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Articles 91 - 109 of 109
Full-Text Articles in Physical Sciences and Mathematics
Evaluation Of The Natural Biodegradation Of Aircraft Deicing Fluid Components In Soils, Laura M. Johnson
Evaluation Of The Natural Biodegradation Of Aircraft Deicing Fluid Components In Soils, Laura M. Johnson
Theses and Dissertations
This research effort was conducted to analyze the biodegradation of propylene glycol (PG) and tolyltriazole in two different soil types; a sandy soil and a high clay soil. Both an automated respirometer and a high performance liquid chromatograph (H PLO) were used in the analysis. Two separate experiments were conducted. In the first experiment, one level of tolyltriazole was added to the soils to determine whether or not there was a difference in the biodegradation rates of tolyltriazole in the two soils. The respirometer results indicated that there was a significant difference between the respiration rates of the microorganisms in …
Optimal Pulsed Pumping For Remediation Of Aquifers When Sorption Is Rate-Limited, Lawrence J. Schmitt
Optimal Pulsed Pumping For Remediation Of Aquifers When Sorption Is Rate-Limited, Lawrence J. Schmitt
Theses and Dissertations
A variational optimization technique is developed to acquire an optimal schedule of pulsed pumping operations for use at existing pump-and-treat aquifer remediation sites. The optimization problem is stated as a minimization of a generic management objective functional, constrained by the contaminant transport equations in two-dimensional or three-dimensional flow models which account for rate-limited sorption. The two-dimensional case is fully developed and a first-order rate equation is used to describe the transport of sorbing contaminant. The first variation provides necessary optimality conditions that must be met by any optimal solution, in turn leading to a pulsed pumping schedule of operation. The …
Mobilization Of Trace Elements In Aquifers By Biodegradation Of Hydrocarbon Contaminants, Scott L. Kearney
Mobilization Of Trace Elements In Aquifers By Biodegradation Of Hydrocarbon Contaminants, Scott L. Kearney
Theses and Dissertations
This study had two objectives: (1) to determine the extent of metal mobility within petroleum-contaminated aquifers, (2) to determine if biodegradation of petroleum hydrocarbons can explain metal mobility. The approach reviewed analytical results from 2305 groundwater sampling events, taken from 958 wells, located at 136 sites found at 53 Air Force installations. The study showed that high levels of metals are present at petroleum hydrocarbon sites where metals would not generally be expected. Of the metals with drinking water maximum contaminant levels (MCLs), mercury and silver were detected the least frequently. Barium and copper were detected at the sites, but …
A System Dynamics Model Of The Bioavailability Of Metals In Constructed Wetland Sediment, Timothy S. Wood
A System Dynamics Model Of The Bioavailability Of Metals In Constructed Wetland Sediment, Timothy S. Wood
Theses and Dissertations
Constructed wetlands used for storm water treatment accumulate metals primarily in their sediment. This sediment has the potential to produce toxic effects in benthic organisms at some period in time. Bioavailability of metals in sediment is directly linked to pore water metal activity. The mechanisms that influence pore water metal activity are included in physical, chemical, and biological processes. A system dynamics model was developed to represent these processes and the major influences affecting pore water metal activity in a treatment wetland receiving storm water influent. The model structure and behavior was tested and validated using several system dynamics validation …
Modeling Uptake And Translocation Of Lead (Pb) In Maize For The Purposes Of Phytoextraction, Mark A. Brennan
Modeling Uptake And Translocation Of Lead (Pb) In Maize For The Purposes Of Phytoextraction, Mark A. Brennan
Theses and Dissertations
Phytoextraction is a remediation technology that uses plants to remove heavy metals from soil. This technology has the potential to decrease the costs of remediating contaminated sites by several orders of magnitude compared to traditional technologies. To effectively implement this technology requires an understanding of the plant processes that control uptake and translocation of metals from the soil. Currently these processes are poorly understood, and especially so for Pb. The purpose of this thesis was to gain insights concerning the plant mechanisms that control uptake and translocation of Pb and how these mechanisms interact to control levels of Pb accumulation …
