UMD Theses and Dissertations
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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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Item Evaluation of Nutrients and Suspended Solids Removal by Stormwater Control Measures Using High Flow Media(2017) Landsman, Matthew Robert; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)High Flow Media (HFM) is able to treat large runoff volumes using small- footprint systems. Seven full-scale HFM Stormwater Control Measures (SCMs) in a residential area were monitored over 11 months to assess the removal of Total Suspended Solids (TSS), Nitrogen, and Phosphorus in First Flush (FF) stormwater runoff. Excellent removal of TSS and particulate-bound nutrients was noted, but, in most SCMs, removal of dissolved species was limited. Sorption of dissolved P occurred, although most likely on captured and suspended sediment and not on the HFM itself. Mineralization and nitrification of dissolved N species during dry periods led to nitrate export. HFM grain size and organic content did not significantly impact TSS or P removal, but higher organic content was associated with higher N removal. FF was present in TSS (strongest), TN, and TP (weakest). Optimal HFM SCM design incorporates sedimentation before filtration.Item Bioretention Media for Enhanced Permeability and Phosphorus Sorption from Synthetic Urban Stormwater(2017) Yan, Qi; Davis, Allen Porter; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bioretention systems have been proven as effective urban stormwater control measures (SCMs), and are commonly used to improve both quantity and quality (pollutant removal) aspects of urban runoff. A promising media modification process is developed to simultaneously achieve both high infiltration rate and improved P removal in bioretention systems, Bioretention soil media (BSM) and a sandy ‘high flow medium’ (HFM) were modified with three Al-based amendments: water treatment residual (WTR), alum, and partially hydrolyzed aluminum (PHA), 10% by dry mass, respectively. The sorption of adenosine monophosphate (AMP) and myo-Inositol hexakisphosphate (IHP), two forms of organic phosphorus, and inorganic phosphate by modified media mixtures were studied. Compared with unmodified BSM and HFM, the sorption of AMP was increased by a factor of 26 and 80 for media with alum and PHA, respectively. Similarly, the IHP removal capacity were increased by factors of 7 and 8, respectively. Alum and PHA modified media mixtures can reduce P concentrations to <0.01 mg P/L within a contact time < 1 min. Adsorption and chemical precipitation are two predominated mechanisms for P removal using modified media mixtures. HFM modified with HFM and WTR showed high permeability and excellent P removal relative to other media mixtures and most importantly, it requires simplified modification conditions and is recommended for use in bioretention and related SCMs.Item The Diversity of Burrowing Benthic Invertebrates and their Impact on Phosphorus Dynamics in Agricultural Drainage Ditches(2014) Leslie, Alan William; Lamp, William O; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Agriculture remains the most widespread cause of impairment of freshwater habitats, but farm lands with artificial drainage structures such as ditches have specific locations where natural physical and biogeochemical processes can be used to reduce nutrients delivered to local watersheds. Agricultural drainage ditches can also be sources of biodiversity, serving as patches of uncropped aquatic habitat that may provide a significant amount of diversity to agricultural landscapes. Macroinvertebrate communities play important roles in nutrient cycling in natural aquatic ecosystems, but to this date no information exists on the role of invertebrate communities in biogeochemical processes occurring in ditches. The overall goal of my dissertation was to determine the structure of the aquatic macroinvertebrate community of agricultural drainage ditches, and to determine the functions these species play in nutrient cycling. First, I performed a broad survey of aquatic macroinvertebrates in drainage ditches and related the community composition to environmental conditions. Ditches support different communities of macroinvertebrates, and community composition is correlated with physical habitat characteristics such as flow velocity (r2=0.58) and ditch size (r2=0.56), rather than water quality. I then measured the burrowing community of small (field) and large (collection) ditches over a year to determine how size class and seasonality affect taxonomic and functional group composition. I found small and large ditches support different taxa due to the intermittent