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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Item Steriod Hormones in Biosolids and Poultry Litter: A Comparison of Potential Environmental Inputs(2010) Bevacqua, Christine Elizabeth; Torrents, Alba; Rice, Clifford; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Steroid hormones can act as potent endocrine disruptors when released into the environment. The main sources of these chemicals are thought to be wastewater treatment plant discharges and waste from animal feeding operations. While these compounds have frequently been found in wastewater effluents, few studies have investigated biosolids or manure, which are routinely land applied, as potential sources. This study assessed the relative environmental contribution of steroid hormones from biosolids and chicken litter. Samples of limed biosolids collected over a four year period and chicken litter from 12 mid-Atlantic farms were analyzed for 17β-estradiol (E2), estrone (E1), estriol (E3), 17α-ethinylestradiol (EE2), progesterone, and testosterone, and the conjugated hormones E1-sulfate (E1-S), E2-3-sulfate (E2-3-S), and E2-17-sulfate (E2-17-3). Results showed that E1 and progesterone were the most prevalent compounds in both of these materials, with E1-S also present in chicken litter.Item Multi-Scale Pedologic Investigation of Manganiferous Soils in the Maryland Piedmont(2008) Bourgault, Rebecca; Rabenhorst, Martin; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Manganese oxides are usually found in trace quantities in soils, but they are important due to their effects on soil chemistry and morphology. There are rare soils in the Maryland Piedmont that have extremely high amounts of manganese oxides that have not been previously studied. These manganiferous soils were examined at multiple scales in order to determine their spatial extent, to characterize their fundamental morphology, mineralogy, and chemical and physical properties, and to better understand their pedogenesis. The soils occupy areas of 1-2 ha in size, within 200 km2 in eastern Frederick County and western Carroll County. The soils can have as much as 140 g kg-1 Mn as oxides, which pigments the entire soil matrix black in subsoil horizons. It appears that the black, porous, Mn-rich material is derived directly from the dissolution of marble bedrock and accumulation of silicate residues plus Mn and Fe from within the rock.Item Oxidation-Reduction Transformations of Chromium in Aerobic Soils and the Role of Electron-Shuttling Quinones in Chemical and Microbiological Pathways(2008-05-05) Brose, Dominic; James, Bruce R; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Soils from three toposequences in Maryland with minimal heavy metal contamination were sampled to investigate oxidation-reduction transformations of chromium in whole soil samples. Chromium (VI) reduction to Cr(III) was observed in all 18 samples, and 11 demonstrated enhanced reduction with the electron shuttle anthraquinone-2,6-disulfonate (AQDS). Oxidation of Cr(III) to Cr(VI) was observed in 12 samples, and 7 samples demonstrated diminished oxidation with AQDS. Lactate was added to the Watchung series to enhance biological activity, and high salt concentration was added to inhibit it. Both treatments reduced Cr(VI) to below detection limits by 11 d, suggesting abiotic reduction. The control treatment demonstrated reduction of Cr(VI) without soil. To further investigate, increasing lactate concentrations were added to Cr(VI) and AQDS. Reduction increased with increasing concentration; 60 mM lactate reduced all Cr(VI) within 1 hr. Other organic acids were tested for similar interactions; tartrate and citrate reduced Cr(VI), which was enhanced with AQDS.Item Physical and Potentiometric Constant of Ferrous and Ferric Phytate Applied to Organic Phosphate Transport in Poorly Drained Soil(2005-08-16) Heighton, Lynne; Siefert, Ronald L; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Inositol phosphates are metabolically derived organic phosphates that increasingly appear to be an important sink and source of phosphate in the environment. Inositol hexakis dihydrogen phosphate or phytic acid is the most common inositol phosphate in the environment. Iron is abundant in many terrestrial systems. Mobility of phytic acid iron complexes are potentially pH and redox responsive. Ferric and ferrous complexes of phytic acid were investigated by proton nuclear magnetic resonance spectroscopy, enzymatic dephosphoralation and potentiometrically in solution. The redox potential and concentration of iron were measured in a soil column containing a benchmark poorly drained soil from Maryland (Elkton). Ferrous phytate was found to form quickly and persist for a longer period then ferric phytate. Dissociation constants were 1.113 and 1.186 and formation constants were 0.899 and 0.843 for ferric and ferrous phytate respectively. Enzymatic dephosphoralation recoveries supported the magnitude of the kinetic and equilibrium rate constants.