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Articles 1 - 16 of 16
Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology
A South Polar View Of Late Paleozoic Glaciation: Physical Sedimentology And Provenance Of Glacial Successions In The Tasmanian And Transantarctic Basins, Elizabeth Rosa Woodford Ives
A South Polar View Of Late Paleozoic Glaciation: Physical Sedimentology And Provenance Of Glacial Successions In The Tasmanian And Transantarctic Basins, Elizabeth Rosa Woodford Ives
Theses and Dissertations
The Late Paleozoic Ice Age (LPIA; ~ 374 – 256 Ma) is the longest Phanerozoic icehouse interval. this interval in Earth’s history was largely defined by extensive glaciation of the southern hemisphere at both polar and temperate latitudes. Glaciers are powerful climatic and geologic actors, especially during icehouse periods, and widespread glaciation can have a significant influence on both regional and global climate and geology. Therefore, constraining the characteristics of LPIA glaciers is essential to developing a global-scale understanding of this key climatic event in Earth’s history. The manuscripts in this dissertation examine the sedimentology, transport directions, stratigraphy, and detrital …
Analysis Of Titan's Fluvial Features Using Numerical Modeling, Jeshurun Horton
Analysis Of Titan's Fluvial Features Using Numerical Modeling, Jeshurun Horton
Mechanical Engineering Undergraduate Honors Theses
River channels have been observed near the Huygens probe landing site on the surface of Titan, along with evidence of rounded water ice boulders transported through fluid flow. Evidence near the landing site suggests active flow of liquid methane, which has motivated the study of the effects of sediment load and channel sizes on Titan’s fluvial features. A numerical model is used to determine the viscosity, flow velocity, and critical boulder transport diameter based on channel size, slope, and a range of sediment concentrations. This model achieves two ends: first, observed boulder diameters are used to determine the ideal channel …
Coastal Groundwater Catchments Of The Gulf Of Alaska, Aeon Russo
Coastal Groundwater Catchments Of The Gulf Of Alaska, Aeon Russo
Masters Theses
High latitude mountain environments are experiencing disproportionately adverse effects in a currently changing climate. The Gulf of Alaska (GoA) region is an exemplar of this. Dramatic shifts are occurring in the region’s freshwater reservoirs as glaciers retreat more with each passing year. Research in the region places much focus on observing and predicting climate driven shifts in glacier mass balance, surface discharge, and associated nutrient fluxes to the ocean. On the other hand, coastal groundwater discharge (CGD) is given very little attention. Global and near-global estimates of CGD indicate variable results spanning an order of magnitude. Focusing on regionally specific …
Water Clarity And Suspended Particle Dynamics In The Chesapeake Bay: Local Effects Of Oyster Aquaculture, Regional Effects Of Reduced Shoreline Erosion, And Long-Term Trends In Remotely Sensed Reflectance, Jessica Turner
Dissertations, Theses, and Masters Projects
Water clarity is a key indicator of the ecosystem health in the Chesapeake Bay. Estuarine water clarity fluctuates due to external inputs from the watershed as well as processes occurring within the estuary itself, such as sediment resuspension and organic matter production. Therefore, water clarity requires study at multiple spatial and temporal scales and with multiple metrics. One local-scale process potentially influencing water clarity is shellfish aquaculture. One part of this dissertation examined how water quality and hydrodynamics varied among oyster farms as well as inside versus outside the extent of caged areas located in southern Chesapeake Bay. Current speed …
Past Ice-Ocean Interactions On The Sabrina Coast Shelf, East Antarctica: Deglacial To Recent Paleoenvironmental Insights From Marine Sediments, Kara J. Vadman
Past Ice-Ocean Interactions On The Sabrina Coast Shelf, East Antarctica: Deglacial To Recent Paleoenvironmental Insights From Marine Sediments, Kara J. Vadman
USF Tampa Graduate Theses and Dissertations
The East Antarctic Ice Sheet (EAIS) contains ~53 meters of sea level equivalent (SLE) ice, and observations suggest it is sensitive to ongoing and past climate change. The EAIS has traditionally been considered insensitive to climate perturbations because it is largely grounded above sea level. However, aerogeophysical surveys, oceanographic observations, and models indicate that large areas of the EAIS are grounded below sea level and contain 19.2 m SLE. Marine-based parts of the EAIS are thought to be located on inland-sloping beds that drain through marine terminating outlet glaciers, indicating large areas of the EAIS may be more sensitive to …
Small-Scale Resuspension And Redistribution Of Surface Sediments In The Northeast Gulf Of Mexico, Austin Harris
Small-Scale Resuspension And Redistribution Of Surface Sediments In The Northeast Gulf Of Mexico, Austin Harris
