UNT Libraries - 135 Matching Results

Search Results

prev Results: 61 - 84 next
open access

Use of In-Stream Water Quality Measurements and Geospatial Parameters to Predict Consumer Surfactant Toxic Units in the Upper Trinity River Watershed, Texas

Description: Surfactants are used in a wide assortment of "down-the-drain" consumer products, yet they are often discharged in wastewater treatment plant effluent into receiving water, potentially causing environmental harm. The objective of this project was to predict surfactant toxic units and in-stream nutrients in the upper Trinity River watershed. Surface and pore water samples were collected in late summer 2005. General chemistries and surfactant toxic units were calculated. GIS models of anthropo… more
Date: May 2008
Creator: Johnson, David Richard
Item Type: Refine your search to only Thesis or Dissertation
open access

Space Use, Microhabitat and Macrohabitat Use of the Three-Toed Box Turtle (Terrapene carolina) in North Texas

Description: Box turtle (Terrapene carolina) populations are steadily declining due their unique natural history, effects of climate change, and anthropogenic land use change. There is a need for updated information on box turtle space and micro and macro-habitat use to inform conservation efforts. This study used VHF radiotelemetry and GPS data loggers to examine box turtle space and habitat use in North Texas. Box turtle home range sizes averaged 6.6ha (range = 0.79 - 18.08, n = 23), and males (n = 9) had… more
Date: December 2022
Creator: Joseph, Sara A.
Item Type: Refine your search to only Thesis or Dissertation
open access

Spatially Explicit Modeling of West Nile Virus Risk Using Environmental Data

Description: West Nile virus (WNV) is an emerging infectious disease that has widespread implications for public health practitioners across the world. Within a few years of its arrival in the United States the virus had spread across the North American continent. This research focuses on the development of a spatially explicit GIS-based predictive epidemiological model based on suitable environmental factors. We examined eleven commonly mapped environmental factors using both ordinary least squares regress… more
Date: December 2015
Creator: Kala, Abhishek K.
Item Type: Refine your search to only Thesis or Dissertation
open access

An Assessment of Storm Water Toxicity from the Dallas/Fort Worth Metroplex and Denton, Texas

Description: With the advent of national storm water regulations, municipalities with populations greater than 100,000 are required to obtain National Pollutant Discharge Elimination System Permits (NPDES) for storm water discharges. In addition to the sampling required for the permit process, the City of Fort Worth contracted with the University of North Texas' Institute of Applied Sciences to conduct acute toxicity testing using Pimephales prcmelas and Ceriodaphnia dubia on storm water samples received fr… more
Date: August 1995
Creator: Keating, Paul Redmond
Item Type: Refine your search to only Thesis or Dissertation
open access

Density, Distribution and Habitat Requirements for the Ozark Pocket Gopher (Geomys Bursarius Ozarkensis)

Description: A new subspecies of the plains pocket gopher (Geomys bursarius ozarkensis), located in the Ozark Mountains of north central Arkansas, was recently described by Elrod et al. (2000). Current range for G. b. ozarkensis was established, habitat preference was assessed by analyzing soil samples, vegetation and distance to stream and potential pocket gopher habitat within the current range was identified. A census technique was used to estimate a total density of 3, 564 pocket gophers. Through automo… more
Date: May 2004
Creator: Kershen, Audrey Allbach
Item Type: Refine your search to only Thesis or Dissertation
open access

Evaluation of the Developmental Effects and Bioaccumulation Potential of Triclosan and Triclocarban Using the South African Clawed Frog, Xenopus Laevis

Description: Triclosan (TCS) and triclocarban (TCC) are antimicrobials found in U.S. surface waters. This dissertation assessed the effects of TCS and TCC on early development and investigated their potential to bioaccumulate using Xenopus laevis as a model. The effects of TCS on metamorphosis were also investigated. For 0-week tadpoles, LC50 values for TCS and TCC were 0.87 mg/L and 4.22 mg/L, respectively, and both compounds caused a significant stunting of growth. For 4-week tadpoles, the LC50 values… more
Date: December 2010
Creator: King, Marie Kumsher
Item Type: Refine your search to only Thesis or Dissertation
open access

The impact of climate and flooding on tree ring growth of Fraxinus pennsylvanica in north-central Texas.

