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.

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Now showing 1 - 4 of 4
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    FULL SCALE STUDY OF PATHOGEN, METAL POLLUTANTS, NUTRIENTS, AND POLYBROMINATED DIPHENYL ETHERS IN CLASS A BIOSOLIDS STABILIZED BY THERMAL HYDROLYSIS AND ANAEROBIC DIGESTION PROCESSES
    (2017) Wang, Xuanzhao; Torrents, Alba; Andrade, Natasha Almeida; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Class A biosolids are solid by-product of wastewater treatment which meet Environmental Protection Agency requirements to be used as fertilizer in farms, vegetable gardens, and can be sold directly to consumers. In 2014, this study’s target nutrient recovery facility adopted thermal hydrolysis pretreatment and anaerobic digestion to upgrade biosolids quality from Class B (previously lime-stabilized) to Class A. In order to certify if this newly produced material met all regulatory requirements, we performed laboratory analysis to characterize fecal coliforms, volatile solids, and metals content. In addition, we showed a baseline for nutrient management of total nitrogen, phosphorus, and the change in levels of polybrominated diphenyl ethers (PBDEs). Samples were collected for over a year since the start of THP-AD operation. Results were compared with the Class B biosolids produced at the same facility. Based on EPA standards, Class A biosolids were produced with stable quality after March, 2015, 16 weeks after process initiation. This work suggests that THP-AD is effective in producing Class A biosolids. In general, PBDEs in biosolids decreased from 1790 ± 528 (Class B) to 720 ± 110 µg/kg d.w. Our results suggest that the total levels of PBDEs decrease, however, the impact of the THP-AD on specific congeners are complex.
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    ASSESSING THE FATE AND BIOAVAILABILITY OF HYDROPHOBIC ORGANIC POLLUTANTS IN AGRICULTURAL SOILS
    (2012) Almeida e Andrade, Natasha; Torrents, Alba; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Persistent organic pollutants have been the cause of concern for many decades; however, little information is available about their environmental fate. One goal of this work was to assess whether land application of biosolids represents a source of persistent organic pollutants to agricultural soils. To address this goal, we developed a methodology to quantify low levels of the flame retardants polybrominated diphenyl ethers (PBDEs) in biosolids and soils and conducted field studies to determine the fate and persistence of PBDEs upon the land application of biosolids. We found that biosolids can take up to one year to completely incorporate into the soil matrix after application and biosolids-bound chemicals are released during this time. PBDEs profiles in soils that receive biosolids applications are similar to PBDEs profiles in biosolids and both reflect commercial formulations of these flame retardants, indicating that biosolids are a source of these chemicals to soil. Residence time of these chemicals was reported for the first time and it was estimated at 16 yr. for the sum of BDE-47 and BDE-99. An abiotic methodology to assess bioavailability of aged soil residues was developed and results were compared to earthworms. The study illustrated that the polymer-based abiotic methodology can be used to assess the bioavailability of soil-bound hydrophobic organic chemicals to earthworms. Measured soil-polymer equilibrium concentration ratios of organic pollutants correlated strongly with earthworm bioaccumulation factors using the same soils. A laboratory protocol to introduce the concept of fugacity and bioavailability to undergraduate and graduate environmental science and engineering students was developed based on the methodology developed for research. The experiment provided an excellent opportunity for students to become familiar with the laboratory protocols and techniques for quantitative analysis as well as graphical analysis of data. The totality of this work improves knowledge of the fate of two classes of organic pollutants in soils. This work substantially adds information and understanding of chemical behavior to the general environmental engineering field. Although this unique experiment provided original and essential pieces of information, additional research is crucial to address the difficulties involved in assessing the environmental behavior of organic pollutants.
