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Articles 1 - 21 of 21
Full-Text Articles in Environmental Sciences
Complexity And Uncertainty In Human And Ecological Risk Assessment, Matthew Jordan Dellinger
Complexity And Uncertainty In Human And Ecological Risk Assessment, Matthew Jordan Dellinger
Theses and Dissertations
Multiple interacting stressors in the environment present increasingly complex risks to human health. Too often, however, the data required for traditional risk assessment are either lacking or unavailable at the necessary spatial or temporal scale. In addition, assessment practices and management policies need to move away from single factor approaches in order to accommodate the reality of complex chemical mixtures and environmental stressors. Recent literature suggests that a paradigm shift is under way. This points to a need for the development of new techniques both for rapid data collection and flexible risk assessment strategies that can adapt to make use …
Modeling Energy Production Of Solar Thermal Systems And Wind Turbines For Installation At Corn Ethanol Plants, Elizabeth Ehrke
Modeling Energy Production Of Solar Thermal Systems And Wind Turbines For Installation At Corn Ethanol Plants, Elizabeth Ehrke
Theses and Dissertations
Nearly every aspect of human existence relies on energy in some way. Most of this energy is currently derived from fossil fuel resources. Increasing energy demands coupled with environmental and national security concerns have facilitated the move towards renewable energy sources. Biofuels like corn ethanol are one of the ways the U.S. has significantly reduced petroleum consumption. However, the large energy requirement of corn ethanol limits the net benefit of the fuel. Using renewable energy sources to produce ethanol can greatly improve its economic and environmental benefits. The main purpose of this study was to model the useful energy received …
The Effects Of River Sediment, Endosulfan, And Moderate Hypoxia On Blue Crabs (Callinectes Sapidus) From The Tidal, Freshwater James River, Laura Williams
The Effects Of River Sediment, Endosulfan, And Moderate Hypoxia On Blue Crabs (Callinectes Sapidus) From The Tidal, Freshwater James River, Laura Williams
Theses and Dissertations
Juvenile male blue crabs move into the tidal, freshwater James River during warmer months to feed and grow by undergoing molting. In crustaceans, growth and molting are hormonally controlled. The physiological effects of a multiple-stressor environment are determined by comparing the blue crab’s oxygen uptake after exposure to pure sand, James River sediment, or endosulfan-spiked sand. The effect of multiple stressors on molting is measured by the activity level of N-acetyl-ß-glucosaminidase (NAG), an enzyme in epidermal tissue important to molting. The oxygen uptake was decreased by exposure to James River sediment but not for exposure to endosulfan for seven days. …
Demographic And Genetic Consequences Of Small Population Size In Remnant Populations Of Arabis Georgiana Harper (Georgia Rockcress), Alicia M. Garcia
Demographic And Genetic Consequences Of Small Population Size In Remnant Populations Of Arabis Georgiana Harper (Georgia Rockcress), Alicia M. Garcia
Theses and Dissertations
The goal of this thesis is to provide a greater scientific understanding of the demographic and genetic consequences of small population size in remnant populations of Arabis georgiana Harper (Georgia Rockcress). Specifically, 1 ) traits associated with phenological progression, fitness and reproductive success were compared between naturally occurring "native" plants and plants grown ex situ and subsequently restored to one of the largest remaining populations of A. georgiana, and 2) a preliminary analysis of population genetic structure in remnant populations across the species' range was performed. In addition to updating census information on remnant populations of A. georgiana, chapter one …
Using Macroinvertebrate Community Composition To Distinguish Between Natural And Anthropogenic Sedimentation, Amanda E. Schutt
Using Macroinvertebrate Community Composition To Distinguish Between Natural And Anthropogenic Sedimentation, Amanda E. Schutt
Theses and Dissertations
Excess fine sediment from human activity is a major pollutant to streams across the U.S.; however, distinguishing human-induced sedimentation from natural fine sediment is complex. The U.S. Environmental Protection Agency recently implemented a protocol for the quantitative field assessment of human-induced sedimentation using measurements of stream geomorphology. Macroinvertebrate community composition, streambed sediment stability, and sediment composition were studied at 49 sites in the James River watershed in central Virginia. Sediment composition was found to be a stronger driver of community composition than sediment stability. Although I was not able to show that macroinvertebrate metrics were related to sediment stability independently …
