Physical Sciences and Mathematics Commons^™

Unsaturated Flow And Transport Of 90Sr, Co(Ii)Edta, And U(Vi) In Undisturbed Cores From The Hanford Formation, Hanford, Wa, Mary Fairfax Nichols-Pace

Doctoral Dissertations

At the U.S. Department of Energy’s Hanford Site in Richland, WA nuclear processing wastes, such as Sr-90, organic chelating agents such as EDTA, Co-60, and U(VI) have been detected in the vadose zone beneath the underground storage tanks. There is concern that waste released to the vadose zone could reach the groundwater and eventually flow into the Columbia River. The goal of this paper is to provide an improved understanding of coupled hydrologic and geochemical mechanisms that influence contaminant transport in the Handford vadose zone. Disturbed sediment and undisturbed sediment cores were collected from the Environmental Restoration Disposal Facility (ERDF) …

C3/C4 Variations In High Salt Marsh Sediments: An Application Of Compound Specific Isotopic Analysis Of Lipid Biomarkers To Late Holocene Paleoclimatic Research, Benjamin Ryan Tanner

Doctoral Dissertations

Chapter 1

Bulk carbon isotopes were previously used as a tool to differentiate between C3 and C4 plant communities in ancient salt-marsh deposits (Chmura and Aharon 1995). However, the bulk carbon values reflect organic matter contributions not only from salt-marsh plants, but also from algal bacterial inputs, as well as allochtonous terrestrial organic matter. The introduction of gas chromatography-isotope ratio mass spectrometery (GC-IRMS) allows for the separation of algal vs. higher plant contributions to the sediment pool. In the present study, this technique is applied to a core and modern plant samples collected from two Maine salt-marshes. We sampled 10 …

A Tree-Ring Oxygen Isotope Record Of Tropical Cyclone Activity, Moisture Stress, And Long-Term Climate Oscillations For The Southeastern U.S., Dana Lynette Miller

Doctoral Dissertations

Geological proxies are needed to extend the record of hurricane occurrence beyond historical observations. Tree rings preserve uniquely high resolution and precisely dated records of past environmental conditions. Oxygen isotopic compositions of alpha cellulose in seasonally-resolved components (earlywood (EW) and latewood (LW)) of tree rings of southeastern coastal plain pines predominantly reflect precipitation source and/or temperature providing a snapshot of climate activity for the region.

Tropical cyclones produce large amounts of precipitation with distinctly lower oxygen isotope ratios than typical low-latitude thunderstorms. Evidence of isotopically depleted precipitation may persist in surface and soil waters for several weeks after a large …

Geochemical Investigations Of Ordinary Chondrites, Shergottites, And Hawaiian Basalts, Valerie Slater Reynolds

Doctoral Dissertations

Part I: Quantifying peak temperatures achieved during metamorphism is critical for understanding the thermal histories of ordinary chondrite parent asteroids. I performed two-pyroxene geothermometry, using QUILF95, on the same Type 6 chondrites for which peak temperatures were estimated using the plagioclase geothermometer. Pyroxenes record a narrow, overlapping range of temperatures in H6 (865-926°C), L6 (812-934°C), and LL6 (874-945°C) chondrites. Lower plagioclase temperature estimates may not reflect peak metamorphic temperatures because chondrule glass probably recrystallized to plagioclase prior to reaching the metamorphic peak. The average temperature for H, L, and LL chondrites (~900°C) is at least 50°C lower than peak temperatures …

Analysis Of Martian Parental Melts And Thermal Infrared Studies Of Putative Paleolake Basins On Mars, Karen Renée Stockstill

Doctoral Dissertations

Both martian meteorites and remote sensing data allow us to study the geologic history of Mars. Martian meteorites can reveal information regarding partial melting of the Mars mantle and the surface processes that affected the meteorite following eruption (weathering, impact ejection, etc.). Remote sensing data can be used to investigate the local-, regional- or global-scale surface of Mars in terms of composition and geomorphology. A well-rounded approach is necessary to address fundamental questions regarding the geologic history of Mars.

We studied melt inclusions in augite of the martian meteorite Nakhla to better understand the magma that produced this rock. This …

The Middle Ordovician Tellico-Sevier Syncline: A Stratigraphic, Structural And Paleoseimic Investigation., Stephen Christopher Whisner

Doctoral Dissertations

Analyses of remote-sensing satellite data, aerial photography, radar images, and digital elevation models, and detailed (1:24,000-scale) geologic mapping of bedrock and surficial deposits were conducted in a portion of the southeastern Tennessee. This area contains the southern portion of the Tellico-Sevier Alleghanian syncline and the highest concentration of modern earthquakes as well as two major rivers with unconsolidated floodplain and terrace deposits that would be most susceptible to disruption by earthquakes. Cambrian to Mississippian age rocks occurs in the syncline. The majority of detailed mapping was conducted in Middle Ordovician Chickamauga Group rocks.

Earthquakes occur in the East Tennessee seismic …