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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)
Partner: UNT Libraries

City of Denton Municipal Solid Waste Characterization and Management Strategies

Description: Due to concern about diminishing landfill space, the City of Denton contracted a municipal solid waste characterization study in 1999 that would identify materials for diversion. This paper describes the results of 5 1-week waste sorting events, a scale-house analysis, a recycling participation study, a recycler profile and a similar city study. The results of the characterization studies suggest that at least 50% of each waste stream is recyclable or divertible though paper products accounted for no more than 45% by weight of any waste stream. Curbside recycling participation rate was 71% during the 6-week study period though the average weekly set-out rate was 37%. Recycling participation rates varied significantly by zip code and by home value categories but not by gender. Denton is fairly progressive in its waste management approach when compared to demographically similar cities on a 15-question assessment though recommendations for improvement have been identified.
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Date: May 2004
Creator: Brady, Patricia D.
Partner: UNT Libraries

Multiple Regression Equations to Estimate Mean Nutrient Concentrations in Streams of North Central Texas from Landsat Derived Land Use

Description: Nutrients are of critical concern in water quality assessment. The development of empirical models to estimate mean nutrient concentrations, based on satellite derived land use, could aid water resource managers. Models using land use acreages outperformed those using percentages, and discrete urban land uses were superior to lumped urban. Regressions of the combinations of two, three and four of the eight possible land use variables were investigated. Sensitivity analyses, with one stream deleted each series, identified robust combinations of variables at each level. Although uncertainty exists regarding the final regression coefficients, five of the six actual measured nitrate and total phosphorus mean concentrations were within the 95 percent confidence limits.
Date: May 1994
Creator: Kerr, Barry Douglas
Partner: UNT Libraries

Use of Automated Sampler to Characterize Urban Stormwater Runoff in Pecan Creek

Description: The purpose of this study was to use the Global Water Stormwater Sampler SS201 to characterize the urban runoff in Pecan Creek. Location of the samplers was influenced by land use and ease of installation. Determination of the constituents for analysis was modeled after those used in the NPDES permit for seven cities within the Dallas/Ft.Worth metroplex. Some metals, notably cadmium and arsenic, exceeded the U.S. EPA's MCL's. Statistical analysis revealed first flush samples to be significantly more concentrated than composite samples. Minimum discharge loadings were found to be significantly lower than maximum discharge loadings. Additionally there were significant differences of specific constituents between station locations and storm events.
Date: December 2000
Creator: Appel, Patrick L.
Partner: UNT Libraries

Assessment of the Efficacy of a Constructed Wetland to Reduce or Remove Wastewater Effluent Estrogenicity and Toxicity Using Biomarkers in Male Fathead Minnows (Pimephales Promelas Rafinesque, 1820)

Description: Vitellogenin in Pimephales promelas was used to assess estrogenicity of a local municipal effluent. Vitellogenin induction in male P. promelas increased in frequency and magnitude with increased exposure duration and was greater ("=0.05) than controls after 2 and 3 weeks of exposure. The level of vitellogenesis induced by effluent exposure was high compared to similar studies. A spring season evaluation followed. Biomarkers in P. promelas were used to assess the efficacy of a treatment wetland to remove toxicity and estrogenicity in final treated wastewater effluent. Comparisons were made with an effluent dominated stream and laboratory controls. Vitellogenin, GSIs (gonado-somatic indices), HSIs (hepato-somatic indices) and secondary sexual characteristics were biomarkers used in P. promelas models to assess aqueous estrogenicity. Biological indicators used to assess general fish health included hematocrit and condition factors. The estrogenic nature of the effluent was screened, concurrent with fish exposure, with GC/MS analysis for target estrogenic compounds including: 17-b estradiol, estrone, ethynylestradiol, Bisphenol A, nonylphenolic compounds, phthalates, and DDT. Plasma vitellogenin measured in P. promelas was significantly elevated (p < 0.0001) at the inflow site of the wetland and stream sites. GSIs for these exposures were less (a=0.001) at the wetland inflow site. At wetland sites closest to the inflow, secondary sexual charateristics, tubercle numbers and fat pad thickness, were less (a=0.0001). Hematocrit and condition factors were less (a=0.001) at sites closer to the wetland inflow. Seasonal variation was examined by repeating the effluent characterization in summer. Additionally, summer testing included exposure to an effluent dilution series. Fish condition heavily influenced interpretation of the results. Pre-acclimation exposure to spawning stresses may have altered many of the biological markers measured. Results are discussed relative to fish health and pre-exposure environment. Toxicity assessed with P. promelas biomarkers was compared with Ceriodaphnia dubia and Vibrio fischeri toxicty tests on this ...
Date: December 2000
Creator: Hemming, Jon M.
Partner: UNT Libraries