A Water Quality Investigation Of Kimages Creek, Michael Trop
A Water Quality Investigation Of Kimages Creek, Michael Trop
Theses and Dissertations
Analysis of continuous monitoring water quality data (temperature, specific conductivity, depth, pH, dissolved oxygen, and turbidity) at two locations in a tidal freshwater creek (Kimages Creek) characterized seasonal variation and responses to short-term events. Supplemental water quality measurements were collected to describe longitudinal variations in the creek. There were significant differences in water quality between the two continuous monitoring stations (one tidal and unforested, the other non-tidal and forested) over varying time scales. Rain events showed increases in turbidity, depth and dissolved oxygen, and reductions in temperature, conductivity, and pH at both stations. Tides influenced the water quality at the …
Essential Spawning Habitat For Atlantic Sturgeon In The James River, Virginia., Geoffrey Austin
Essential Spawning Habitat For Atlantic Sturgeon In The James River, Virginia., Geoffrey Austin
Theses and Dissertations
Substrate composition plays a critical role in determining the spawning success of Atlantic sturgeon. A benthic analysis of the tidal freshwater portion of the James River, Virginia, was performed to locate and protect remaining sturgeon spawning habitat within the James River system. I modeled structural habitat, substrate distribution, and river bathymetry from Richmond, Virginia to the Appomattox River confluence. A classification model was developed to describe the dominant substrate type (mud/silt, sand, gravel, bedrock) using side scan sonar data collected from August 2011-Febuary 2012. River depth, bottom imagery, substrate density (hardness), and ground truth substrate samples were interpolated into a …
Decadal Changes And Future Projections Of Precipitation In The Metropolitan Area Of Milwaukee, Anke Petra Maria Keuser
Decadal Changes And Future Projections Of Precipitation In The Metropolitan Area Of Milwaukee, Anke Petra Maria Keuser
Theses and Dissertations
This research investigated decadal changes and future projections of precipitation in the Metro Milwaukee and surrounding area, the largest urban area in Wisconsin. Spatial and temporal precipitation patterns derived for the Metro Milwaukee from the high-resolution gridded historical climatic dataset for Wisconsin were analyzed for 1950-2006. In addition, precipitation scenarios were generated via statistical downscaling of the Third Generation Coupled Global Climate Model (CGCM3) outputs. The delta method was chosen for the statistical downscaling of the CGCM3 output for the two future time periods, 2041-2070 (2050s) and 2071-2100 (2080s). The Mann-Kendall test and the Sen's slope test were applied to …
Analysis Of The Fish Community On Tidal-Freshwater Constructed Reefs, Briana Langford
Analysis Of The Fish Community On Tidal-Freshwater Constructed Reefs, Briana Langford
Theses and Dissertations
Constructed reefs are used successfully in marine systems to enhance spawning habitat; this study examines the effectiveness of constructed reefs in a tidal-freshwater river. Fish abundance, species diversity and richness, residency, water column position, reproductive guilds, and feeding guilds were analyzed on two constructed reefs in the tidal-freshwater James River and compared to silted regions representing the primary substrate in the river. Reefs were sampled using hydroacoustics, electroshocking, gillnetting, trawling, and egg mats. The constructed reefs had a greater proportion of fish that broadcast spawn over hard substrate and a trend of more overall individual, residential, and demersal fish. The …
Determination Of Toxic Heavy Metals In Wet Deposition And Ambient Air In Columbus, Ga, Melissa K.M. Nestor
Determination Of Toxic Heavy Metals In Wet Deposition And Ambient Air In Columbus, Ga, Melissa K.M. Nestor
Theses and Dissertations
Atmospheric pollution is one of the most significant and potentially catastrophic environmental issues threatening the United States and the world today. One such source of this pollution is heavy metals. The impact of heavy metal pollution on living organisms can be disastrous, having the potential to cause the deterioration of ecosystems and posing danger to the health and survival of the human race. Chronic and acute human exposure to this type of pollution can damage the proper functioning of vital body organs by inhibiting important neurological pathways. In plants, it essentially acts as a counter-agent to proper growth. In areas …
Spatial Patterns Of Herbaceous And Woody Recruitment In A Recently Restored Mixed Tidal Regime Freshwater Wetland, James B. Deemy
Spatial Patterns Of Herbaceous And Woody Recruitment In A Recently Restored Mixed Tidal Regime Freshwater Wetland, James B. Deemy
Theses and Dissertations
