UNT Theses and Dissertations - 22 Matching Results

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Influence of Sediment Exposure and Water Depth on Torpedograss Invasion of Lake Okeechobee, Florida

Description: Torpedograss (Panicum repens) was first observed in Lake Okeechobee in the 1970s and appears to have displaced an estimated 6,400 ha of native plants, such as spikerush (Eleocharis cellulosa), where inundation depths are often less than 50 cm. Two series of studies evaluated substrate exposure and water depth influences on torpedograss establishment and competitiveness. Results revealed that fragments remain buoyant for extended periods and so facilitate dispersal. Once anchored to exposed s… more
Date: December 2006
Creator: Smith, Dian H.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Temperature tolerances and predation susceptibilities of transgenic and wildtype zebra danios, Danio rerio.

Description: Both the upper and lower temperature tolerances of red fluorescent protein transgenic zebra danios and wildtype zebra danios, Danio rerio, were significantly different via two different methods; however, all differences are small (< 1°C) and probably not ecologically important. The U.S. geographic distributions of both transgenic and wildtype zebra danios will not be restricted by their upper thermal tolerances, but will be limited to the southern and western portions of the U.S. by their lowe… more
Date: August 2005
Creator: Cortemeglia, Cheryl
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Bioavailability and toxicity of 2,4,6-trinitrotoluene in sediment.

Description: TNT (2,4,6-trinitrotoluene) is a persistent contaminant at many military installations and poses a threat to aquatic ecosystems. Data from environmental fate and toxicity studies with TNT revealed that sediment toxicity test procedures required modification to accurately assess sediment TNT toxicity. Key modifications included aging TNT-spiked sediments 8-14 d, basing lethal dose on measured sediment concentrations of the molar sum of TNT and its main nitroaromatic (NA) transformation product… more
Date: May 2004
Creator: Conder, Jason M.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

On-Road Remote Sensing of Motor Vehicle Emissions: Associations between Exhaust Pollutant Levels and Vehicle Parameters for Arizona, California, Colorado, Illinois, Texas, and Utah

Description: On-road remote sensing has the ability to operate in real-time, and under real world conditions, making it an ideal candidate for detecting gross polluters on major freeways and thoroughfares. In this study, remote sensing was employed to detect carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxide (NO). On-road remote sensing data taken from measurements performed in six states, (Arizona, California, Colorado, Illinois, Texas, and Utah) were cleaned and analyzed. Data mining and explorat… more
Date: May 2003
Creator: Dohanich, Francis Albert
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Solid phase microextraction of amino-dinitrotoluenes in tissue.

Description: TNT (2,4,6-trinitrotoluene) readily and predominantly transforms to 2ADNT (2-amino-4,6-dinitrotoluene) and 4ADNT (4-amino-2,6-dinitrotoluene) in environmental matrixes and tissues. Solid phase microextraction (SPME) was used to extract ADNTs (amino-dinitrotoluenes) from tissue as a potential method to investigate the recalcitrance of metabolically-generated ADNTs versus absorbed ADNTs. Tubifex tubifex was allowed to metabolize TNT into ADNTs in 24-hr static non-renewal exposure test followed b… more
Date: December 2004
Creator: Tsui-Bowen, Alethea
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Culturing Vallisneria americana for Restoration Efforts

Description: Robust Vallisneria americana was cultured for restoration purposes. Preliminary studies, with various iron treatments, were conducted to ascertain the amount of phosphorous release into the water column from sediments. There was a significant difference in the amount of phosphorous released if commercial sediment was used with a low iron amendment or without an iron amendment. The second study consisted of planting V. americana on two different sediment types while supplying half of the pla… more
Date: May 2004
Creator: Tanski, Erin M.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

City of Denton Municipal Solid Waste Characterization and Management Strategies

Description: Due to concern about diminishing landfill space, the City of Denton contracted a municipal solid waste characterization study in 1999 that would identify materials for diversion. This paper describes the results of 5 1-week waste sorting events, a scale-house analysis, a recycling participation study, a recycler profile and a similar city study. The results of the characterization studies suggest that at least 50% of each waste stream is recyclable or divertible though paper products accounted … more
Date: May 2004
Creator: Brady, Patricia D.
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Partner: UNT Libraries

Comparative Bioavailability of Dietary and Dissolved Cadmium to Freshwater Aquatic Snails

