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Browsing by Subject "Geochemistry"
Now showing items 1-20 of 24
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A Thermodynamic Analysis of Microbial Surface Chemistry and Metabolic Strategies
A thorough understanding of microbial life on Earth and effective methods of searching for life beyond Earth require the description of possible interactions between those organisms and their geochemical environments. Such ... -
Chemical and Biological Controls on Coral Nucleation
Coral reefs are vibrant and important ecosystems in the oceans, but reefs today are under threat from multiple sources. One such threat is ocean acidification due to anthropogenic climate change, which is reducing both ... -
Co-evolution of Life and Environment across Earth History: Empirical & Modeling Constraints on Nutrient Cycling, the Rise of Oxygen, and Eukaryotic Evolution
That life and its environment have co-evolved through Earth’s history, and in doing so have maintained the conditions required for planetary habitability, is one of the great discoveries in the natural sciences during 20th ... -
Early evolution of environments and metabolism: insights from nitrogen, selenium and sulfur isotopes
The evolution of planet Earth and its biosphere are tightly linked through global biogeochemical cycles, and this dissertation seeks to explore this linkage during the Precambrian with new strategies and geochemical ... -
Effects of the mid-Miocene Climatic Optimum on ecosystem structure and plant-animal interactions: a phytolith and stable isotope perspective
The mid-Miocene Climatic Optimum (MMCO, 17–14.75 Ma) is one of Earth’s most recent, prolonged global warming events that is thought to have promoted ecological change across the globe. Although there is general agreement ... -
Fundamental controls on triple oxygen-isotope ratios in Antarctic precipitation and ice cores
Stable isotope ratios of water (δD and δ18O) in polar precipitation and ice cores have long been used to study past climate variations and the hydrological cycle. Recently-developed methods permit the precise measurement ... -
Hydrogen Isotopes from Lipid Biomarkers: Purification, Field Calibration, and Application to Reconstructing Galapagos Paleohydrology
(2013-11-14)The tropics are centrally important in determining global climate patters as the primary heat and moisture source for atmosphere and ocean circulation. Understanding of the range of natural variability and the sensitivity ... -
Investigating the effects of <italic>Bacillus subtilis</italic> endospore surface reactivity on low-temperature aqueous geochemical systems
Microbes are a ubiquitous component in water-rock systems including ground and surface waters, soils, mid-ocean ridge hydrothermal systems, and deep sedimentary basins. Microbial envelopes provide complex organic surfaces ... -
Magnesium isotope fractionation associated with biotic and abiotic weathering -and- Developing a scalable method for rare earth element extraction from non-traditional feedstocks using engineered Escherichia coli
This dissertation is divided into two sections, with the first discussing magnesium (Mg) isotope behavior during biotic and abiotic rock weathering, and the second describing the application of engineered microbes for the ... -
Novel studies of McMurdo Dry Valleys ice-cemented permafrost cores document chemical weathering in permafrost and the timing of Plio-Pleistocene glaciations
The McMurdo Dry Valleys (MDV) are a frigid, hyperarid desert of Antarctica with a landscape dominated by ice-rich permafrost. This research focuses on using two ice-rich permafrost cores collected from the MDV to study ... -
The Paleocene Eocene Thermal Maximum in the Hanna Basin, WY: Constraints from Organic Carbon Isotopes and Palynological Data
(2014-02-24)The P-E boundary, approximately 56 Ma, coincides with a global climatic event, the Paleocene-Eocene Thermal Maximum (PETM). The PETM is believed to have resulted from a 2-8 fold increase in atmospheric pCO2 in less than ... -
Pyroxene Chemistry in Polymict Eucrite Northwest Africa 6475: Contrasts with Juvinas, Stannern and Igdi, and Evaluation of Models for Eucrite Magmatic Evolution
(2013-02-25)The eucrite meteorite suite is the mafic component of a silicate profile that formed from a magma ocean on a minor body, potentially the asteroid Vesta. There are four chemical divisions of eucrites: cumulate (CE), main ... -
Quantifying the deep: The importance of diagenetic reactions to marine geochemical cycles
Marine sediments play a fundamental role in long-term element cycles on Earth and host an expansive microbial ecosystem known as the “oceanic deep biosphere”. The biogeochemical and inorganic reactions that occur in the ... -
Re-Evaluating the Late Devonian Mass Extinction: A Geochemical Investigation of the Relationship between Carbon Isotope Fluctuations, Faunal Turnover, and Paleoenvironmental Change Recorded in Upper Devonian Carbonates of the Lennard Shelf, Western Australia
The primary goal of this dissertation is to increase understanding of the so-called Late Devonian mass extinction through the use of stable isotope geochemistry. Despite decades of research, the timing, cause(s), and extent ... -
Stable Isotopes in Unstable Times: A geochemical investigation of the end Cretaceous mass extinction
This primary goal of this dissertation is to increase understanding of the end Cretaceous (or Cretaceous - Paleogene or K-Pg) mass extinction through the use of light stable isotope geochemistry. These studies attempt to ... -
Structural controls and diagenetic conditions associated with fluid migration on the Moab Fault, UT
Faults and fault zones can have strong effects on fluid migration within the Earth’s crust, with important implications for resource management and earthquake hazards. The research presented within this dissertation addresses ... -
Temporal and Spatial Analysis of Groundwater Quality and Unconventional Gas Well Density in Washington County, Pennsylvania
A total of 265 household water supply samples were collected from 154 houses in Washington County, Pennsylvania between 2012 and 2014. The inorganic and anion constituent concentrations were compared to active unconventional ... -
Terrestrial Paleoclimate of the Cenozoic: Insights from and Developments of the Soil Carbonate Clumped Isotope Thermometer
Land temperature at the surface of the Earth is a first-order parameter used to describe climate, but reliable and widespread measurements of this basic parameter through geologic time has eluded geochemists and geologists ... -
The co-evolution of life and the nitrogen cycle on the early Earth
Nitrogen is an essential element for all life as we know it. Its abundance and speciation in the atmosphere and ocean has been dynamic through Earth’s history. The dynamic nature of nitrogen cycling is invariably linked ... -
The Okanogan lobe and Moses Coulee during the last glaciation
This thesis examines last-glacial chronologies of the Okanogan lobe of the Cordilleran Ice Sheet and explores whether this glacier released floods. The findings include age ranges for ice advance and retreat across the ...