A Modeling Study For The Implementation Of In Situ Cometabolic Bioremediation Of Trichloroethylene-Contaminated Groundwater., John A. Christ
A Modeling Study For The Implementation Of In Situ Cometabolic Bioremediation Of Trichloroethylene-Contaminated Groundwater., John A. Christ
Theses and Dissertations
The limitations of conventional groundwater remediation technologies have led to the development of innovative technologies which may achieve national hazardous waste site remediation goals. Before an innovative technology can be implemented in the field, remedial project managers, regulators and other stakeholders require adequate modeling tools to help assess the applicability of the technology at a particular site. This modeling study investigates how an innovative technology, in situ cometabolic bioremediation, might be implemented to remediate a TCE-contaminated site, under different site conditions. A steady-state model is developed which couples an analytical expression to simulate the effect of flow between multiple pumping …
The Effect Of Meteorological Data Averaging Times On Plume Concentrations From Explosive Ordnance Disposal Open Burning Operations, Ida L. Widmann
The Effect Of Meteorological Data Averaging Times On Plume Concentrations From Explosive Ordnance Disposal Open Burning Operations, Ida L. Widmann
Theses and Dissertations
Explosive Ordnance Disposal (EOD) Open Burning (OB) operations are performed to treat and dispose of unserviceable munitions in the Department of Defense (DOD) inventory. Air pollution modeling of OB operations is an Environmental Protection Agency requirement for permit issuance at OB sites. Specific OB regulation is still in its infancy; therefore, establishment of OB modeling techniques is still in the early stages. This thesis effort sought to develop a computer model, based upon the Gaussian Puff Equation. The model varies from standard plume modeling practices by not making the assumption that the wind direction, wind speed and turbulence are uniform …
Evaluating The Feasibility Of Sequential Indicator Simulation In Reproducing Spatial Connectivity In A Heterogeneous Transmissivity Field, D. Duane Kenyon
Evaluating The Feasibility Of Sequential Indicator Simulation In Reproducing Spatial Connectivity In A Heterogeneous Transmissivity Field, D. Duane Kenyon
Theses and Dissertations
A Non-Parametric estimation technique was used to simulate realizations of a heterogeneous transmissivity field based upon sampled values from three different sampling scenarios. These realizations were compared to output from a parametric estimation technique with respect to truth as defined by an exhaustive data set of 6,000 transmissivity values. Estimated transmissivity fields were then used as input into a flow model from which fields of heads and specific discharges were obtained and compared. Given the financial limitations imposed upon the number and quality of samples reasonably available, Sequential Indicator Simulation, a non-parametric technique, was shown to be of considerable value …
Geostatistical Analysis Of Hydraulic Conductivity In Heterogeneous Aquifers, Craig S. Biondo
Geostatistical Analysis Of Hydraulic Conductivity In Heterogeneous Aquifers, Craig S. Biondo
Theses and Dissertations
Observations of the spatial variability of hydraulic conductivity of the heterogeneous alluvial aquifer at Columbus Air Force Base in Mississippi are analyzed using parametric geostatistical approaches. Field studies have revealed that the heterogeneity of the aquifer hydraulic conductivity field controls the movement and dispersion of groundwater solutes. Therefore, a means of quantifying spatial variability is essential for the application of flow and solute transport models to practical problems. Application of these models requires a large number of hydraulic conductivity measurements. Geostatistical analysis and kriging estimation procedures assist in providing these large numbers of values when sampling designs have provided sparse …
Comparison Of Gravel Substrate Vs Soil Substrate For The Construction Of An Experimental Fen, Carolyn S. Langley
Comparison Of Gravel Substrate Vs Soil Substrate For The Construction Of An Experimental Fen, Carolyn S. Langley
Theses and Dissertations