water condition of small ditches, but both types of ditches support similar functional groups. There is limited diversity among functional feeding groups in ditches, but the majority of macroinvertebrates (101 of 140 taxa) are benthic taxa that may cause bioturbation of ditch sediments. I used microcosms to measure the effect that different burrowing species (Ilyodrilus templetoni, Limnodrilus hoffmeisteri, Crangonyx sp., Chironomus decorus S.G.) have on phosphorus dynamics between ditch sediments and water. Results show different species can increase (0.28 to 2.05 mg/L) or decrease (0.08 to 0.41 mg/L) soluble, reactive phosphorus concentrations in surface water, depending on the type of burrowing and environmental conditions. Different types of burrowers likely alter phosphorus dynamics through different mechanisms, and increasing diversity of burrowers could have non-additive effects on phosphorus uptake by ditch sediments.Item FIELD EVALUATION OF ENHANCED PHOSPHORUS AND NITROGEN REMOVAL IN STORMWATER CONTROL MEASURES(2014) Liu, Jiayu; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This project evaluates two innovative stormwater control measures (SCMs) installed on the University of Maryland campus in College Park, Maryland. One project retrofitted an existing bioretention cell with 5% (by mass) aluminum-based water treatment residual (Al-WTR) to enhance phosphorus removal (P1 site). The other combined a porous parking area with underground anoxic vaults to promote nitrogen removal (N1 site). At the P1 site, the net reduction of the total runoff was 40% and the volume reduction ratios ( ) were lower than before the retrofit. The total suspended solids (TSS), total phosphorus (TP), and particulate phosphorus (PP) concentrations were significantly reduced by the bioretention cell, due to the filtration of the particulate matter, while TP export occurred before WTR retrofit. Soluble reactive phosphorus (SRP) and dissolved organic phosphorus (DOP) concentrations in the stormwater runoff were not obviously changed compared to the system effluent. The near constant outflow of SRP and DOP concentrations suggest an equilibrium adsorption treatment mechanism. Mass loads were reduced for TSS and all P species. WTR incorporation decreased the bioretention media phosphorus saturation index (PSI) from approximately 0.075 to approximately 0.041, which stayed relatively constant during the two year study period, even with the media P continually increasing, indicating a significant increase in media P sorption capacity. At the N1 site, the flow management achieved nearly zero runoff discharge due to infiltration from the vaults during dry weather. With regard to the porous pavement, approximately 34% of the total nitrogen (TN) (4.7 kg/ha-yr) was mitigated by filtration processes; 6.5 kg/ha-yr particulate organic nitrogen (PON) and 1.8 kg/ha-yr ammonium nitrogen ( ) were removed, and 4.0 kg/ha-yr oxidized nitrogen (NOx) were created. In the denitrification vaults, approximately 26% of the TN (3.7 kg/ha-yr) was decreased by system reaction, mostly due to the decrease in NOx (3.8 kg/ha-yr). PON was reduced slightly, by 0.2 kg/ha-yr. The small amount of DON and produced likely resulted from leaching from the wood logs. As a result, the N mass reduction that occurred was not only due to volume reduction, but also to system reactions (60%).Item THE EFFECTS OF DRAINAGE DITCH FILTER COMPOSITION ON HYDRAULIC PROPERTIES AND P SORPTION(2014) Hamrum, David; Hill, Robert L; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Phosphorus (P) in agricultural runoff is considered a primary contributor to waterway eutrophication. Currently filters made with P-sorbing materials (PSMs) in drainage ditches have been shown to effectively remove P in some situations, but further optimization is necessary. Sorption isotherms were used to determine PSM and temperature effects on P sorption. No effect was found due to temperature, although significant differences were found among the materials used. The different mechanisms of P sorption suggest the retention time used was not suitable for this study. A mesocosm experiment was set up to maximize the flow through filters by mixing gypsum with sand to increase the hydraulic conductivity without sacrificing P sorption. The mixture containing 90% mined gypsum and 10% sand had the highest hydraulic conductivity without a reduction in total P sorption. The mixture containing 80% mined gypsum and 20% sand could have potential as an alternate mixture.Item Redox and Soil Manipulation Effects on Ditch Soil Phosphorus Processing(2012) Ruppert, David Emmanuel; Needelman, Brian A; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Ditches increase the connectivity of landscapes