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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.
131

Atrazine Contamination and Suspended Sediment Transport within Logsdon River, Mammoth Cave, Kentucky

Schenck Brown, Julie Eileen 01 December 2008 (has links)
Understanding the potential for karst aquifer contamination by sediment-sorbed pesticides is important for cave conservation efforts in agricultural landscapes. Flow rate, water quality parameters and suspended sediment concentrations were measured in Logsdon River, a ~10km karst conduit within the Turnhole Spring Groundwater Basin of Mammoth Cave National Park to determine characteristics of storm-period transport of sediment-sorbed atrazine through a conduit-flow karst aquifer. Analysis of two independent precipitation events occurring in the Spring of 2008 from May 2-4 and May 27-29 demonstrated the rapid response of the Logsdon River to precipitation events with detections of atrazine increasing during the initial turbidity peak and decline in spC, indicating that the atrazine arrives with the initial flush of surface waters that enters the conduit. Distinct peaks of atrazine did not coincide with fine grained (silt and clay-sized) sediment peaks and concentrations of atrazine remained elevated on the falling limb of the hydrograph as turbidity declined. In addition, no systematic relation between filtered and unfiltered samples was evident. There was also exceedingly weak correlation between the concentration of atrazine and suspended sediment, suggesting that if atrazine is sorbed to fine sediment particles this sorption involves only the fractions finer than 0.22 μm.
132

Overcoming the Obstacles to Sustainability in Ghana

Scott, Ashley M 01 January 2011 (has links)
For several decades following its independence from Great Britain, Ghana’s policies continued to promote over-extraction of natural resources to the detriment of its economy and rural communities. Agricultural and forestry policy has gradually evolved to foster more sustainable and equitable practices, as in building partnerships with the private sector to fund infrastructure improvements. Policy has recently recognized the dire need to adopt agricultural practices and means of forest resource extraction that are compatible with ecological stewardship. However, many shortcomings are still apparent. Large logging operations completely disregard forestry regulations with impunity, whereas rural sustenance extractors are severely punished in the rare event that policy is actually enforced. Although the severe disadvantages that agricultural policies had imposed in the 1960s have been partially alleviated, much improvement is still needed. Recent agricultural policy has recognized the lack of funding available to invest in more efficient and higher-yielding agricultural practices, but partnerships with the actual lending institutions do not exist. The scarcity of crucial inputs, such as fertilizer and technical assistance remains a major problem in the agricultural sector, as the soils are becoming rapidly depleted, leading to declining crop yields and further encroachment on the 20 percent of forests remaining. Overly ambitious targets and unrealistic policies require more careful and detailed formulation so that Ghana’s resources can be managed effectively before famine sweeps the food-insecure country once more.
133

National Park Service Cave and Karst Resources Management Case Study: Great Smoky Mountains National Park

Nolfi, Daniel C. 01 May 2011 (has links)
As discussed in the National Parks Service’s (NPS) Directors Orders/Natural Resources Management Reference Manual #77 and the 2006 NPS Management Policy Handbook, implementing a management plan specifically for cave and karst resources within a national park is paramount to afford these resources appropriate protection. With support from the Federal Cave Resources Protection Act and the National Park Service Organic Act of 1906, management actions protecting caves has begun to place significant importance outside the traditional cave environment onto a broader karst landscape. The need to understand and protect the karst environment and caves as a karst resource has taken a much larger role in the scientific literature and has increased interest in its federal management application. Proactive management through the use of holistic karst wide management plans and programs is shown to provide superior measures for resource protection when compared to the shortcomings associated with reactive cave focused management. The use of Great Smoky Mountains National Park (GRSM) as a case study supports the need to develop and implement a proactive cave and karst management plan specific to their resources. Management decisions with regards to cave and karst resources currently follow the park's general directives and Superintendent's Compendium. GRSM’s caves and karst areas represent unique resources, such as extensive vertical relief and rare biota, requiring special management in order to effectively protect them and to manage those who study and recreate within them. Characteristics such as these necessitate holistically addressing management of these resources.
134

Water Quality Impacts from Agricultural Land-Use in the Karst Groundwater Basin of Qingmuguan, Chongqing, China

