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  Partner: UNT Libraries
 Decade: 2010-2019
 Degree Discipline: Environmental Science
 Degree Level: Master's
 Collection: UNT Theses and Dissertations
Adaptive Advantages of Carotenoid Pigments in Alpine and Subalpine Copepod Responses to Polycyclic Aromatic Hydrocarbon Induced Phototoxicity

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

Date: May 2010
Creator: Kovach, Matthew James
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 ...
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Bioconcentration of Triclosan, Methyl-Triclosan, and Triclocarban in the Plants and Sediments of a Constructed Wetland

Bioconcentration of Triclosan, Methyl-Triclosan, and Triclocarban in the Plants and Sediments of a Constructed Wetland

Date: August 2011
Creator: Zarate, Frederick M., Jr.
Description: Triclosan and triclocarban are antimicrobial compounds added to a variety of consumer products that are commonly detected in waste water effluent. The focus of this study was to determine whether the bioconcentration of these compounds in wetland plants and sediments exhibited species specific and site specific differences by collecting field samples from a constructed wetland in Denton, Texas. The study showed that species-specific differences in bioconcentration exist for triclosan and triclocarban. Site-specific differences in bioconcentration were observed for triclosan and triclocarban in roots tissues and sediments. These results suggest that species selection is important for optimizing the removal of triclosan and triclocarban in constructed wetlands and raises concerns about the long term exposure of wetland ecosystems to these compounds.
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A Characterization Of Jackson Blue Spring, Jackson County, Florida

A Characterization Of Jackson Blue Spring, Jackson County, Florida

Date: December 2011
Creator: Reiser, Cora
Description: Jackson Blue is a first magnitude spring in the karst terrane of northeast Florida. Previous studies have identified inorganic fertilizer as the source of high nitrate levels in the spring. Agricultural land use and karst vulnerability make Jackson Blue a good model for conservation concerns. This work offers an aggregation of studies relating to the springshed, providing a valuable tool for planning and conservation efforts in the region. An analysis of nitrate levels and other water quality parameters within the springshed did not reveal significantly different values between agricultural and forested land use areas. Confounding factors include: high transmissivity in the aquifer, interspersed land use parcels, and fertilizer application in forested areas due to commercial pine stand activity.
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Comparative Phyto-uptake Across Distribution Coefficients of Pharmaceutical Compounds and Aquatic Macrophytes: Carbamazepine and Amiodarone Uptake in Lemna Spp

Comparative Phyto-uptake Across Distribution Coefficients of Pharmaceutical Compounds and Aquatic Macrophytes: Carbamazepine and Amiodarone Uptake in Lemna Spp

Date: August 2013
Creator: Woodard, Jennifer Kristin
Description: Few studies have been conducted on the effectiveness of phytoremediation of pharmaceutical compounds, although the persistent and non-acutely toxic nature of many of these compounds in today's water bodies may yield an ideal application for this practice. To quantify the potential effectiveness of plant uptake, kinetic and proportional bioconcentration factors (BCFk, and BCFp, respectively) in nanograms (ng) carbamazepine and amiodarone per gram (g) wet weight plant tissue for Lemna spp. were determined utilizing a 14-day continuous flow-through study. Samples were analyzed using isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) running in positive ion mode. Kinetic BCF was estimated at 0.538, while proportional BCF was estimated at 0.485. Kinetic BCF for the amiodarone study was estimated at 23.033, whereas proportional BCF was estimated at 41.340. Possible contamination of the C18 column and peristaltic pump failure may have impacted uptake results. In light of variability and current lack of research in the field, this work should be considered exploratory rather than conclusive.
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Ecological Significance and Underlying Mechanisms of Body Size Differentiation in White-tailed Deer

Ecological Significance and Underlying Mechanisms of Body Size Differentiation in White-tailed Deer

Date: May 2012
Creator: Barr, Brannon
Description: Body size varies according to nutritional availability, which is of ecological and evolutionary relevance. The purpose of this study is to test the hypothesis that differences in adult body size are realized by increasing juvenile growth rate for white-tailed deer (Odocoileus virginianus). Harvest records are used to construct growth rate estimates by empirical nonlinear curve fitting. Results are compared to those of previous models that include additional parameters. The rate of growth increases during the study period. Models that estimate multiple parameters may not work with harvest data in which estimates of these parameters are prone to error, which renders estimates from complex models too variable to detect inter-annual changes in growth rate that this simpler model captures
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Effects of Layer Double Hydroxide Nanoclays on the Toxicity of Copper to Daphnia Magna

Effects of Layer Double Hydroxide Nanoclays on the Toxicity of Copper to Daphnia Magna

Date: May 2012
Creator: Blake, Deanne Renee
Description: Nanoparticles may affect secondary pollutants such as copper. Layer Double Hydroxides (LDH) are synthetically produced nanoparticles that adsorb copper via cation exchange. Pretreatment of copper test solutions with LDH nanoparticles followed by filtration removal of LDH nanoparticles demonstrated the smallest LDH aggregates removed the most copper toxicity. This was due to increased surface area for cation exchange relative to larger particle aggregates. Co-exposure tests of copper chloride and clay were run to determine if smaller clay particles increased copper uptake by D. magna. Coexposure treatments had lower LC50 values compared to the filtration tests, likely as a result of additive toxicity. LDH nanoclays do reduce copper toxicity in Daphnia magna and may serve as a remediation tool.
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Effects of Suspended Multi-Walled Carbon Nanotubes on Daphnid Growth and Reproduction