Description: Tree cores of Fraxinus pennsylvanica were used in a dendrochronological analysis investigating the species' responses to climate and flooding. The objective was to develop a model that incorporates the effects of precipitation, temperature, and flooding on radial growth in this species in north-central Texas. The trees exhibited strong climatic signals. The study clearly shows that all three factors have significant impacts on tree ring growth both prior to and during growth; however, the natur… more
Date: December 2009
Creator: Komperod, Mari
Item Type: Refine your search to only Thesis or Dissertation
open access

Adaptive Advantages of Carotenoid Pigments in Alpine and Subalpine Copepod Responses to Polycyclic Aromatic Hydrocarbon Induced Phototoxicity

Description: Alpine zooplankton are exposed to a variety of stressors in their natural environment including ultraviolet radiation. Physiological coping mechanisms such as the accumulation of photoprotective compounds provide these zooplankton protection from many of these stressors. Elevated levels of carotenoid compounds such as astaxanthin have been shown to help zooplankton survive longer when exposed to ultraviolet radiation presumably due to the strong antioxidant properties of carotenoid compounds. T… more
Date: May 2010
Creator: Kovach, Matthew James
Item Type: Refine your search to only Thesis or Dissertation
open access

The Role of Rainfed Farm Ponds in Sustaining Agriculture and Soil Conservation in the Dry High Valley Region of Cochabamba, Bolivia: Design Considerations and Post Impoundment Analysis

Description: Lack of sufficient water for irrigation is a major problem in and around the valleys surrounding the town of Aiquile, Cochabamba Bolivia. In addition, much of the region is undergoing desertification compounded by drought, deforestation, bad traditional agricultural practices, over grazing and a "torrential" rainfall pattern leading to severe soil erosion and low agricultural production. Between 1992 and 1994, the author constructed a network of 24 small, mostly rainfed farm ponds to increase a… more
Date: August 1999
Creator: Kuiper, John R.
Item Type: Refine your search to only Thesis or Dissertation
open access

Assessment of Radio-Tagged Grass Carp (Ctenopharnygodon idella) Dispersion, Vegetation, and Temperature Preferences in North Lake Reservoir

Description: Twenty-nine (Group One, June 8,1995) grass carp (Ctenopharyngodon idella) and five (Group Two, April 18, 1996) grass carp were radio-tagged to monitor movement patterns and habitat preferences on North Lake, a 335 hectare multi-use reservoir located in Irving, Texas. Overall fish mean Average Daily Movement (ADM) rates were 49.2 meters/day (during Half One, 6/8/95-11/30/95) and 5.3 meters/day (during Half Two, 12/14/95-6/6/96). Aquatic macrophtye distribution data were obtained. Radio-tagged gr… more
Date: August 1996
Creator: Lacewell, Jason (Jason Lawrence)
Item Type: Refine your search to only Thesis or Dissertation
open access

Evaluation of the Chlorophyll/Fluorescence Sensor of the YSI Multiprobe: Comparison to an Acetone Extraction Procedure

Description: The purpose of this study was to examine the suitability of the YSI model 6600 Environmental Monitoring System (multiprobe) for long term deployment at a site in Lewisville Lake, Texas. Specifically, agreement between a laboratory extraction procedure and the multiprobe chlorophyll/fluorescence readings was examined. Preliminary studies involved determining the best method for disrupting algal cells prior to analysis and examining the precision and linearity of the acetone extraction procedur… more
Date: May 2001
Creator: Lambert, Patricia
Item Type: Refine your search to only Thesis or Dissertation
open access

Modeling the Effects of Chronic Toxicity of Pharmaceutical Chemicals on the Life History Strategies of Ceriodaphnia Dubia: a Multigenerational Study

Description: Trace quantities of pharmaceuticals (including carbamazepine and sertraline) are continuously discharged into the environment, which causes concern among scientists and regulators regarding their potential long-term impacts on aquatic ecosystems. These compounds and their metabolites are continuously interacting with the orgranisms in various life stages, and may differentially influence development of embryo, larvae, juvenile, and adult stages. To fully understand the potential ecological risk… more
Date: December 2013
Creator: Lamichhane, Kiran
Item Type: Refine your search to only Thesis or Dissertation
open access

