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 IMPACT OF PERIODIC HIGH CONCENTRATIONS OF SALTS ON BIORETENTION NUTRIENTS PERFORMANCE(2018) McManus, Meigan; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bioretention is a stormwater control measure commonly used to remove pollutants, including nitrogen (N) and phosphorus (P), from urban runoff. This project seeks to evaluate the impacts of high concentrations of sodium chloride (NaCl) deicer on bioretention N and P removal performances. Bioretention mesocosm studies were conducted to examine N and P removal efficiencies following periodic 2,000, 5,000, and 10,000 mg/L NaCl salt applications. Episodic washouts of TSS, N and P, likely due to ion exchange with the sodium and chloride ions, were observed for all three columns and mass export of P was observed for the 2,000 and 5,000 mg/L NaCl columns after 26 m and 7 m applied water, respectively. No mass N export was observed. Based on a mass balance of N and P, it is recommended to limit the use of deicers to prevent long-term P export.Item Evaluation of the Simple Wetting Method to Reduce Total Cyanogens in Flaxseed(2016) Sanders, Kathleen Suzanne; Buchanan, Robert; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A simple wetting method used to significantly reduce the % total cyanide remaining (TCR) in cassava was evaluated for its applicability to flaxseed. An optimal simple wetting method (SWM) in terms of time, temperature, and exposed surface area (SA) depth was developed for reducing the % TCR in ground flaxseed. The optimal parameters were a treatment time of 12 h, an ambient temperature of approximately 22°C, and an increased exposed SA achieved through spreading the wetted flaxseed mixture out to a thin depth of 0.5 cm. General mixed model analysis confirmed that the variables time and SA were significant factors in minimizing the %TCR in the optimal model. Pairwise comparison showed that the 0.5 cm depth had the greatest effect. The desirable lignan secoisolariciresinol diglucoside (SDG) was significantly retained, as determined by HPLC quantification of pre- and post-processing levels.Item ENVIRONMENTAL SUSTAINABILITY AND WASTE TREATMENT CAPABILITIES OF SMALL-SCALE ANAEROBIC DIGESTION SYSTEMS(2012) Moss, Andrew Robert; Lansing, Stephanie A.; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Anaerobic digestion is a common form of waste treatment and energy production throughout the world, and in the United States the number of agricultural digesters is increasing at a rate of approximately 10% annually. As the number of digesters grows, efforts to assess the environmental cost of their installation and the potential utility of their by-products are required. This research investigates the relative environmental sustainability of small-scale digesters treating dairy manure in the U.S. and human waste in Haiti, and explores the biogas potential and nutrient transformations resulting from the anaerobic digestion of dairy manure. Specifically, the objectives of the research are: 1) to conduct an eMergy analysis on the two digestion systems to assess the effect of waste source, climate, and infrastructure on system sustainability; and 2) to provide an overview of waste treatment and energy production options for agricultural digesters treating dairy manure in the United States.Item Nutrient Levels and Organic Matter Decomposition in Response to Prescribed Burns in Mid-Atlantic Coastal Marshes(2012) Geatz, George Walter; Needelman, Brian A.; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Prescribed winter burning is a commonly used management practice in coastal marshes along the Atlantic Coast. I conducted a manipulative field study to explore the mechanisms by which fire increases plant productivity. I found that prescribed fire does not provide a fertilization effect for vegetation through ash deposition due to the low amounts of nutrients in ash. Modeling biomass nutrient stocks in other marshes with similar vegetation types shows that this lack of a fertilization effect likely exists across all coastal marsh types. Through the mechanism of canopy removal, organic matter decomposition rates in marsh areas tended to decrease later in the growing season, corresponding with a decrease in porewater ammonium and phosphate, which were taken up in much higher quantities in the biomass. These effects were stronger and more consistent in areas dominated by the sedge species, as these areas showed more of a biomass response to canopy removal.Item Relating pollutant and water quality parameters to landuse in a subwatershed in the Choptank River watershed(2010) Nino de Guzman, Gabriela Tejeda; Torrents, Alba; Hapeman, Cathleen J; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Agriculture and animal feeding operations have been implicated as sources of water pollution along the Choptank River, an estuary and tributary of the Chesapeake Bay. This survey examined a subwatershed within the Choptank River watershed for impacts of a poultry facility on its adjacent surface water. Water and sediment samples were collected May - October 2009 under mostly baseflow conditions and analyzed for antibiotics, nutrients, heavy metals, and selected bacteria. Of the antibiotics recovered, no significant difference was observed spatially, but a significant difference emerged between spring and fall/winter. For nutrients, the greatest phosphorus concentrations were at the subwatershed outlet (4) and at two branches not containing the poultry house (3 and 5); nitrogen concentrations at sites 2 and 5 were as high as site 4. Arsenic concentrations at 2 were lower than both the low-agriculture (control) site and a site neighboring 3. Bacterial counts in water and sediment remained fairly constant throughout the sampling regime.