agricultural use. Among proposed solutions to combat groundwater decline is the construction of off-farm surface water infrastructure to meet the irrigation needs of producers. Despite the importance of irrigated agriculture to Arkansas, there is little know about the economic value of irrigation water to producers. Thus, we implement a double-bounded dichotomous choice contingent …

A Gis Approach To Modeling Groundwater Levels In The Mississippi River Valley Alluvial Aquifer, Josef Orion Lilly

Graduate Theses and Dissertations

Groundwater depletion, a subject of growing concern for a significant portion of Arkansas, may lead to future economic challenges for the Arkansas Delta region. The Mississippi River Valley Alluvial Aquifer is the uppermost aquifer and features the largest groundwater capacity in the Mississippi Embayment Aquifer System. The Mississippi River Valley Alluvial Aquifer, commonly referred to as the “alluvial aquifer”, spans 53,000〖 km〗^2 underlying portions of Arkansas, Kentucky, Louisiana, Mississippi, Missouri, Illinois, and Tennessee. As the alluvial aquifer trends southward for approximately 250 miles alongside the Mississippi River, its geographical extent ranges from 50 to 125 miles wide. There is a …

Examining Denitrification In Agricultural Ditch Sediments Vegetated With Rice Cutgrass (Leersia Oryzoides): Modeling Seasonal Variation Across Increasing Levels Of Nitrate Loading And Model Application To Pre-Existing Datasets, Shannon Lee Speir

Graduate Theses and Dissertations

Nitrogen (N) derived from fertilizer application in agricultural systems may contribute to significant environmental impacts, including eutrophication of fresh and coastal waters. Rice cutgrass (Leersia oryzoides) can significantly enhance denitrification potential in agricultural ditch sediments, but relationships with known drivers are not well understood. To address this, I examined effects of nitrate (NO3-) availability on dinitrogen gas (N2) and NO3- fluxes seasonally in Chapter 2. Denitrification rates were measured as N2 flux from intact vegetated sediment cores using Membrane Inlet Mass Spectrometry (MIMS). Michaelis-Menten models were developed from observations to mathematically describe N2 fluxes across the spring, summer, and fall …

Effects Of Mars Regolith Analogs, Uvc Radiation, Temperature, Pressure, And Ph On The Growth And Survivability Of Methanogenic Archaea And Stable Carbon Isotope Fractionation: Implications For Surface And Subsurface Life On Mars, Navita Sinha

Graduate Theses and Dissertations

Mars is one of the suitable bodies in our solar system that can accommodate extraterrestrial life. The detection of plumes of methane in the Martian atmosphere, geochemical evidence, indication of flow of intermittent liquid water on the Martian surface, and geomorphologies of Mars have bolstered the plausibility of finding extant or evidence of extinct life on its surface and/or subsurface. However, contemporary Mars has been considered as an inhospitable planet for several reasons, such as low atmospheric surface pressure, low surface temperature, and intense DNA damaging radiation. Despite the hostile conditions of Mars, a few strains of methanogenic archaea have …

Stratigraphy And Depositional Environment Of The Middle Atoka Formation, Central Arkoma Basin, Western Arkansas, Yueyang Wang

Graduate Theses and Dissertations

Wire line logs are widely used in analysis of the subsurface stratigraphy of the middle Atoka Formation, Central Arkoma Basin, Western Arkansas. SP log, Gamma ray log, resistivity log and conductivity log provide valuable information to construct cross sections.

The middle Atoka formation is composed of a succession of shale and sandstone alternations with thickness reaching approximately 3000 feet in the study area. It contains several sandstone units which include Morris, Tackett, Areci, Bynum, Casey and Dunn”A” separated by shale intervals. The purpose of this study is to identify these units and predict sequence stratigraphy and depositional environment by constructing …

Temporal Co2 Variations And The Influence Of Bat Colonies In Speleogenesis: Continuous Co2 Monitoring In War Eagle Cavern, Arkansas, Ginny Sue Holcomb

Graduate Theses and Dissertations

Dissolved concentrations of CO2 in a karst aquifer are a major control on calcite dissolutional processes, as CO2 combines chemically with water to form carbonic acid. As increasing amounts of CO2 are added to the system, greater resultant water aggressivity generates greater rates of dissolution. Spatial and temporal variations in carbon flux through the system may occur over a range of time scales, and high-resolution data collection is needed to truly understand and characterize such variability. Continuous CO2 monitoring in War Eagle Cavern, Arkansas, will suggest a number of influential parameters with varying degrees of importance throughout an annual cycle. …

Development Of A Pluto Chamber For Surface Simulations, Zachary Michael Mcmahon

Graduate Theses and Dissertations

In light of the exciting new discoveries being made by the New Horizons team, more data on Pluto is available than ever before. However, with the increase in recovered data, there is now a need for laboratory data to interpret it. Laboratory simulation of these conditions and subsequent testing of materials and samples therein is now possible and necessary to understand what has been observed. To do these simulations, a vessel that can achieve low temperatures and high vacuum is required. The scope of this work presented here was to design, build, and test a chamber that could perform these …

