Doctor of Philosophy, The Ohio State University, 2022, Earth Sciences

The study of past geologic records and present-day oceanographic processes can benefit society by better understanding how climate and biogeochemical processes interact in ocean. I present research that helps better understand these interactions by studying marine sediments, specifically barium in aqueous settings. This dissertation is separated into three projects that utilize geochemical interpretation of sediments and fluxes from the ocean to understand biogeochemical changes in past and present oceans. The first two projects study the export of carbon from ocean surface to deep waters in the tropical Pacific. The Maastrichtian records confirm that organic carbon export proxies related to barite (BaSO4) can be reconstructed at high-resolution using non-destructive X-ray fluorescence (XRF) Ba. This scanning XRF Ba record from 71.5 to 66 million years ago (Ma), after 405 kyr tuning, shows direct precessional cycle influence on organic carbon export during the cool greenhouse conditions of Late Cretaceous in the tropical Pacific. This suggests high frequency climate variability existed in the tropical Pacific and precession had a role in driving these changes, which were enhanced after Deccan volcanism when CO2 concentrations increased. A modern sediment trap record of carbon export determined by analyzing excess-Ba content (proxy for barite) from 2003 to 2013 records changed across a shift in the phase of the Pacific Decadal Oscillation (PDO). This record suggests upwelling is the main driving force for carbon export in the Eastern Tropical Pacific (ETP) by the carbon export showing variations following the PDO phases as similar to the upwelling magnitude changes, rather than the surface dust input. The dust deposition at the surface decoupled from dust export at depth leads to the conclusion that dust has limited role as a micronutrient source. Together these records suggest that hydrological changes in the tropical Pacific are important drivers of change for or (open full item for complete abstract)

Committee: Elizabeth Griffith (Advisor); Lonnie Thompson (Committee Member); Matthew Saltzman (Committee Member); Lawerence Krissek (Committee Member) Subjects: Geochemistry; Geology; Paleoclimate Science

Master of Science, The Ohio State University, 2015, Evolution, Ecology and Organismal Biology

Tree root exudation of soluble organic carbon (SOC) is often considered an important but under-assessed component of terrestrial net primary productivity that also strongly influences rhizosphere and soil biogeochemical processes. Although riparian and bottomland systems are often considered “hot spots” of biogeochemical activity that are potentially supported by root exudate SOC, in situ tree root exudation rates of SOC have not been previously reported for these systems. Additionally, there is an outstanding need to understand the δ13C signatures of root exudates in relation to not only different plant components such as leaves and roots but also different ecosystem pools of C, such as CO2 emitted from soil. In the present study we used an in situ method to collect root exudate SOC in order to assess root exudation rates in a bottomland forest for Acer saccharinum, Populus deltoides and Platanus occidentalis trees over five sampling dates ranging from mid-summer to late-autumn. Leaves from Acer negundo, Acer saccharinum, Lonicera maackii, Populus deltoides and Platanus occidentalis were also collected. δ13C values were determined for all of the root exudates, roots and leaves collected in this study. Exudation rates and δ13C values were evaluated in relation to leaf and root morphology, leaf and root C and N contents and a number of environmental parameters (e.g. vapor pressure deficit) and net ecosystem exchange (NEE). Findings indicate that exudation rates and δ13C values of leaves and roots were significantly correlated to time-lagged measurements of NEE, suggesting a strong link between exudation rates and δ13C values of leaves and roots and photosynthetic rates. Various time lagged environmental parameters (e.g., vapor pressure deficit) were correlated to the δ13C of exudates, leaves and roots—suggesting a rapid transfer of recent photosynthate from the canopy to roots and root exudates and relatively rapid turnover of C in leaves. When pooled toge (open full item for complete abstract)

Committee: James Bauer (Advisor); Brian Lower (Committee Member); Peter Curtis (Committee Member) Subjects: Biogeochemistry; Ecology; Plant Biology

