Digital Commons Network^™

Impact Of Cover Crop Species Diversity On Soil Nutrient Availability And Crop Productivity, Amanda Kramer

Masters Theses

Cover crops provide multiple environmental benefits that improve both soil and water quality; however, farmers only utilize them on approximately 5% of harvested U.S. cropland. Low adoption rates are attributed to yield impact concerns, seed and planting costs, and lack of advocacy. This study, which began in October 2019, assessed the effects of nitrogen rate and cover crop diversity on weed biomass, soil coverage, in-situ residue decomposition, soil nitrogen and phosphorus availability, and cash crop yield to better understand the costs and benefits of cover crop adoption at two locations in Tennessee (Milan and Spring Hill). Treatments were replicated 4 …

Influence Of Physical Variability Of Highly Weathered Sedimentary Rock On Nitrate In Area 3 Of The Enigma Field Research Site At Y-12, Erin Kelly

Masters Theses

Uranium processing and waste storage in unlined waste ponds leached contaminants into the groundwater at Y-12, Oak Ridge, Tennessee, from the 1950s to 1980s. Groundwater wells near the S-3 ponds have had the highest nitrate concentrations of groundwater anywhere in the world (>10,000 mg/L). For reference, the maximum contaminant level for nitrate in drinking water set by the U.S. Environmental Protection Agency is 10 mg/L. Since 2012, the ENIGMA (Ecosystems and Networks Integrated with Genes and Molecular Assemblies) group has been characterizing, monitoring, and conducting field experiments to understand the interactions between contaminants, microbes, and the subsurface. The goals …

Dissolved Organic Carbon And The Potential Role To Stream Acidity In The Great Smoky Mountains National Park, Jason R. Brown

Masters Theses

A substantial societal shift towards environmental awareness has focused research efforts on the impacts of pollution on natural landscapes. Improvements to pollutant regulations and technology have resulted in sizeable reductions of atmospheric deposition of anthropogenic acids, especially nitrates and sulfates, which has altered the role of these ions in the environment. As such, understandings of environmental chemistry dynamics have required regular updating.

Through the National Park Service Vital Signs monitoring program, increases in precipitation pH observed in Great Smoky Mountains National Park (GRSM) has been attributed to the reduction of inorganic acid concentrations. Unfortunately, these improvements have not been uniformly …

Application Of Titrations For Verification Of Small Molecule Interaction In Relation To Amidoximated Fibers For Uranium Extraction From Seawater, Kc Michael Mote

Masters Theses

Nuclear energy is a promising substitute for fossil fuels due to possessing low carbon emissions and providing scalable base-load power. However, one major drawback of using nuclear fuel as an energy source is that it needs a steady source of uranium. While the most economical method of obtaining uranium is through conventional terrestrial mining of the ore uranite, mining uranium ores is both harmful to the environment and limited by the terrestrial uranium supply, which is estimated at only 100 more years. However, more than 1000× more uranium is dissolved in seawater than is reasonably inferred and assured in terrestrial …

Sustained Release Of Persulfate And Iron(Ii) Ions From Inert Inorganic Materials For Groundwater Remediation, Peter Pham

Masters Theses

Contamination of groundwater, initiated from years of human negligence, continues to persist despite major advancements in water remediation technologies. The generated groundwater plumes can continuously replenish contaminants such as dense nonaqueous phase liquids (DNAPLs) through the aid of slow-moving water. Thus, long-term treatment of this flow system has proven to be problematic. A selection of sophisticated sustained diffusion technologies is needed to help prevent further damage to this prominent freshwater source.

