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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 4 days with samples at 330 to 400 meter intervals. Data generated with this system compared favorably with previous studies of Lake Texoma. Two sets of raster format maps were developed for the monthly distributions of chlorophyll-a, turbidity, and specific conductivity across the lake. Spatial and temporal relationships generally took the form of decreasing gradients running from the lake arms towards the Main Lake Zone in the case of chlorophyll-a and turbidity. Or, in the case of specific conductivity, a decreasing gradient from the Red River arm to the Washita River arm. All three water quality indicators were strongly influenced by river discharge levels.
Date: December 2002
Creator: Mabe, Jeffrey A.

Organic carbon dynamics of the Neches River and its floodplain.

Description: A large river system typically derives the majority of its biomass from production within the floodplain. The Neches River in the Big Thicket National Preserve is a large blackwater river that has an extensive forested floodplain. Organic carbon was analyzed within the floodplain waters and the river (upstream and downstream of the floodplain) to determine the amount of organic carbon from the floodplain that is contributing to the nutrient dynamics in the river. Dissolved organic carbon was significantly higher at downstream river locations during high discharge. Higher organic carbon levels in the floodplain contributed to increases in organic carbon within the Neches River downstream of the floodplain when Neches River discharges exceeded 10,000 cfs. Hurricane Rita passed through the Big Thicket National Preserve in September 2005. Dissolved organic carbon concentrations recorded after Hurricane Rita in the Neches River downstream of the floodplain were significantly higher than upstream of the floodplain. Dissolved organic carbon was twice as high after the hurricane than levels prior to the hurricane, with floodplain concentrations exceeding 50 ppm C. The increase in organic carbon was likely due to nutrients leached from leaves, which were swept from the floodplain trees prior to normal abscission in the fall. A continuum of leaf breakdown rates was observed in three common floodplain species of trees: Sapium sebiferum, Acer rubrum, and Quercus laurifolia. Leaves collected from blowdown as a result of Hurricane Rita did not break down significantly faster than leaves collected prior to abscission in the fall. Processing coefficients for leaf breakdown in a continuously wet area of the floodplain were significantly higher than processing coefficients for leaf breakdown on the floodplain floor. The forested floodplain of the Neches River is the main contributor of organic carbon. When flow is greater than 10,000 csf, the floodplain transports organic carbon directly ...
Date: December 2007
Creator: Stamatis, Allison Davis

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 visual and numeric distribution of oaks in the transition area between the eastern hardwood forests and the Great Plains. Oak distributions are changing on this transition area of the South Central Plains. The sandy Woodbine and Antlers formations traditionally associated with the largest oak distribution are carrying oak coverage of approximately 31-32% in Choctaw and Denton Counties. The calcareous Blackland and Grand Prairies are traditionally associated with treeless grasslands, but are now carrying oak and other tree landcover up to 18.9%. Human intervention, including the establishment of artificial, political and social boundaries, urbanization, farming and fire control have altered the natural distribution of oaks and other landcover of this unique georegion.
Date: December 2007
Creator: Maxey, George F.

A geospatial tool for assessing potential wildland fire risk in central Texas.

Description: Wildland fires in the United States are not always confined to wilderness areas. The growth of population centers and housing developments in wilderness areas has blurred the boundaries between rural and urban. This merger of human development and natural landscape is known in the wildland fire community as the wildland urban interface or WUI, and it is within this interface that many wildland fires increasingly occur. As wildland fire intrusions in the WUI increase so too does the need for tools to assess potential impact to valuable assets contained within the interface. This study presents a methodology that combines real-time weather data, a wildland fire behavior model, satellite remote sensing and geospatial data in a geographic information system to assess potential risk to human developments and natural resources within the Austin metropolitan area and surrounding ten counties of central, Texas. The methodology uses readily available digital databases and satellite images within Texas, in combination with an industry standard fire behavior model to assist emergency and natural resource managers assess potential impacts from wildland fire. Results of the study will promote prevention of WUI fire disasters, facilitate watershed and habitat protection, and help direct efforts in post wildland fire mitigation and restoration.
Date: August 2005
Creator: Hunter, Bruce Allan

