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Optimizing Scientific and Social Attributes of Pharmaceutical Take Back Programs to Improve Public and Environmental Health

Description: Research continues to show that pharmaceutical environmental contamination has caused adverse environmental effects, with one of the most studied effects being feminization of fish exposed to pharmaceutical endocrine disruptors. Additionally, there are also public health risks associated with pharmaceuticals because in-home reserves of medications provide opportunities for accidental poisoning and intentional medication abuse. Pharmaceutical take back programs have been seen as a remedy to these concerns; however a thorough review of peer-reviewed literature and publicly available information on these programs indicates limited research has been conducted to validate these programs as a purported solution. Furthermore, there are significant data gaps on key factors relating to take back program participants. The purpose of this dissertation was therefore to address these gaps in knowledge and ultimately determine if take back programs could actually improve public and environmental health. This was accomplished by conducting social and scientific research on a take back program called Denton Drug Disposal Day (D4). Socioeconomic, demographic, and geographic characteristics of D4 participants were investigated using surveys and geographic analysis. Impacts on public health were determined by comparing medications collected at D4 events with medications reported to the North Texas Poison Center as causing adverse drug exposures in Denton County. Impacts to environmental health were determined by monitoring hydrocodone concentrations in wastewater effluent released from Denton’s wastewater treatment plant before and after D4 events. Data collected and analyzed from the D4 events and the wastewater monitoring suggests D4 events were successful in contributing to improvements in public and environmental health; however there was insufficient evidence to prove that D4 events were exclusively responsible for these improvements. An additional interesting finding was that willingness to travel to participate in D4 events was limited to a five to six mile threshold. This geographic information, combined with other findings related to socioeconomic, ...
Date: August 2012
Creator: Stoddard, Kati Ireland

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

A paleozoological perspective on predator extermination and white-tailed deer (Odocoileus virginianus Boddaert) overabundance in central Texas.

Description: Archaeological and paleontological datasets are used in conservation to add time-depth to ecology. In central Texas several top carnivores including prehistoric Native American hunters have been extirpated or have had their historic ranges restricted, which has resulted in pest-level white-tailed deer (Odocoileus virginianus texana) populations in some areas. Predator extermination has dramatically reduced the average body size of members of the extant predator guild, and large carnivores most capable of hunting white-tailed deer are extirpated. Character release in the remaining “large” predatorsmesocarnivoresis a predicted outcome related to the adaptive vacuum at the top of the trophic hierarchy. Differences in body size of deer between prehistory and modernity are expected given that a lack of predation likely has increased intraspecific competition for forage among deer resulting in smaller body size today. In fact modern deer from settings without harvest pressure are significantly smaller than those from harvested areas and from prehistoric deer. From a natural history perspective, this research highlights potential evolutionary causes and effects of top-predator removal on deer populations and related components of biological communities in central Texas.
Date: May 2007
Creator: Wolverton, Steven J.

Photo-induced Toxicity of Deepwater Horizon Spill Oil to Four Native Gulf of Mexico Species

Description: The 2010 Deepwater Horizon oil spill resulted in the accidental release of millions of barrels of crude oil into the Gulf of Mexico (GoM). Photo-induced toxicity following co-exposure to ultraviolet (UV) radiation is one mechanism by which polycyclic aromatic hydrocarbons (PAHs) from oil spills may exert toxicity. Blue crab (Callinectes sapidus) are an important commercial and ecological resource in the Gulf of Mexico and their largely transparent larvae may make them sensitive to PAH photo-induced toxicity. Mahi-mahi (Coryphaena hippurus), an important fishery resource, have positively buoyant, transparent eggs. These characteristics may result in mahi-mahi embryos being at particular risk from photo-induced toxicity. Red drum (Sciaenops ocellatus) and speckled seatrout (Cynoscion nebulosus) are both important fishery resources in the GoM. They spawn near-shore and produce positively buoyant embryos that hatch into larvae in about 24 h. The goal of this body of work was to determine whether exposure to UV as natural sunlight enhances the toxicity of crude oil to early lifestage GoM species. Larval and embryonic organisms were exposed to several dilutions of water accommodated fractions (WAF) from several different oils collected in the field under chain of custody during the 2010 spill and two to three gradations of natural sunlight in a factorial design. Here, we report that co-exposure to natural sunlight and oil significantly reduced larval survival and embryo hatch compared to exposure to oil alone.
Date: December 2015
Creator: Alloy, Matthew Michael

Plankton Community Response to Dechorination of a Municipal Effluent Discharged into the Trinity River