The Last Laugh: Selected Edwardian Punch Cartoons of Edward Linley Sambourne

Description: The illustrative work of Edward Linley Sambourne for Punch magazine during the period 1901-1910 addresses a myriad of political topics prevalent during the Edwardian period in British history. This thesis examines two of those topics - Women's Suffrage and Socialism - through their artistic treatment by one of Britain's most influential periodicals. Through a study of the historical context and iconography of selected cartoons-of-the-week, one is better equipped to understand and appreciate the… more
Date: May 2001
Creator: Larson, Alison
Item Type: Refine your search to only Thesis or Dissertation
open access

Assessing the Spatial and Temporal Distribution of MTBE and BTEX Compounds in Lake Lewisville, Texas February 1999 - February 2000

Description: The spatial and temporal distribution of Methyl Tertiary-Butyl Ether (MTBE) and BTEX (Benzene, Toluene, Ethylbenzene, Xylenes) compounds were assessed in a multipurpose reservoir, Lake Lewisville, Texas between February 1999 and February 2000. Concentrations of MTBE ranged from 0.0 - 16.7 mg/L. Levels of MTBE in the lake were related to watercraft. BTEX concentrations were never detected above 2.0 mg/L during the sampling period. Finished drinking water from Denton and the Upper Trinity Regio… more
Date: August 2000
Creator: Lee, Anne W.
Item Type: Refine your search to only Thesis or Dissertation

Investigating the Spatial Relationship between Suicide and Race/Ethnicity: The Case for Alternate Rate Adjustment Techniques in Medical Geography

Description: This work explores potential distortions created by race and ethnicity on the visualization, interpretation, and understanding of the spatial distribution of suicide in the United States. Due to radically different suicide rates among racial/ethnic groups, traditional crude or age-adjusted rates may introduce statistical confounding in both linear and spatial models. Using correlation, choropleth mapping, hot spot analysis, and location-allocation modeling, this work shows how traditional metho… more
Date: December 2022
Creator: Lester, Katherine Ann
Item Type: Refine your search to only Thesis or Dissertation
open access

Water Quality Mapping on Lake Texoma USA

Description: The primary objective of this study was to develop and evaluate a system capable of rapid, continuous collection of water quality and locational data on Lake Texoma. Secondary objectives included developing monthly distribution maps for chlorophyll-a, turbidity, and specific conductivity in Lake Texoma and investigating the spatial and temporal relationships between these common water quality indicators. A modified YSI multiprobe was used to develop a system capable of surveying the lake within… more
Date: December 2002
Creator: Mabe, Jeffrey A.
Item Type: Refine your search to only Thesis or Dissertation
open access

Recovery of the Fish Population of a Municipal Wastewater Dominated, North Texas Creek After a Major Chlorine Disturbance

Description: This study evaluated the effects of a major chlorine disturbance on fish communities in Pecan creek by the City of Denton's Pecan Creek Water Reclamation Plant. Fish communities in Pecan Creek were sampled using a depletion methodology during February, April, July, and November, 1999. February and April sampling events showed that the fish communities were severely impacted by the chlorine. Sampling during July and November showed fish communities recovered in Pecan Creek. The first-twenty minu… more
Date: August 2002
Creator: Maschmann, Gerald F.
Item Type: Refine your search to only Thesis or Dissertation
open access

Quantifying Forest Vertical Structure to Determine Bird Habitat Quality in the Greenbelt Corridor, Denton, Tx

Description: This study presents the integration of light detection and range (LiDAR) and hyperspectral remote sensing to create a three-dimensional bird habitat map in the Greenbelt Corridor of the Elm Fork of the Trinity River. This map permits to examine the relationship between forest stand structure, landscape heterogeneity, and bird community composition. A biannual bird census was conducted at this site during the breeding seasons of 2009 and 2010. Census data combined with the three-dimensional map … more
Date: August 2013
Creator: Matsubayashi, Shiho
Item Type: Refine your search to only Thesis or Dissertation
open access

Geology as a Georegional Influence on Quercus Fagaceae Distribution in Denton and Coke Counties of Central and North Central Texas and Choctaw County of Southeastern Oklahoma, Using GIS as an Analytical Tool.

