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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.
11

Environmental Geophysical Analysis of a Portion of the Muddy and Roaring Creek Watersheds, West Virginia

Alfouzan, Fouzan Ali 18 October 2002 (has links)
This thesis presents a new environmental geophysical analysis derived from airborne and ground measurements of electromagnetics and total magnetic field collected from the Muddy and Roaring Creek watersheds located in northeastern Preston County, West Virginia. This region is referred to as the T&T mine area. In the simplest representation, with respect to subsurface Acid Mine Drainage (AMD) impacted water systems, the subsurface regions can be thought of as containing three pools of AMD contaminated water. The objectives of this project were to determine the location of these subsurface pools, the lateral extent of a contaminated mine pool located at a depth of about 300 feet, and to determine areas of groundwater recharge to the mine pool. Geophysical data analyzed included frequency-domain electromagnetic (EM) conductivity (380, 1400, 6200, 25k and 102k Hz), VLF (VLF1I from Cutler station, VLF2I from Seattle station), and total field magnetics. In order to check the airborne data, ground measurements were collected using EM34 and EM47 instruments. These data were collected for the National Energy Technology Laboratory of the U.S. Department of Energy as part of their active and ongoing environmental geophysical program. Cultural noise was removed from some of the conductivity dataset using ER MAPPER software and applying a variety of spatial frequency filters. ER MAPPER, ERDAS Imagine, ERDAS Virtual GIS, ESIR Arc/Info, and ESRI ArcView software package were then used to display and interpret the data. The geometry of the high-conductivity pools were imaged using a variety of techniques including Hue Saturation and Intensity (HSI) algorithms and unsupervised classification using ER MAPPER and Arc/Info software. After the pool geometry was determined, a series of geophysical profiles were extracted from the edges of the three pools. I interpret these data as showing the geometry of the mine pools and regions of contrasting groundwater conductivity related to discharge.
12

RADIOGENIC ISOTOPE INVESTIGATION OF SOURCES, TRANSPORT, AND DEPOSITION OF RARE EARTH ELEMENTS IN THE OWENS LAKE DRAINAGE BASIN, EASTERN CALIFORNIA

Minervini, Joseph Mario 11 March 2002 (has links)
Owens Lake is situated in a mostly-closed basin fed by water and sediments derived primarily from the eastern Sierra Nevada range. Radiogenic isotope variations in USGS Owens Lake core OL-92 were used in conjunction with major and trace element concentrations in streams draining the eastern Sierras to investigate sediment provenance, the chemical weathering and transport of rare earth elements (REE) in the Owens Lake drainage basin, and possible climate-related shifts in weathering patterns of the eastern Sierras during the last ~30 ka. Filtered (<0.45 &#x03BC;m) stream water samples not influenced by hydrothermal fluids or agriculture fall below world average-normalized values for major cations. Concentrations of Nd in the stream water samples are less than 1 nmol L-1, too dilute for isotopic analysis. Strontium and neodymium isotopic analyses were conducted on the carbonate and silicate fractions of sediment samples representing deposition in Owens Lake from ~30 ka to ~10 ka. The fraction of carbonate in Owens Lake sediments increases from ~7 to 67 % during this period, reflecting the desiccation of the lake. Strontium, samarium, and neodymium are strongly partitioned into Owens Lake chemical sediments. Over the past ~30 ka, epsilon Nd values of clastic sediments in Owens Lake remain relatively constant, near -6.5. Chemical sediments remain approximately one epsilon unit higher than the clastic sediments until ~12 ka ago, at which time they shift to less radiogenic values, matching those of the clastic sediment. Differential mineral weathering of more common mineral phases over REE-enriched accessory phases is the most likely cause of the isotopic shift in Owens Lake chemical sediments at ~12 ka ago. Preferential weathering of hornblende could displace the Nd isotopic composition of Owens Lake chemical sediments away from that of the clastic fraction. Depletion of hornblende could allow the Nd isotopic composition of the two sediment fractions to return to similar values. This study represents the first Nd isotope study of a lacustrine system and suggests Nd isotopes could be a useful paleoclimate proxy. Additional work in older Owens Lake sediments and in other lake systems is clearly warranted.
13