Assessing Outcomes of a Recycling Education and Service Program within an Elementary School

Description: During the spring 2004 a pilot school recycling program was implemented within Robert E. Lee Elementary. The primary goal of the program was to determine how recycling education in the school would affect curbside recycling rates within the surrounding community. The program was a cooperative effort between the University of North Texas, City of Denton Solid Waste Department and Keep Denton Beautiful. Throughout the first months of the study during the spring 2004, an increase in curbside recycling within the Robert E. Lee Elementary attendance zone was observed, with a dramatic decrease in participation over the summer and a rapid increase once again during the second full semester of the study. In a survey conducted with 3rd and 5th grade students at the pilot project school, most students expressed positive attitudes about recycling. Students whose survey responses indicated a high level of knowledge about what could be recycled were 37% more likely to claim to recycle regularly, than those students that scored low on the knowledge portion of the survey. Although the total amount of waste generation (recyclable and non-recyclable) at Robert E. Lee Elementary did not decrease during the study, the campus was able to divert recyclable material from their trash at a much higher rate than two other local elementary campuses with paper-only recycling and no associated recycling education program. Based upon the success of the recycling program at Robert E. Lee Elementary, the City of Denton Recycling Division has agreed to move forward with offering recycling to more schools within the Denton Independent School District during the 2005-2006 school year.
Date: August 2005
Creator: Cunningham-Scott, Carey Beth

Revisiting Aldo Leopold's "Perfect" Land Health: Conservation and Development in Mexico's Rio Gavilan

Description: The Rio Gavilan watershed, located in Mexico 's northern Sierra Madre Occidental , has significance in conservation history. Upon visiting the remote, largely un­developed watershed during two hunting trips in the 1930s, renowned conservationist Aldo Leopold thought it was the best picture of land health he had seen. His main indicators of healthy land were slow water runoff rates regulating erosion and historical predator-prey relationships. The visits confirmed Leopold's concept of land health, inspired many of his essays, and helped shape his land ethic. Leopold proposed the area as a control site to research healthy land throughout North America . The proposal never went forward and the area has since been more intensively logged and grazed. This dissertation research used extensive literature review, archives, oral histories, citizen surveys, and rapid assessment of forest, rangeland, riparian, and socioeconomic health to assess impacts of past cultures and update the area's land health status. Projects that could restore land health, such as linked eco-tourism, forest density reduction, and rotational grazing, were assessed for feasibility. Recent critiques of Leopold's land ethic were also reviewed. Results indicate most pre-1940s impacts were light, current land health status is moderate, and local interest exists in restoring land health. Many fish and wildlife populations are reduced, temporarily stabilized, but still at risk. Soil and riverbed erosion, service sector economics, and (at some ridge-top sites) forest density are the land health indicators in worst condition. Land health restoration projects are feasible.
Date: December 2004
Creator: Forbes, William

Determination of Habitat Preferences of Pronghorn (Antilocapra americana) on the Rolling Plains of Texas Using GIS and Remote Sensing

Description: The Rocker b Ranch on the southern Rolling Plains has one of the last sizeable populations of pronghorn (Antilocapra americana) in Texas. To investigate habitat utilization on the ranch, pronghorn were fitted with GPS/VHF collars and were released into pastures surrounded by a variety of fences to determine how fence types affected habitat selection. Habitat parameters chosen for analysis were vegetation, elevation, slope, aspect, and distances to water, roads, and oil wells. Results showed that pronghorn on the ranch crossed modified fencing significantly less than other types of fencing. Pronghorn selected for all habitat parameters to various degrees, with the most important being vegetation type. Habitat selection could be attributed to correspondence of vegetation type with other parameters or spatial arrangements of physical features of the landscape. Seasonal differences in habitat utilization were evident, and animals tended to move shorter distances at night than they did during daylight hours.
Date: May 2005
Creator: Aiken, Robin A.