Description: This study elucidates the underlying relationships for the distribution of oak landcover on bedrock and soil orders in two counties in Texas and one in Oklahoma. ESRI's ArcGis and ArcMap was used to create surface maps for Denton and Coke Counties, Texas and Choctaw County, Oklahoma. Attribute tables generated in GIS were exported into a spreadsheet software program and frequency tables were created for every formation and soil order in the tri-county research area. The results were both a vis… more
Date: December 2007
Creator: Maxey, George F.
Item Type: Refine your search to only Thesis or Dissertation

Metacommunity Dynamics of Medium- and Large-Bodied Mammals in the LBJ National Grasslands

Description: Using metacommunity theory, I investigated the mechanisms of meta-assemblage structure and assembly among medium- to large-bodied mammals in North Texas. Mammals were surveyed with camera-traps in thirty property units of the LBJ National Grasslands (LBJNG). In Chapter II the dispersal and environmental-control based processes in community assembly were quantified within a metacommunity context and the best-fit metacommunity structure identified. A hypothesis-driven modelling approach was used … more
Date: May 2022
Creator: McCain, Wesley Craig Stade
Item Type: Refine your search to only Thesis or Dissertation
open access

Integration of field-based analysis of plant community dynamics with quantitative analysis of landscape change in the Ray Roberts Lake area, 1987—1997

Description: This study focused on the effectiveness of integrating traditional plant community analyses with landscape ecological analyses based on remotely sensed data. A temporal analysis of plant community diversity was conducted for major plant communities of the Ray Roberts Lake area using transect monitoring data collected between 1987 and 1997. Landscape analyses were performed with FRAGSTATS*ARC using classified SPOT satellite imagery for 1987 and 1997. Although the methodology developed in this wo… more
Date: May 2000
Creator: McDonough, Theresa J.
Item Type: Refine your search to only Thesis or Dissertation
open access

Management Tools for Prescribed Burning for Tallgrass Prairie Restoration at the Lewisville Lake Environmental Learning Area

Description: The Lewisville Lake Environmental Learning Area (LLELA) is a wildlife management area with tallgrass prairie, an endangered ecosystem. Essential ecosystem processes, especially fire, are part of restoration. To support fire management efforts at LLELA and surrounding areas, this project evaluated and developed tools for fire restoration. The four primary prairie grasses respond favorably to burning. Fuel loads and fuel models vary by scale and survey method. One- and 10-hour fuel moisture can b… more
Date: December 2003
Creator: Moreno, Maria C.
Item Type: Refine your search to only Thesis or Dissertation
open access

Comparison of Risk Assessment-Predicted Ecologically Safe Concentrations of Azinphos-Methyl and Fenvalerate to Observed Effects on Estuarine Organisms in a South Carolina Tidal Stream Receiving Agricultural Runoff

Description: A prospective ecological risk assessment method was developed evaluating the cumulative probabilistic impact of chemical stressors to aquatic organisms. This method was developed in response to the need to evaluate the magnitude, duration and episodic nature of chemical stressors on aquatic communities under environmental exposure scenarios. The method generates a probabilistic expression of the percent of an ecosystem's species at risk from a designated chemical exposure scenario.
Date: August 1997
Creator: Morton, Michael Gerard, 1957-
Item Type: Refine your search to only Thesis or Dissertation
open access

The impact of invertebrates to four aquatic macrophytes: Potamogeton nodosus, P. illinoensis, Vallisneria americana and Nymphaea mexicana.

Description: This research investigated the impact of invertebrates to four species of native aquatic macrophytes: V. americana, P. nodosus, P. illinoensis, and N. mexicana. Two treatments were utilized on each plant species, an insecticide treatment to remove most invertebrates and a non-treated control. Ten herbivore taxa were collected during the duration of the study including; Synclita, Paraponyx, Donacia, Rhopalosiphum, and Hydrellia. Macrophyte biomass differences between treatments were not measu… more
Date: August 2008
Creator: Nachtrieb, Julie Graham
Item Type: Refine your search to only Thesis or Dissertation
Back to Top of Screen