Master of Science, The Ohio State University, 2012, Geological Sciences

Rivers and streams draining active mountain terrains are known to transport an amount of sediment and chemical weathering products that is disproportionately large compared to the amount of land area occupied by active mountain terrains on the earth's surface. SuchThese high rates of material transport are attributed to the high rates of physical erosion that accompany active mountain building events. Physical erosion mobilizes particulate material, including organic carbon, and can expose un-weathered bedrock to atmospheric weathering. Chemical weathering in active mountain terrains plays a significant role in the global carbon cycle and thus plays a role in global climate change over geologic time scales by removing CO2 from the atmosphere. The relationship between CO2 and climate has been illustrated, as has the theory that current atmospheric CO2 concentrations will result in global climate change. It is critical that carbon fluxes from the atmosphere be quantified in order to better understand the mechanisms controlling atmospheric CO2 concentrations. Natural mechanisms controlling atmospheric CO2 concentrations vary regionally, and so it is important that CO2 yields from watersheds in previously unstudied actively uplifting regions be quantified and controls on these yields elucidated. Here, CO2 yields from watersheds draining the Sierra de las Minas in Guatemala are quantified. These yields are similar to the high yields observed in other active mountain regions worldwide and underscore the importance of these areas in the global carbon cycle and global climate forcing. In addition, this study also supports the positive relationship between annual precipitation and chemical yields that has been observed elsewhere. This relationship may be influenced by mountain uplift causing local orographic increases in precipitation. Extreme storm events such as typhoons and hurricanes have been shown to transport a large percentage of annual particulate organic carbon y (open full item for complete abstract)

Committee: Dr. Anne E. Carey PhD (Advisor); Dr. Carla Restrepo PhD (Committee Member); Dr. W. Berry Lyons PhD (Committee Member); Dr. Michael Barton PhD (Committee Member) Subjects: Earth

Doctor of Philosophy, The Ohio State University, 2008, Geological Sciences

Tropical small mountainous rivers (SMRs) may transport up to 33% of the total carbon (C) delivered to the oceans. However, these fluxes are poorly quantified and historical records of land-ocean carbon delivery are rare. Corals have the potential to provide such records in the tropics because they are long-lived, draw on dissolved inorganic carbon (DIC) for calcification, and isotopic variations within their skeletons are useful proxies of palaeoceanographic variability. The ability to quantify riverine C inputs to the coastal ocean and understand how they have changed through time is critical to understanding global carbon budgets in the context of modern climate change. A seasonal dual isotope (13C & 14C) characterization of the three major C pools in two SMRs and their adjacent coastal waters within Puerto Rico was conducted in order to understand the isotope signature of DIC being delivered to the coastal oceans. Additionally a 56-year record of paired coral skeletal C isotopes (δ13C & Δ14C) and trace elements (Ba/Ca, Mn/Ca, Y/Ca) is presented from a coral growing ~1 km from the mouth of an SMR. Four major findings were observed: 1) Riverine DIC was more depleted in δ13C and Δ14C than seawater DIC, 2) the correlation of δ13C and Δ14C was the same in both coral skeleton and the DIC of the river and coastal waters, 3) Coral δ13C and Ba/Ca were annually coherent with river discharge, and 4) increases in coral Ba/Ca were synchronous with the timing of depletions of both δ13C and Δ14C in the coral skeleton and increases in river discharge. This study represents a first-order comprehensive C isotope analysis of major C pools being transported to the coastal ocean via tropical SMRs. The strong coherence between river discharge and coral δ13C and Ba/Ca, and the concurrent timing of increases in Ba/Ca with decreases in δ13C and Δ14C suggest that river discharge is simultaneously recorded by multiple geochemical records. Based on these findings, the development of coral-b (open full item for complete abstract)

Committee: Andrea Grottoli PhD (Advisor); James Bauer PhD (Committee Member); Anne Carey PhD (Committee Member); Yu-Ping Chin PhD (Committee Member); Matthew Saltzman PhD (Committee Member) Subjects: Biogeochemistry; Geochemistry; Geology; Oceanography

Doctor of Philosophy, The Ohio State University, 2006, Chemistry

Biomass burning and fossil fuel combustion have resulted in the global distribution and accumulation of black carbon in soils and sediments. Black carbon is currently produced at an estimated rate of 1014 g per year, but little is known about its environmental fate and reactivity. Most of this black carbon is charcoal formed by forest fires. The original research in this dissertation is divided among two overarching themes involving the organic geochemistry of the charcoal deposited to soils by biomass burning. The first theme is oriented toward understanding the importance of environmental charcoal as a geosorbent for hydrophobic contaminants (PAHs). The sorption capacity of environmental charcoal differs significantly from that of recently deposited or lab-generated chars. The competitive sorption of natural organic matter is implicated as the cause of diminished sorption capacity. New sorption models are proposed to address the prediction of PAH uptake by fire-impacted soils. The second research theme deals with the environmental fate of charcoal black carbon. Advanced imaging and magnetic resonance techniques were used to compare and contrast the morphology and chemical composition of recently-formed forest fire charcoals to those aged in soil. The colonization of charcoal particles by filamentous microorganisms was an intriguing observation that motivated an investigation of the feasibility of enzymatic charcoal degradation. The lignolytic fungal enzyme, laccase, causes a modest but discernable oxidation and humification of soil charcoal. The spectroscopic analyses also extend to natural waters of a fire-impacted watershed as a potential conduit for the export of charcoal black carbon from soils. Condensed aromatic leachates from the soil charcoal are prevalent in the dissolved organic matter of the soil pore, river, and ground water.

