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Evaluation of a Constructed Wetland to Reduce Toxicity from Diazinon at the Pecan Creek Wastewater Treatment Plant, Denton, TX

Description: The City of Denton Pecan Creek Wastewater Treatment Facility has periodically failed effluent toxicity testing. A Toxicity Identification Evaluation has determined that Diazinon in the effluent is contributing to the observed toxicity. Chlorpyrifos is also implicated as a factor. The City of Denton constructed a half acre experimental wetland to remove Diazinon related toxicity. Results from spiking and microcosm experiments indicate that the wetland can reduce the Diazinon.
Date: May 1996
Creator: Baerenklau, Amy L. (Amy Lyn)
Partner: UNT Libraries
open access

A Comparison of Predicted and Actual Trophic Status of Lake Ray Roberts, Texas Based on Chlorophyll A

Description: Two years before impoundment, the trophic status of Lake Ray Roberts was predicted by applying the total phosphorus input into the Organization for Economic Cooperation and Development (OECD) eutrophication model. Predicted mean summer epilimnetic (MSE) chlorophyll a of Elm Fork arm, Isle duBois arm and Main Body were in the eutrophic category of the OECD model. Observed MSE chlorophyll a two years after impoundment of Elm Fork arm, Isle duBois and Main Body had not reached their predicted mean… more
Date: May 1999
Creator: Lytle, Lili Lisa
Partner: UNT Libraries
open access

Development and Application of an Assessment Protocol for Watershed Based Biomonitoring

Description: With numerous bioassessment methodologies available, a regional protocol needs to be developed to ensure that results are comparable. A regional assessment protocol was developed that includes collecting five benthic macroinvertebrate samples, identifying organisms to genus, and calculating the following metrics: Number of Taxa, Total Number of Individuals, Simpson's Diversity Index, Shannon's Diversity Index, Percent Contribution of Dominant Taxa, Hilsenhoffs Biotic Index, and Percent Contribu… more
Date: May 1998
Creator: Schwartz, Joseph Howard
Partner: UNT Libraries
open access

Light Spectra Distributions in Temperate Conifer-Forest Canopy Gaps, Oregon and in Tropical Cloud-Forest Canopy, Venezuela

Description: Light spectra distributions were measured in two different montane forests: temperate and tropical. Spectral light measurements were made in different sized canopy gaps in the conifer forest at H. J. Andrews Experimental Forest in Oregon, USA. Researchers at Oregon State University created these gaps of 20 m, 30 m, and 50 m in diameter. In the tropical cloud forest, spectral light measurements were made in two plots that were permanently established at La Mucuy Parque Nacional in Venezuela, in … more
Date: December 1997
Creator: Monteleone, Susan Elaine
Partner: UNT Libraries
open access

Primary Productivity and Nutrient Relationships in Garza-Little Elm Reservoir

Description: A large, multi-basin, reservoir (Garza-Little Elm Reservoir) in north central Texas was studied to determine the relative effects of various parameters on primary productivity. The basins were impounded several years apart,thus allowing the influence of age on water chemistry and biota to be considered. Another principal influence on water quality was secondary sewage effluent that entered one basin from a nearby source.
Date: May 1973
Creator: Smith, Jerry Allen
Partner: UNT Libraries
open access

Assessment of Changes in Aquatic Macrophyte Occurrence Following Introduction of Triploid Grass Carp in a North Texas Reservoir

Description: The objectives of this project were to measure changes in frequency of occurrence of submerged macrophytes over the first two growing seasons following stocking with triploid grass carp at two fish per acre and to measure differences in macrophyte biomass between areas excluded from herbivory and adjacent control sites after 16 months following establishment of exclosures. The project also seeks to measure concentrations of fluridone following the herbicide treatment, and to compare two methods… more
Date: August 1997
Creator: Bickel, Ken (Kenneth E.)
Partner: UNT Libraries
open access

Remote Sensing of Landscape-Level Ecological Attributes at Ray Roberts Lake in North Texas