Here, a novel in-situ chemical oxidation (ISCO) method was designed to incorporate persulfate into silica mediums such as zeolite, diatom, and silica flour for the treatment of groundwater contaminants …

The Use Of Sodium Persulfate In Hydraulic Fracturing Fluids: A Degradation Study Based On Furfural, Katherine Elizabeth Manz

Masters Theses

Hydraulic fracturing has allowed natural gas to become a viable energy source via extraction of unconventional shale reserves, but this process requires an enormous amount of water. To ensure a productive fracture, a proprietary blend of chemical additives is added to the water. In this research, a hydraulic fracturing chemical additive – an enzyme breaking agent – is analyzed for organic components using gas chromatography mass spectrometry. The chemical changes that occur over the course of a fracture are also investigated using one model chemical found in the additive, furfural, in order to help assess the environmental risk that hydraulic …

Siloxane And Silane-Functionalized Polynorbornenes As Membranes For Passive Carbon Dioxide Separation, Eunice Koheun Hong

Masters Theses

In 2012, carbon dioxide (CO₂) [carbon dioxide] accounted for approximately 82% [percent] of all U.S greenhouse gas emissions.¹ These excessive CO2 levels have been attributed to climate changes that have a range of negative effects on human health and welfare.1 In an effort to decrease these emissions, polymeric membranes consisting of silane- and siloxane-functionalized norbornene units have been targeted as a potential solution for the passive separation of CO2 from other non-greenhouse gases. These substituted norbornene-based polymers were synthesized via vinyl-addition polymerization. Through a series of catalyst trials, commercially available palladium and nickel catalysts were compared along …

Real-Time Spectroscopic Analysis Of Microalgal Adaptation To Changing Environmental Conditions, Robert Ked Byrd

Masters Theses

Increases in anthropogenic pollution are causing many environmental problems; understanding their impact on the environment has become an important issue. Industrialization and the burning of fossil fuels have caused increased levels of carbon dioxide to enter the atmosphere, which is contributing to global warming and ocean acidification. Agricultural runoff has caused levels of inorganic nitrogen and phosphorus to rise, where they have been noted to cause harmful algal blooms. Marine ecosystems have been particularly affected as both of these forms of pollution accumulate in bodies of water. Microalgae are important organisms in these ecosystems because they sequester these pollutants and …

Characterizing Groundwater Ch4 And 222rn In Relation To Hydraulic Fracturing And Other Environmental Processes In Letcher County, Ky, St. Thomas Majeau Ledoux

Masters Theses

Hydraulic fracturing of shale deposits has greatly increased the productivity of the natural gas industry by allowing it to exploit previously inaccessible reservoirs. However, previous research has demonstrated that this practice can contaminate shallow aquifers with CH₄ [methane] from deeper formations. This study compares concentrations and isotope compositions of CH₄ sampled from domestic groundwater wells in Letcher County, Kentucky in order to characterize its occurrence and origins in relation to neighboring hydraulically fractured natural gas wells. Additionally, this study tests the reliability of ²²²Rn [radon] as an alternative tracer to CH₄ in identifying processes of gas …

Adsorption Of Antimony By Birnessite And The Impact Of Antimony On The Electrostatic Surface Properties Of Variable-Charge Soil Minerals, Kalyn Alaine Vergeer

Masters Theses

Antimony (Sb) is a toxin that can be found in high concentrations in the soil due to anthropogenic sources. Antimony exists in soil as Sb(V) in the monovalent antimonate hydroxyanion. The adsorption mechanisms of Sb(V) are not well-characterized. The objective of this study was to further elucidate Sb(V) adsorption mechanisms by examining the impact of adsorption on surface charging characteristics of gibbsite, goethite, birnessite, and kaolinite. Also examined was Sb(V), SO₄ [sulfate], and PO₄ [phosphate] adsorption by birnessite. Electrophoretic mobility and potentiometric titrations were employed to examine the ζ-potential [zeta-potential] and net proton surface charge density as a …

Classification And Fertility Of Soils In The Big South Fork National River And Recreation Area Based On Landscape Position And Geology, Ryan H. Blair

Masters Theses

The Big South Fork National River and Recreation Area encompasses more than 50,585 hectares (125,000 acres) of the Cumberland Plateau along the border of Tennessee and Kentucky. Highly dissected and steep terrain have made accessibility to much of the park limited, thus little work has been done to investigate the formation of these soils. Seven native soil profiles were selected for chemical and physical analysis representing Pennsylvanian-aged acidic sandstone and shale geology and landforms. The objectives of this study included the characterization of selected native profiles by physical and chemical analysis, as well as classification using US Soil Taxonomy, to …