Description: Heavy metal bioaccumulation in aquatic organisms may occur through direct or indirect uptake routes. Research indicates that the significance of uptake route varies with contaminant and organism exposed. The relative importance of different metal sources in aquatic systems was investigated by exposing freshwater snails to dietary or dissolved sources of cadmium. Snails were exposed to control, contaminated food only, contaminated water only, and contaminated food and water treatments. During… more
Date: December 2003
Creator: White, Jessica C.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Modeling of Land Use Change Effects on Storm Water Quantity and Quality in the City of Carrollton and the North Texas Area

Description: Development and population are rapidly increasing in urbanizing areas of North Texas and so is the need to understand changes in storm water runoff flow and its contamination by nutrients, sediment, pesticides and other toxicants. This study contributes to this understanding and has two primary components: first, development of a graphical user interface for a geographic information system and storm water management database, and second, performing a two-scale hydrological modeling approach (th… more
Date: December 2003
Creator: Duncan, Phillip Brent
Item Type: Refine your search to only Thesis or Dissertation
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Removal of selected water disinfection byproducts, and MTBE in batch and continuous flow systems using alternative sorbents.

Description: A study was conducted to evaluate the sorption characteristics of six disinfection byproducts (DBPs) on four sorbents. To investigate sorption of volatile organic compounds (VOCs), specially designed experimental batch and continuous flow modules were developed. The investigated compounds included: chloroform, 1,2-dichloroethane (DCE), trichloroethylene (TCE), bromodichloromethane (BDCM), methyl tertiary butyl ether (MTBE), bromate and bromide ions. Sorbents used included light weight aggregate… more
Date: December 2002
Creator: Kadry, Ahmed Y.
Item Type: Refine your search to only Thesis or Dissertation
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Development, Validation, and Evaluation of a Continuous, Real-time, Bivalve Biomonitoring System

Description: A biological monitoring tool to assess water quality using bivalve gape behavior was developed and demonstrated. The purpose of this work was to develop methodologies for screening water quality appropriate to the goals of the watershed paradigm. A model of bivalve gape behavior based on prediction of behavior using autoregressive techniques was the foundation of the bivalve biomonitoring system. Current technology was used in developing the system to provide bivalve gape state data in a contin… more
Date: December 2002
Creator: Allen, H. Joel
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Integrating life cycle analysis and the ecological footprint calculator to foster sustainable behaviors

Description: Many tools have been developed to assess global, national or regional sustainable development policies. However, as governments develop sustainable policies, individuals must also feel empowered to affect their personal impact on the planet. This thesis integrates three sustainability concepts that lend themselves to individual sustainability: The natural step, life cycle assessment, and the ecological footprint. TNS serves to provide the meaning and substance toward sustainable development. … more
Date: December 2002
Creator: Anderle, Kathryn
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Partner: UNT Libraries

Phosphorus Retention and Fractionation in Masonry Sand and Light Weight Expanded Shale Used as Substrate in a Subsurface Flow Wetland

Description: Constructed wetlands are considered an inefficient technology for long-term phosphorus (P) removal. The P retention effectiveness of subsurface wetlands can be improved by using appropriate substrates. The objectives of this study were to: (i) use sorption isotherms to estimate the P sorption capacity of the two materials, masonry sand and light weight expanded shale; (ii) describe dissolved P removal in small (2.7 m3) subsurface flow wetlands; (iii) quantify the forms of P retained by the sub… more
Date: August 2002
Creator: Forbes, Margaret G.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Development of a Pre-Impact Environmental Site Characterization for the Bryan Mound, Texas Strategic Petroleum Reserve

Description: This thesis presents a model for developing site-specific contingency plans to be used during spill response, remediation, and post-spill monitoring using the Strategic Petroleum Reserve's Bryan Mound site as a case study. Bird and vegetation observations provide baseline data for biological conditions, and sediment sampling for total petroleum hydrocarbons serves as a chemical component of the model. Results demonstrate previously unknown conditions that would hinder remediation and affect the… more
Date: December 2001
Creator: Hernandez, Sylvia A.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

An examination of the riparian bottomland forest in north central Texas through ecology, history, field study, and computer simulation

