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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

Factors Affecting Landowner Participation in the Candidate Conservation Agreements with Assurances Program

Womack, Kendra 01 December 2008 (has links)
The United States’ Endangered Species Act of 1973 has been recognized as one of the most powerful laws enacted to protect endangered species in the world. Its protections for animal species extends onto private land, which has in some cases created conflict between the law, its enforcers, and private landowners. The Candidate Conservation Agreements with Assurances (CCAA) program was developed in 1999 to provide a regulatory incentive for private landowners to engage in pro-active conservation for sensitive species to preclude the need for listing under the ESA in the future. Since 1999, however, there have only been 17 CCAAs signed, a relatively small number given the thousands of species eligible for the program across the U.S. This research used semi-structured qualitative interviews with individuals from four participant categories to expand our understanding of why landowners might choose to participate in the CCAA program, and of what benefits and barriers they perceive in program implementation. Participant categories included 1) private landowners enrolled in a CCAA; 2) private landowners that are eligible to enroll, but declined to participate; 3) State fish and wildlife agency employees who have participated in CCAAs across the county; and 4) Fish and Wildlife Service employees responsible for CCAA program implementation. Twenty-six interviews were completed during this research project. Results suggest that program implementation is affected by a multitude of factors; no exclusive drivers were identified. However, the variety of factors that were identified are assessed and management and policy recommendations are made. Hopefully these results and recommendations can potentially affect program policy to increase participation and the potential of the CCAA program as an effective tool for conservation on private lands in the United States.
242

Effects of Antibiotic Mixtures across Marine Intertidal Trophic Levels: Examining Environmentally-Relevant Contaminant Concentrations

Teixeira, Jaclyn Rebecca 08 November 2016 (has links)
Approximately 48% of Americans use prescription drugs within each 30-day period, and there are signs this trend is increasing. Although many studies track pharmaceuticals’ fates in contaminating waterways, only fairly recent efforts have examined the potential impacts of these drugs on non-target organisms. The antibiotics sulfamethoxazole and trimethoprim, often prescribed together to treat bacterial infections, have been detected worldwide in marine and estuarine environments at concentrations up to 700-800 ng/L each. Toxic effects of these drugs have been identified in freshwater organisms, with synergistic effects observed in short-term studies of mixtures of the two; however, little research has examined possible sub-lethal and longer-term effects of antibiotics in environmentally-relevant mixture concentrations on marine organisms. I examined the long-term effects of mixtures of these two antibiotics in species of a marine system: marine microalgal species, and marine mussels, to determine whether the levels currently present in waterways affect organism health and reproduction. Microalgal species may be among the most sensitive organisms to pharmaceutical contaminants based on ecotoxicity research. I exposed three species of marine microalgae (Isochrysis galbana, Chaetoceros neogracile, and Nannochloropsis oculata) to environmentally-relevant mixtures of sulfamethoxazole and trimethoprim and examined their three-week growth rates. I found that for each species, the antibiotic treatments significantly suppressed algal growth. Specifically, I found that sulfamethoxazole was a driving factor in suppression of C. neogracile and I. galbana growth, while N. oculata responded more sensitively to a broader range of treatment mixture levels, which also included trimethoprim-only treatment groups and mixtures. These results on marine microalgae address critical data gaps, and identify the impacts of pharmaceuticals on marine primary producers, which could have direct ecosystem implications to higher trophic levels. Antibiotic pharmaceuticals can also affect marine mussel health, based on previous study of sub-cellular endpoints. I hypothesized that the important benthic foundational species, the Mytilus californianus mussel, would be significantly impacted by long-term 12-week exposure to environmentally-relevant concentrations and mixtures of sulfamethoxazole and trimethoprim. Specifically, I measured growth rate, feeding rate, condition index, and gonando-somatic index as indicators of whole-organism and reproductive health. Sulfamethoxazole concentrations, in particular, and trimethoprim to a lesser extent, suppressed mussel growth and significantly affected condition index and gonandosomatic index over time. The results of this study offer an understanding of how an intertidal system responds to chronic presence of antibiotic mixtures in the water, and a more complete picture of the environmental consequences of pharmaceutical contaminants released into marine ecosystems at ever-growing rates.
243