Sedimentary Petrology Of The Hartshorne Formation, Southeastern Arkoma Basin, Arkansas, Ruizhe Yin

Graduate Theses and Dissertations

The Pennsylvanian Hartshorne Sandstone crops out in an east trending belt across central Arkansas immediately north of the Ouachita orogenic belt and south of the Boston Mountains. The unit, composed of massive to cross bedded sandstone ranging to 150m in thickness, was deposited by a west-flowing river system that extended from central Arkansas to southeastern Oklahoma. The source of the sediment has been extensively discussed but not completely established. The object of this thesis is to constrain the source area and terrain based on thin section mineralogy and texture. Thin sections were prepared from outcrops in the Arkoma Basin and …

Asbestos Cement Pipe Condition Assessment And Remaining Service Life Prediction, Abiy Melles Ghirmay

Graduate Theses and Dissertations

This research details a condition assessment of asbestos cement (AC) pipe within in the Bella Vista Village Property Owners Association water distribution system. Bella Vista Village contains appropriately 300 miles of AC pipe with nominal diameters from 6-14 inch. The goal of the research is to determine the current condition of AC pipe within the system and predict future performance of the pipes. AC pipe samples were obtained from 23 locations disturbed across the distribution system with nominal pipe diameters of 6-8 inch. Estimates of current level of degradation were obtained using phenolphthalein staining and hardness measurements of each sample. …

The Role Of The Picuris Orogeny In The Tectonic Evolution Of Proterozoic North America, Ruth Frances Aronoff

Open Access Dissertations

North America is a continent that has grown over time by horizontal attachment of material onto its margins. Studying the process of continental growth in the geologic past gives insight into fundamental components of plate tectonics, and sheds light onto processes at work at modern plate boundaries, in which mid- and lower-crustal rocks are generally hidden from view.

This study focuses on the growth of North America during the Proterozoic. Researchers have debated the role of three orogenies in shaping the southwestern margin of North America: the ∼1.80-1.60 Ga Yavapai and Mazatzal orogenies, and the newly recognized ∼1.40 Ga Picuris …

Studies Of Arctic Tropospheric Ozone Depletion Events Through Buoy-Borne Observations And Laboratory Studies, John W. Halfacre

Open Access Dissertations

The photochemically-induced destruction of ground-level Arctic ozone in the Arctic occurs at the onset of spring, in concert with polar sunrise. Solar radiation is believed to stimulate a series of reactions that cause the production and release of molecular halogens from frozen, salty surfaces, though this mechanism is not yet well understood. The subsequent photolysis of molecular halogens produces reactive halogen atoms that remove ozone from the atmosphere in these so-called “Ozone Depletion Events” (ODEs). Given that much of the Arctic region is sunlit, meteorologically stable, and covered by saline ice and snow, it is expected that ODEs could be …

The Use Of Stable Isotopes And Particulate Matter In The Investigation Of Local And Regional Atmospheric Chemistry, Tanya Lynn Katzman

Open Access Dissertations

The chemical composition of particulate matter (PM), a known contributor to air pollution, is highly variable, and elemental analysis reveals information about local and regional sources, as well as how air masses and climate influence PM compositions. Seasonal changes in climate, such as temperature, amount of daylight, or meteorological patterns influence source emissions (increased residential heating activities, decreased natural soil emissions) and the relative importance of certain chemical pathways in the atmosphere. Since the magnitude of these seasonal changes are highly dependent on location, each sampling site is unique and the chemical composition of PM provides valuable insight into local …

Evolutionary Potential Of A Dispersal-Restricted Species In Response To Climate Change, Lorena Torres Martinez

Open Access Dissertations

Habitat replacement and fragmentation associated with projected climate change pose a critical threat to global biodiversity. Edaphically limited plant species with restricted dispersal abilities will be especially handicapped to track their optimal climate spatially. Instead, the persistence of these species will depend on their capacity to adapt in situ to novel climate regimes. Here I evaluated the evolutionary potential of Lasthenia fremontii, an annual plant species restricted to ephemeral wetlands called vernal pools in California to adapt to the projected patterns of climate change. Across L. fremontii distribution there is a latitudinal gradient in precipitation which, combined with reduced …

Simulation Of Flow And Water Quality From Tile Drains At The Watershed And Field Scale, Colleen Moloney

Open Access Theses

Simulation models such as the Soil and Water Assessment Tool (SWAT) have become widely used in determining the water quality impacts of various management practices. Ensuring that the algorithms accurately represent the processes simulated has become an important goal. Tile drainage is a standard practice in the Midwest, US in order to reduce risk of yield loss due to excess water. Multiple tile drainage and water table algorithms have been available in the SWAT model between the initial SWAT release and revision 638 used in this study. Testing of those algorithms is often limited. Furthermore, algorithms in the current version …