Committee: Patrick Hatcher (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2023, Civil Engineering

Reducing CO2 emissions will be critical for meeting global targets of net zero CO2 emissions by the year 2050 and net negative CO2 emissions by 2100. To help meet these emission reduction targets there will need to be a rapid transition from a historical reliance on fossil fuels for energy generation to renewable and low CO2 emission energy generation technologies, a so-called energy transition. The energy transition will feature an increase in demand for valuable resources like rare earth elements and see widespread deployment of carbon capture, utilization, and storage infrastructure. In the first chapter we explore a novel trap-extract-precipitate (TEP) system that looks to trap rare earth elements (REEs) found in coal mine drainage before later extracting the REEs from the trap material. We apply a techno-economic analysis and life cycle assessment to two different iterations of the TEP system design to determine a levelized cost of the process and associated environmental and human health impacts. Our results indicate that the levelized cost of the process is $278/gT-REE and $86/gT-REE for two designs using different industrial by-products. Further, when considering just the passive treatment cell of the system design, we observe environmental and human health benefits that are lost once we shift the scope to include the chemical extraction of REEs. Chapter 3 evaluates the impact of stacked storage on carbon capture and storage (CCS) systems by looking at how networks change when CO2 is emplaced in different geologic CO2 storage (GCS) locations. This case study focuses on Oklahoma, which has GCS resources and existing CO2-EOR operations, both needed for stacked storage. We use an economic engineering geospatial linear optimization model, SimCCSPRO, to determine the least cost combination of point sources, GCS locations, and pipeline networks. Our results suggest point sources of CO2 drive CCS pipeline network deployment. Additionally, we identify counties t (open full item for complete abstract)

Committee: Jeffrey Bielicki (Advisor); Daniel Gingerich (Committee Member); Gil Bohrer (Committee Member); Jordan Clark (Committee Member) Subjects: Civil Engineering; Environmental Engineering

Doctor of Philosophy, The Ohio State University, 2023, Earth Sciences

Our understanding of the Earth's multimillion-year carbon cycle, with primary implications for the evolution of life, depends on our ability to decipher information encoded in chemical signals of shallow marine sediments. This dissertation attempts to develop our knowledge of two main topics: (1) the causes of multimillion-year global climate change in terms of changes in the sources and sinks of atmospheric carbon dioxide (CO2), and (2) the causes and meaning of post-depositional alteration of shallow marine sediments with respect to chemical proxy records of the evolution of global (and/or local) Earth processes. To this end, this work applies radiogenic strontium and neodymium (87Sr/86Sr, εNd(t)) and stable calcium (δ44/40Ca) isotopic records in bulk carbonate rocks and conodont apatite from Middle–Late Ordovician (Darriwilian–Katian stages; ~470–450 million years ago, abbrev. Ma) sections in the Antelope Range, central Nevada; Clear Spring, Maryland; and the Fjacka and Kargarde sections of the Siljan district, Dalarna province, central Sweden. Bulk rock samples from the tropical Middle–Late Ordovician setting of the Antelope Range, Nevada were analyzed for proxy records of regional and global continental weathering source lithology (87Sr/86Sr and εNd(t)) which were paired with published paleotemperature proxy measurements (δ18O) of conodont apatite from the same section. This paired suite of proxy records is used to test the hypothesis that low-latitude island arc accretion during the Middle–Late Ordovician Taconic Orogeny enhanced the weatherability of Earth's crust, increasing the rate of CO2 removal by the weathering of mafic silicate minerals and producing the global cooling observed in the Middle–Late Ordovician paleotemperature record. These records show coeval inflections in 87Sr/86Sr and εNd(t) values at ~463 Ma that reveal the influence of tectonic uplift and enhanced weathering of mafic ophiolite provinces on the Taconic margin. This change in weather (open full item for complete abstract)

Committee: Matthew Saltzman (Advisor); Audrey Sawyer (Committee Member); Elizabeth Griffith (Committee Member); William Ausich (Committee Member) Subjects: Chemistry; Earth; Geochemistry; Geology

