Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
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 SPATIAL AND TEMPORAL VARIANCE OF MICROBIAL WATER QUALITY IN TWO MARYLAND IRRIGATION PONDS(2019) Kierzewski, Rachel Annette; Hill, Robert; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Farm ponds must be regularly sampled for Escherichia coli (E. coli) concentrations to evaluate the health risks of using pond water for irrigation. However, no guidance is available regarding sampling locations and/or irrigation pump placement. We hypothesized that there exists spatial and/or temporal patterns of E. coli concentrations across ponds. To test this hypothesis, we sampled two irrigation ponds in Maryland biweekly during the summers of 2016 and 2017. Results from data analysis of mean relative differences and Spearman correlation coefficients are presented. Empirical orthogonal functions indicated spatial patterns of Log E. coli concentrations were temporally maintained. More sample variance existed over time in the pond interiors versus near shore locations. Furthermore, larger patterns of sample variance existed within the spatial analysis variance versus the temporal analysis variance over both ponds for this study. Therefore, the spatio-temporal E. coli variance may have significant impacts on sampling and pump intake locations.Item Nutrient effects on phytoplankton community composition in the eutrophic Anacostia River and a focus on diatom physiology(2019) Gleich, Samantha Julia; Glibert, Patricia M; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Anacostia River, Washington D.C., is a freshwater ecosystem that historically received high concentrations of nutrients from sewage and stormwater outfalls. Restoration efforts have been implemented recently that may improve water quality and alter the relative abundance of different phytoplankton taxa in the river. To determine the effects that environmental shifts may have on diatom abundance and phytoplankton community composition in the Anacostia River, a mesocosm experiment and laboratory studies were conducted. The results of the mesocosm study revealed that diatoms were consistently outcompeted by cyanobacteria. Additionally, phosphorus enrichment led to a 50% increase in cyanobacterial abundance and decreased the abundance of diatoms. In the culture study, shifts in water temperature and nutrient availability altered diatom growth rates, photosynthesis, silica deposition, and NO3- reduction. Together, these studies highlight the interactive effects that nutrient availability and temperature may have on the physiology and subsequent growth of diatoms in the Anacostia River.Item Toward the Development of Integrated Oyster-Algae Aquaculture in the Chesapeake Bay(2014) Ray, Nicholas; Kangas, Patrick C; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Oyster aquaculture is a rapidly expanding industry in the Chesapeake Bay. Experiments were conducted to investigate the biogeochemical impact of a commercial oyster aquaculture facility on downstream waters at a facility on Maryland's Eastern Shore. An algal production system (ATS) was installed at the facility to assess the potential for bioremediation and algal production in an integrated multi-trophic aquaculture system (IMTA). Results of the experiments showed an increase in available ammonia downstream of the aquaculture facility, coupled with decreases in dissolved oxygen and total phytoplankton. The algal production system demonstrated an average productivity rate of 82.8 g/m2*day-1, a nitrogen (N) removal rate of 9.6 gN/m2*day-1, a phosphorus (P) removal rate of 0.20 gP/m2*day-1, and harvests consisted of an average of 7.8% organic content. Productivity and N and P removal rates from this study are higher than other systems tested in the Chesapeake Bay region at sites without an aquaculture facility.Item CHARACTERIZATION OF ALGAL BIOMEAL FOR APPLICATIONS IN FOOD(2009) Sanghvi, Avani Mukesh; Lo, Martin; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Conventionally used as animal feeds, microalgae are now cultivated for products such as omega-3 fatty acids, resulting in a high amount of biomass as by-product. The biomass obtained after the extraction of DHA from Crypthecodinium cohnii is called `algal biomeal'. Being nutritionally rich, the biomeal has potential to be used as a value-added ingredient in human food and animal feeds. Evaluation of the biomeal properties resulted in the development of a water-based sauce formulation which was analyzed for its proximate composition, textural attributes and microbial stability. The sauce was rich in carbohydrate and protein with low fat and ash content. It was microbiologically and texturally stable under refrigeration. This research shows that development of a shelf-stable palatability enhancer using algal biomeal offers a new ingredient for the food and feed industries, whereas the ability to produce a value-added ingredient also offers a viable option for algal biomeal.