Description: This paper explores the characterization of a riparian bottomland forest in north central Texas in two ways: field study, and computer simulation with the model ZELIG. First, context is provided in Chapter One with a brief description of a southern bottomland forest, the ecological services it provides, and a history of bottomland forests in Texas from the nineteenth century to the present. A report on a characterization study of the Lake Ray Roberts Greenbelt forest comprises Chapter Two. The … more
Date: August 2001
Creator: Holcomb, Sheralyn S.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Comparison of GPS Point Selection Methods for GIS Area Measurement of Small Jurisdictional Wetlands

Description: U.S. Army Corps of Engineers (USACE) regulates fill of jurisdictional waters of the United States including wetlands. Recent USACE regulations set a threshold of impacts to wetlands at one-half acre. Impact area can be determined by Global Positioning System (GPS) measurement of wetland boundary and Geographic Information System (GIS) calculation of impact area. GPS point selection methods include (1) equal time interval, (2) transect and (3) intuition. Four two-acre shapes were measured with e… more
Date: August 2001
Creator: Shelton, Michael
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Riparian Forest Width and the Avian Community in a Greenbelt Corridor Setting

Description: The forest avian community of the Ray Roberts Greenbelt (Denton Co., Texas) was characterized for two years using point count station sampling, from fall 1998 to summer 2000. Richness data for both breeding seasons were correlated with two-spatial metrics: width of the riparian forest and distance to the nearest edge. There were significant correlations between forest interior species richness and both spatial metrics, for both breeding seasons. Based on these data, a minimum riparian forest wi… more
Date: May 2001
Creator: Hoffman, Karl W.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Development of a Procedure to Evaluate Groundwater Quality and Potential Sources of Contamination in the East Texas Basin

Description: This study contributes a procedure, based on data analysis and geostatistical methods, to evaluate the distribution of chemical ratios and differentiate natural and anthropogenic contaminant sources of groundwater quality in the East Texas Basin. Four aquifers were studied, Sparta, Queen City, Carrizo and Wilcox. In this study, Carrizo- Wilcox is considered as one aquifer, and Sparta-Queen City as another. These aquifers were divided into depth categories, 0-150 feet for Sparta-Queen City and 3… more
Date: May 2001
Creator: Alderman, John H.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

A Data Fusion Framework for Floodplain Analysis using GIS and Remotely Sensed Data

Description: Throughout history floods have been part of the human experience. They are recurring phenomena that form a necessary and enduring feature of all river basin and lowland coastal systems. In an average year, they benefit millions of people who depend on them. In the more developed countries, major floods can be the largest cause of economic losses from natural disasters, and are also a major cause of disaster-related deaths in the less developed countries. Flood disaster mitigation research was c… more
Date: August 2000
Creator: Necsoiu, Dorel Marius
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Characterizing the Municipal Solid Waste Stream in Denton, Texas

Description: Forty-two commercially collected dumpsters from Denton’s Municipal Solid Waste Stream were emptied, sorted and weighed to characterize the material types and make preliminary recycling policy recommendations. The general composition of Denton’s solid waste stream was not significantly different from the composition of the nation’s solid waste stream. Fifty-eight percent of the observed waste stream was recyclable. Paper made up the largest portion of recyclable materials and the "grocery" sourc… more
Date: August 2000
Creator: Brady, Patricia D.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Ecological Enhancement of Timber Growth: Applying Compost to Loblolly Pine Plantations

Description: This study explored the application of compost onto a small loblolly pine tree forest in northeast Texas. Its purpose was to determine if the application of various amounts of compost would provide for accelerated rates of growth for the trees. Soil parameters were also monitored. A total of 270 trees were planted and studied in a northeast Texas forest ecosystem. Compost rates of 5, 25, and 50 tons per acre with either soil or compost backfill were utilized and compared to a control without co… more
Date: December 1999
Creator: Stuckey, Harold Troy
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The Potential of Coelomocyte Chemotaxis as an Immune Biomarker in the Earthworm, Lumbricus terrestris

Description: Coelomocyte migration responses, both random and chemotatic, were examined in the earthworm Lumbricus terrestris. Coelomocyte random migration patterns towards non-stimulatory, non-chemotatic solutions were described. Migration responses to immunostimulatory agents lipopolysaccharides (LPS), N-formly-methionyl-leucyl-phenylalanine (FMLP), sheep erythrocytes, Saccharomyces cerevisiae, Aeromonas hydrophila, Eisenia fetida and Rhabditis pellio were characterized. Chemotaxis was reported to LPS, FM… more
Date: December 1999
Creator: Mota, Jennifer A.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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