Master of Science, The Ohio State University, 2022, Earth Sciences

Equatorial upwelling makes the eastern equatorial Pacific (EEP) one of the largest source regions of CO2 to the atmosphere today, but primary production is limited by scarce micronutrients. This pattern of upwelling was likely present during the middle Miocene Climate Optimum (mMCO; 16.9 – 14.7 Ma), a warmer interval that is a potential analogue for near-future conditions, although productivity variations are less well known. Here I examined whether variations in micronutrient flux impacted productivity in the EEP in response to orbital eccentricity cycles (100 and 400 k.y.) during the mMCO. Eccentricity has a well-noted impact on middle Miocene climate, as seen by nine short-term positive benthic δ13C maxima (CM) events occurring at 400 k.y. eccentricity minima as well as bottom water warming and cooling at 100 k.y. eccentricity. A new marine pelagic barite record spanning 16.94 -14.0 Ma at International Ocean Discovery Program Site U1337 was produced and is compared to published XRF paleoproductivity and micronutrient data from the same site. Within the first ~ 500 k.y. interval of this study (16.94 – 16.46 Ma), extraterrestrial (ET) 3He and terrestrial 4He concentrations were measured to better constrain accumulation rates. During this interval, there is no consistent association between barite accumulation and 100 k.y. eccentricity, suggesting variability in barite is due primarily to carbonate dissolution. However, corresponding increases in the ET 3He-normalized barite and terrestrial proxies (Ti, Al, Fe) occurred during these first two CM events. Increases in upwelled micronutrient iron in the EEP during these CM events likely stimulated and increased export production in the early mMCO. However, because carbonate accumulation increased more than opal or barite during one of these events, the EEP did not likely contribute to net carbon sequestration at this time. Instead, a stimulated carbonate counterpump may have expanded the EEP's role as a carbon sou (open full item for complete abstract)

Committee: Elizabeth Griffith (Advisor); Lonnie Thompson (Committee Member); Jill Leonard-Pingel (Committee Member) Subjects: Geochemistry; Geology; Paleoclimate Science

Master of Science (MS), Ohio University, 2021, Environmental Studies (Voinovich)

Life cycle analysis (LCA) allows for evaluation of the environmental costs of production systems from creation to disposal. Many LCA studies are available for various renewable energy production systems, however, there is a need for LCAs that quantify the benefits of energy coproduction systems. Coproduction systems refer to a partnership of energy production systems that reciprocate waste products in a mutually beneficial way, thereby decreasing waste streams and offsetting input streams from both systems. This study evaluates how biomass crop coproduction with an anaerobic digestion (AD) system affects the life cycle greenhouse gas emissions and material waste streams relative to standalone bioenergy systems. A literature meta-analysis was used to collect life cycle inventories, emissions, and cost for: 1) Advanced biofuel production from perennial grass, 2) Biogas production from AD. The reduction in emissions due to coproduction was 0.28 kgCO2eq per kWh electricity produced. Life cycle impacts were most influenced by the following categories: facility construction, harvest and lignin use, transportation and biorefinery, and effluent, fertilizer, and soil. The cost for coproduction of biogas from food waste and bioethanol from perennial grass was reduced by 10.8% and 7.0%, respectively, when compared to the cost for individually managed systems.

Committee: Sarah Davis (Committee Chair); David Bayless (Committee Member); Derek Kauneckis (Committee Member) Subjects: Agriculture; Alternative Energy; Biogeochemistry; Climate Change; Energy; Environmental Economics; Environmental Science