Baker, Ted W 01 December 2008 (has links)
Karst regions are composed of soluble rock, often limestone, which leads to the formation of fissures, sinkholes and water flow conduits such as caves. Pollutants in karst waters tend to be quickly directed and concentrated into these subsurface conduits. As a result of this and other factors, water resources are especially sensitive to contamination and pollution in karst areas. Pollutant concentrations going into fluvial systems travelling through the subsurface in karst areas are often very similar to the concentrations arriving at outlets such as springs. Areas connected by karst conduit flows must be distinctly determined and special attention should be given to water quality impacts from land-use practices near conduit inputs. The climate which affects a certain karst area can also have different impacts on water resources considerations. For example, in the temperate climate of Kentucky precipitation is essentially even in distribution throughout the year. In contrast, southwest China is affected by a monsoon climate with high precipitation in the spring to summer and drier conditions in other seasons. In the wet season large storm pulses can effectively transport contaminants to water sources resulting in loads that can be unhealthy for frequent human consumption in drinking water. The dry seasons can be particularly severe in karst areas as water quickly drains to the subsurface, making water access a major hardship. The research for this study focused on the seasonal influences that the climate of southwest China poses for water quality, including differences in pesticide concentrations between agricultural and residential areas hydrologically linked by karst conduits. In late 2007 the fluvial connections in a simple karst system near Chongqing were confirmed using dye tracing techniques. Once these connections were established and the flow of the subterranean stream was assessed, the transport of agricultural runoff in the system was studied. Data loggers were used to record continuous data of the water conditions, including nitrate concentrations. The pesticides in the agricultural runoff entering and exiting the subterranean stream were quantified using ELISA methods. The concentrations were found to be within safe limits for drinking water. The hypothesis that there is a close relationship between concentrations of the pesticides glyphosate, chlorothalonil, and triazines in the input and the output of the system was supported by the results. When considering the hydrology and water chemistry data of the site, along with the water samples tested for pesticides, non-parametric statistical testing showed the correlations between these factors to be significant with p<0.01. The percent difference between the input and the output concentrations of glyphosate, chlorothalonil, and triazines were 31, 43, and 57% respectively. Taking into account the rapid and direct flows in this karst system, the concentrations of the pesticides found in the output were more similar to the input than would be expected in a surface stream. This suggests that there are fewer natural remediation effects reducing contamination in subsurface karst rivers of southwest China than in surface rivers. Therefore, these systems should be handled with extra attention to possible contamination of water resources. The research was conducted in the spring and summer of 2007-2008 and funded by the U.S. Agency for International Development.
135

Relative Survival of Gags Mycteroperca microlepis Released Within a Recreational Hook-and-Line Fishery: Application of the Cox Regression Model to Control for Heterogeneity in a Large-Scale Mark-Recapture Study

Sauls, Beverly J. 01 January 2013 (has links)
The objectives of this study were to measure injuries and impairments directly observed from gags Mycteroperca microlepis caught and released within a large-scale recreational fishery, develop methods that may be used to rapidly assess the condition of reef fish discards, and estimate the total portion of discards in the fishery that suffer latent mortality. Fishery observers were placed on for-hire charter and headboat vessels operating in the Gulf of Mexico from June 2009 through December 2012 to directly observe reef fishes as they were caught by recreational anglers fishing with hook-and-line gear. Fish that were not retained by anglers were inspected and marked with conventional tags prior to release. Fish were released in multiple regions over a large geographic area throughout the year and over multiple years. The majority of recaptured fish were reported by recreational and commercial fishers, and fishing effort fluctuated both spatially and temporally over the course of this study in response to changes in recreational harvest restrictions and the Deepwater Horizon oil spill. Therefore, it could not be assumed that encounter probabilities were equal for all individual tagged fish in the population. Fish size and capture depth when fish were initially caught-and-released also varied among individuals in the study and potentially influenced recapture reporting probabilities. The Cox proportional hazards regression model was used to control for potential covariates on both the occurrence and timing of recapture reporting events so that relative survival among fish released in various conditions could be compared. A total of 3,954 gags were observed in this study, and the majority (77.26%) were released in good condition (condition category 1), defined as fish that immediately submerged without assistance from venting and had not suffered internal injuries from embedded hooks or visible damage to the gills. However, compared to gags caught in shallower depths, a greater proportion of gags caught and released from depths deeper than 30 meters were in fair or poor condition. Relative survival was significantly reduced (alpha (underline)<(/underline)0.05) for gags released in fair and poor condition after controlling for variable mark-recapture reporting rates for different sized discards among regions and across months and years when individual fish were initially captured, tagged and released. Gags released within the recreational fishery in fair and poor condition were 66.4% (95% C.I. 46.9 to 94.0%) and 50.6% (26.2 to 97.8%) as likely to be recaptured, respectively, as gags released in good condition. Overall discard mortality was calculated for gags released in all condition categories at ten meter depth intervals. There was a significant linear increase in estimated mortality from less than 15% (range of uncertainty, 0.1-25.2%) in shallow depths up to 30 meters, to 35.6% (5.6-55.7%) at depths greater than 70 meters (p < 0.001, R2 = 0.917). This analysis demonstrated the utility of the proportional hazards regression model for controlling for potential covariates on both the occurrence and timing of recapture events in a large-scale mark-recapture study and for detecting significant differences in the relative survival of fish released in various conditions measured under highly variable conditions within a large-scale fishery.
136