Nutrient Runoff And Leachate After Land-Application Of Digestate In A Laboratory Study Using Rainfall Simulations, Min Xiao

Open Access Theses

There has been an increasing number of anaerobic digesters on livestock farms in the United States during the past two decades. Anaerobic digestion of manure allows production of renewable energy and generation of stabilized and nutrient-rich digestate that can be used as organic fertilizer. However, the majority of the existed studies using liquid digestate as fertilizer only focused on the effectiveness for crop yield, nutrient content and microorganism in soil. There is insufficient understanding in the environmental impact of digestate land-application. This laboratory study used six treatments including four different liquid digestate treatments, a chemical fertilizer treatment, and an unfertilized …

Role Of River Bathymetry In Hydraulic Modeling Of River Channels, Sayan Dey

Open Access Theses

Accurate geometric representation of the river channel is required for accurate hydraulic modeling of rivers. These are generally obtained through remote sensing techniques such as Light Detection and Ranging (LIDAR). However, these techniques lack the ability to model the submerged channel bed effectively and need to be complemented with surveyed bathymetric data for complete representation of the channel bathymetry, which can be time and cost prohibitive. An alternative to address this issue is to develop conceptual models that can estimate bathymetry.

This study aims to evaluate the potential of a conceptual model, the River Channel Morphology Model (RCMM) which estimates …

Seismic Body-Wave Interferometry Using Noise Autocorrelations For Crustal Structure And A Tutorial On 3d Seismic Processing And Imaging Using Madagascar, Can Oren

Open Access Theses

Seismic body-wave interferometry is applied to selected seismic stations from the USArray Earthscope Transportable Array (TA) by autocorrelating ambient seismic noise recordings to construct effective zero-offset reflection seismograms. The robustness of the auto-correlations of noise traces is first tested on a TA station in Nevada where body-wave reflections similar to those found in an earlier study are identified. This approach is then applied to several TA stations in the central U.S., and the results are compared with synthetic data. Different stacking time periods are then examined to find the shortest time intervals that provide stable correlation stacks.

A tutorial on …

Experimental Simulations Of Recurring Slope Lineae And Other Flow Formation Features On Mars, Julia Ann Heydenreich

Graduate Theses and Dissertations

Various flow formation features from gullies to recurring slope lineae (RSL) have been identified across the martian surface. The formation of these geologic features are still being determined. Recently, several aspects of these flow features indicate that salt water flows in the subsurface during the warmer months when the ice melts. This paper explores the formation of these processes using laboratory experimental simulations. Experiments were conducted in a wooden flume under varying martian conditions of temperature, slope angle, regolith simulant and a liquid subsurface flow. By adjusting the flume at specific heights, several slopes were obtained to mimic the slopes …

Evaluating A Measure-Calculate Method For Determining Sediment Oxygen Demand In Lakes, Adrian Beirise

Graduate Theses and Dissertations

A steady-state mass diffusion model used with simple measurable and calculable inputs for determining sediment oxygen demand (SOD) is compared to an intact core incubation (ICI) SOD method using samples from three lakes. The mass diffusion model coupled with inputs is known as the measure-calculate method (M-C) and is a potential alternative to existing methods for measuring SOD which are more complex, time-consuming, and costly. The M-C method requires inputs for volumetric sediment oxygen uptake (Ṅsed), sediment density and porosity, and water properties. Ṅsed was determined by suspending sediment in oxygen-saturated water with a DO probe and determining the steady …

Optical Water Quality And Human Perceptions Of Rivers, Amie West

Graduate Theses and Dissertations

Understanding water quality dynamics in recreational rivers is integral in shaping management strategies that maintain ecosystem health, perceived value and appeal, and regional economic significance in a changing environment. Optical water quality describes the behavior of light in water as governed by its physical and chemical composition, and is among the strongest influences on human perceptions of water quality. Ethnohydrology is the study of culturally constructed knowledge and understanding of water. This work is the culmination of an interdisciplinary approach to water resources research—integrating optical water quality and ethnohydrology methods to recognize the intersection between measured water quality and visible …

Chlorine Demand Shows Thresholds And Hierarchy With Source Water Quality At Beaver Lake, Arkansas, Jaime M. Gile

Graduate Theses and Dissertations

This study investigated the effects of source water quality in Beaver Lake on the amount of chlorine (Cl) needed to develop decision support system to help guide chlorination practices in pre-treatment of source water. Chlorine demand assays were performed on water samples from Beaver Lake collected from the intake structure at Beaver Water District from March 2014 through August 2015, and using data from these assays, the two points of interest in this study were the Cl dose at which Cl residuals began to accumulate and the mean Cl demand occurring after that dose. Three methods of analysis were used …