Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"Source zone"”.
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Method comparison for analysis of LNAPL natural source zone depletion using CO₂ fluxes
… are needed to address impacts. Natural source zone depletion (NSZD) is a remedial approach gaining wide acceptance, wherein natural mechanisms in the subsurface act to deplete LNAPL in the source zone. Recent research indicates biodegradation of contaminant-related carbon results in a …
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Impacts of Source Zone Architecture on Nonaqueous Phase Liquid Dissolution and Cleanup: A Magnetic Resonance Imaging Study
Alternate flushing with water and two surfactant pulses (5∼6 pore volumes) resulted in 63% of NAPL mass removal from both aquifers. However, NAPL mass flux reduction was lower from aquifer 2 (68%) with a shorter correlation length than from aquifer 1 (82%). Local effluent concentrations from …
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Prediction of mass flux from DNAPL source zone with complex entrapment architecture: model development, experimental validation, and up-scaling
Includes bibliographical references (pages 219-229).
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Seismic Risk Analysis for Mid-America Communities
… for communities in the small and the large source zones (represented by Sikeston and Carbondale, respectively) would be an M8 earthquake along the New Madrid seismic fault, and in the outside source zone (represented by Urbana) an on-site M6 earthquake; the dominant seismic risk source for …
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Modeling the Dissolution of Immiscible Contaminants in Groundwater for Decision Support
… amounts of non-aqueous phase liquids (NAPL) and source zone dimensions, inconsistent historical monitoring of contaminant mass discharge, and the mathematical simulation of field-scale mass transfer processes. Effective methods for simulating NAPL dissolution must therefore be able to assimilate …
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Extraction, transport, and transformation of poly- and perfluoroalkyl substances in soils impacted by aqueous film-forming foam
… military bases and airports is one significant source of PFAS contamination to groundwater and communities. AFFF formulations are composed of diverse PFAS classes, including anionic, zwitterionic, and cationic structures. Many of the polyfluorinated substances have been shown to transform to the …
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The rupture process of recent tsunamigenic earthquakes by geophysical data inversion
Subduction zones are the favorite places to generate tsunamigenic earthquakes, where friction between oceanic and continental plates causes the occurrence of a strong seismicity. The topics and the methodologies discussed in this thesis are focussed to the understanding of the rupture process of …
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Redutive Dehalogenation of Chlorinated Alkanes by Novel Bacteria at the PetroProcessor of Louisiana Inc. Superfund Site
… the dense non-aqueous phase liquid (DNAPL) source zone at the PPI site. Results revealed the presence of bacteria similar or identical to strains BL-DC-8 and BL-DC-9 as well as “Dehalococcoides” strains throughout the DNAPL source zone. 16S rRNA gene copy concentrations as high as 1.88 ± …
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Sustainability of Reductive Dechlorination at Chlorinated Solvent Contaminated Sites: Metrics for Assessing Potentially Bioavailable Natural Organic Carbon in Aquifer Sediments
… at sites with no anthropogenic carbon sources is often influenced by the availability of readily-biodegradable natural organic carbon along with favorable geochemical conditions for supporting microbial dehalogenation. Recent research studies have suggested that the pool of labile …
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Quantification of Parameters in Models for Contaminant Dissolution and Desorption in Groundwater
… when modeling mass transfer from contaminant source zones is uncertainty regarding parameter estimates. These rate parameters are of particular importance because they control the connectivity between a simulated contaminant source zone and the aqueous phase. Where direct observation has …
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Stochastic analysis of dense nonaqueous phase liquid dissolution in naturally heterogeneous subsurface systems
… quasi-static DNAPL saturation distribution in a source zone is derived, based on the previous research to describe the field-scale nonuniform residual DNAPL distribution. A local-scale dissolution model is generalized from the laboratory experimental results. Effective transport and dissolution …
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A new passive surface water flux meter for simultaneous measurement of contaminant and water fluxes in streams and rivers
… concentrations were measured nearest the source zone following a prolonged period of high discharge. Conversely, the concentration of the pesticides atrazine, desethyl-atrazine, and metolachlor were not correlated with distance from the source zone, but increased dramatically with the …
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Modeling the impact of petroleum mixtures released from railroad tank car accidents on groundwater contamination and cleanup times
… professor. He developed a new semi-analytical source zone reduction model (SZRM) for multi-component light nonaqueous phase liquids (LNAPLs), and incorporated this into an existing screening model for estimating cleanup times for chemicals spills from railroad tank cars that previously …
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Evaluation of Impacts Resulting from Home Heating Oil Tank Discharges
… and the flow of oxygen to the release source zone. We found that many sites exceeded the sub-slab risk target threshold in naphthalene concentration, which has negative implications on previous abatement strategy efficacy.
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An investigation of nitrogen cycling processes in a coastal fynbos ecosystem in the South Western Cape Province, South Africa
… well as being economically important as a water source zone, as a source of flowers for the cut flower industry and as a recreation area. Sound ecological knowledge is required in order to manage and conserve fynbos because the extent of this unique, species-rich, endemic flora has been …
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Continuous NAPL loss rates using subsurface temperatures
To view the abstract, please see the full text of the document.
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Characterization of Subsurface Heterogeneity Using Transient Hydraulic and Tracer Tomography
… These equations demand less computational resources as opposed to the parabolic equation that governs drawdown evolution. Therefore, a temporal moment approach is expected to expedite the interpretation of THT surveys. Based on this premise, we extended our sequential successive linear …
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Analysis of Solute Mixing at the Pore-Scale Using Micromodels and Lattice -Boltzmann Finite Volume Modeling
… downgradient concentrations depend on initial source zone concentrations and the extent to which the contaminant mixes (i.e., dilutes) with surrounding groundwater. For a (bio)reactive contaminant, downgradient concentrations also depend on the rate of reaction. In this work I examine the …
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Biotic control of LNAPL longevity - laboratory and field- scale studies
Natural source zone depletion (NSZD) is an emerging strategy for managing light nonaqueous phase liquids (LNAPLs). Unfortunately, little is known about NSZD rates over extended periods of time, where heterogeneous redox conditions and changing LNAPL saturations may influence processes governing …
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