Theses and Dissertations from UMD
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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item The Spillover Effect of Environmental Disclosures: Evidence from Customers' Net-zero Pledges(2024) Castillo, Juan; Hann, Rebecca; Business and Management: Accounting & Information Assurance; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This paper investigates the real impact of customers’ voluntary environmental disclosures, specifically, Net-Zero Pledges (NZPs), on the direct greenhouse gas emissions of their suppliers. NZPs represent a growing trend in corporate disclosure, where companies commit to reducing carbon emissions to a minimum level by a specified date, with any remaining emissions being offset by carbon removal actions. Using firms’ connections along the supply chain and a staggered difference-in-differences design, this study provides evidence that suppliers significantly reduce their direct emissions following customers’ NZPs. This effect is more pronounced for NZPs made by customers with greater bargaining power, while suppliers’ reactions are stronger when they have higher carbon intensity and better environmental performance. Furthermore, NZPs of higher quality elicit a stronger response, especially when they limit the use of carbon offsets, set interim targets, and establish public reporting mechanisms. The evidence suggests that this reduction in emissions is achieved by suppliers’ investments in green technologies and innovation, as well as improvements in environmental policies in the years following customers’ NZPs. While these modifications do not seem to change firms’ profitability, they are associated with increased business output and capital investments, though at the expense of additional debt. These findings suggest that customers’ voluntary environmental disclosures can trigger positive spillover effects in upstream suppliers’ real operations, even in the absence of mandatory regulations.Item QUANTIFYING NITROUS OXIDE AND METHANE FLUXES USING THE TOWER-BASED GRADIENT METHOD ON A DRAINAGE WATER MANAGED FARM ON THE EASTERN SHORE OF MARYLAND(2022) Zhu, Qiurui; Davidson, Eric A.; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Excess nitrogen resulting from agricultural fertilizer and manure applications on the Eastern Shore degrades the Chesapeake Bay's water quality and causes environmental issues such as algal blooms and "dead zones". Drainage water management (DWM) is an effective best management practice (BMP) to reduce hydrological nitrate export from croplands to surface and ground water by controlling the timing and the amount of ditch discharge and retaining water within ditches and adjacent fields using drainage control structures (DCS). While promoted denitrification in the subsurface and reduction in nitrate leaching are intended consequences of maintaining higher water table level, an unintended environmental consequence is possible production of nitrous oxide (N2O) from denitrification and methane (CH4) from methanogenesis, which are both potent greenhouse gases (GHGs). Whether the application of DWM leads to a "pollution swapping" concern (i.e., trading reduction of nitrate concentrations in ditch water for increases in emissions of N2O and CH4 to the atmosphere) is a question that must be addressed before more widespread implementation of DWM can be endorsed. In this dissertation, I employed a micrometeorological method called the flux gradient (FG) method to a corn-soybean rotation agricultural system with DCS in eastern Maryland on the Delmarva Peninsula to answer this question. This method was chosen because it allows near-continuous measurements of soil trace gas exchanges at multiple locations with a single laser spectrometer at a fine temporal resolution without disturbing the microclimate between soils and the atmosphere. Soil N2O and CH4 fluxes were quantified using the FG method on this drainage water managed farm for three consecutive years when no fertilizer, synthetic fertilizer, and biosolids were applied in 2018 (soybean), 2019 (corn), and 2020 (corn), respectively. Statistical tests indicated that there were no consistent treatment effects of DWM on soil GHG emissions between DWM and non-DWM conditions, suggesting that DWM did not trade the intended consequence of reduced nitrate leaching for the unintended consequence of increased soil GHG emissions. The biosolid addition in 2020 led to the largest N2O emissions among the three years, while the lowest N2O emissions in the growing season were found in the unfertilized soybean year of 2018. In contrast, different fertilization regimes did not yield distinct differences between the three years for CH4 fluxes. In addition, some potential methodological concerns associated with this tower-based micrometeorological approach were addressed and resolved, conferring confidence that the FG method can be applied simultaneously to multiple plots for N2O and CH4 measurements. This research adds to the existing understanding of the impacts of DWM on soil GHG emissions and suggests that this BMP could be applicable in other regions of the Chesapeake Bay as well as other watersheds. This work also contributes to the efforts of studying the impacts of soil organic amendments on soil GHG emissions and deriving improved estimates of emission factors (EFs) for organic amendments.Item Demand-Driven Climate Mitigation in the United States: Challenges and Opportunities to Reduce Carbon Footprints from Households and State-Level Actors(2022) Song, Kaihui; Baiocchi, Giovanni; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Subnational and non-governmental actors have great potential to push for bolder climate actions to limit the global average temperature increase to 1.5 degrees Celsius above pre-industrial levels. A consistent and accurate quantification of their GHG emissions is an important prerequisite for the success of such efforts. Although an increasing number of subnational actors have developed their climate mitigation plans with medium- or long- term goals, whether these progressive commitments can yield effectiveness as planned still remains unclear. This dissertation research focuses on two large groups of climate mitigation actors in the U.S. – households and state-level actors – to improve the understanding of potential mitigation challenges and shed light on climate policies. This dissertation consists of three principle essays. The first essay reveals a key challenge of emission spillover among state-level collective mitigation efforts in the U.S. It quantifies consumption-based GHG emissions at the state level and analyzes emissions embodied in interstate and international trade. By analyzing major emission transfers between states from critical sectors, this essay proposed potential policy strategies for effective climate mitigation collaboration. The second essay addresses unequal household consumption and associated carbon footprints in the U.S., with a closer look at different contributions across income groups to the national peak-and-decline trend in the U.S. This analysis further analyzes changes in consumption patterns of detailed consumed products by income groups. The third essay proposed a framework to link people’s needs and behaviors to their consumption and associated carbon footprints. This framework, built on existing models that connect carbon footprints with consumer behaviors, extends to people’s needs with simulation over time. Such an extension provides a better understanding of carbon footprints driven by various needs in the context of real-world decision-making. Based on this framework, this essay selects a basket of behavioral changes driven by changing fundamental human needs and analyzes associated carbon footprints. The dissertation identifies opportunities and challenges in demand-driven climate mitigation in the U.S. Its findings provide implications for effective climate actions from state-level actors and households.