Browsing by Subject "Gulf Coast"
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Item Aquatic macrophyte and animal communities in a recently restored brackish marsh: possible influences of restoration design and the invasive plant species Myriophyllum spicatum(2012-07-16) Bell, Michael ThomasThe numerous benefits that wetlands provide make them essential to ecosystem services and ecological functions. Historically, wetland losses have been caused by natural and anthropogenic changes. In Texas, nearly 50% of coastal wetland habitat has been lost since the 1930s and losses in the Lower Neches watershed have been some of the most extensive. Restoration is a way to mitigate these losses and can be accomplished in many ways. Each restoration design creates different aquatic habitats that can influence both submerged aquatic vegetation (SAV) and faunal communities. The restoration of the Lower Neches Wildlife Management Area (LNWMA) has created the conditions for the growth of the invasive submerged macrophyte, Myriophyllum spicatum (Eurasian watermilfoil) which may be competing with the native aquatic grass, Ruppia maritima (widgeongrass) for essential nutrients. In this study, an attempt was made to link restoration design with both SAV and aquatic fauna community structures by using a throw trap to characterize assemblages observed in three different types of restored marshes. We also performed two controlled mesocosm experiments in 0.5 gal aquariums to determine growth inhibition by M. spicatum on R. maritima. Analyses using Kruskal-Wallis non-parametric test determined that temporal variations in fauna and SAV community composition was greater than any restoration effect. Discriminant Function Analyses (DFAs) determined two to three key faunal species that best predicted association among restoration designs, but linear regressions could not determine any consistent relationship between individual species density and biomass of the dominant SAV species, M. spicatum. For the mesocosm experiments, M. spicatum inhibited the biomass production and branch count of R. maritima when the two species are grown together (ANOVA, p = 0.004 and 0.003, respectively). Changes in SAV assemblages due to competition and habitat characteristics could play a major role in determining faunal community. In order to minimize the temporal effect observed and better determine any habitat pattern that may be present, a much longer study is necessary.Item Depositional and diagenetic processes in the formation of the Eocene Jackson Group bentonites, Gonzales County, Texas(2011-12) Michaelides, Michael Nicholas; Kyle, J. Richard; Gardner, James; Heister, Lara; Serenko, ThomasBentonite clays are exposed in Paleogene strata stretching over 650 km parallel to the Texas coastline. This study focuses on a white and blue and a yellow and brown commercial Ca-montmorillonite bentonite near the city of Gonzales, Gonzales county, Texas. The deposits have stratigraphic ages of Late Eocene (~36.7 - 32.7 Ma). The bentonites in these deposits have varying colors, purities and brightness affording them diverse industrial uses. The distribution and geologic character of the high purity white and blue bentonite suggests that the deposit represents an accumulation of volcanic ash in a secondary tidal channel during the ash-fall event. A low rate of terrigenous clastic sedimentation and rapid accumulation of fresh ash were critical to the formation of high purity clay. The lower purity yellow and brown bentonites appear to have a fluvial origin marked by higher rates of detrital sedimentation and episodic accumulation of clay and ash. The bentonite and associated strata were studied using optical microscopy, SEM, XRD and REE analyses to constrain their textural, mineralogic, and chemical character. vii Eocene pyroclastic volcanism is well documented from sources in southwestern North America, specifically in the Sierra Madre Occidental (Mexico), Trans-Pecos (Texas) and Mogollan-Datil (New Mexico) volcanic fields. Projected Eocene wind patterns support this region as a potential source for the Gonzales bentonites. A comparison of the trace and REE fingerprints of the white and blue bentonites and the yellow and brown bentonites with data available for Late Eocene volcanics in the North American Volcanic Database provides a couple of potential matches. The strongest potential match for the Late Eocene bentonite protolith is described as a sample of silicic tuff with an age range of 32.2 – 30.6 Ma, located in the southern Mexican state of Oaxaca. While the trace and REE match is strong, the tuff is somewhat young compared to the Jackson Group sediments. In addition, the sample location is due almost directly south of the Gonzales deposits, rather