Rainfall-runoff changes due to urbanization: a comparison of different spatial resolutions for lumped surface water hydrology models using HEC-HMS.

Description: Hydrologic models were used to examine the effects of land cover change on the flow regime of a watershed located in North-Central Texas. Additionally, the effect of spatial resolution was examined by conducting the simulations using sub-watersheds of different sizes to account for the watershed. Using the Army Corps of Engineers, Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS), two different modeling methods were evaluated at the different sub-watershed resolutions for four rainfall events. Calibration results indicate using the smaller spatial resolutions improves the model results. Different scenarios for land cover change were evaluated for all resolutions using both models. As land cover change increased, the amount of flow from the watershed increased.
Date: December 2005
Creator: Redfearn, Howard Daniel

Simulation of physical and chemical processes in reservoirs: Two case studies.

Description: Managing water quality aspects requires the use of integrative tools that allow a holistic approach to this problem. Water quality models coupled to hydrodynamic models are these tools. This study presents the application of the water quality model WASP coupled to the hydrodynamic model DYNHYD for two distinct reservoirs: Lake Texoma and Tocoma Reservoir. Modeling the former included simulations of water velocities, water level, and four chemical and physical compounds: chlorides, dissolved oxygen (DO), biochemical oxygen demand (BOD), and total suspended solids (TSS); and validation of the results by comparing with observed values during March - May, 1997. The latter is still under project status and the simulation was performed in a prospective way. The analysis included simulations of water velocities under current and for expected conditions, DO and BOD. Both models, DYNHYD and WASP, fitted pretty well to observed conditions for Lake Texoma and for where Tocoma Reservoir has been planned. Considering management and decision support purposes, the role of boundary and loading conditions also was tested. For Lake Texoma, controlling boundary conditions for chlorides is a determinant factor for water quality of the system. However, DO and TSS in the reservoir are governed by additional process besides the condition of the boundary. Estimated loadings for this system did not provided significant effects, even though the allocation of a load for chlorides resulted in significant changes in the trend for expected chloride concentrations at the Washita River Arm of Lake Texoma. For Tocoma Reservoir, the expected concentration of DO all over the reservoir is going to driven by boundary conditions, as well as by the management of autochthonous BOD loadings provided by vegetation decomposition. These two factors will be determinant for the resulting water quality of the future reservoir.
Date: December 2005
Creator: García Iturbe, Selma L.

Reproductive and Growth Responses of the Fathead Minnow (Pimephales Promelas) and Japanese Medaka (Oryzias Latipes) to the Synthetic Progestin, Norethindrone

Description: A commonly prescribed contraceptive, the synthetic progestin norethindrone (NET) inhibits ovulation in humans. However, ecotoxicological data are lacking. Preliminary tests produced an LC50 for NET of > 1.0 mg/L (96-hour, fathead minnow (FHM) and medaka) and a NOEC of 242.0 µg/L, a LOEC of 485.0 µg/L (7-day, growth for FHM and medaka). Reproductive testing revealed a LOEC for fecundity of 24.1 ng/L (21 days, medaka). Further testing confirmed the LOEC of 24.1 ng/L while defining a NOEC of 4.7 ng/L (28 days, medaka). Effect of NET in medaka life-cycle exposure at concentrations exceeding 4.7 ng/L was evident. Few females were present in the 24.7 ng/L exposure concentration, with none in the 104.6 ng/L. Egg production was significantly reduced at concentrations exceeding 4.7 ng/L. Additionally, weight, condition factor and somatic indices were significantly different in males exposed to concentrations exceeding 4.7 ng/L. For fecundity and sexual differentiation; the NOEC was 4.7 ng/L, the LOEC 24.6 ng/L; growth and somatic indices, the NOEC was more appropriately 0.9 ng/L, with effect evident at 4.7 ng/L. Sexual differentiation of the F1 population was similar to the F0. A defining result of this test was development of exceptionally large ovaries in NET- exposed female medaka, perhaps indicative of a threshold limit for exposure in these fish. Results of FHM life-cycle testing were similar, establishing a NOEC for fecundity of 0.9 ng/L, a LOEC of 4.8 ng/L. NET's inhibitory effect on gonadal development was obvious; GSI NOEC for males, 4.8 ng/L, and histological examination confirmed the presence of intersex development at elevated concentrations. Normal physical development and growth were impaired, generally at concentrations exceeding 24.1 ng/L. At exposure concentrations exceeding 4.8 ng/L, external sexual confirmation of fish was difficult; LOEC for finspot development in females, 4.8 ng/L. Sexual determination of the 97.1 ng/L exposure group was ...
Date: May 2011
Creator: Paulos, Peter M.