Description: Chorine is used by the Village Creek Waste Water Treatment Plant to kill pathogenic microorganisms prior to discharge of the effluent into the Trinity River. The residual chlorine in the river impacted aquatic life prompting the U.S. Environmental Protection Agency in December 1990 to require dechlorination using sulfur dioxide. One pre-dechlorination and four post-dechlorination assessments of phytoplankton, periphyton, and zooplankton communities were conducted by the Institute of Applied Sciences at the University of North Texas. Dechlorination had no effect on the phytoplankton community. The periphyton community exhibited a shift in species abundance with a more even distribution of organisms among taxa. No change occurred in zooplankton species abundance, however, there was a decrease in zooplankton density following dechlorination.
Date: December 1994
Creator: Bryan, Brynne L. (Brynne Lee)

Population Dynamics of Zebra Mussels (Dreissena Polymorpha) in a North Texas Reservoir: Implications for Invasions in the Southern United States

Description: This dissertation has two main objectives: first, quantify the effects of environmental conditions on spatio-temporal spawning and larval dynamics of zebra mussels (Dreissena polymorpha [Pallas 1771]) in Lake Texoma, and second, quantify the effects of environmental conditions on survival, growth, and reproduction of young of the year (YOY) juvenile zebra mussels. These biological responses directly influence population establishment success and invasive spread dynamics. Reproductive output of the zebra mussel population in Lake Texoma was significantly related to water temperature and lake elevation. Annual maximum larval (veliger) density decreased significantly indicating a population crash, which was likely caused by thermal stress and variability of lake elevation. In 2011, temperatures peaked at 34.3°C and lake elevation decreased to the lowest level recorded during the previous 18 years, which desiccated a substantial number of settled mussels in littoral zones. Estimated mean date of first spawn in Lake Texoma was observed approximately 1.5 months earlier than in Lake Erie, and peak veliger densities were observed two months earlier. Veligers were observed in the deepest oxygenated water after lake stratification. During a 69-day in situ experiment during summer in Lake Texoma, age-specific mortality of zebra mussels was generally high until temperatures decreased to approximately 28°C, which was observed after lake turnover in late summer. No study organism died after temperatures decreased to less than 26°C, which indicates individuals that survive high summer temperatures are likely to persist into autumn/winter. Shell length growth and soft tissue growth rates were related to temperature and chlorophyll-a concentration, respectively. Growth rates of study organisms were among the highest ever reported for D. polymorpha. Water temperature and body size influenced reproduction of YOY zebra mussels in Lake Texoma. Fecundity of females were positively related to temperature; however, sperm production was negatively related to temperature, which indicates males could be more ...
Date: December 2013
Creator: Churchill, Christopher J.

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.

Pretreatment Optimization of Fiberglass Manufacturing Industrial Wastewater

Description: Wastewater effluent produced in the fiberglass manufacturing industry contains a significant amount of total suspended solids. Environmental regulations require pretreatment of effluent before it is discharged to the municipal wastewater treatment plant. Chemical precipitation by coagulation and flocculation is the method of pretreatment used at the Vetrotex CertainTeed Corporation (VCT). A treatability study was conducted to determine conditions at which the VCT Wastewater Pretreatment Plant could operate to consistently achieve a total suspended solids concentration ≤ 200-mg/L. Jar tests varied pH, polymer dosage, and ferric sulfate dosage. Total suspended solids and turbidity were measured to evaluate treatment performance. The data were used to determine an optimum set of conditions under project guidelines. Of twelve polymers screened, BPL 594 was selected as the most effective polymer. For cost efficiency in the wastewater pretreatment operation, recommendations suggested that treatment chemical injection be electronically controlled according to turbidity of the treated effluent.
Date: December 1998
Creator: Dragoo, Ron

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 suggest that local breeding bird abundance, community structure, and spatial distribution patterns are highly influenced by vertical heterogeneity of vegetation surface. For local breeding birds, vertical heterogeneity of canopy surface within stands, connectivity to adjacent forest patches, largest forest patch index, and habitat (vegetation) types proved to be the most influential factors to determine bird community assemblages. Results also highlight the critical role of secondary forests to increase functional connectivity of forest patches. Overall, three-dimensional habitat descriptions derived from integrated LiDAR and hyperspectral data serve as a powerful bird conservation tool that shows how the distribution of bird species relates to forest composition and structure at various scales.
Date: August 2013
Creator: Matsubayashi, Shiho

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

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 minutes of shocking and seining data were analyzed to mirror an equal effort methodology. This methodology was compared to the depletion methodology to see if the equal effort methodology could adequately monitor the recovery of Pecan Creek after the chlorine disturbance. It was determined that the equal effort methodology was capable of monitoring the recovery of Pecan Creek, but could not accurately represent the fisheries community as well as the depletion method. These data using the twenty-minute study were compared to a previous study. Results of this study were similar to those found in a previous study, although fish communities were more severely impacted and took longer to recover.
Date: August 2002
Creator: Maschmann, Gerald F.