Under the Clean Water Act Section 404 of 1972 and 33 CFR 320-330 and 40 CFR 230 moderate the destruction of wetlands by the Air Force to make way for other uses. To obtain a permit for a design or construction project which affects a wetland, the Air Force must agree to create new wetlands, or replace lost wetland acreage through wetland creation or restoration. The Air Force is interested in building 'successful' wetlands as inexpensively as possible. It has been common practice to use hydric soil, which often had to be hauled in, as the substrate at the restored …
A System Dynamics Approach To Modelling The Degradation Of Biochemical Oxygen Demand In A Constructed Wetland Receiving Stormwater Runoff, Leslie A. Mudgett
A System Dynamics Approach To Modelling The Degradation Of Biochemical Oxygen Demand In A Constructed Wetland Receiving Stormwater Runoff, Leslie A. Mudgett
Theses and Dissertations
The objective of this research was to develop a tool to aid the Air Force Environmental Manager in the identification of the design parameters of a constructed wetland system that may be optimized to provide a desired biochemical oxygen demand (BOD) removal efficiency during the treatment of Air Force stormwater runoff. The objective is achieved through the development and use of a system dynamics model which simulates the hydrological functions of a constructed wetland as well as the processes within the wetland responsible for degradation of BOD. Based on literature review, the primary mechanism responsible for the degradation of BOD …
A Comparison Of Response Surface Methodology And A One-Factor-At-A-Time Approach As Calibration Techniques For The Bioplume-Ii Simulation Model Of Contaminant Biodegradation, Benjamin Shuman
Theses and Dissertations
This thesis compared Response Surface Methodology (RSM) to the one-factor-at-a-time approach for calibrating the Bioplume-II simulation model of contaminant biodegradation. The MADE-2 data set from Columbus Air Force Base, Mississippi was used. The one-factor-at-a-time approach reduced the root-mean-squared (RMS) error for the flow to 0.921225 feet in a total of 36 runs of Bioplume-II. The RSM approach reduced the error criterion to 0.918875 in a total of 47 runs. The one-factor-at-a-time approach was unable to reduce the error below 67.1831 parts per billion (ppb) after 21 runs. The RSM approach reduced the RMS error to 67.0327 ppb after 47 runs. …
Groundwater Model Parameter Estimation Using Response Surface Methodology, Richard M. Cotman
Groundwater Model Parameter Estimation Using Response Surface Methodology, Richard M. Cotman
Theses and Dissertations
This thesis examined the use of response surface methodology (RSM) to estimate the parameters of a finite-element groundwater model. An existing two-dimensional, steady-state flow model of a fractured carbonate groundwater system in southwestern Ohio served as the calibration target data set. A Plackett-Burman screening design showed that only four of the ten hydraulic conductivity zones significantly contributed to the output of the finite-element model. Also, the effective porosity parameter did not significantly affect the model's output. Using only the four significant hydraulic conductivity parameters; four two-level, four-factor designed experiments were conducted to exploit the first-order response surface defined by a …
Modeling Trihalomethane Formation Potential From Wastewater Chlorination, Carol A. Mccormick
Modeling Trihalomethane Formation Potential From Wastewater Chlorination, Carol A. Mccormick
Theses and Dissertations
The deletion of federally mandated fecal coliform limits has led many states to review and modify their wastewater disinfection requirements. One issue in analyzing wastewater disinfection is the discharge of potentially carcinogenic halogenated organics formed during the chlorination process. This research investigates the formation of one class of the halogenated organics, the trihalomethanes. The applicability of using drinking water trihalomethane formation models for use with wastewater effluent is examined. Three models are compared for predictive capability by using measured trihalomethane values from previous research data. The results show that a previously developed model is applicable for use based on assumptions …
Optimal Pulsed Pumping For Aquifer Remediation When Contaminant Transport Is Affected By Rate-Limited Sorption: A Calculus Of Variation Approach, Richard T. Hartman
Optimal Pulsed Pumping For Aquifer Remediation When Contaminant Transport Is Affected By Rate-Limited Sorption: A Calculus Of Variation Approach, Richard T. Hartman
Theses and Dissertations