than the western location expected for a Gonzales bentonite source. The other potential matches are located in New Mexico, and the Mexican state of Chihuahua. These potential matches only have 6 REE available for comparison, and require further investigation. Many Paleogene volcanic units in southern North America are undocumented with regard to REE data or precise absolute ages. As additional geochemical analyses become available for a more extensive suite of Paleogene volcanic units, stronger matches with Gulf of Mexico Basin bentonites are expected to emerge.Item Empirical analysis of fault seal capacity for CO₂ sequestration, Lower Miocene, Texas Gulf Coast(2012-05) Nicholson, Andrew Joseph; Meckel, Timothy Ashworth; Tinker, Scott W. (Scott Wheeler); Trevino, Ramon H.; Steel, Ronald J.The Gulf Coast of Texas has been proposed as a high capacity storage region for geologic sequestration of anthropogenic CO₂. The Miocene section within the Texas State Waters is an attractive offshore alternative to onshore sequestration. However, the stratigraphic targets of interest highlight a need to utilize fault-bounded structural traps. Regional capacity estimates in this area have previously focused on simple volumetric estimations or more sophisticated fill-to-spill scenarios with faults acting as no-flow boundaries. Capacity estimations that ignore the static and dynamic sealing capacities of faults may therefore be inaccurate. A comprehensive fault seal analysis workflow for CO₂-brine membrane fault seal potential has been developed for geologic site selection in the Miocene section of the Texas State Waters. To reduce uncertainty of fault performance, a fault seal calibration has been performed on 6 Miocene natural gas traps in the Texas State Waters in order to constrain the capillary entry pressures of the modeled fault gouge. Results indicate that modeled membrane fault seal capacity for the Lower Miocene section agrees with published global fault seal databases. Faults can therefore serve as effective seals, as suggested by natural hydrocarbon accumulations. However, fault seal capacity is generally an order of magnitude lower than top seal capacity in the same stratigraphic setting, with implications for storage projects. For a specific non-hydrocarbon producing site studied for sequestration (San Luis Pass salt dome setting) with moderately dipping (16°) traps (i.e. high potential column height), membrane fault seal modeling is shown to decrease fault-bound trap area, and therefore storage capacity volume, compared with fill-to-spill modeling. However, using the developed fault seal workflow at other potential storage sites will predict the degree to which storage capacity may approach fill-to-spill capacity, depending primarily on the geology of the fault (shale gouge ratio – SGR) and the structural relief of the trap.Item An energy return on investment for a geothermal power plant on the Texas Gulf Coast(2013-05) Kampa, Kyle Benjamin; King, Carey Wayne, 1974-This thesis examines the energy return on investment (EROI) of a model 3 MW hybrid gas-geothermal plant on the Texas Gulf Coast. The model plant uses a design similar to the DOE Pleasant Bayou No. 2 test geothermal plant, and uses a gas engine to harness entrained methane and an Organic Rankine Cycle turbine to harness thermal energy from hot brines. The indirect energy cost was calculated using the Carnegie Mellon University Economic Input-Output Life Environmental Life Cycle Analysis (EIO-LCA) model. The EROI of the plant using the 1997 EIO-LCA energy data is 12.40, and the EROI of the plant using 2002 EIO-LCA energy data is 14.18. Sensitivity analysis was run to determine how the plant parameters affect the EROI. A literature review of the EROI of different power sources shows that the EROI of the hybrid geothermal plant is greater than the EROI of flash steam geothermal and solar, but is lower than the EROI of dry steam geothermal, wind power, nuclear, coal, gas, and hydroelectric plants. An analysis of the EROI to financial return on investment (FROI) shows that the FROI for a hybrid geothermal plant could be competitive with wind and solar as a viable renewable resource in the Texas electricity market.Item Narrative salvage(2016-05) Shapland, Jennifer Ann; Houser, Heather; Cvetkovich, Ann, 1957-; Cullingford, Elizabeth; Bennett, Chad; Lewis, RandolphNarrative Salvage brings together contemporary writing and film of what I call wastescapes: places made expendable—wasted—under late capitalism. In hybrid works of the 2000s by Bonnie Jo Campbell, Agnes Varda, Natasha Trethewey, Brenda Longfellow, Rebecca Solnit, Claire Vaye Watkins, and Eileen Myles, I analyze tactile and emotional representations of everyday life in the wastescape. Each of