Master's Theses
Following the release of ~4.9 million barrels of oil into the Gulf of Mexico from the Macondo wellhead, a vast area of the seafloor contained recently deposited marine sediments contaminated by the oil spill. The initial deposition of these contaminated marine sediments was likely not the end of the journey for the particles. Downslope gravitational processes and events of increased current speed in the deep ocean setting can result in recently deposited sediments to resuspend and be moved laterally with the current flow, increasing the area effected by the oil spill. Erosion experiments performed in a closed-loop resuspension flume were …
Diversity – Independent Factors Predict Elevated Extinction Rates, Dustin Perriguey, Corinne Myers, Jason Moore, Louis Scuderi
Diversity – Independent Factors Predict Elevated Extinction Rates, Dustin Perriguey, Corinne Myers, Jason Moore, Louis Scuderi
Earth and Planetary Sciences ETDs
Multiple linear regression was used to determine the relationships between diversity-independent factors (i.e., abiotic, climatic) 2, 5, and 10 Myrs-prior to the most elevated Phanerozoic extinctions. We constructed five abiotic variables from Phanerozoic proxy records1–5 to compare to extinction rates: mean temperature, temperature instability, carbon cycle instability, continental weathering rates, and habitat instability. All three models were statistically significant (P < 0.05) and explained > 70% of the variation in Alroy’s6 three-timer generic extinction rates. However, the 2 Myr-prior model explained the most variance in extinction rates and had the most predictive power, based on adjusted and predictive R2 (~ 72% and 41%, respectively). Carbon …
Investigating The Hydrology Of The Western Greenland Ice Sheet: Spatiotemporal Variability And Implications On Ice-Dynamics, Jessica Z. Mejia
Investigating The Hydrology Of The Western Greenland Ice Sheet: Spatiotemporal Variability And Implications On Ice-Dynamics, Jessica Z. Mejia
USF Tampa Graduate Theses and Dissertations
Since the 1990's the Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate in response to climatic warming and is currently the largest terrestrial contributor to sea-level rise. While ice sheet models agree the GrIS will continue losing mass throughout the century, there are significant uncertainties associated with future sea-level rise contributions. Predicting the GrIS's response to future climate warming scenarios is limited by gaps in our understanding of the links between ice sheet hydrology and dynamics. Meltwater produced on the ice surface flows within supraglacial streams that deliver it to crevasses or moulins—vertical conduits extending from …
Reconstructing Surface Water Carbonate Ion Concentration Changes In The Eastern Equatorial Pacific Across Glacial Transitions, Lenzie Gail Ward
Reconstructing Surface Water Carbonate Ion Concentration Changes In The Eastern Equatorial Pacific Across Glacial Transitions, Lenzie Gail Ward
OES Theses and Dissertations
Today, the eastern equatorial Pacific (EEP) plays a critical role in the global CO2 budget as a major source of CO2 to the atmosphere, but recent studies suggest the region may shift to a sink for atmospheric CO2 under different climate states. Here, I focus on two transitional periods, the last deglaciation (25 kyr to present) and last glaciation (the Marine Isotope Stage (MIS) 5a-4 transition, 96 to 60 kyr), to investigate how the carbon system in the EEP responds to major climate changes. I measured B/Ca ratios in the planktic foraminifera Globigerina bulloides from core MV1014-17JC …
Hydro-Morphodynamics Of Sandy Coastal Embayments, Shamim Murshid
Hydro-Morphodynamics Of Sandy Coastal Embayments, Shamim Murshid
LSU Doctoral Dissertations
This dissertation investigates the hydro-morphodynamics of two major components of a sandy coastal environment: tidal inlets and embayment shorelines. In the first study, I focused on the evolution of inlet geometry by compiling and analyzing a database with 226 inlets worldwide with a special attention given to their width to depth ratio (or aspect ratio). I found that the aspect ratio has a weak dependency on tidal range and wave height, and they lie in different ranges for three types of tidal inlets: engineered, natural single-thread, and natural compound. I also developed a 2D hydro-morphodynamic model of an idealized barrier-inlet …
Investigating The Impact Of Meteoric Diagenesis On The Geochemistry Of Carbonate Eolianites, Eleuthera And Water Cay, The Bahamas, Graham S. Bonnot
Investigating The Impact Of Meteoric Diagenesis On The Geochemistry Of Carbonate Eolianites, Eleuthera And Water Cay, The Bahamas, Graham S. Bonnot
LSU Master's Theses
