Physical Sciences and Mathematics Commons^™

Computational And Experimental Investigations Of Alkali Cation Interactions At The Rutile – Water Interface, Isaac Johnston

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Overall, the objective of this dissertation was to investigate the degree of sorption for the alkali cations on rutile to ascertain the impact of different cation properties, such as ion size and charge density, on sorption mechanics as well as probe how the ion may alter the surface – aqueous interface. Initial molecular dynamic simulations and batch experiments showed minimal surface sorption for any alkali cation at relatively low concentrations while simultaneously suggesting the enthalpy of deprotonation shifts slightly in the presence of the alkali cations at different ionic strengths. The cations are likely causing small reorientations of the near-surface …

Cover Cropping And Organic Amendments To Improve Sandy Soils Under Organic Vegetable Production, Charles Williamson

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Coastal Plain soils in the Southeastern USA are typically sandy with poor soil structure, low soil organic carbon (SOC) content, and meager soil fertility that pose challenges to organic agriculture. Adding organic inputs is a strategy to improve these soils' physical, chemical, and biological characteristics. Here, we aim to investigate the impacts of Cover Cropping (CC) and manure inclusions on sandy soils under organic vegetable production. The experiment design was a randomized complete block with two treatments of manure application (with and without) and four CC treatments of cereal rye (Secale cereale), hairy vetch (Vicia villosa), …

Ligand-Promoted Dissolution Of Uranyl Phosphate Across Scales, Brennan Ferguson

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The formation of uranyl phosphate precipitate is a remediation strategy because the low solubility of uranyl phosphate minerals, like chernikovite, limits the mobility of uranium in contaminated soils. However, organic ligands can complex with aqueous metal cations to form more soluble species. For example, citrate is a commonly occurring organic ligand produced by plants and microbes that increases the solubility of uranium and therefore the dissolution of uranyl phosphate minerals in the uranyl phosphate-citrate system. This effect is an important control on the mobility of uranium in organic-rich, and near-surface vegetated environments. Nevertheless, key aspects of the citrate-uranyl phosphate system …

Geology-Based Shear-Wave Velocity Model Of Reference Site Conditions In South Carolina For Seismic Site Response Analysis, Camilius Amevorku

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Assessing earthquake hazard in the State of South Carolina is important because it is one of the most seismically active regions of the eastern United States and has experienced earthquakes of damaging levels in the historical past. Examples of these damaging seismic events are the 1886 Charleston earthquake (M 6.7 to 7.5) and the 1913 Union County earthquake (M 4.5 to 5.5).

Small-strain shear-wave velocity (V_S) is an important parameter in performing site response analysis. The deep nature of the top of reference firm rock (i.e., V_S ≥ 760 m/s or B-C boundary) due to …

Application Of A 14c-Assay To Assess Methanotrophic Biodegradation Of Tce In Low Ph Groundwater, Evan Groome

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Current biological strategies for remediating trichloroethylene (TCE) in low pH aquifers (i.e., pH14C-TCE assay was developed to determine pseudo first-order rate constants for the degradation of TCE in microcosms containing soil and groundwater from the Boeing Michigan Aeronautical Research Center (BOMARC) superfund site, where the pH ranges from 4.1 to 4.9. The ¹⁴C-TCE assay was also adapted to calculate soil-normalized rate constants for data from this site, as well as data that Szwast²¹ collected from the Beltsville Agricultural Research Center (BARC). In addition to natural attenuation, biostimulation through amendments of methane and nutrients were also assessed. This treatment …

Characterization Of Water Flow And Solute Transport Driven By Preferential Flow In Soil Vadose Zone, Abdullah Al Mamun

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The vadose zone acts as a buffer zone between the ground surface and the aquifers underneath and controls the transmission of infiltrating water and contaminants, for example, pesticides and chemical spills. Therefore, understanding the flow and transport processes that dominate the vadose zone is important. Macropores are ubiquitous and particularly found in abundance in the vadose zone. These macropores facilitate preferential flow, through which water travels rapidly deep into the soil, bypassing most of the porous matrix. Preferential flow and transport have environmental significance as their processes impact hydrology, ecology, agriculture, subsurface contamination, and waste management sectors. Thus, the overall …

Wetland Uranium Transport Via Iron-Organic Matter Flocs And Hyporheic Exchange, Connor J. Parker

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Uranium (U) released from the M-Area at the Department of Energy Savannah River Site into Tims Branch, a seasonal wetland and braided stream system, is estimated to be 43,500 kg between 1965 and 1984. The motivation for this work is the uranium’s persistence in the wetland for decades, where it is estimated that 80% of the U currently remains in the Tims Branch wetland. U has begun to incorporate into wetland iron (Fe) and carbon cycles, associating with local Fe mineralogy and deposits of rich wetland organic matter (OM). The objective of this work is to characterize the chemical phases …

Fate And Transport Of Toxoplasma Gondii Oocysts In Saturated Porous Media: Effects Of Electrolytes And Natural Organic Matter, Christian Pullano

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Toxoplasma gondii is a pathogenic microorganism that is currently a threat to public health. Understanding the fate and transport of T. gondii through the soil and groundwater is vital in determining the risk it poses to water resources and human health. The physico-chemical interactions between the groundwater and the bio colloid within an aquifer will dictate its mobility and its ability to infect humans. This research examines how various naturally occurring groundwater chemistries containing organic compounds and monovalent and divalent salt solutions will alter the fate and transport of T. gondii. Solutions containing various concentrations of humic acid, fulvic …

A Conservative Numerical Scheme For The Multilayer Shallow Water Equations, Evan Butterworth

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An energy-conserving numerical scheme is developed for the multilayer shallow water equations (SWE’s). The scheme is derived through the Hamiltonian formulation of the inviscid shallow water flows related to the vorticity-divergence variables. Through the employment of the skew-symmetric Poisson bracket, the continuous system for the multilayer SWE’s is shown to preserve an infinite number of quantities, most notably the energy and enstrophy. An energy-preserving numerical scheme is then developed through the careful discretization of the Hamiltonian and the Poisson bracket, ensuring the skew-symmetry of the latter. This serves as the groundwork for developing additional schemes that preserve other conservation properties …

Vermont Global Warming Solutions Act: The Costs Of Inaction From Land Conversions, Grayson L. Younts

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The Vermont (VT) Global Warming Solutions Act (GWSA, 2020) sets greenhouse gas (GHG) emissions reduction targets as 26% below 2005 by 2025, 40% below 1990 by 2030 and 80% below 1990 by 2050 for energy-related emissions only. Vermont’s omission of GHG emissions from land conversions can result in significant costs of inaction (COI), which can hinder state’s mitigation and adaptation plans and result in a climate crisis-related risks (e.g., credit downgrade). Science-based spatio-temporal data of GHG emissions from soils as a result of land conversions can be integrated into the conceptual framework of “action” versus “inaction” to prevent GHG emissions. …