Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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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 A Molecular and Isotopic Approach to Examine the Role of Terrestrial Organic Matter in the Carbon Cycle of the Arctic Ocean(2008) Belicka, Laura Lee; Harvey, H. Rodger; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The organic carbon cycle in the Arctic Ocean is complicated by the delivery and redistribution of terrigenous material through rivers, sea-ice, and erosion. This dissertation combines an isotopic and molecular biomarker approach to assess the role that terrestrial organic carbon plays in the Arctic organic carbon cycle, with a focus on a comparison of geochemical proxies for the quantification of organic matter, an analysis of the sources and transformation of organic carbon to particulate organic matter (POM) and sediments, and an experimental investigation on the kinetics of recycling. Estimates for preserved terrestrial organic components varied considerably for identical sediment samples, suggesting that proxies account for different sources of terrestrial material (i.e., soil versus vascular plants). In spite of the variability, an estimated 12-43% of the organic carbon preserved in surface sediments was terrestrial in origin. This contrasted sharply with surface and halocline POM, in which marine inputs dominated despite spatial variability. With depth, POC composition reflected the increasing significance of inputs from secondary production and microbial degradation, as well as continental material. Acid-volatile sulfide (AVS) and redox-sensitive elements coupled with δ13C and lipid biomarkers demonstrated a transition from intense metabolism of labile marine organic matter in shelf sediments to slower sedimentary metabolism from occasional delivery of labile organic matter in the basin. Experimental determinations of the kinetics of microbial recycling revealed striking contrasts in marine and terrestrial organic carbon lability. Marine organic matter was recycled on very short timescales compared to terrestrial organic matter, corresponding to results of sedimentary and particle analyses. A simplified box model of organic carbon cycling in the Chukchi/Alaskan Beaufort Sea region reveals that 0.9 Mt and 0.7 Mt of marine and terrestrial organic matter, respectively, are buried in shelf sediments, while an additional 0.2 Mt marine and 0.1 Mt of terrestrial organic carbon are buried in basin sediments annually, confirming that land-derived organic matter plays a large role in carbon dynamics in Arctic systems, even on non-river dominated margins.Item Vehicular Ammonia Emissions in Baltimore, Maryland(2005-08-15) Erwin, Amy Corner; Siefert, Ronald L; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Atmospheric ammonia is a precursor to the formation of fine particulate matter, which contributes to human health problems and decreased visibility. Atmospheric ammonia may also be transported through wet and dry deposition to water bodies such as the Chesapeake Bay, contributing to excess nutrient loadings that cause eutrophication. Vehicle exhaust contains ammonia, created by a reaction of NOx with H2 in the three-way catalytic converter. Ammonia emissions were measured using a mass balance on the Fort McHenry Tunnel, Baltimore, Maryland. Atmospheric concentrations of gas-phase and particulate-phase ammonium were measured during 2003-2004 using denuders and filter packs. The average vehicle (veh) emission rate for these studies was 8.1 ± 4.3 mg NH3-N veh-1 km-1. We estimate the annual emission of ammonia from vehicles to be 151 metric tons NH3-N yr-1 in Baltimore City and County and 707 metric tons NH3-N yr-1 in all of Maryland.Item PCB Desorption from Resuspended Hudson River Sediment(2005-08-03) Schneider, Abby Ruth; Baker, Joel E; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)From the late 1940's until 1977 two General Electric Plants discharged 200,000 - 1.3 million pounds of polychlorinated biphenyls (PCBs) into the upper Hudson River. Field studies and detailed modeling efforts indicate that PCB release from sediments under realistic mixing conditions determines the efficiency of both 'natural recovery' and proposed dredging operations. In this study, Hudson River sediment was resuspended into clean water in large mesocosms. The desorption rates of individual PCB congeners were determined by measuring dissolved PCB concentrations using solid-phase microextraction. Immediately following the initiation of resuspension, large particles with an average median diameter of 140 ± 14 mm were lifted into the water column. Dissolved PCBs rose rapidly and after two hours of resuspension 6 to 38% of the PCBs in the water column were in the dissolved phase. Rate constants for this rapid release ranged from 0.04 to 0.34 hour-1 and decreased significantly as log Kow of the PCBs increased. Both the total suspended solids concentration and dissolved PCBs reached steady state in 24 hours. At steady state the flocs volume median diameter averaged 112 ± 3 mm, porosity averaged 0.90 ± 0.02, and 15-50% of the resuspended PCBs were dissolved. The PCB concentration on resuspended particles was an average of two times greater than the bulk sediment PCB concentration and 8% of the resuspended mass did not settle after twenty hours without mixing. At steady state the particle-water PCB partition coefficients were similar to values measured in the Hudson River and constant across the range of congeners examined. With only one-day quiescence between resuspension events the percent of dissolved PCBs at steady state decreased significantly from the first to the third resuspension event (p = 0.02). When quiescent time was increased to four days, there was no change in the percent dissolved PCBs at steady state for the low molecular weight congeners (Log Kow ≤ 5.85, p = 0.45). This analysis suggests there was a large release of PCBs from particles when they were initially resuspended; however, chronic resuspension resulted in less PCB release per event due to the slow recharge of a labile pool.Item IN SITU MEASUREMENT OF SULFIDE IN NATURAL WATERS(2004-08-10) Rearick, Michael; Mason, Robert P; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Dissimilative sulfate reduction is a major source of sulfide in sediments and the water column of lakes and estuaries. Resulting dissolved sulfide can be incorporated into organic or inorganic sulfur complexes. When present in aquatic systems, sulfide is the dominant ligand for many trace metals and may control metal bioavailability to organisms. Laboratory tests were performed to validate the coupling of the diffusive gradient in thin films technique to a solid-state ion selective electrode to quantify in situ sulfide concentrations. Diffusive gradient in thin films probes were deployed in three lakes and estuary pore water and compared with parallel sulfide measurements using the Cline method and potentiometry. Differences between the recently validated method and the other methods were found with the former resulting in lower concentrations. Laboratory experiments examined these differences, and the experimental results identified measurement artifacts associated with sulfide antioxidant buffer usage.