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    Comparative sub-lethal effects of polybrominated diphenyl ethers following simulated maternal transfer and dietary exposure in two species of turtles
    (2011) Eisenreich, Karen Marie; Rowe, Christopher L; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Polybrominated diphenyl ethers (PBDEs) are contaminants of concern as their concentrations have been increasing in the environment in recent years. This project sought to determine the effects of embryonic and dietary exposure to two PBDE congeners (BDE-47 and BDE-99) on a suite of endpoints including development, growth, metabolic rate, behavior and thyroid function of embryonic, hatchling and juvenile red-eared slider turtles (Trachemys scripta elegans) and snapping turtles (Chelydra serpentina). Topical egg dosing was employed for embryonic exposures; transfer efficiencies across the red-eared slider eggshell were 25.82 % and 9.87 % for BDE-47 and -99 respectively whereas they were 31.30 % and 12.53 % across the snapping turtle eggshell. These transfer efficiencies were taken into account when topically dosing eggs in a subsequent exposure-response study of embryonic exposure to BDE-47. Sodium perchlorate was included as a positive control for thyroid disruption in the embryonic exposure study. Embryonic exposure to five concentrations of BDE-47 (target exposure range from 40 ng/g - 1000 ng/g ww) led to patterns of elevated standard metabolic rate in hatchlings of both species and increased liver weights in snapping turtles. No impacts were found on incubation time, hatching success or total glandular thyroxine (T4) of the hatchlings. Embryonically exposed red-eared slider juveniles displayed delayed righting response behavior and both species showed patterns of reduced thyroid size and T4 following exposure. Sodium perchlorate had significant impacts on survival, incubation time, volume of the external yolk and T4 in the red-eared slider hatchlings. In snapping turtles, sodium perchlorate exposures led to impacts on hatching success, standard metabolic rate, liver and thyroid sizes, and T4. A separate study of dietary exposure to BDE-47 and BDE-99 (2055 ng/g and 1425 ng/g respectively) over a six month period in both species revealed altered behavior and decreased T4 in red-eared sliders and elevated standard metabolic rate in snapping turtles. Embryonic and dietary exposures to BDE-47 and -99 can elicit a suite of impacts potentially related to thyroid system function and are cause for concern, but the observed species specific differences in response require further investigation.
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    Contaminants in the atmosphere of the Delmarva Peninsula: impact of local activities and atmospheric transport
    (2007-04-10) Goel, Anubha; Torrents, Alba; McConnell, Laura L; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Anubha Goel, Doctor of Philosophy, 2007 Upper Delmarva Peninsula (within the Chesapeake Bay watershed), where the land use is predominantly agricultural, may be a significant source of pesticides (contributors in the declining water quality and bio-diversity of associated wetlands of the Chesapeake Bay) to the region. Although the Peninsula is predicted to be receiving significant inputs of herbicides through atmospheric deposition, the extent of local or regional atmospheric transport and deposition of pesticides to this area is poorly understood. The goal of this research was to determine the atmospheric levels and estimate deposition flux of pesticides in the Upper Delmarva Peninsula. This was accomplished by collecting weekly air samples (n=271) and event based rain samples (n=489) from three locations in the region (Dover and Lewes, DE; Cambridge, MD) for the period 2000-2003. The samples were analyzed for the presence of 34 pesticides (19 current use (CUPs), 15 historical (HUPs)) and 4 congeners of penta-BDE (PBDEs) using gas chromatograph-mass spectrometry (GC-MS). Statistically analyzed data was used to evaluate factors impacting phase distribution and the contribution of wet deposition to the levels in Chesapeake Bay. The more persistent insecticides and fungicides occur ubiquitously while application on corn influences herbicide occurrence and levels. Atmospheric CUP levels are driven by regional agricultural activity. CUPs do not exist in equilibrium and local meteorological conditions (like high relative humidity) influence phase distribution. The wet deposition flux of insecticide and fungicide is dependent on the total rainfall amount during the sampling period while timing and frequency relative to application on corn impacts herbicide flux. Levels in rainwater of some pesticides (endosulfans, chlorothalonil, diazinon etc.) were high enough to be of concern for the biota associated with the region's water bodies and associated wetlands and reveals that atmospheric deposition arising out of short range atmospheric transport can result in significant pesticide input to non-target areas. HUP atmospheric levels are lower than in the Great Lakes and are decreasing at a faster rate. This study reveals that spray irrigation of treated wastewater is an unknown source of toxic PBDEs to the atmosphere and can result in elevated levels at locations downwind of the irrigation field