The geochemical signatures imparted in major, minor, and trace elements, combined with light isotopes, suggest promising applications regarding the stabilization of meteorically altered limestone eolianites. Previous high-resolution studies have indicated that elements associated with carbonate diagenesis such as Mg and Sr can be valuable proxies for salinity and aragonite dissolution, respectively. In addition to testing these proxies, the analyses of several temperature-, diagenetic-, bioactive-, and redox-sensitive elements were evaluated using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) to identify additional indicators during carbonate diagenesis. Two geochemical drivers of U were identified; (1) aragonite dissolution similar to Sr and (2) oxidation …
Controls On Estuarine Sediment Bed Erodibility: Insights From The York River Estuary, Cristin Lee Wright
Controls On Estuarine Sediment Bed Erodibility: Insights From The York River Estuary, Cristin Lee Wright
Dissertations, Theses, and Masters Projects
The erodibility of estuarine sediment beds has a number of ecological and societal implications, including alteration of benthic habitats, light-limitation of primary production, and reintroduction of pollutants to the water column, as well as impacts on dredging operations and on the fate of potentially dangerous objects on the seafloor. The objectives of this study are to better understand controls on bed erodibility in estuarine environments, including the roles of sediment grain size, water content, percent organics, and bed fabric, as well as effects of tides, storms, salinity distribution, river discharge, and location within the estuary. An extensive set of erosion …
Sediment And Terrestrial Organic Carbon Budgets For The Offshore Ayeyarwady Delta: Establishing A Baseline For Future Change, Evan Rose Flynn
Sediment And Terrestrial Organic Carbon Budgets For The Offshore Ayeyarwady Delta: Establishing A Baseline For Future Change, Evan Rose Flynn
Dissertations, Theses, and Masters Projects
Large river deltas serve as globally important archives of terrestrial and shallow marine biogeochemical signatures because of rapid sediment burial, and have the potential to impact global biogeochemical cycling on modern and geologic timescales. This study investigates modern sediment and terrestrial organic carbon (TerrOC) accumulation within the offshore Ayeyarwady Delta in order to determine sediment and TerrOC budgets for this largely understudied mega-delta. The Ayeyarwady is the world’s third largest delta in terms of sediment supply, and remains one of the last long free-flowing rivers in Asia. However, recent increases in regional anthropogenic impacts risk severe alterations to sediment and …
Diatoms And Their Response To Tectonic Gateway Changes: Case Studies From Southern Hemisphere Sites, Jason James Coenen
Diatoms And Their Response To Tectonic Gateway Changes: Case Studies From Southern Hemisphere Sites, Jason James Coenen
Graduate Research Theses & Dissertations
This dissertation covers three major transitions in Earth's climate system throughout theCenozoic (the past 65 million years of Earth's history). The progressive breakup of the super continent Pangea and the ultimate change in ocean circulation (and redistribution of heat) as a result of tectonic events dating back to the Mesozoic, primed Earth's climate system for cooling and ultimately bipolar glaciation. Climate transitions in three distinct environments were studied using absolute diatom abundance, diatom assemblages, and geochemical tracers of diatoms (i.e., biogenic silica weight%). Two geographic regions are the focus of this dissertation work. Region one is the Ross Embayment of …
Recent Flooding Events On The Chagrin And Cuyahoga Rivers, Ohio, Kayley Martin
Recent Flooding Events On The Chagrin And Cuyahoga Rivers, Ohio, Kayley Martin
Williams Honors College, Honors Research Projects
From the 1910s through the 1980s, the number of intense daily precipitation events in the United States remained constant, however, since the 1980s there has been an increasing trend in intense single-day precipitation events (U.S Environmental Protection Agency, 2016). One outcome of intense precipitation events is river flooding, particularly in the upper Midwest region where floods have increased in magnitude and frequency (U.S Environmental Protection Agency, 2016). In this thesis project, recent flooding history on the Chagrin and Cuyahoga Rivers in Ohio was studied to expand on previous research that observed an abrupt increase in high magnitude flood events on …
Mapping Michigan's Historic Coastlines, Ryan A. Williams
Mapping Michigan's Historic Coastlines, Ryan A. Williams
Dissertations, Master's Theses and Master's Reports
This five-year project, sponsored by the Michigan Department of Environment, Great Lakes, and Energy, is working to map how Michigan’s Great Lakes shorelines have changed over the past 80+ years. Products of this project include publicly available digital, georeferenced, historic aerial photography datasets, as well as map layers depicting the locations of historic shorelines and bluff lines from 1938, 1980, 2009, 2016, 2018, and 2020. Additional products include bluff retreat risk areas, shoreline rate of change map layers, and tools to assist in the development of future Coastal Vulnerability Index projects for the Great Lakes. All products are available as …