Description: Biological diversity is a key component in assessing ecosystem health. Alteration, degradation and loss of habitat due to human influence is currently the primary stressor resulting in decreases in diversity. Reliable assessment of large areas in terms of biological integrity are needed for conservation and preservation efforts. Remotely sensed data provide an integrated view of reflected electromagnetic energy over large areas of the earth. These energy patterns provide unique spectral signatu… more
Date: December 1997
Creator: Smith, David P. (David Paul), 1956-
Partner: UNT Libraries
open access

Genetic Variation in a Population of the Plains Woodrat Neotoma micropus

Description: Neotoma micropus from Jack County, Texas, were studied over a 9-month period. Loci from blood and saliva were used to determine genetic variation within the population. Deviations from Hardy-Weinberg equilibrium were found at one locus. The average temporal F over all seven loci was 0.040. Genetic structuring was subtle, fluctuated on a seasonal basis, and was due to differential migration or predation on genotypes. Heterozygotes tended to move more than homozygotes, and a greater proportion of… more
Date: August 1988
Creator: Stewart, John E. B. (John Edward Bakos)
Partner: UNT Libraries
open access

Estimated Extent and Fate of Chlorinated Solvent Contamination in the Soil of the Naval Air Station, Dallas, Texas

Description: This thesis estimates the spatial extent of chlorinated solvent contamination of the soil at the Naval Air Station, Dallas, then estimates the fate and transport of these contaminants, over time, using the Soil Transport and Fate database and the Vadose-Zone Interactive Processes (VIP) modeling software. Geostatistical analysis identifies two areas with serious chlorinated solvent contamination. Fate and transport modeling estimates that this contamination will degrade and disperse from the soi… more
Date: August 1998
Creator: Trescott, Jill V. (Jill Virginia)
Partner: UNT Libraries
open access

A Vegetative Analysis of and Distribution of the Grasses of North Central Texas

Description: Accurate identification is fundamental in any study of grasses by farmers, ranchers, range specialists, ecologists, or students interested in the changes taking place in the grass habitat. Frequently it is convenient, and sometimes it is necessary, to identify the grasses by their vegetative characters. Some are readily recognized at a glance by their habitat and certain characters well known to the experienced observer. In other cases, identification is more difficult; and, perhaps with a few,… more
Date: August 1970
Creator: Smith, David Lawrence, 1932-
Partner: UNT Libraries
open access

Landscape Ecological Characteristics of Habitat of the Red-cockaded Woodpecker

Description: Geographic information systems (GIS) technology was used to analyze factors influencing habitat use by an endangered species, the red-cockaded woodpecker. The study area was the western part of the Raven Ranger District of the Sam Houston National Forest, Texas. The factors considered included both structural characteristics and spatial relationships among stands of trees in the habitat.
Date: December 1993
Creator: Thomlinson, John Richard
Partner: UNT Libraries
open access

The Response of Aquatic Insect Communities and Caged In situ Asiatic Clams (Corbicula fluminea) to Dechlorinated Municipal Effluent in the Trinity River in North Texas

Description: Dischargers to the Trinity River in North Texas were required to dechlorinate their effluents in 1990-91. Field surveys were conducted above and below an outfall to determine the response of resident immature insects and caged in situ juvenile Asiatic clams to chlorinated and dechlorinated effluent. Within six months after dechlorination began, insect community composition and C. fluminea survival significantly improved at stations below the outfall. Significantly lower clam growth within one m… more
Date: December 1994
Creator: Spon, Sandra T. (Sandra Teresa)
Partner: UNT Libraries
open access

The Use of Similarity Indicies to Assess the Spatial Differences of the Phytoplankton Communities in Lake Ray Roberts, Texas

Description: A study of the phytoplankton communities of Lake Ray Roberts was conducted at three sampling sites on two sampling dates during the summer of 1995, assessing both community structure and chlorophyll a concentrations. Eight similarity indices were then used to characterize and compare the communities of these sites. Both community similarity and chlorophyll a concentrations were evaluated using a minimum detectable difference equation to determine the amount of change that must occur in these pa… more
Date: August 1996
Creator: Banks, Kenneth E. (Kenneth Edward)
Partner: UNT Libraries
open access

