UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

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 given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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2009 - 200912010 - 20172

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    Release, Survival, And Removal of Bovine Manure-Borne Indicator Bacteria Under Simulated Rainfall
    (2017) Stocker, Matthew Daniel; Hill, Robert L; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The effects of simulated rainfall intensities and its interactions with manure consistency and weathering on the release, survival, and removal of fecal indicator bacteria, Escherichia coli and enterococci, from land-applied dairy manure were evaluated. Rainfall intensity had significant effects on the number of bacteria in the soil following rainfall. Bacteria concentrations in soil decreased with increased soil depths and the topmost centimeter of soil accounted for the greatest proportion of bacteria. Escherichia coli persisted longer than enterococci once removed from manure. Manure consistency was not a significant factor in the removal of bacteria when manure was fresh, but as manure weathering progressed, consistency became a significant factor. The Vadas-Kleinman-Sharpley model was preferred over the exponential model for simulating the removal of manure-borne bacteria. Results of this work will be useful for improving predictions of the human health risks associated with manure-borne pathogenic microorganisms.
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    INVESTIGATING COMPOSTING AS A METHOD FOR REDUCING ESTROGENICTY IN POULTRY LITTER AND BIOSOLIDS
    (2015) Hammett, Kirsten; Yonkos, Lance; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Biosolids and poultry litter contain the natural estrogens 17β-estradiol and estrone, which can be transported to receiving waters via runoff when these materials are used as fertilizers. Estrogens are of concern because of their ability to act as endocrine disruptors and feminize fish. In this study, In-Vessel Aerated and Turned composting was investigated for its efficacy at mitigating estrogen concerns in BS and PL. Pre- and post- composted, BS and PL samples were investigated for total estrogenicity and estrogen species concentrations. In addition, conversion of estrone to 17β-estradiol was investigated by measuring the creation of deuterated 17β-estradiol from a deuterium-labeled estrone stock within aqueous PL mixtures. Data from these studies indicates that there may be efficacy in composting BS and PL prior to land application and suggest that estrone is capable of converting to the more potent 17β-estradiol species as a result of entering microbially active environments.
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    EFFECTS OF BAR FORMATION ON CHANNEL STABILITY AND SEDIMENT LOADS IN AN URBAN WATERSHED
    (2009) Blanchet, Zachary; Prestegaard, Karen L; Geology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This study investigates channel adjustment due to urbanization in the Little Paint Branch creek of the Anacostia River watershed. In the past 15 years, large gravel bars have formed in the channels, more than doubling the active channel width of some reaches. Field data was collected to analyze downstream hydraulic geometry and the effects of gravel bars on shear stress, turbidity, and morphological change. The watershed was gauged at three locations to document the contributions of discharge and sediment to the downstream Anacostia Estuary. The results indicate that Little Paint Branch Creek generates proportionally more runoff per basin area than the watershed does as a whole, even though the impervious surface area is lower in the upstream tributaries, like Little Paint Branch Creek. Bar formation induces channel widening, which decreases flow depth and thus shear stress for bankfull and higher stages. This shoaling limits bed transport and will eventually limit bank erosion.