Ecological restoration of a converted wetland was characterized within a recently drained impoundment along the James River in Charles City County, Virginia. Colonizing vegetation was assessed over three growing seasons in both tidal and non-tidal environments. Study objectives were to (1) examine geospatial relations of recruitment patterns among colonizing species over three growing seasons, (2) quantify species composition and potential differences between extant species cover and soil seed banks across restored and natural wetland habitats and (3) assess geospatial patterns to develop a GIS model of bald cypress (Taxodium distichum L.) recruitment. The two most common native colonizing species during …
Host Fish Assessment And Gravidity For The Mussel Elliptoideus Sloatianus, Andrew Hartzog
Host Fish Assessment And Gravidity For The Mussel Elliptoideus Sloatianus, Andrew Hartzog
Theses and Dissertations
Elliptoideus sloatianus (purple bankclimber) is a freshwater mussel that m endemic to the Apalachicola River Basin, which includes the Chattahoochee, Flint, Chipola, and Apalachicola Rivers. Populations of E. sloatianus also exist in the Ochlockonee River, which discharges independently from the ACF basin into the Gulf of Mexico. In 1998, E. sloatianus was listed as federally threatened due to the loss of suitable habitat and the potential blockage of host fish passage into areas where the mussel lives. For this study, we located three populations of £. sloatianus in the Flint River in southwest Georgia. Gravid mussels were collected in late …
Interspecific Hybridization Among Black Basses (Micropterus Spp.) In The Chattahoochee River, Columbus Georgia, Kimberly S. Holley
Interspecific Hybridization Among Black Basses (Micropterus Spp.) In The Chattahoochee River, Columbus Georgia, Kimberly S. Holley
Theses and Dissertations
Interspecific hybridization can lead to the evolution of a new hybrid species or extinction of parental species due to competition or excessive backcrossing, When parental populations differ in abundance, hybrids tend to backcross more frequently with the more abundant parent, resulting in asymmetrical introgression. The objective of this study was to determine the extent and apparent direction of hybridization between shoal bass {Micropterus cataractae), a rare endemic species to the Apalachicola drainage, and spotted bass (M. punctulatus), an introduced and more abundant species. Pelvic fin tissue (N = 130) was taken from bass species in the Chattahoochee River between Columbus, …
Sources And Fates Of Nutrients In The Tidal, Freshwater James River, William Isenberg
Sources And Fates Of Nutrients In The Tidal, Freshwater James River, William Isenberg
Theses and Dissertations
Tidal freshwater reaches of estuaries may play an important role in mitigating nutrient fluxes from watersheds to the coastal zone due to their location at the interface between riverine and estuarine systems. We developed annual N and P budgets for the tidal, freshwater James River over 4 calendar years (2007-2010) taking into account riverine inputs at the Fall Line, local points sources (including CSO events), ungagued inputs, riverine outputs, and tidal exchange. The tidal freshwater James River experiences high areal loading rates of TN (383 mg/m2/d) and TP (70 mg/m2/d) due to the combined effects of large watershed area and …
Optimization Of Nanoscale Zero-Valent Iron For The Remediation Of Groundwater Contaminants, Andrew W. E. Mcpherson
Optimization Of Nanoscale Zero-Valent Iron For The Remediation Of Groundwater Contaminants, Andrew W. E. Mcpherson
Theses and Dissertations
Nanoscale zero-valent iron (nZVI) is an emerging tool for the remediation of groundwater contaminants. The nanoparticles are capable of reductively destroying or immobilizing a wide range of contaminants. Their small size results in a high surface area to mass ratio, making them much more reactive compared to their more-coarse predecessors. Small particle size also allows nZVI particles to be injected directly into contaminated areas via a well, limiting the above-ground footprint and allowing access to contaminated areas that are beyond the reach of some conventional methods. nZVI technology has the potential to facilitate remediation in difficult situations, improve remediation outcomes, …
Comparative Analysis Of Two Biological Warfare Air Samplers Using Live Surrogate Agents, James C. Enderby
Comparative Analysis Of Two Biological Warfare Air Samplers Using Live Surrogate Agents, James C. Enderby
Theses and Dissertations
The United States Air Force has several high-volume biological air samplers, including the XMX/2L-MIL and the Biocapture 650. Limited information is available on either in terms of its collection of viruses and bacteria. However, previous research on the XMX/2L-MIL has determined that modifications to the secondary flow rate and the use of a virus preserving collection media may provide improved virus collection rates. In this thesis, these modifications were investigated to determine their impact on the collection of viral and bacterial aerosols. Additionally, relative collection rates were compared against those for the Biocapture 650. MS2 bacteriophage was the viral surrogate …