the four chapters examines a particular wastescape featured by these writers and filmmakers: the postindustrial junkyard, the oil-slicked Gulf Coast, the nuclear waste strewn Nevada desert, and the melting Arctic tundra. Within these spaces, I track practices of repurposing that occur in the inhabitants’ everyday lives and analyze the potential for writing and film to reclaim and transform place through representation. I argue that waste is a crucial site of trans-corporeal experience, which in Stacy Alaimo's words constitutes a "literal contact zone between human corporeality and more-than-human nature." The trans-corporeal wastescape affects ecosystems, human communities, and material objects; however, the representation of waste has not been a primary focus in environmental criticism. Narrative Salvage addresses this gap by approaching waste interdisciplinarily, drawing on the critical tools of environmental studies, sociology, and material culture studies. Practices of repurposing in the works I study dismantle the ideologies that create wastescapes by calling into question the production of value and rejection of waste that undergird capitalist and patriarchal enterprise. In the deviant ethics of the wastescape, the telos of progress loses its hold, making way for makeshift epistemologies and queer temporalities of continuous making do and regeneration. These experimental contemporary works' alinear, fragmented, and polyvocal forms embrace the vital ongoingness of decay and contamination. In Narrative Salvage, adamantly personal literatures and films of the wastescape urge audiences to rethink waste by seeing it anew, by defamiliarizing it, and in so doing help to rethink the human's relationship to—immersion within—place and environment.Item Topographic and Base-level Control on Back-Barrier Lagoon Evolution: West Galveston Bay, TX(2014-12-02) Laverty, Paul HEstuaries are economically and ecologically significant regions that are highly sensitive to external forcing from sea-level rise, storm events, and anthropogenic change. West Galveston Bay (West Bay) is a back-barrier lagoon system located immediately landward of Galveston Island, Texas, and it represents a sub-system of the larger Galveston estuary complex in the Northern Gulf of Mexico (NGOM). Previous studies have documented the evolution of many large estuaries along the NGOM in response to Holocene sea-level rise. However, the prehistory of smaller estuaries like West Bay remain largely overlooked and poorly understood. The primary purpose of this study is to complete a paleoenvironmental reconstruction of West Bay in Texas using geophysical and sedimentological approaches. A total of 30 core samples and more than 160 km of CHIRP seismic data were collected from West Bay and neighboring Chocolate Bay, within which several unique lithofacies and seismic facies were identified. As with other regional studies, the Pleistocene unconformity presents as an impedance change in the seismic profiles, and is most likely the Beaumont Formation. Multiple incised channels were observed on the Pleistocene Unconformity that are most likely seaward extensions of the tributaries that flow into Chocolate Bay, and formed the basal surface of the accommodation available for Holocene infill. Radiocarbon dating of salient lithologic and seismic transitions in a few key cores revealed that several flooding events related to Holocene sea-level rise caused the landward back-stepping and geographic reorganization of depositional environments within West Bay. The first flooding event occurred at ~7,600 Cal. yr. BP caused both fluvial-dominated sedimentation to cease and initiation of estuarine conditions. The next flooding event occurred at ~6,800 Cal. yr. BP tripled the spatially inundated area and created ideal brackish conditions for oyster reef proliferation. This was short lived, however, as reduced salinity and increased turbidity from the paleo-Brazos River that was flowing into the area between ~6,100 and ~4,400 Cal. yr. BP ceased oyster reef production. The final flooding event occurred at ~4,400 Cal. yr. BP, which possibly established the connection between Galveston Bay and West Bay. At this time, an ephemeral tidal inlet formed within the incised channels, and then migrated west until stabilizing in the paleo-Brazos River incised valley as the modern day San Luis Pass. This study reveals how the antecedent topography and sea-level rise controlled the environmental changes within West Bay throughout the Holocene. It also provides insight into how a small coastal system responds to varying rates of sea-level rise. Additionally, it may be useful as a baseline for West Bay for predicting future flooding associated with accelerating rates of sea-level rise.