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.

Residential Grid-Connected Photovoltaics Adoption in North Central Texas: Lessons from the Solarize Plano Project

Description: Residential Grid-Connected Photovoltaics (GPV) systems hold remarkable promise in their potential to reduce energy use, air pollution, greenhouse gas emissions, and energy costs to consumers, while also providing grid efficiency and demand-side management benefits to utilities. Broader adoption of customer-sited GPV also has the potential to transform the traditional model of electricity generation and delivery. Interest and activity has grown in recent years to promote GPV in north central Texas. This study employs a mixed methods design to better understand the status of residential GPV adoption in the DFW area, and those factors influencing a homeowner's decision of whether or not to install a system. Basic metrics are summarized, including installation numbers, distribution and socio-demographic information for the case study city of Plano, the DFW region, Texas, and the United States. Qualitative interview methods are used to gain an in-depth understanding of the factors influencing adoption for the Solarize Plano case study participants; to evaluate the effectiveness of the Solarize Plano program; and to identify concepts that may be regionally relevant. Recommendations are presented for additional research that may advance GPV adoption in north central Texas.
Date: August 2016
Creator: Jack, Katherine G.

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

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

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 agricultural production and alleviate soil erosion and land-use problems by improving cover conditions. A 5-year post-impoundment analysis was carried out in 1998. The analysis examined current pond conditions, design criteria, irrigation water / crop production increases and the alleviation of land-use problems. Current pond conditions fell into four distinct categories with only 25 percent of the ponds being deemed as "functioning well." The project increased irrigation in the region and improved cover conditions in 66 percent of the pond sites.
Date: August 1999
Creator: Kuiper, John R.

Selection and Use of Aquatic Vegetation by Migratory Waterfowl in North Central Texas

Description: Assessment of aquatic plant selection by waterfowl has been conducted during the winters of 1997-2000 on 49 0.2-0.79 ha research ponds in north central Texas. Ponds were categorized by dominant plant species into eight habitat types. Census with waterfowl species identification were performed to investigate impacts of aquatic vegetation and water depth on waterfowl. Eighteen waterfowl species were observed. Peak migration occurred in late December/early January. Mixed native ponds and mixed native/hydrilla ponds were the most frequently selected habitat types. The study included correlation analysis between pond water levels and waterfowl use. Full ponds received greatest use followed by half full ponds, while almost empty ponds received minimal use. Time activity budgets were conducted on waterfowl utilizing mixed native and hydrilla ponds to compare waterfowl time partitioning on native aquatic vegetation versus hydrilla. Although only minor differences were found in time budgets, social status appears to be strongly related to habitat selection. Ducks on native ponds were paired (86%), conversely no ducks on hydrilla ponds were paired. Hydrilla pond although frequently utilized, were populated by lower status birds mostly single hens.
Date: May 2001
Creator: Smith, JoEtta Kaye

Simulation of local watershed nutrient and sediment delivery to Lake Texoma.

Description: A hydrologic model and watershed export model was used to estimate the loading of nutrients and total suspended solids from un-gaged local watersheds associated with Lake Texoma. Discharge to the reservoir from local watersheds was predicted using a modification of the curve number method in HEC Hydrologic Modeling System (HEC-HMS). Event mean concentrations were applied to land use to estimate loadings of nutrients and TSS. Total discharge from the local watersheds was estimated to be 3.02 x 107 cubic meters for a study window of March 1 to May 31, 1997, less than 10 percent of the input to the lake from the Red River and Washita River systems. Loadings were estimated to be 33,553 kg nitrogen, 4,401 kg phosphorus, and 3,423,140 kg TSS. The models and results obtained from their application appear to have potential utility for use in a water quality management decision support system for the reservoir.
Date: May 2004
Creator: Upton, Alexandra C.

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.

Soil and Forest Variation by Topography and Succession Stages in the Greenbelt Corridor, Floodplain of the Elm Fork of the Trinity River, North Texas.

