Doctor of Philosophy, The Ohio State University, 2015, Evolution, Ecology and Organismal Biology

Planting of semi-domesticated grasses for habitat restoration and bioenergy has raised concerns about potential ecological consequences, for instance, genetic swamping of wild populations through crop-to-wild gene flow, and introgression of crop traits into wild relatives resulting in more invasive wild populations. In this dissertation, I explored different aspects of gene flow in two popular bioenergy candidates — switchgrass (Panicum virgatum) and Miscanthus (Miscanthus spp.) — and aimed to provide necessary information to mitigate potential gene flow from new switchgrass and Miscanthus cultivars. Switchgrass cultivars have been planted in Conservation Reserve Program (CRP) areas when wild seed sources are limited. However, the close proximity of CRP areas and remnant prairies may have allowed rapid crop-to-wild gene flow. In the first chapter, I investigated ploidy levels, genetic diversity, and genetic structure of seventeen prairie and sixteen CRP populations in eastern Kansas, along with five standard cultivars. The results suggested that the prairie and CRP populations were genetically similar, and the CRP populations were mainly established using local prairie seeds rather than cultivars. In addition, the prairie populations still harbor unique alleles that are of conservation value. Sufficient isolation distance between cultivated plants and their wild relatives is essential to prevent crop-to-wild gene flow, especially when the crop carries transgenes. In the second chapter, I documented the pattern and predicted the extent of pollen-mediated gene flow in switchgrass using two small field experiments with ~100 pollen donor plants and regression models. Data suggested that the pattern of gene flow was best described by a negative exponential model, and the estimated minimum isolation distance for a threshold of 0.01% gene flow was 60m and 109m for the experimental arrays. Seed-mediated gene flow could result in volunteers when favorable conditions (open full item for complete abstract)

Committee: Allison Snow (Advisor); Kristin Mercer (Committee Member); Maria Miriti (Committee Member); Andrea Wolfe (Committee Member) Subjects: Ecology

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

Master of Science (MS), Ohio University, 2019, Environmental Studies (Voinovich)

Miscanthus x giganteus (miscanthus), a perennial rhizomatous grass with a C4 photosynthetic pathway, has the potential to reduce greenhouse gas (GHG) emissions as it sequesters carbon into soil. Although fertilizer application to miscanthus sometimes increases yield, especially after five growing seasons, unintended impacts of GHG emissions resulting from the application of fertilizer has also been documented. This study evaluated the effects of four different fertilization treatments (digestate from a biodigester, synthetic nitrogen fertilizer, hydrochar from hydrothermal carbonization of digestate, and a control) on soil GHG emissions and biomass yield of an established miscanthus stand grown on abandoned agricultural land. Soil greenhouse gas fluxes (including CH4, CO2, and N2O) were sampled in all treatments using the static chamber methodology. There were no significant differences in biomass yield among the four treatments. Average biomass yield varied from 20.2 Mg/ha to 23.5 Mg/ha between the four treatments. Even though there was no significant difference between CO2 fluxes in the four treatments over the growing season, the hydrochar treatment reduced CO2 fluxes by up to 34% compared to the control treatment. Applying digestate to miscanthus resulted in a CH4 source while nitrogen and hydrochar acted as CH4 sinks. Overall, fertilization did not improve biomass yield but the hydrochar treatment appeared to be a better alternative at reducing GHG fluxes when compared to the other treatments.

Committee: Sarah Davis PhD (Committee Chair); Jared DeForest PhD (Committee Member); Toufiq Reza PhD (Committee Member) Subjects: Agriculture; Alternative Energy; Biogeochemistry; Climate Change; Energy; Environmental Studies; Soil Sciences

Bachelor of Arts (BA), Ohio University, 2018, Environmental Studies

True emissions from bioenergy fuel sources not only depend on direct emissions from burning the fuel but also emissions associated with growing and processing the crop. An increase in demand for biofuel crops could cause an increase in agricultural land, increased competition with food crops and a decrease in pasture or forest land. This phenomenon is known as land use change (LUC) and is a concerning potential source of greenhouse gas (GHG) emissions from dedicated biofuel crops. To reduce emissions associated with land management, advanced bioenergy crops are often proposed to be produced on marginal or abandoned agricultural land. The change in land use may cause a change in soil GHG respiration, sometimes referred to as a flux. Direct measurement is critical to develop models and land management practices that mitigate the efflux of GHGs to the atmosphere. In this study, GHG fluxes under the growth of the lignocellulosic feedstock Miscanthus x giganteus was monitored and compared to GHG fluxes of fallow agricultural plots on land formerly used for hay and pasture. Knowing the GHG fluxes of soils under Miscanthus growth will help determine the viability of this grass as a cellulosic feedstock and potential carbon sink. This study found that replacing fallow land in SE Ohio with Miscanthus x giganteus did not change the respiration rates of CO2 during the fall season. No N2O fluxes were detected. This study only examined fall fluxes, but comparable literature included summer data, thus the fluxes were higher in CO2 flux. The CH4 fluxes, however, were comparable across studies. Repurposing abandoned land for production of Miscanthus x giganteus as a bioenergy crop did not lead to higher GHG emissions from soil respiration.

Committee: Sarah Davis PhD (Advisor) Subjects: Agriculture; Biogeochemistry; Climate Change; Energy; Environmental Studies; Soil Sciences

Doctor of Philosophy, Case Western Reserve University, 2017, Macromolecular Science and Engineering

This dissertation focuses on the design and fabrication of different cellulose nanocrystals (CNCs) polymer nanocomposites, with the goal of impacting the structure-property relationship between CNCs and the CNCs/matrix interactions through the surface functionalization of the CNCs with different chemical functional groups. Chapters 2-4 focus on how CNCs from sea tunicates (t-CNCs) functionalized with different chemical moieties affect the mechanical properties of the resulting nanocomposite. First (Chapter 2), t-CNCs were functionalized with lower critical solution temperature (LCST) responsive poly(oligoethylene glycol)monomethyl ether (meth)acrylates, which were incorporated into a poly(vinyl acetate) (PVAc) matrix to create reversible, thermal stiffening nanocomposites. When placed in water below the LCST the nanocomposites are soft, however, when placed in water above the LCST the nanocomposites stiffened as a result of the collapse of the grafted polymer chains allowing the engagement of t-CNCs nanorods. Secondly (Chapter 3), t-CNCs were used as fillers by functionalizing the surface with carboxylic acid moieties which aided in its dispersion in solvents such as N-methyl-2-pyyrolidone (NMP). The dispersion was further used in the synthesis of polyimide aerogels which demonstrated improved physical and mechanical properties as well as thermal stability with the incorporation of t-CNCs as a filler. Lastly (Chapter 4), by functionalizing the surface of t-CNCs with carboxylic acid and amine moieties, t-CNCs were demonstrated to be electrically active. Applying electric current across aqueous solutions of such t-CNCs, resulted in the fabrication of aligned micron-sized t-CNC fibers. Electrically aligned fiber composites with collagen were fabricated by matching the carboxylic acid/amine ratio of t-CNC and collagen. These aligned nanocomposite fibers demonstrated improved mechanical properties with higher contents of t-CNCs. Chapter 5 highlights the isolation of (open full item for complete abstract)

Committee: Stuart Rowan (Committee Chair); LaShanda Korley (Committee Member); David Schiraldi (Committee Member); Ozan Akkus (Committee Member) Subjects: Chemistry; Materials Science; Polymer Chemistry; Polymers