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

Description: This study explored the application of compost onto a small loblolly pine tree forest in northeast Texas. Its purpose was to determine if the application of various amounts of compost would provide for accelerated rates of growth for the trees. Soil parameters were also monitored. A total of 270 trees were planted and studied in a northeast Texas forest ecosystem. Compost rates of 5, 25, and 50 tons per acre with either soil or compost backfill were utilized and compared to a control without compost. Nonparametric and parametric ANOVA and Chi-Square tests were utilized. The results indicated that greater application rates retained greater moisture and higher pH levels in the soil. Compost applications also yielded a greater survival rate as well as larger tree height and diameter when compared to the control. The 25 ton/acre application backfilled in native soil achieved the greatest average in height and diameter when compared to the averages for the control plot. Greater growth differences for the 25S application can be attributed to additional nutrients coupled with a stable pH consistent with native soil acidity.
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Date: December 1999
Creator: Stuckey, Harold Troy
Partner: UNT Libraries

The Effects of Pulp and Paper Mill Wastewaters on Phytoplankton Primary Productivity in the Red River, Louisiana

Description: Responses of phytoplankton productivity in the Red River to unbleached pulp and paper mill wastewaters were monitored using in situ ^14C incubation. Preoperational studies, conducted prior to the discharge of mill wastewaters varied seasonally, but revealed similar productivity trends when compared with postoperational studies, conducted after mill discharges began entering the Red River. Carbon assimilation rates measured downstream of mill discharge were generally greater than upstream levels in both preoperational and postoperational studies. Selected physical, chemical, and biological parameters varied seasonally, but showed similar upstream-downstream values and preoperational-postoperational values. Total Organic Carbon (TOC), Dissolved Organic Carbon (DOC), and Biochemical Oxygen Demand (BOD_5) were positively correlated with postoperational productivity rates. Apparent color was negatively correlated with productivity rates.
Date: May 1984
Creator: Holler, Jeffrey Dee
Partner: UNT Libraries

Thresholds in avian communities at multiple scales: Relationships between birds, forests, habitats, and landscapes in the Ray Roberts greenbelt, Denton

Description: Environmental management agencies make efforts to reduce pollution loading in streams and rivers by promoting vegetated buffer zones between human activity and water. Most of these efforts do not mesh water quality-based buffer zone width requirements with conservation and wildlife values, specifically, the use of these riparian forest corridors for wildlife dispersal between habitats in highly fragmented landscapes. Forest interior birds are of the most concern to management in riparian forests due to their population declines across much of their breeding range. This dissertation investigates the role that landscape-level and habitat-level factors play on the presence of breeding birds in riparian forests, particularly the landscape and habitat factors that are influenced by human-caused fragmentation. This study describes research at the Ray Roberts Greenbelt, Denton, Texas, that explores the relationships between the landscape and forest habitats of the Greenbelt with its breeding bird community. The major findings of this study are that bird communities in the corridor forests are associated with a greater array of factors than are bird communities in patches, suggesting that the birds of patch forests are somewhat insulated from landscape-scale effects. Also, habitat values can be maintained in corridors, but there does not seem to be a significant relationship between the bird communities and the habitat. Forest factors are the primary influences (as inferred from the number of associations and the relative strength of these associations) on the bird communities of the Ray Roberts Greenbelt. Thresholds of richness or abundance in the amount of forest as compared with the forest interior bird community suggest that patches are better than corridors to support this community, and that the more interior forest available, the better for forest interior birds. The suggested minimum amount of forest derived from these thresholds is 35% of the amount of forest within 1 kilometer ...
Date: December 2000
Creator: Barry, Dwight
Partner: UNT Libraries