Doctor of Philosophy, The Ohio State University, 2020, Earth Sciences

In the ocean and on land, many biogeochemical processes have feedbacks on climate. How these processes affect climate or respond to climate changes over long timescales is not always well understood as they are difficult to study in the modern day. The research reported here aims to better understand some of these processes, specifically erosion and sediment deposition, as well as the biogeochemical cycling of barium in the oceans. This research is separated into four projects that use geochemical and computational techniques to link long-term regional climate changes with atmosphere and ocean dynamics. The first two projects use samples from the Arabian Sea, collected during International Ocean Discovery Program Expedition 355 Arabian Sea Monsoon. During this expedition two sites were drilled, Sites U1456 and U1457 located within Laxmi Basin in the Arabian Sea. Samples range in age from 0-11 Ma. In project one, strontium isotope ratios (87Sr/86Sr) from pore fluids from Sites U1456 (n = 21) and U1457 (n = 20) were measured to characterize diagenetic reactions. Pore fluid 87Sr/86Sr is useful to establish fluid-rock reactions, sources, and fluid mixing that may have occurred after deposition, processes that could influence the signal recorded by proxy records from these marine sediment cores. The measured pore fluid 87Sr/86Sr has significant variations at both sites and three distinct zones of diagenetic processes are identified, with similar characteristics at both sites. In the second project, 87Sr/86Sr (n=127) and neodymium isotopes (εNd) (n=38) are measured from the separated clay fraction in sediments from the same cores to investigate their provenance. Provenance is the geographic origin of sediments deposited in a basin and is important to reconstruct so we can understand sediment pathways and constrain paleoclimate and erosion records. The records produced are also compared to 87Sr/86Sr and εNd of the carbonate-free bulk sediment from the same sites in ord (open full item for complete abstract)

Committee: Elizabeth Griffith (Advisor); Andrea Grottoli (Committee Member); Matthew Saltzman (Committee Member); Audrey Sawyer (Committee Member) Subjects: Geochemistry; Geology; Paleoclimate Science

Master of Science, The Ohio State University, 2020, Environmental Science

In the arctic region, permafrost exists as a deep, frozen layer of soil, some of which formed during cold glacial periods thousands of years ago. This freeze effectively trapped carbon and other nutrients from decomposing and/or cycling into the ecosystem. However, due to climate warming, this frozen layer is thawing, releasing long-storage carbon stocks and transforming the landscape as ground sinks to fill space left by ice. This consequently drives shifts in hydrology (i.e., water-levels) and in plant communities, with their own impacts on carbon balance. My master's thesis work examines arctic wetland plants under climate change, as part of an interdisciplinary US Department of Energy-funded exploration of carbon cycling of these wetland systems that spans microbiology to models, and via which I get to actively and regularly engage with project colleagues from 13 institutions across 3 continents (The IsoGenie Project). A major goal of this work is to better understand and predict changing carbon budgets in the Arctic, and the magnitude of their climate feedbacks, thereby directly informing climate mitigation and adaptation efforts. The IsoGenie Project has been studying this phenomenon at Stordalen Mire, a northern peatland in Sweden, which is actively thawing. This active thaw allows us to observe three unmistakable habitat-types in one location, each with their own distinct hydrology and plant community. After thaw-associated inundation, the Stordalen Mire dwarf-shrub dominated palsa experiences an intermediate shift to moss dominated (Sphagnum sp.) bog and finally into a graminoid dominated (Eriophorum sp.) fen. We refer to this linear progression of habitat and vegetation changes as the thaw gradient. Prior studies have supported that post-thaw shifts in community composition, coupled with shifts in environmental conditions, will influence the vegetation's role in rate of C and nutrient cycling after thaw. My thesis research asks how permafrost thaw ch (open full item for complete abstract)

Committee: Virginia Rich (Advisor); Gil Bohrer (Committee Member); Scott Saleska (Committee Member); Mark Dilley (Committee Member) Subjects: Climate Change; Environmental Studies; Freshwater Ecology; Plant Biology

Master of Science, The Ohio State University, 2019, Chemical Engineering

Carbon capture has been regarded as one of the viable solutions to mitigate the global warming effect due to CO2 emission and sustain the use of fossil fuels, but the energy load associated with implementing carbon capture in coal-fired power stations can notably decrease the efficiency of power generation. To overcome the deficiency, exploring novel materials for carbon capture has drawn significant attention. Specifically, metal-organic frameworks (MOFs) have been identified as promising adsorbents for carbon capture because of their highly tunable nature, selective adsorption, and large adsorption capacity. A large number of MOFs have been discovered in recent years, and many of them have been demonstrated to possess promising separation performance. To date, most of the studies reported have mainly focused on exploring potential MOF candidates by evaluating their adsorption properties (e.g., selectivity) or their performance using a process model. Although MOFs have been demonstrated to show potentially better performance (i.e., less energy intensity) than MEA, the overall impact by this emerging new class of materials remains unknown. To this end, to facilitate the development of a new technology based on MOF adsorbents, the overall impacts of implementing MOF-based carbon capture, including the energy load and resource depletion from the MOF synthesis process as well as other steps in the whole life cycle of MOFs, should be considered. In this study, we present a comprehensive life-cycle analysis for a selected set of 50 MOFs to evaluate the overall impact of MOF-based post-combustion carbon capture and compared with that by MEA. Our results again show the great promise of MOFs in carbon capture. From the life cycle point of view, besides the energy load of capturing carbon using MOFs, we find significant impacts from the use of solvent in MOF-based carbon capture. Furthermore, the key role of MOF stability is also identified in determining the overall impact. (open full item for complete abstract)