Effects of Suspended Multi-Walled Carbon Nanotubes on Daphnid Growth and Reproduction

Date: May 2010
Creator: Alloy, Matthew Michael
Description: Multi-walled carbon nanotube aggregates can be suspended in the aqueous phase by natural organic matter. These aggregates are ingested by filter feeding zooplankton. Ingested aggregates result in decreased growth and decreased reproduction. These effects may be caused by reduction in energy input from normal feeding behavior. pH alters natural organic matter structure through changes in electrostatic repulsion. Altered natural organic matter structure changes multi-walled carbon nanotube aggregate size. This size variation with variation in pH is significant, but not large enough a change in size to alter toxicity, as the aggregate size range remains well within the particle size selection of the organisms.
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Hepatotoxicity of Mercury to Fish

Hepatotoxicity of Mercury to Fish

Date: August 2010
Creator: Barst, Benjamin Daniel
Description: Tissue samples from spotted gar (Lepisosteus oculatus) and largemouth bass (Micropterus salmoides) were collected from Caddo Lake. Gar and bass livers were subjected to histological investigation and color analysis. Liver color (as abs at 400 nm) was significantly correlated with total mercury in the liver (r2 = 0.57, p = 0.02) and muscle (r2 = 0.58, p = 0.01) of gar. Evidence of liver damage as lipofuscin and discoloration was found in both species but only correlated with liver mercury concentration in spotted gar. Inorganic mercury was the predominant form in gar livers. In order to determine the role of mercury speciation in fish liver damage, a laboratory feeding study was employed. Zebrafish (Danio rerio) were fed either a control (0.12 ± 0.002 µg Hg.g-1 dry wt), inorganic mercury (5.03 ± 0.309 µg Hg.g-1 dry wt), or methylmercury (4.11 ± 0.146 µg Hg.g-1 dry wt) diet. After 78 days of feeding, total mercury was highest in the carcass of zebrafish fed methylmercury (12.49 ± 0.369 µg Hg.g-1 dry wt), intermediate in those fed inorganic mercury (1.09 ± 0.117 µg Hg.g-1 dry wt), and lowest in fish fed the control diet (0.48 ± 0.038 µg Hg.g-1 dry wt). Total mercury was ...
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Integrating Selective Herbicide and Native Plant Restoration to Control Alternanthera philoxeroides (Alligator Weed)

Integrating Selective Herbicide and Native Plant Restoration to Control Alternanthera philoxeroides (Alligator Weed)

Date: December 2011
Creator: Adams, Justin
Description: Exotic invasive aquatic weeds such as alligator weed (Alternanthera philoxeroides) threaten native ecosystems by interfering with native plant communities, disrupting hydrology, and diminishing water quality. Development of new tools to combat invaders is important for the well being of these sensitive areas. Integrated pest management offers managers an approach that combines multiple control methods for better control than any one method used exclusively. In a greenhouse and field study, we tested the effects of selective herbicide application frequency, native competitor plant introduction, and their integration on alligator weed. In the greenhouse study, alligator weed shoot, root, and total biomass were reduced with one herbicide application, and further reduced with two. Alligator weed cumulative stem length and shoot/root ratio was only reduced after two applications. In the greenhouse, introduction of competitors did not affect alligator weed biomass, but did affect shoot/root ratio. The interaction of competitor introduction and herbicide did not significantly influence alligator weed growth in the greenhouse study. In the field, alligator weed cover was reduced after one herbicide application, but not significantly more after a second. Introduction of competitor species had no effect on alligator weed cover, nor did the interaction of competitor species and herbicide application. This ...
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Modeling the Relationship Between Golden Algae Blooms in Lake Texoma, Usa, Versus Nearby Land Use and Other Physical Variables

Modeling the Relationship Between Golden Algae Blooms in Lake Texoma, Usa, Versus Nearby Land Use and Other Physical Variables

Date: August 2012
Creator: Ware, Trudy M.
Description: Pyrmnesium parvum, commonly known as golden algae, is an algal species that under certain circumstances releases toxins which can lead to fish kills and the death of other economically and ecologically important organisms. One of the major objectives of the study was to investigate whether a relationship exists between land use and Prymnesium parvum abundance in littoral sites of Lake Texoma, USA. Another objective was to investigate whether a relationship exists between other physical variables and counts of P. parvum. Lastly, developing a valid model that predicts P. parvum abundance was an objective of the study. Through stepwise regression, a small but highly significant amount of the variation in P. parvum counts was found to be explained by wetlands, soil erodibility and lake elevation. The developed model provides insight for potential golden algae management plans, such as maintaining wetlands and teaching land owners the relationship between soil erosivity and golden algae blooms.
Contributing Partner: UNT Libraries
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