Characterization of Triclocarban, Methyl- Triclosan, and Triclosan in Water, Sediment, and Corbicula Fluminea (Müller, 1774) Using Laboratory, in Situ, and Field Assessments

Description: In the last decade emerging contaminants research has intensified in a bid to answer questions about fate, transport, and effects as these chemicals as they get released into the environment. The chemicals of interest were the antimicrobials; triclocarban (TCC) and triclosan (TCS), and a metabolite of triclosan, methyl triclosan (MTCS). This research was designed to answer the question: what is the fate of these chemicals once they are released from the waste water treatment plant into receiving streams. Three different assessment methods; field monitoring, in-situ experiments, and laboratory studies were used to answer the overall question. TCS, TCC, and MTCS levels were measured in surface water, sediment and the Asiatic clam Corbicula fluminea. Field studies were conducted using four sites at Pecan Creek, Denton TX. Levels of all three chemicals in clams were up to fives orders of magnitude the water concentrations but an order of magnitude lower than in sediment. Highest sediment levels of chemicals were measured in samples from the mouth of Pecan Creek (highest organic matter). TCC was the most and TCS was the least accumulated chemicals. In-situ and lab studies both indicated that uptake of these chemicals into the clams was very rapid and measurable within 24hours of exposure. The after clams were transferred into clean water most of the compounds were depurated within 14 days.
Date: May 2011
Creator: Edziyie, Regina E.

Developing a Forest Gap Model to Be Applied to a Watershed-scaled Landscape in the Cross Timbers Ecoregion Using a Topographic Wetness Index

Description: A method was developed for extending a fine-scaled forest gap model to a watershed-scaled landscape, using the Eastern Cross Timbers ecoregion as a case study for the method. A topographic wetness index calculated from digital elevation data was used as a measure of hydrologic across the modeled landscape, and the gap model modified to have with a topographically-based hydrologic input parameter. The model was parameterized by terrain type units that were defined using combinations of USDA soil series and classes of the topographic wetness index. A number of issues regarding the sources, grid resolutions, and processing methods of the digital elevation data are addressed in this application of the topographic wetness index. Three different grid sizes, 5, 10, and 29 meter, from both LiDAR-derived and contour-derived elevation grids were used, and the grids were processed using both single-directional flow algorithm and bi-directional flow algorithm. The result of these different grids were compared and analyzed in context of their application in defining terrain types for the forest gap model. Refinements were made in the timescale of gap model’s weather model, converting it into a daily weather generator, in order to incorporate the effects of the new topographic/hydrologic input parameter. The precipitation model was converted to use a Markov model to initiate a sequence of wet and dry days for each month, and then daily precipitation amounts were determined using a gamma distribution. The output of the new precipitation model was analyzed and compared with a 100-year history of daily weather records at daily, monthly, and annual timescales. Model assumptions and requirements for biological parameters were thoroughly investigated and questioned. Often these biological parameters are based on little more than assumptions and intuition. An effort to base as many of the model’s biological parameters on measured data was made, including a new ...
Date: August 2014
Creator: Goetz, Heinrich

Role of N-Acylethanolamines in Plant Defense Responses: Modulation by Pathogens and Commercial Antimicrobial Stressors