The Effects of Organic Surface Amendments on Soil Nutrients and Initial Tree Establishment

Description: This study examined the effects of replicating woodland soil surface horizonation on the nutrient status of underlying soils and the initial establishment and growth of trees. A total of 283 container grown trees were planted in a bufferzone around a future landfill site. Control amendments consisted of an 8 cm layer (0.5 m3) of wood chips applied in a circular area of 4.6 m2 around the trees' planting pit. For the treatment, a 2.5 cm layer of composted biosolids (0.15 m3 or 80 Mg/ha) was appli… more
Date: May 1999
Creator: Thuesen, Kevin (Kevin Andrew)
Partner: UNT Libraries
open access

Biological and Toxicological Responses Resulting from Dechlorination of a Major Municipal Wastewater Treatment Plant Discharge to the Trinity River

Description: Federal regulations such as the Clean Water Act (P.L. 92-500), and its amendments, direct the Environment Protection Agency (EPA) to implement programs to control the releases of conventional pollutants and toxics into the waterways of the United States. The EPA began requiring treatment plants to conduct toxicity tests (biomonitoring) of their effluent discharges. To control toxicity caused by chlorination of wastewater discharges, the EPA also began requiring some treatment facilities to dech… more
Date: August 1995
Creator: Guinn, Richard J. (Richard Joe)
Partner: UNT Libraries
open access

Sanitary Aspects of Milk and Dairy Products Dispensed in Sherman, Texas

Description: The aim of this investigation is to determine whether there is a correlation between the sanitary condition of milk and dairy products dispensed in Sherman, Texas, and the plate counts, the morphology, and the Gram stain reaction of the organisms in predominant colonies from these.
Date: 1948
Creator: Bryant, J. Forrest
Partner: UNT Libraries
open access

The Age and Rate of Growth of the Black Crappie, Pomoxis Nigro-Maculatus (Le Sueur), and the White Crappie, Pomoxis Annularis Rafinesque, in the Koon Kreek Klub Lakes, Texas

Description: This study is another phase of the overall research program designed to furnish basic information for the management of East Texas lakes and has as its specific purpose the determination of the age and growth characteristics of two valuable species on these waters. The species to be considered are the black crappie, Pomoxis nigro-maculatus (Le Sueur) and the white crappie, Pomoxis annularis Rafinesque. Both species are highly regarded as food fish and have for many years offered recreational ou… more
Date: 1948
Creator: Elliott, James M.
Partner: UNT Libraries
open access

The Taxonomic Significance of the Foliar Epidermal Hairs of Several Families of Dicotyledons

Description: The present investigation deals with the study of non-glandular epidermal hairs from the leaves of two hundred representative dicotyledons of forty-eight families in the Central North Texas area. Special attention has been given to the Compositae and Leguminosae in an effort to find a possible correlation between epidermal hair morphology and the taxonomic position of the plants concerned.
Date: 1945
Creator: McCarty, Faye A.
Partner: UNT Libraries
open access

Seasonal Variations in Microflora of Four Denton County, Texas, Clay Soils

Description: This investigation has for its aim the confirmation of the correlation between soil moisture and the microflora of soils, and a lesser relation between the soil temperature and the microflora. The soils used in this study are typical clay soils of Denton County, Texas. The samples were taken from virgin pasture lands and analyses made monthly or semimonthly. The wide seasonal variation of temperature and rainfall afford a good opportunity for this study.
Date: 1941
Creator: Manire, Philip
Partner: UNT Libraries
open access

Food Habit Analysis of the Two Species of Texas Crappie

Description: This study is based upon information taken from stomach analysis of 302 black crappie and 561 white crappie; the following data will be presented: 1. Food of adults and fingerlings; 2. Diet variation in relation to food availability; 3. Seasonal variation of feeding habits; 4. Diet variation in relation to size of crappie. Collections were made from ten lakes located in North, East, Central, and South Texas.
Date: 1941
Creator: Mitchell Glenn C.
Partner: UNT Libraries
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