Characterization of Precipitates Associated with Bituminous Coal Mine Drainage, Northern Appalachian Region, USA

Kairies, Candace Lianne 28 May 2003 (has links)
Changes in precipitate mineralogy, morphology, and major and trace elemental concentrations and associations throughout five coal mine drainage remediation systems in Pennsylvania and Maryland that treat discharges of varying chemistries were investigated. The precipitates are dominantly (>70%) goethite with minor amounts of other iron and/or manganese oxides and quartz. Crystallinity varies throughout an individual system and is a function of the treatment system and how rapidly ferrous iron oxidizes, precipitates, and settles. Precipitates formed earlier in the systems have the highest crystallinity; less crystalline precipitates are associated with enhanced sorption of trace metals. High surface area and vacancies within the goethite structure enable incorporation of metals from mine drainage polluted waters. Sorption affinities follow the order Al>Zn>Co=Ni>Mn. As pH increases in the individual treatment systems toward the pHpzc, arsenic sorption decreases and aluminum and transition metal sorption increases. Sulfate, sodium and ferrous iron potentially influence the sorption of trace metals. A sequential extraction procedure was developed to determine how trace elements are associated with the precipitates. Arsenic, cobalt, manganese, nickel and zinc are not released until the iron hydroxide phase is dissolved, indicating these metals are either tightly sorbed to the surface or incorporated into the hydroxide structure. Cobalt and nickel preferentially partition into a manganese oxide/hydroxide phase (if present), over the iron hydroxide phase. The stability of the precipitate controls the long-term mobility of trace metals. Associated trace metals will remain unavailable to the environment as long as the precipitate is not altered. Additionally, spatial and temporal variations between precipitates formed from a net-alkaline coal mine discharge were examined. The precipitates are all moderately crystalline goethite with minor variations in morphology and composition. They contain 20 30% more iron than the natural mined iron oxides examined in this study, and concentrations of manganese, nickel and zinc are up to three orders of magnitude lower than the natural iron oxides. Geochemical analysis indicates that mine drainage precipitates formed from net-alkaline waters are of a higher purity than natural iron oxides. Results of this study have implications for disposal, resource recovery, and the optimization of mine drainage passive remediation systems.
14

The Role of Spinose Ornament in Predator Deterrence and Epibiont Colonization: The Bivalve Arcinella, Pinecrest (Pliocene) of Florida

Beatty, William Lee 23 May 2003 (has links)
The spinose shells of the sessile, epifaunal bivalve Arcinella cornuta, from the fossiliferous Pliocene Pinecrest and Caloosahatchee beds of Florida, provide evidence of ecological interactions with both boring predatory gastropods and commensal bivalves. The number, sizes, and positions of borings in A. cornuta were compared to parameters such as size of the valve and density of spines at the boring site to determine to what extent spines influenced the borers. Records of attacks by naticid and muricid gastropods are preserved as borings in the shells of their putative prey. Gastropods can exhibit stereotyped attack patterns and can be highly selective with regard to prey size and boring site in order to optimize net energy return. Although some site and size selectivity was evident, attack strategies toward A. cornuta shifted over time. Spine density at boring sites was negatively correlated with boring frequency, demonstrating that spines hindered predatory attacks. Smaller predators were selective and most often bored at the thinner posterior region of the shell. Larger predators were less selective and most often bored at the lunule; the thickest portion of the shell, but the only area unobstructed by spines. Larger predators apparently accepted longer boring times in order to increase chances at success. Over time, establishing two preferred boring sites enabled predators to optimize their attacks. This direct link between prey morphology and predator adaptation signals that an arms race between these two species may have been underway. A. cornuta shells were also the preferred habitat of boring gastrochaenid bivalves, signaling a shift in the borer's habitat. Some species of the bivalve family Gastrochaenidae dwell in semiendolithic boreholes partially covered by secreted calcareous envelopes or crypts. Gastrochaenids selectively colonized shells of A. cornuta to exploit the feeding currents, armor, and raw materials provided by the host. The distribution of borings and crypts indicates that gastrochaenids colonized and grew within the spines of A. cornuta, orienting their siphons to exploit feeding currents created by the host. As the gastrochaenids matured and outgrew the space available within the spines, they incorporated them into their crypts.
15