The remediation of groundwater contamination continues to persist as a social and economic problem due to increased governmental regulations and public health concerns. Additionally, the geochemistry of the aquifer and the contaminant transport within the aquifer complicates the remediation process to restore contaminated aquifers to conditions compatible with health-based standards. Currently, the preferred method for aquifer cleanup pump-and-treat has several limitations including, the persistence of sorbed chemicals on soil matrix and the long term operation and maintenance expense. The impetus of this research was to demonstrate that a calculus of variations approach could be applied to a pulsed pumping aquifer …
Simulation Of Hydrologic Influences On Wetland Ecosystem Succession, Robert A. Pompilio
Simulation Of Hydrologic Influences On Wetland Ecosystem Succession, Robert A. Pompilio
Theses and Dissertations
This research focuses on the development of a simulation model to determine the effects of hydrological influences on a wetland ecosystem. The model allows perturbations to the inputs of various wetland data which in turn, influences the successional development of the ecosystem. This research consisted of converting a grassland ecosystem model to one which simulates wetland conditions. The critical factor in determining the success of wetland creation is the hydrology of the system. There are four of the areas of the original model which are affected by the hydrology. The model measures the health or success of the ecosystem through …
Modeling Of Ground Water Aquifer Remediation By Pulsed Pumping When Contaminant Transport Is Affected By Physical, Non-Equilibrium Sorption And Desorption, Jeffrey L. Caspers
Modeling Of Ground Water Aquifer Remediation By Pulsed Pumping When Contaminant Transport Is Affected By Physical, Non-Equilibrium Sorption And Desorption, Jeffrey L. Caspers
Theses and Dissertations
This research postulates and demonstrates a modification incorporating rate-limited sorption effects in the USGS SUTRA code for cleanup of a hypothetical sandy aquifer by pump-and-treat remediation methods. Contaminant transport is assumed to be affected by advection, dispersion, and rate-limited sorption/desorption. Sorption is assumed to be either equilibrium or rate-limited, with the rate-limitation described by either a first-order law, or by Fickian diffusion of contaminant through a spherical immobile pore region. Solutions are arrived at by split operator methods for the transport and one-dimensional Galerkin solutions for the solute concentration equations. The resulting model is tested against an analytical Laplace transform …
Development Of Computer Software To Aid Environmental Decision Makers In The Education And Training Of Air Force Remedial Project Managers, Roger R. Ouellette, Bruce K. Lyman
Development Of Computer Software To Aid Environmental Decision Makers In The Education And Training Of Air Force Remedial Project Managers, Roger R. Ouellette, Bruce K. Lyman
Theses and Dissertations
By the end of Fiscal Year 1991, the Air Force had identified 4,354 contaminated sites. Much like the 177 toxic sites at McClellan AFB, bases across the country and throughput the world are filled with chrome, lead, paint solvents and many other toxics that are rendering water supplies unusable and endangering the health of millions of people living in and around these bases. Air Force officials continue to identify contaminated sites with no end in sight. Since the cleanup of these toxic materials involves diverse, complex activities, the Air Force created the duty position of Remedial Project Manager to manage …
Factors That Influenced Homesteading And Land Abandonment In San Juan County, Utah, Melvin J. Frost
Factors That Influenced Homesteading And Land Abandonment In San Juan County, Utah, Melvin J. Frost
Theses and Dissertations
Homesteading in San Juan County, Utah is for the most part, located on Sage Plain at elevations between 6,000 to 7,200 feet. Sage Plain is an undulating surface deeply dissected with canyons. The soil is relatively shallow and the predominant vegetation is pinyon, juniper, sage brush and blue-stem grass.
The 52 year mean precipitation is 15.47 inches. Since the beginning of weather records there has been a noticeable decrease in the annual precipitation. There is generally sufficient moisture to mature winter wheat. Pinto beans are also grown in the more favorable locations.
Principle factors that have influenced homesteading and land …