to open water systems, potentially facilitating the degradation of downstream waterways. A treatment and an observational experiment were conducted to identify processes behind phosphorus (P) cycling in ditch soils. If the ditch had not undergone recent dredging soils were observed in the treatment experiment to release P to surface water whether the soil system was iron (Fe)-oxidizing or Fe-reducing. Also in the treatment experiment, Fe was released to surface water in appreciable amounts only if the soil system was Fe-reducing. From the observational experiment P release due to mineralization was inferred due to a positive trend with temperature. Also in the observational experiment Fe-reducing conditions were weakly correlated with diminished P concentrations in the ditch water. It was inferred that emergent Fe(II) released from within the soil through reductive dissolution captures P from ditch surface water upon oxidation. In the treatment experiment dredging and saturated conditions resulted in similar effluent P concentrations as drained soils that were undredged. This may explain a lack of dredging effect that was observed in the field.Item Modeling Nitrogen, Phosphorus and Water Dynamics in Greenhouse and Nursery Production Systems(2011) Majsztrik, John Christopher; Lea-Cox, John D.; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Nutrient and sediment runoff from the six states and Washington, DC that form the Chesapeake Bay watershed is a major cause of environmental degradation in the Bay and its tributaries. Agriculture contributes a substantial portion of these non-point source loads that reach the Bay from its tributaries. Research in this area has traditionally focused on agronomic farm contributions, with limited research on the nursery and greenhouse industry. This research presents the first known attempt to model operation-specific information, validated by published research data, where multiple variables are assessed simultaneously. This research provides growers and researchers with a tool to assess and understand the cultural and environmental impact of current practices, and predict the impact of improving those practices. Separate models were developed for greenhouse, container-nursery and field-nursery operations, since specific production variables and management practices vary. Each model allows for simple entry of production input variables, which interface with the Stella modeling layer. Each model was first calibrated with one published research study, and subsequently validated with another peer-reviewed study, with multiple independent runs for each model. Validation results for all three models showed consistent agreement between model outputs and published results, increasing confidence that models accurately process all input data. Verified models were then used to run a number of what-if scenarios, based upon a database of production practices that was gathered from 48 nursery and greenhouse operations in Maryland. This database provided a detailed analysis of current practices in Maryland, and adds significantly to our understanding of various operational practices in these horticultural industries. Results of the what-if scenarios highlighted model sensitivities and provided answers to hypotheses developed from the analysis of the management database. Some model functions, such as denitrification, would greatly benefit from additional research and further model modification. Models were designed to be easily adapted to local conditions for use throughout the U.S. and potentially other parts of the world.Item USE OF INORGANIC BY-PRODUCT AMENDED COMPOST/MANURE TO SEQUESTER METALS AND PHOSPHORUS FROM DIFFUSE SOURCE POLLUTION(2010) Kim, Hunho; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Heavy metals and nutrients released from diffuse sources by urban and agricultural runoff are important pollutants causing aquatic toxicity and/or eutrophication in water bodies. Diffuse source pollution is difficult to address because of the dispersed and often dynamic nature of the flows, which often lead to economic impracticality of traditional approaches. Beneficial use of industrial and agricultural byproducts as amendments or media/barriers to treat diffuse source pollution can provide cost-effective solutions over various ranges of pollutants and flows. Two applications of this concept were examined in this research study: 1) Immobilization of phosphorus using Fe/Mn inorganic materials and an anaerobic incubation process; (2) Heavy metal removal from roof/wall runoff using a Biomat barrier supplemented with compost and inorganic byproducts. Through the first study, three different low cost Fe/Mn-rich materials (iron ore, steel slag and Mn tailings) were