Size-Dependent Scattering Properties of Planetary Regolith Analogs

Piatek, Jennifer Lynn 11 December 2003 (has links)
The physics of the interaction of light with a particulate surface are important to understanding and analyzing remote sensing data from planetary surfaces. An examination of the angular scattering properties of powder samples with known compositions and particle sizes was undertaken to try and further understand the interaction of light with a closely packed particulate medium. The samples range in size from smaller than to larger than the wavelength(l) of incident light (0.05 30.09 µm in diameter, l=0.635 µm). Based on a rich history of both theoretical treatments and laboratory measurements, results would be expected to show any dependence of scattering parameters on composition and/or particle size. Scanning electron microscope analyses of the powders were done to characterize particle size, composition, and shape as the major contributors to observed trends in scattering parameters. Models currently in wide use to describe light scattering by planetary regoliths make two important assumptions: (1) the propagation of light through the medium can be described by the equation of radiative transfer, which treats the medium as if it were made up of a continuous distribution of independent scatterers and absorbers; and (2) these fundamental scatterers are the individual particles that make up the medium. Models based on the radiative transfer equation were found to provide good empirical descriptions of the light scattering properties of particulate media composed of complex particles, such as planetary regoliths. However, the results reported here show that changes in scattering parameters predicted by the assumption that the particles are the scatterers are not observed in these samples, and that such models do not accurately predict the transport mean free path, scattering coefficient, or extinction coefficient of such media. In particular, the transport mean free path shows remarkably little dependence on particle size over the size ranges studied, whereas the particle scattering assumption predicts a large variation. Theoretical models based on the second assumption should only be used with great caution when analyzing data taken on particulate surfaces.
16

Thermal infrared data analyses of Meteor Crater, Arizona: Implications for Mars spaceborne data from the Thermal Emission Imaging System

Wright, Shawn Patrick 19 November 2003 (has links)
Thermal infrared (TIR) data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument are used to identify the lithologic distribution of the Meteor Crater ejecta blanket and nearby (within ~3 km) region. This has many applications to the analysis of data from the Thermal Emission Imaging System (THEMIS) instrument that is currently in orbit at Mars. ASTER and THEMIS, whereas orbiting different planets, have similar spatial and spectral resolutions. THEMIS represents the highest spatial resolution (100 m) to date of the Martian surface, thereby allowing small (~ 1km) impact craters to be studied in detail for the first time. Meteor Crater serves as an analog for the many similar-sized impact sites on the surface of Mars. These sites are future research targets with THEMIS, and ASTER data of Meteor Crater provides ideal data and geologic landscape in preparation for future THEMIS investigations. Fieldwork at Meteor Crater yielded sample collection of the primary lithologies and an opportunity to validate previously-collected high-resolution (3.2 m), airborne Thermal Imaging Multispectral Scanner (TIMS) data. Laboratory thermal emission spectra were obtained for the samples collected. Deconvolution of ASTER TIR emissivity data were performed with image end-members and sample end-members. Comparisons of the spaceborne data to high-resolution airborne TIMS data were used to assess the validity of the ASTER end-member analyses. The ASTER image end-member analysis agreed well with the earlier TIMS end-member analysis where the effects of resolution degradation were accounted for. Laboratory spectra and mineral spectral libraries provided poor fits of deconvolution of multispectral TIR data. Lithologies with similar spectral signatures or with low areal abundances were difficult to identify. Using the same methodology as that applied to the ASTER TIR data of Meteor Crater, THEMIS TIR data of a small (~ 1 km) impact crater in Syrtis Major were analyzed. The craters rim and ejecta blanket was found to contain larger particle sizes than the surrounding (ejecta-free) plain, indicating a young (fresh) impact age and little or no accumulation of dust. The composition of the rim, ejecta, and surrounding plain was determined to be basaltic. It is hoped that the work performed here will complement future investigations of fresh impact sites with THEMIS data that may be used to solve geologic questions such as 1.) the composition of ejecta blocks that represent pre-impact, underlying stratigraphy in high-albedo, dust-covered regions of Mars, 2.) the approximate age of impact, and 3.) regolith/dust thickness, which appears to be a factor of #2.
17