THE EFFECTS OF MOUNTAINTOP REMOVAL MINING AND VALLEY FILLS ON STREAM SALAMANDER COMMUNITIES

Muncy, Brenee' Lynn 01 January 2014 (has links)
Mountaintop removal mining and valley filling (MTR/VF) is a common form of land conversion in Central Appalachia and threatens the integrity of stream ecosystems. We investigated the effects of MTR/VF on stream salamander occupancy probabilities and community structure by conducting area constrained active searches for stream salamanders within intermittent streams located in mature forest (i.e., control) and those impacted by MTR/VF. During March to June of 2013, we detected five stream salamander species (Desmognathus fuscus, D. monticol, Eurycea cirrigera, Pseudotriton ruber, and Gyrinophilus porphyriticus) and found that the probability of occupancy was greatly reduced in MTR/VF streams compared to control streams. Additionally, the salamander community was greatly reduced in MTR/VF streams; the mean species richness estimate for MTR/VF streams was 2.09 (± 1.30 SD), whereas richness was 4.83 (± 0.58 SD) for control streams. Numerous mechanisms may be responsible for decreased occupancy and diminished salamander communities at MTR/VF streams, although water chemistry of streams may be a particularly important mechanism. Indeed, we detected elevated levels of specific conductivity, pH, total organic carbon, and dissolved ions in MTR/VF streams. Our results indicate that salamander communities, with other invertebrates, fish, and other aquatic and/or semi-aquatic animals, are susceptible to MTR/VF mining practices.
137

Changing The Climate Narrative: How A Long-Term Climate Change Might Save Our Lives

Harreld, Natalie P 01 January 2014 (has links)
The goal of this paper is to offer new insights into the climate change debate by shifting away from the heated anthropologic arguments that dominate politics, media, and popular science. Instead, I choose to rely on the long-term impacts of a changing climate on our planet. The paper begins with a break down of key processes involved in short-term and long-term climate change, using the latest research. After a foundational understanding of climate sciences is established, we will discuss the failure of the climate change debate in educating the general public about the facts of a changing climate. Finally, the importance of long-term foresight in climate policy and education, and how this perspective could drastically progress the climate debate, will be discussed.
138

The Future of Squaw Valley and Alpine Meadows

Friel, Brian 01 January 2015 (has links)
This paper examines the ongoing conflict between Squaw Valley Ski Holdings and the local Tahoe community and analyzes this conflict within the greater historical context of ski resort consolidation and development across the Western United States.
139

Spatial and Temporal Variation in Mangrove Distribution (1950-2014) in Tampa, Florida USA

Cheatham Rhodes, Carolyn 28 June 2017 (has links)
I carried out an observational study of historic high resolution aerial imagery spanning six decades (1950-2014) to identify recent and historic spatial extent of mangrove forests, within the municipal boundaries of the City of Tampa, Florida USA. My objectives were to map mangrove distribution and spatial extent and any change or patterns of change discernable. I observed variable patterns of change and rates of expansion varied between sites spatially as well as within sites between time intervals. I found notable changes in mangrove extent in the Tampa from historic and modern aerial imagery for the ~64-year period between 1950 and 2014. There were significant losses in areal extent between 1950 and 1973, much of which could be directly attributed to anthropogenic modification of the Tampa coastal landscape. All the regions observed had recovered or surpassed their original extent by the end of the period reviewed (1950-2014). It appears much of the recovery observed is a result of recolonization of created or modified shorelines. Results of these observations may contribute to the body of information used to inform conservation and management objectives in the City of Tampa and Tampa Bay.
140

An Economic Valuation Analysis of Buccoo Reef Marine Park, Tobago, West Indies

Da Costa, Dionne J 10 November 2010 (has links)
The purpose of this study was to evaluate tourism capacity, the effectiveness of the management plan and the visitors’ willingness to pay (WTP) for increased conservation effort in the Buccoo Reef Marine Park (BRMP) in Tobago. Non-market contingent valuation was applied to estimate tourists’ WTP, using the data from a survey of 164 tourists. Local residents and government agencies were consulted to evaluate the management plan and the tourism capacity. Eighty-eight percent of local residents stated that the park was not well managed and that they lacked trust in the park agency. The density of tourists was 67-97% more than socially acceptable crowding norm. The tourists were willing to pay an additional entry fee of US$11.72 per person, which would generate additional revenue for the park management. In conclusion, the BRMP management needs modification in order to increase stakeholders’ trust, reduce tourists crowding intensity, and generate additional user-based revenue.

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