Application of Satellite Data to Model Storm Runoff Into Rosamond Dry Lake

Oli, Mridul 01 October 2014 (has links) (PDF)
Antelope Valley is situated in Southern California and is bounded by the Tehachapi and the San Gabriel Mountains. It stretches over 2,200 mi2 and encompasses Rosamond Dry Lake and the 1,200 mi2 watershed draining into it. The cities of Lancaster and Palmdale are the two major urban centers that lie in the watershed draining into Rosamond Dry Lake. The lake lies within the vicinity of the Edwards Air Force Base and provides an important site for aviation research and test operations in addition to ecosystem services. Hence, it is necessary to balance the need to remove water from the lake to support Edwards Air Force Base’s aircraft missions and the need to inundate the lake to protect the its surface and the ecosystem it supports. In this study, satellite-based elevation, state of the science land cover and soil data are used to create a model that predicts storm runoff volume into Rosamond Dry Lake. Geographical Information Systems software is used delineate and divide the watershed into 98 sub-basins. Each sub-basin is assigned a land cover type, percent impervious area, and hydrologic soil type to calculate the Natural Resource Conservation Service curve number. The model also incorporates two detention basins to represent existing flood control structures in Lancaster and Palmdale. Runoff in each subbasin is estimated using the Natural Resource Conservation Service Curve Number method and accumulated into the channels. In a hydraulic modeling software developed by the Army Corps of Engineers, the modeling system is applied to calculate the total storm runoff volume into Rosamond Dry Lake for ten historical storm events as well as a 100-year event. Due to the lack of stream gauge data, a technique that couples Landsat 7 satellite images of Rosamond Lake with LIDAR elevation data to estimate observed runoff volume is developed to evaluate model performance. In comparison to these estimates, the model overestimates runoff volume by approximately 7%. However, there are considerable biases for two storm events that are caused by the effects of evaporation, wind and snow on the lake’s water and various deficiencies in the model. The impacts of past and future urbanization on the runoff volume into the lake are examined by modifying the curve number in sub-basins representative of the urban centers. For a 100-year, 24-hour, precipitation event, urbanization results in increased runoff at both the sub-basin and watershed levels. Additional simulations indicate that measures such as building detention basins and repurposing unused or undeveloped areas within an otherwise developed area (infill) can mitigate increased runoff due to urbanization. Overall, the model proves to be an effective tool for predicting runoff into Rosamond Dry Lake. It can also be used to study the rainfall-runoff processes in the lake. The ability to predict water volumes in the lake will allow engineers and planners to establish a balance between the Air Force Base’s aircraft missions and the lake’s ecological function. Lastly, the techniques used to develop the model can be used to develop similar models for other watersheds. iii
244

Investigation of Non-Lethal Electric Shock on American Crows as a Predator Aversion Treatment for Reducing Depredation on California Least Tern Eggs

Velasco, Vanessa Nicole 01 July 2015 (has links) (PDF)
The response of American crows (Corvus brachyrhynchos) to electrified eggs at the Venice Beach California least tern nesting colony was monitored throughout the 2014 season. Game cameras were deployed beside the artificial nests to record crow behavior towards the electrified eggs. Conditioned crows were defined as crows that were present within <15 feet but >1 foot of the electrified eggs and unconditioned crows were considered crows that were present within 1 foot of the eggs. The number of conditioned crows observed in the video clips significantly differed from a homogenous distribution using a chi-square test (p<0.001). The first 5 weeks of the experiment experienced a larger number of unconditioned crows than the remaining weeks of the experiment. A modified approach to the Lincoln index was also used to estimate population flux of crows at the Venice Beach colony. The nesting California least terns at Venice Beach successfully produced fledges when this predator aversion experiment was deployed, after 5 years of no reproductive success and the 2014 fledging per pair ratio was the second highest ratio recorded in 2013 and 2014. Further multi-year research is needed to clarify the efficacy of this management intervention as there may be associated confounding variables.
245

Assessing the distribution of environmental stewardship organizations and their relationship to the demographics of Los Angeles County

Golly, Krystle M. 01 July 2017 (has links) (PDF)
An equal distribution of environmental stewardship organizations across the urban landscape provides an environment that facilitates community empowerment. The systemic issues found in Los Angeles County play an important role in the social development of the area. Through the utilization of modern technology and geographical mapping software, spatial distribution of environmental stewardship organizations provided an understanding of social conditions within Los Angeles County. Environmental stewardship organizations provide the capability for communities to be more engaged in helping to eliminate environmental injustice. The comparison of minority populations at the census tract-level emphasizes the importance of connecting environmental stewardship organizations with their target community at a static level of measurement. The assistance of the geographical mapping software provided the capability of conducting spatial autocorrelation, drawing the conclusion that environmental stewardship organizations are not equally distributed across Los Angeles County. The needs of the community continue to expand into different areas requiring an improvement to be made in order to improve the quality of life in various neighborhoods and the insurance of environmental equity. Currently it is difficult for organizations to cohesively work with one another to maximize their overlapping resources that would benefit the communities they provide environmental services to.
246

Study of heavy metal accumulation mechanisms in the Lachine Canal sediments

Galvez de Cloutier, Rosa January 1995 (has links)
No description available.
247

Laccase-catalyzed oxidation of bisphenol A in a non-aqueous liquid reverse micelles

Liu, Yan, 1975- January 2004 (has links)
No description available.
248

Three-dimensional visualization and quantification of residual non-aqueous phase liquids using x-ray computed tomography

Goldstein, Lucas January 2004 (has links)
No description available.
249

Photochemical degradation of selected polycyclic aromatic compounds

Warner, Stephanie D. January 2002 (has links)
No description available.
250

Environmental Contamination by Metabolites of Microbial Degradation of Plasticizers

Horn, Owen January 2003 (has links)
No description available.

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