Characterization of Dome Processes at Soufrière Hills Volcano, Montserrat: Synthesis of Infrared Remote Sensing Data with a Multi-parameter Database

Kuhn, Sally Susan 28 January 2004 (has links)
The Advanced Spaceborne Thermal Emission Reflectance Radiometer (ASTER) is a high resolution multispectral imager ideal for discerning physical variations on the active Soufrière Hills volcanic dome. Five band thermal infrared data at 90 meter spatial resolution can produce accurate temperature and emissivity data. These data can potentially provide information of glass and vesicle distribution across the changing dome, and therefore on internal processes. One cloud-free image is captured every three months on average, with increased frequency in 2002, where the volcano was a high priority target. Six nighttime ASTER scenes of the dome have been chosen based on coverage of the entire dome, the presence of thermal infrared anomalies, and pyroclastic flow activity, as well as a relative lack of cloud cover over the active dome. Montserrat Volcano Observatory (MVO) weekly reports from 1999 to present (available online) were also ingested into a multi-parameter, searchable database. These data, which detail specific volcanic activity, were compared against the ASTER data. The database fields include SO2 flux, high temporal resolution weather satellite-derived radiance measurements, description of dome growth and collapse, and intensities of pyroclastic flows, rockfalls, fumarolic activity, and seismic activity. This database provides a unique cross-reference for the interpretation of the spaceborne data, as well as highlighting observable trends in each of the volcanic activity types. Results from this study will provide a better understanding of the capabilities of the ASTER instrument to accurately describe active dome processes and to characterize these and other processes statistically. This knowledge can be applied to other active areas to study potential indicators of volcanic activity, dome collapse, the generation of hazardous pyroclastic activity, as well as the transition from effusive dome growth to explosivity.
18

Multi-frequency, Multi-temporal, Brush Fire Scar Analysis in a Semi-Arid Urban Environment

Misner, Tamara Janelle 28 January 2004 (has links)
The number of forest fires has increased dramatically over the past five years in western areas of the United States, due to both human and natural causes. Urban areas, such as the city of Phoenix, continue to increase in size and population, with a majority of the development occurring in rural areas that have burned, or are threatened by brush fires. As people move into these environments there is an increased risk of damage to human property and lives due to fires. These areas have experienced a number of recent brush fires that have been expensive to fight, and caused a considerable amount of property damage. The ability to predict and control fires is thus increasingly important as urban centers encroach upon rural lands. Remote sensing can be utilized to characterize fire scarred areas, and predict areas that have an increased risk for burning again in the future. Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER), Landsat Thematic Mapper (TM), and Spaceborne Imaging Radar - C (SIR-C) remote sensing data have been combined with a geographic information system (GIS) to characterize fire scars in a semi-arid urban area outside of Phoenix, Arizona. This data was also used to quantify the relationship of fire scar age to vegetative recovery. In addition to the remote sensing aspect of this project, an initial geomorphological investigation was conducted to determine the effect of fire on sediment flux and landscape evolution. Detailed topographic surveys, combined with sediment trap data, were used to examine differences in erosion between burned and unburned catchments. These results have implications for potential flooding risks due to removal of vegetative cover by fires. By combining remote sensing data with a GIS database, and through comparison with geomorphic/sedimentological investigations, this work may permit city officials and urban planners to better calculate potential risks for both future fire and flood hazards within the region.
19

Syn-eruptive incision of Koko Crater, Oahu, Hawaii by condensed steam and hot cohesive debris flows: a re-interpretation of the type locality of "surge-eroded U-shaped channels"