evaluated as amendments to decrease phosphorus mobility from manure. Anaerobic incubation of fresh dairy manure with the Fe/Mn rich materials was also evaluated. Steel slag addition significantly decreased water soluble phosphorus by 93% and Mehlich III extracted phosphorus by 80%, compared to manure-only control. An anaerobic incubation of manure with Fe ore decreased 62% water extractable P compared to fresh manure and 76% compared to incubated manure, due to oxalate extractable Fe (considered as amorphous Fe) increase. This work suggests possible anaerobic incubation use for non-active crystalline byproducts to decrease P loss from manure. Through the second study, the feasibility of Biomat use, a mixture of sand, compost and inorganic byproducts, was evaluated through column and bench-scale experiments to remove dissolved heavy metals. A 25% grass/food waste compost + steel slag + sand column was the best media, not only demonstrating excellent metal removals from diffuse sources but also exhibiting the immobility of sorbed metals on the media. Throughout bench scale experiments, hydraulic characteristics and heavy metal removal performance of the mat media were evaluated in perpendicular flow. After all bench scale experiments, metal extractions showed performed very limited metal mobility in the media. Design parameters, implementations, and recommendations for future full scale Biomat application in a field were established.Item Genetic Variation in Nitrogen and Phosphorus Levels in Broiler Excreta: Opportunity for Improving both Birds and the Environment(2010) sasikala appukuttan, arun kirshna; Siewerdt, Frank; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The increase in poultry meat consumption has resulted in intensified poultry farming operations with consequent concentration of excreta in major production areas. The nutrient content in the soil surrounding the poultry farms has increased as a result of the high content of nitrogen (N) and phosphorus (P) in the poultry excreta. The current study aimed to propose a strategy to reduce the N and P content in excreta through genetic selection of broilers for efficient nutrient utilization. The traits measured (on a dry matter basis) were the percentage of N in the excreta (PNE) and the percentage of P in the excreta (PPE). Individual 24-hr excreta samples were collected from 6 wk old birds. Excreta samples were collected from a commercial breeding farm at two different time periods from line A and line B birds respectively, and analyzed for PNE and PPE. Analysis of excreta samples collected during the first period (197 bird samples belonging to 15 sire families) and second period (278 birds belonging to 25 sire families) suggested a heritability of 0.08, 0.16 for PNE and 0, 0.20 for PPE, respectively. Phenotypic and genetic correlations between the measured traits from the two lines were very low; however, phenotypic correlation analysis of PNE and PPE with other traits of commercial interest showed some favorable as well as neutral associations. Blood samples collected from the birds were used for an association study of the excreta traits with four candidate genes. The candidate genes were selected based on the results of previous research. Some of the SNPs from the candidate genes were found to have additive and dominance effect on the excreta and production traits and were usually favorably associated with mutations in higher frequency in the populations. The results suggest that genetic selection of birds for PNE and PPE could improve the environment and the market value of the birds.Item Utilizing Hybrid Poplar Trees to Phytoremediate Soils with Excess Phosphorus(2005-09-01) Neal, Amy; McIntosh, Marla S; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Phytoremediation, using plants to remove soil pollutants, has been suggested as a method to remove P from over-enriched soils. This research investigated the potential of utilizing hybrid poplar trees to remove excess P from soils associated with long-term poultry manure application. Hybrid poplar clones were planted in Snow Hill, MD, on three fields differing in previous poultry manure applications with Mehlich-3 soil-test P levels of 261, 478, and 982 mg P kg-1. During this two year study, soil P decreased on fields planted with hybrid poplar; the magnitude of the reduction was positively associated with initial soil-test P. Plant tissue P concentrations increased with soil P concentration. However, factors other than plant uptake were hypothesized to contribute to the soil-test P reductions. Results suggest that hybrid poplars have the potential to phytoremediate soils with excess P but that soil chemistry also impacts the fate of available P in the soil.