Committee: Li-Chiang Lin (Advisor); Bhavik Bakshi R (Advisor) Subjects: Chemical Engineering

Doctor of Philosophy, University of Toledo, 2018, Civil Engineering

This dissertation explores the eco-design concepts for emerging PV cells. By conducting life cycle assessment (LCA) method, I addressed the following questions: (1) What is the environmental impact of a scalable perovskite PV cell? (2) How important are the metal emissions from the emerging thin film devices during the use phase? (3) What are the environmental impacts and costs of the materials used in emerging PVs? These questions are addressed in the analyses presented in the Chapters two, three and four, respectively. Chapter two assesses the environmental impacts of perovskites PVs that have device structures suitable for low cost manufacturing. A structure with an inorganic hole transport layer (HTL) was developed for both solution and vacuum based processes, and an HTL-free structure with printed back contact was modeled for solution-based deposition. The environmental impact of conventional Si PV technology was used as a reference point. The environmental impacts from manufacturing of perovskite solar cells were lower than that of mono-Si. However, environmental impacts from unit electricity generated were higher than all commercial PV technology mainly because of the shorter lifetime of perovskite solar cell. The HTL-free perovskite generally had the lowest environmental impacts among the three structures studied. Solution based methods used in perovskite deposition were observed to decrease the overall electricity consumption. Organic materials used for preparing the precursors for perovskite deposition were found to cause a high marine eutrophication impact. Surprisingly, the toxicity impacts of the lead used in the formation of the absorber layer were found to be negligible. Chapter three addresses the life cycle toxicity of metals (cadmium, copper, lead, nickel, tin and zinc) that are commonly used in emerging PVs. In estimating the potential metal release, a new model that incorporates field conditions (crack size, time, glass thickness) and phy (open full item for complete abstract)

Committee: Defne Apul (Committee Chair); Michael Heben (Committee Member); Randall Ellingson (Committee Member); Constance Schall (Committee Member); Cyndee Gruden (Committee Member); Kumar Ashok (Committee Member) Subjects: Energy; Environmental Engineering

Master of Science (M.S.), University of Dayton, 2018, Renewable and Clean Energy

The off-grid location and unreliable electricity supply to medical clinics in remote parts of India make it difficult to safely store vaccines and other medications using traditional refrigeration systems. The Engineers in Technical Humanitarian Opportunities of Service-learning (ETHOS) program at the University of Dayton, in collaboration with Solar Alternative and Associated Programmes (SAAP) of Patna India, are developing a novel refrigeration system which works on the principle of solar thermal adsorption. This refrigeration system does not require electricity for operation and uses safe, environmentally benign and locally available adsorption pair of ethanol-activated carbon. A bench -scale prototype was developed at the University of Dayton using ethanol-activated carbon as working pair which can generate evaporative temperatures between 2°C and 8°C. The existing horizontally oriented system can achieve targeted refrigeration temperatures (2 - 8°C) during the adsorption cycle and ethanol can be desorbed from the activated carbon during desorption. However, the horizontal geometry inhibited the return of liquid ethanol to the evaporation chamber. A new vertical oriented bench scale system was built to addresses the limitation of the original prototype. The effects of desorption heating temperature, desorption time duration, double activation of activated carbon on evaporative cooling, and possible decomposition of ethanol during desorption were analyzed. Experimental results suggested better desorption happens at elevated temperature (90-125°C) and most of the desorption happens in the first 1-2 hours of heating the adsorbent bed. The high pressure on the evaporator side for multiple adsorption-desorption process, and analysis of GC/MS of desorbed ethanol obtained from the analytical chemist showed possible decomposition of ethanol. The ethanol decomposition prevented multiple cycle operation of the system. The use of double activation techn (open full item for complete abstract)

Committee: Amy Ciric Ph.D. (Committee Chair); Jun Ki Choi Ph.D. (Committee Chair); Li Cao Ph.D. (Committee Member) Subjects: Alternative Energy; Chemical Engineering; Chemistry; Climate Change; Energy; Engineering; Environmental Science; Experiments; Materials Science; Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 1974, Graduate School

Committee: Not Provided (Other) Subjects: Biology

PhD, University of Cincinnati, 2016, Engineering and Applied Science: Aerospace Engineering