Bluth, Jessica Keri 05 October 2004 (has links)
Phreatomagmatic fall, low-concentration PDC deposits and remobilized equivalents dominate the products of craters (tuff cones/rings) of Koko fissure, south-east Oahu. At Koko crater, Fisher (1977) described U-shaped channels, which he interpreted as due to erosion by low-concentration PDCs (surges), with minor modification by stream and debris flows. Similar channels on tuff cones and rings elsewhere in the world have been interpreted as surge-eroded by subsequent authors. However, no evidence for erosion by PDCs was observed during recent fieldwork, which suggested rather the following model. An important observation is that initial incision is always correlated with the emplacement of vesiculated ash layers (derived from Hanauma Bay), and is only very rarely associated with other facies. Incision of the vesiculated ash by run-off generated an initial and widespread network of sinuous, narrow (<15 cm) and shallow (<15 cm) rills. The strong correlation of rills with vesiculated ash and the lack of obvious water-escape structures in these ashes implies that run-off was mostly derived from associated steam-rich plumes. Initial steam and rain-fed incision was probably also enhanced in these very fine-grained cohesive deposits as a consequence of lowered infiltration rates. The rill network developed locally into deeper channels (i.e. gullies) during steam and rain-fed run-off, and by significant erosion during emplacement of vesiculated (hot) debris flows, derived from remobilized vesiculated ash. Pyroclastic density currents from Hanuama Bay traveling laterally across the flank of Koko Crater, perpendicular to the gully axes, provided the bulk of the gully fills, but gave rise to little or no modification of their margins. Rill and gully development by rainfall alone could explain similar examples of incision of low-concentration PDC deposits elsewhere in the world, but the possibility of steam-fed rills and erosion by hot debris flows should be considered. Low-concentration PDCs do not seem to be able to erode their substrate in all cases.
20

EVOLUTION OF THE MARTIAN HIGHLANDS: IMPLICATIONS FROM DRAINAGE BASIN CHARACTERISTICS AND VALLEY NETWORK MORPHOLOGIES

Mest, Scott Charles 31 January 2005 (has links)
Geologic and geomorphic analyses reveal the effects of fluvial processes within Tyrrhena Terra, Promethei Terra and Libya Montes, Mars. High-resolution Mars Orbiter Camera (MOC), Thermal Emission Imaging System (THEMIS) visible and thermal infrared wavelength images, Viking Orbiter images, Thermal Emission Spectrometer (TES) and Mars Orbiter Laser Altimeter (MOLA) topographic data are used to qualitatively and quantitatively characterize highland fluvial systems and analyze the role of water in the evolution of these highland terrains. Highland materials--including rugged uplands, intermontane basin-filling materials, plains and impact crater ejecta deposits--are dissected by both widespread, well-integrated valley networks, such as Vichada Valles in Tyrrhena Terra, and small-scale isolated networks and single channels. The interior and exterior rims of impact craters, such as crater Millochau, are also dissected by gullies. Characterization of these features and the geologic units in which they occur is necessary to fully understand the nature of martian fluvial activity and the history of Mars' climate. High-resolution (128 pixels/degree) MOLA Digital Elevation Models (DEMs) are used with the Arc/Info GIS software (including GRID, ARCPLOT, and ArcView 3.2a) and GRIDVIEW to quantitatively characterize the surface hydrology of Tyrrhena Terra, Promethei Terra and Libya Montes. Drainage basin divides and valley networks are modeled at different scales dependent on the depth to which anomalous pixel sinks are filled. Modeled drainage divides are defined by the distribution of highland peaks and impact crater rims. Hydrologic modeling results suggest that large areas of apparently undissected terrain in Tyrrhena Terra may have been influenced by fluvial processes. Compared to mapped networks, models of large-scale valley systems in Tyrrhena Terra accurately represent the locations of valleys down to at least second order. Smaller-scale systems observed in Promethei Terra and Libya Montes are more difficult to accurately represent with the model due to a combination of a large amount of topographic interpolation within the MOLA DEM and the close spacing of short, narrow valleys Rigorous comparison of the model results to image data is helping to produce accurate maps of martian drainage basins and their associated valley networks, which provide critical constraints for valley formation mechanisms and climate history.

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