Effects of Suspended Solids on Bioavailability of Chemicals to Daphnia magna and Pimephales promelas

Description: Three suspended solids types containing a range of physicochemical characteristics were used to determine the effect of suspended solids on the bioavailability of acenaphthene, 1,2,4,5-tetrachlorobenzene, zinc, and chlordane to Daphnia magna and Pimephales promelas. Generally, the bioavailability of zinc and chlordane decreased due to interactions with all suspended solids types while bioavailability of acenaphthene and 1,2,4,5-tetrachlorobenzene were not clearly reduced. Partition coefficients and slope of dose-response curves related chemical characteristics and organism sensitivity, respectively, to experimentally determined results. It is believed that the biologically available form of these chemicals to Daphnia magna and Pimephales promelas resides in the aqueous phase.
Date: December 1984
Creator: Hall, W. Scott (Warren Scott)
Partner: UNT Libraries

Effects of Sertraline Exposure on Fathead Minnow (Pimephales promelas) Steroidogenesis

Description: Sertraline is a selective serotonin reuptake inhibitor (SSRI) that is widely used for the treatment of depression and anxiety. Due to the abundant therapeutic use of sertraline, low levels have been detected in municipal wastewater effluents suggesting that aquatic organisms may be exposed. The purpose of this study was to evaluate the steroidogenic effects of sertraline on larval (FHM) and adult female fathead minnows (FFHM), Pimephales promelas. Larval FHM were exposed to 0.1, 1, and 10 µg/L sertraline for 28 days and analyzed via RT-qPCR for differential expression of 11β-Hydroxysteroid dehydrogenase (11β-HSD), 20β-Hydroxysteroid dehydrogenase (20β-HSD), aromatase (CYP19), and nuclear thyroid receptor alpha (TRα). FFHM were exposed to 3 or 10 µg/L sertraline for 7 days with the brain and ovary excised at exposure termination. Juvenile FHM exposed to 0.1 μg/L sertraline had a significant upregulation of both 20β-HSD and TRα. FFHM exposed to 10 µg/L sertraline had a significant upregulation of 11β-HSD expression in brain tissue, while no steroidogenic changes were observed in the FFHM ovary. Similarly, in FFHM brain tissue, CYP19 and 20β-HSD expression levels were significantly higher in fish exposed to 10µg/L sertraline compared to control. The significance of these findings with respect to survival, growth and reproduction are currently unknown, but represent future research needs.
Date: December 2014
Creator: Carty, Dennis R.
Partner: UNT Libraries

Atmospheric Visibility Assessment for Urban Areas Using Photographic Slides and Optical Densitometry

Description: The factors involved in calculating Standard Visual Range (SVR) are discussed, and a comparison is made between the visibility reported by airport observers and the photographic slide/ optical densitometer method of calculating SVR. Using slides of Houston, Texas, from the fall and winter of 1988-89, it was found that the altitude at which the contrast measurements are made significantly affects the SVR. Also an index for predicting high and low humidity was developed using the blue/red ratio of the log exposure of the sky, and sun/shade target condition.
Date: May 1992
Creator: Jacob, Mary Katherine
Partner: UNT Libraries

Desorption/Diffusion of Benzene After Simulated Ground Water Remediation

Description: A study was undertaken to examine the desorption/ iffusion of benzene after simulated ground water remediation in aquifer material of differing carbon content using column experiments and comparing the results to batch experiments and adsorption empirical relationships. It was hypothesized that the organic carbon of the aquifer material will affect desorption/diffusion. Results from the column experiment indicated no significant difference in the increase benzene concentrations after remediation between aquifer materials of differing carbon content, however, a significant increase in benzene concentration was observed for all aquifer material. Fair agreement of retardation factors was observed between empirical relationships and batch and column experiments. However, the desorption phase of the batch experiment showed hysteresis and seemed to differ from the column experiment.
Date: December 1989
Creator: Bennett, Kathryn C. (Kathryn Condreay)
Partner: UNT Libraries