A real fluid heat engine power cycle analysis code has been developed for analyzing the zero dimensional performance of a general recuperated, recompression, precompression supercritical carbon dioxide power cycle with reheat and a unique shaft configuration. With the proposed shaft configuration, several smaller compressor-turbine pairs could be placed inside of a pressure vessel in order to avoid high speed, high pressure rotating seals. The small compressor-turbine pairs would share some resemblance with a turbocharger assembly. Variation in fluid properties within the heat exchangers is taken into account by discretizing zero dimensional heat exchangers. The cycle analysis code allows for multiple reheat stages, as well as an option for the main compressor to be powered by a dedicated turbine or an electrical motor. Variation in performance with respect to design heat exchanger pressure drops and minimum temperature differences, precompressor pressure ratio, main compressor pressure ratio, recompression mass fraction, main compressor inlet pressure, and low temperature recuperator mass fraction have been explored throughout a range of each design parameter. Turbomachinery isentropic efficiencies are implemented and the sensitivity of the cycle performance and the optimal design parameters is explored. Sensitivity of the cycle performance and optimal design parameters is studied with respect to the minimum heat rejection temperature and the maximum heat addition temperature. A hybrid stochastic and gradient based optimization technique has been used to optimize critical design parameters for maximum engine thermal efficiency. A parallel design exploration mode was also developed in order to rapidly conduct the parameter sweeps in this design space exploration. A cycle thermal efficiency of 49.6% is predicted with a 320K [47°C] minimum temperature and 923K [650°C] maximum temperature. The real fluid heat engine power cycle analysis code was expanded to study a (open full item for complete abstract)

Committee: Mark Turner Sc.D. (Committee Chair); Shaaban Abdallah Ph.D. (Committee Member); Milind Jog Ph.D. (Committee Member) Subjects: Energy

Master of Science (MS), Wright State University, 2006, Biological Sciences

Mutant screening and genetic selection in various organisms have shown that residues far from the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) can influence catalytic efficiency and CO2/O2 specificity. Because RubisCO catalyzes the rate-limiting step of photosynthesis, further study of these sites distant from the primary reaction center may provide the necessary information for engineering an increase in primary productivity of crop plants. In a previously described system of random mutagenesis and bioselection (Smith, 2002), the RubisCO genes from the cyanobacterium Synechococcus PCC6301, were randomly mutated and introduced into the photosynthetic bacterium Rhodobacter capsulatus. An A47T substitution resulted in a very modest loss of specific activity. However, this mutant was not functional relative to the wild-type when complementation was performed. Since mutants with even lower catalytic activity were able to complement a RubisCO deletion strain to photoautotrophic growth, it was hypothesized that the A47T mutation affected important kinetic properties of RubisCO. To further explore the role of this residue, A47 in the cyanobacterial enzyme was changed to Glycine and Proline by site-directed mutagenesis. Analysis of the recombinant proteins demonstrated that both mutant enzymes exhibited lower specific activity than the wild-type enzyme when expressed in E. coli. To examine the possibility that the decrease in specific activity was due to decreased expression of the mutant enzymes, SDS-PAGE and Western Blots were performed. SDS-PAGE and Western blotting indicated that there was slightly less of the enzyme present for the mutants. This could be the result of decreased synthesis or increased degradation. Native PAGE demonstrated that the G mutant might be a folding-mutant, since it does not have any detectable holoenzyme on non-denaturing PAGE. To further support this hypothesis, there was also a doublet band present in the mutants (open full item for complete abstract)

Committee: Stephanie Smith (Advisor) Subjects:

MS, University of Cincinnati, 2012, Arts and Sciences: Geology

Soil organic carbon affects soil fertility and agricultural production, and organic C storage can also mitigate increasing atmospheric CO2 concentrations on decadal time scales or longer. However, soil organic C storage is dependent on climatic conditions, especially temperature and precipitation, and changes in these parameters associated with climate change can act as feedback mechanisms to atmospheric CO2 concentrations. The objective of this study is to evaluate regional organic carbon abundance in northern India across orographically-limited precipitation regimes. We hypothesized that the existence of a soil organic carbon (SOC) gradient corresponding to these bioclimatic barriers, a result of this large precipitation and assumed vegetation discrepancy. Samples were collected from the Kulu Lesser Himalaya, Lahul Himalaya, and Zanskar and measured for SOC/TN inventory as well as ?14C and d13C analysis of soil organic matter (SOM). Average annual carbon accumulation and C turnover time were estimated for selected soil chronosequences, and results varied widely among the areas investigated. It was revealed that soil organic C stocks in the Indian Himalaya are sensitive to precipitation, C3 vegetation has been consistently dominant up to ~6ka B.P., and rates of accumulation and turnover are influenced greatly by variations in climate, vegetation, and topography. Examining the distribution of soil organic carbon stock can be useful in helping to predict the potential effects of warming and precipitation on C storage in this region.