Modeling The Impact Of Cracking In Low Permeability Layers In A Groundwater Contamination Source Zone On Dissolved Contamination Source Zone On Dissolved Contaminant Fate And Transport, Katherine W. Sievers
Modeling The Impact Of Cracking In Low Permeability Layers In A Groundwater Contamination Source Zone On Dissolved Contamination Source Zone On Dissolved Contaminant Fate And Transport, Katherine W. Sievers
Theses and Dissertations
The storage and transport of a dense non-aqueous phase liquid (DNAPL) was evaluated using a numerical model. Many DNAPLs are used as solvents by the DoD and industry. The improper disposal and handling of these chemicals has led to long term contamination of groundwater. When spilled, a DNAPL will pool atop low permeability layers and slowly dissolve creating a contaminant plume. The dissolved contaminant within a low permeability layer serves as long-term sources of contamination once the source is removed. In this study, cracks are hypothesized to exist in the low permeability layers, allowing for enhanced transport. A numerical model …
Incorporating Externalities And Uncertainty Into Life-Cycle Cost Analysis, Alec C. Danaher
Incorporating Externalities And Uncertainty Into Life-Cycle Cost Analysis, Alec C. Danaher
Theses and Dissertations
Executive Order 13514 requires federal agencies to consider economic and social benefits and costs when evaluating projects and activities based on life-cycle return on investment. The generation of energy used by federal facilities imposes social externalities, most notably air pollution, upon society. This research utilized the social costs of carbon dioxide, oxides of nitrogen, and sulfur dioxide to develop a probabilistic life-cycle full-cost analysis tool for the analysis of energy efficiency projects. The tool was then used to investigate the effects of incorporating social externalities and uncertainty into life-cycle cost analyses of energy efficiency projects. Calculation of the social benefits …
Analysis Of Leadership In Energy And Environmental Design® Construction In The Air Force, James M. Rozzoni
Analysis Of Leadership In Energy And Environmental Design® Construction In The Air Force, James M. Rozzoni
Theses and Dissertations
The Air Force uses the Leadership in Energy and Environmental Design (LEED) rating system as a third party verification system to ensure sustainable and resource-conscious facilities. The Federal Government has implemented several mandates in recent years that require certain milestones be met for energy reduction, water conservation, renewable energy use, and so forth. This research aims to determine how the Air Force has implemented LEED through credit analysis, and to better understand why LEED is being used in this way. Using a database of 172 military construction projects, the research evaluates the frequency of credit usage individually and by category. …
Prototyping The Use Of Dispersion Models To Predict Ground Concentrations During Burning Of Deployed Military Waste, Val Oppenheimer
Prototyping The Use Of Dispersion Models To Predict Ground Concentrations During Burning Of Deployed Military Waste, Val Oppenheimer
Theses and Dissertations
United States military forces in Iraq and Afghanistan have often used open burning of solid waste as a means to achieve volume reduction and to minimize vector borne illnesses. Assessing exposures to burn pit emissions has proven challenging, requiring significant numbers of personnel and sampling equipment. This study examined the use of three common dispersion models to determine the feasibility of using software modeling to predict short-range exposures to burn pit emissions, in lieu of sole reliance on ground sampling. Four open burn tests of municipal solid waste were conducted at Tooele Army Depot, Utah. Aerial samples were collected above …
Emissions From Simulated Open Burning Of Deployed Us Military Waste, Brian D. Woodall
Emissions From Simulated Open Burning Of Deployed Us Military Waste, Brian D. Woodall
Theses and Dissertations
U.S. military forces have relied primarily on open burning as an expedient method of volume reduction and treatment of solid waste during the conflicts in Afghanistan and Iraq. This study is the first effort to characterize a broad range of pollutants and their emission factors during the burning of military waste and the effects that recycling efforts, namely removing plastics, might have on emissions. Piles of simulated military waste were constructed, burned, and emissions sampled at the U.S. Environmental Protection Agency (EPA) Open Burn Testing Facility (OBTF), Research Triangle Park, NC. Three tests contained polyethylene terephthalate (PET #1 or PET) …