Description: N-acyl ethanolamines (NAEs) are a class of lipids recently recognized as signaling molecules which are controlled, in part, by their degradation by fatty acid amide hydrolase (FAAH). On the basis of previous studies indicating increased NAE levels in a tobacco cell suspension-xylanase elicitor exposure system and the availability of FAAH mutants, overexpressor and knockout (OE and KO) genotypes in Arabidopsis thaliana, further roles of NAEs in A. thaliana plant defense was investigated. The commonly occurring urban antimicrobial contaminant triclosan (TCS) has been shown to suppress lipid signaling associated with plant defense responses. Thus, a second objective of this study was to determine if TCS exposure specifically interferes with NAE levels. No changes in steady state NAE profiles in A. thaliana-Pseudomonas syringae pv. syringae and A. thaliana-flagellin (bacterial peptide, flg22) challenge systems were seen despite evidence that defense responses were activated in these systems. There was a significant drop in enoyl-ACP reductase (ENR) enzyme activity, which catalyzes the last step in the fatty acid biosynthesis pathway in plants, on exposure of the seedlings to TCS at 10 ppm for 24 h and decreased reactive oxygen species (ROS) production due to flg22 in long term exposure of 0.1 ppm and short term exposure of 5 ppm. However, these responses were not accompanied by significant changes in steady state NAE profiles.
Date: August 2010
Creator: Vadapalli, Vatsala

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. This antioxidant capacity is important because it may ameliorate natural and anthropogenic stressor-induced oxidative stress. While previous researchers have shown carotenoid compounds impart increased resistance to ultraviolet radiation in populations of zooplankton, little work has focused on the toxicological implications of PAH induced phototoxicity on zooplankton containing high levels of carotenoid compounds. This thesis discusses research studying the role that carotenoid compounds play in reducing PAH induced phototoxicity. By sampling different lakes at elevations ranging from 9,500' to 12,700' in the front range of the Colorado Rocky Mountains, copepod populations containing different levels of carotenoid compounds were obtained. These populations were then challenged with fluoranthene and ultraviolet radiation. Results discussed include differences in survival and levels of lipid peroxidation among populations exhibiting different levels of carotenoid compounds, and the toxicological and ecological implications of these results.
Date: May 2010
Creator: Kovach, Matthew James

Wind Energy-related Wildlife Impacts: Analysis and Potential Implications for Rare, Threatened and Endangered Species of Birds and Bats in Texas

Description: Texas currently maintains the highest installed nameplate capacity and does not require publicly available post-construction monitoring studies that examine the impacts of wind energy production on surrounding fauna. This thesis examines potential wind energy impacts on avian and bat species in Texas through a three-part objective. The first two objectives synthesize literature on variables attractive to species within wind development areas and estimate impacted ranges outside of Texas, based on studies examining wind energy's environmental impacts. The third objective focuses on Texas wind development potential for interaction with rare, threatened and endangered species of birds and bats using GIS analysis with a potential hazard index (PHI) model, which addresses broad-spectrum, high risk variables examined within the first two objectives. Assuming areas with higher wind speeds have potential for wind development, PHI values were calculated for 31 avian and ten bat species, based on an analysis of species range data obtained from the Texas Parks and Wildlife Department and wind data obtained from the National Renewable Energy Laboratory. Results indicate one avian species, Tympanuchus pallidicinctus, is at high risk for wind development interaction on an annual basis, with 20 species of birds and nine species of bats at higher risk during the spring season. This macro-scale approach for identifying high risk species in Texas could be used as a model to apply to other conterminous states' preliminary evaluation of wind energy impacts.
Date: August 2010
Creator: Graham, Tara L.