Committee: Amy Townsend-Small PhD (Committee Chair); Craig Dietsch PhD (Committee Member); Lewis Owen PhD (Committee Member) Subjects: Geochemistry

Master of Science, The Ohio State University, 2012, Environment and Natural Resources

Carbon storage in eastern U.S. forests is threatened by stem-girdling invasive insects, along with natural succession as pioneer tree species age and die. In Northern lower Michigan we are investigating the impact of these intermediate disturbances on above- and below-ground carbon cycling across a mixed hardwood and pine forest. In spring 2008, early successional tree species, such as aspen (Populus grandidenta and P. tremuloides), were experimentally girdled in the Forest Accelerated Succession Experiment (FASET), while a nearby long-term research site, Ameriflux (AF), remained undisturbed. Soil respiration (Rs) is known to be responsive to disturbance and comprises the largest fraction of total ecosystem respiration (Re). However, determining effects of management on Rs is complicated by difficulties accurately measuring temporal variability in soil respiration and biophysical controlling factors such as soil temperature and soil water content (SWC). The objective of this study was to quantify Rs (soil CO2 efflux) and its constraints and drivers in disturbed and undisturbed forests and under early successional and late successional tree species. Rs, temperature, and SWC were intensively measured at four instrumented sites and extensively measured across the landscape along a number of 1km transects. A nested study design featured paired sites under early- and late-successional tree canopies (aspen and oak) in disturbed and undisturbed forest (FASET and AF). Rs was measured every hourly at the soil pits using an automated closed-chamber CO2 efflux system and biweekly along the 1km transects using a portable closed-chamber CO2 efflux system. Rs decreased under the canopy of disturbed aspen trees compared to controls aspen trees but was unchanged under the canopy of disturbed oak trees compared to control oak trees. Temperature sensitivity of Rs, as measured by a Q10 analysis, decreased under both aspen and oak trees in the disturbed forest compared to the control f (open full item for complete abstract)

Committee: Peter Curtis (Committee Chair); Richard Dick (Committee Member); Gil Bohrer (Committee Member) Subjects: Ecology

Doctor of Philosophy, The Ohio State University, 2009, Geological Sciences

Studies of chemical weathering have shown that high standing islands (HSIs) have some of the highest yet observed rates of chemical weathering and associated CO2 consumption. To determine the role these islands play on climate the following were evaluated: 1. dissolved, particulate and organic carbon fluxes delivered to the ocean from a small-mountainous river (SMR) on an HSI during an intense storm event; 2. relationship between physical and chemical weathering rates on an HSI characterized by ranges of uplift rates and lithology; 3. water and sediment geochemical fluxes and CO2 consumption rates on HSIs with andesitic-dacitic volcanism; and 4. the overall chemical weathering fluxes and CO2 consumption rates from andesitic-dacitic terrains on HSIs of the Pacific and the East and Southeast Asia region. This study, the first comprehensive evaluation of weathering processes on HSIs, provides valuable insights on the relationship of silicate weathering and global CO2 drawdown on various timescales. Storm fluxes observed from the Chosui River in Taiwan during Typhoon Mindulle in 2004 revealed the role these events can play in the delivery of sediment, particulate organic carbon (POC) and solutes to the ocean. Linkage of high amounts of POC with sediment concentrations capable of generating a hyperpycnal plume upon reaching the ocean provides the first known evidence for the rapid delivery and burial of POC from the terrestrial system. These fluxes, when combined with storm derived CO2 consumption from silicate weathering, elucidate the important role of these tropical cyclone events on SMRs as a global sink of CO2. Carbonate weathering was shown to supply a significant portion of the total cation yields while silicate weathering plays a lesser role. Various relationships were observed between chemical, carbonate, and silicate weathering yields with basin average mean annual rainfall, average basin runoff, annual suspended sediment yields, and post-uplift age of the la (open full item for complete abstract)

Committee: Anne E. Carey PhD (Advisor); W. Berry Lyons PhD (Committee Member); Michael Barton PhD (Committee Member); Wendy Panero PhD (Committee Member) Subjects: Earth; Geochemistry; Geology