Description: The Greenbelt Corridor (GBC), located in a floodplain of the Elm Fork of the Trinity River, contains patches of bottomland forest and serves as part of Lake Lewisville’s flood control backwaters. This study examines forest structure and composition in relation to topographic position and forest stage in the GBC. Thirty two plots were surveyed within various stage classes, topographic positions, and USDA soil types. Trees were identified and measured for height and DBH. Density, basal area, and importance value for each of species was calculated. Soil and vegetation were analyzed using ANOVA, Principal Component Analysis, Canonical Correlation, Canonical Correspondence Analysis and Cluster Analysis. Tests confirmed that calcium carbonate and pH show significant differences with topographic positions but not with forest stage. Potassium shows no significant difference with soil texture class. Sand shows a strong negative correlation with moisture, organic matter, organic carbon and negative correlation with calcium carbonate and potassium. Silt shows positive correlation with moisture, organic matter, organic carbon, and calcium carbonate. Clay shows strong positive correlation with moisture, organic matter and organic carbon but negative correlations with pH. Swamp privet is dominant tree types in wetland forest. Sugarberry cedar elm, green ash and American elm are widely distributed species in the study area covering low ridges, flats, and slough. In total, density is significantly different in wetland low forest and late successional stage and basal area is significantly different in early successional stage and late successional stage. Other results show that clay is negatively correlated with American elm but positively correlated with cedar elm. Organic matter and moisture shows a strong positive correlation with cedar elm. Calcium carbonate is associated with green ash and swamp privet, sand is associated with sugarberry and red mulberry, silt and pH with cedar elm and bur oak.
Date: August 2011
Creator: Rijal, Rajan

Spatial Analysis of Atrazine in the Elm Fork Watershed

Description: This study assessed the water quality of the Elm Fork Watershed with regards to the herbicide Atrazine. Atrazine is a potential environmental endocrine disruptor and carcinogen. Overall, concentrations were lower than the four-quarter drinking water average of 3 µg/Lthe Maximum Contaminant Level set by the USEPA. However, three creek stations had four-quarter average concentrations greater than 3 µg/L, and virtually all samples exceeded the 0.1 µg/L standard set in Europe [1,2]. Statistically significant differences in concentrations were detected between the 27 sampling stations and areas of high concentrations were identified. However correlations between Atrazine concentrations and land-use and precipitation were not statistically significant. Further analysis with more detailed data should be conducted before any relationships are discarded.
Date: May 2000
Creator: Ochandio, Mario Roberto

Spatial and Temporal Patterns of Areal and Volumetric Phytoplankton Productivity of Lake Texoma

Description: Phytoplankton productivity of Lake Texoma was measured for one year from August 1999 to August 2000 for four stations, using the oxygen change method and laboratory incubation. Mean values of the photosynthetic parameters, PBmax and alphaB ranged from 4.86 to 46.39 mg O2.mg Chl-1.hr-1 for PBmax and 20.06 to 98.96 mg O2.mg Chl-1.E-1.m2 for alphaB. These values were in the range to be expected for a highly turbid, temperate reservoir. Estimated gross annual areal productivity ranged from 594 g C.m2.yr-1 (P.Q. = 1.2), at a station in the Washita River Zone to 753 g C.m2.yr-1 at a station in the Red River Zone, of the reservoir. Gross annual areal productivity at Station 17, in the Main Lake Zone, was 708 g C.m2.yr-1. Gross areal and volumetric productivity showed distinct seasonal variation with Photosynthetically Available Radiation (PAR) and temperature. Trophic status estimated on a station-by-station basis, using net productivity values derived from gross productivity and respiration estimates, was mesotrophic for all the stations, though one station approached eutrophy. Net productivity values ranged from 0.74 to 0.91 g C. m-2.d-1. An algal bioassay conducted at two stations in August 2000, revealed that phosphorus was most likely the nutrient limiting photosynthesis at both these stations, although the more turbid riverine station was primarily light-limited.
Date: August 2001
Creator: Baugher, Tessy

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 regression (OLS) and geographically weighted regression (GWR). The GWR model was utilized to ascertain the impact of environmental factors on WNV risk patterns without the confounding effects of spatial non-stationarity that exist between place and health. It identifies the important underlying environmental factors related to suitable mosquito habitat conditions to make meaningful and spatially explicit predictions. Our model represents a multi-criteria decision analysis approach to create disease risk maps under data sparse situations. The best fitting model with an adjusted R2 of 0.71 revealed a strong association between WNV infection risk and a subset of environmental risk factors including road density, stream density, and land surface temperature. This research also postulates that understanding the underlying place characteristics and population composition for the occurrence of WNV infection is important for mitigating future outbreaks. While many spatial and aspatial models have attempted to predict the risk of WNV transmission, efforts to link these factors within a GIS framework are limited. One of the major challenges for such integration is the high dimensionality and large volumes typically associated with such models and data. This research uses a spatially explicit, multivariate geovisualization framework to integrate an environmental model of mosquito habitat with human risk factors derived from socio-economic and demographic variables. Our results show that such an integrated approach facilitates the exploratory analysis of complex data and supports reasoning about the underlying spatial ...
Date: December 2015
Creator: Kala, Abhishek K.