Correspondence Between Aquatic Ecoregions and the Distribution of Fish Communities of Eastern Oklahoma

Description: I assessed fish community data collected by the Oklahoma Conservation Commission from 82 minimally impaired wadeable reference streams in eastern Oklahoma to determine whether existing aquatic ecoregions provide the best framework for spatial classification for the development of biological assessment methods and biocriteria. I used indirect ordination and classification to identify groups of sites that support similar fish communities. Although correspondence was observed between fish assemblages and three montane ecoregions, the classification system must be refined and expanded to include major drainage basins and physical habitat attributes for some areas to adequately partition variance in key measures of biological integrity. Results from canonical correspondence analysis indicated that substrate size and habitat type were the primary physical habitat variables that influenced the fish species composition and community structure.
Date: May 2001
Creator: Howell, Charles E.

Portrait of Your Stream: Development and Assessment of a Stream Ecology Program for Middle-School Student

Description: Portrait of Your Stream (POYS) is a stream ecology and student action program designed for use with middle-school students. The program is correlated with learning cycle pedagogical methods emphasizing student-centered lessons and activities in both classroom and outdoor settings. Implementation of a pilot program in the Fall semester of 1999 was used to collect formal and informal responses and data from students and teachers. Data included changes in student knowledge, skills and attitudes and were analyzed for determination of the success of program objectives and modifications to the program. The final POYS program is currently distributed and administered by the Botanical Research Institute of Texas.
Date: May 2001
Creator: Swirczynski, Brenda J.

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-

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 meaning, message, and humor in the cartoons. Chapter 1 introduces the Sambourne, Punch magazine, and the Edwardian period in general. Chapters 2 and 3 discuss four Women's Suffrage cartoons and four Socialism cartoons respectively. Chapter 4 draws conclusions regarding Sambourne's techniques as a cartoonist as well as the relationship between the text and image in his illustrations.
Date: May 2001
Creator: Larson, Alison

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 procedure. Cell disruption by mortar and pestle grinding was preferable to bath sonication. Comparison of the chlorophyll/fluorescence readings from the multiprobe and the extraction procedure indicated that they were significantly correlated but temperature dependent.
Date: May 2001
Creator: Lambert, Patricia

Biotic Factors and Temperature Tolerances via Critical Thermal Methodology in Goldfish

Description: CTMinimum and CTMaximum were measured in 620 goldfish to determine if biotic factors, in particular starvation, condition factor and size, affect temperature tolerance. Twenty-eight days of starvation adversely affected both upper and lower temperature tolerance. Condition factor was related to upper but not lower temperature tolerance.
Date: August 1999
Creator: Ford, Tiiu Kirsti, 1972-

An Evaluation of Fish and Macroinvertebrate Response to Effluent Dechlorination in Pecan Creek

Description: This study evaluated the effects of chlorinated effluent discharged from the City of Denton, Texas' wastewater treatment plant on Pecan Creek's fish and macroinvertebrate assemblages, and their recovery upon dechlorination. A baseline of ecological conditions was established while chlorine was present in the effluent (June 1993- October 1993), and was evaluated again after dechlorination with sulfur dioxide (October 1993-August 1994). In situ Asiatic clam and fathead minnow ambient toxicity tests, and fish and macroinvertebrate collections were used to establish this baseline for comparison to post-dechlorination results.
Date: May 1995
Creator: Wise, Patricia D. (Patricia Diane)

Environmental Factors Influencing Chlorophyll-a Concentrations in Lake Texoma

Description: An analysis of algal biomass measured by chlorophyll-a concentration in Lake Texoma was performed as a part of a monitoring program to develop baseline environmental data in order to detect the potential effects of engineered changes in chloride concentrations in the reservoir. This portion of the research project focused on two main research objectives. The first objective was evaluating the effect of sampling strategy on the ability to adequately reflect standing crop estimates and trends in algal biomass. Two sampling regimes utilizing replication of three versus ten samples were applied and then analyzed using a minimum detectable difference algorithm to determine the necessary magnitude of replication to represent the variation in the metric. Chlorophyll-a distribution was analyzed for zonation patterns expected in a river-run reservoir to establish the importance of representative sampling of river, transition and main lake zones of the reservoir for management decisions and trophic characterization.
Date: December 1998
Creator: Gibbs, Jennifer S. (Jennifer Sokolovic)