Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item OYSTERS’ INTEGRATION ON SUBMERGED BREAKWATERS AS NATURE-BASED SOLUTION FOR COASTAL PROTECTION WITHIN ESTUARINE ENVIRONMENTS(2023) Vona, Iacopo; Nardin, William; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Rising sea levels and the increased frequency of extreme events put coastal communities at serious risk. Due to SLR, traditional solutions such as breakwaters (or gray/artificial structures) will become ineffective for wave attenuation and shoreline erosion control. Moreover, gray solutions do not consider the ecological aspects of the coast, and may negatively affect surrounding ecosystems. The “living shoreline” technique includes natural habitat features, such as oysters and/or vegetation into shoreline stabilization, to provide both protection and ecosystem services. Oysters create three-dimensional, complex reef structures that attenuate wave energy and increase sedimentation rates. If coupled with breakwaters, oysters may maintain breakwaters’ efficiency over time as they are expected to grow with SLR. However, guidance for the correct implementation of Natural and Nature Based Features (NNBF) for coastal protection is still unclear, and many authors within the literature have been repeatedly requested more insights. In this thesis, we have therefore studied the coupling between oysters and breakwaters via field, modeling and laboratory experiments, in order to highlight the benevolent aspects of NNBF regarding coastal defense. Field results showed gray breakwaters allowed for shoreline protection (by reducing incoming wave energy) and increased sedimentation rates. However, SLR modeling scenarios showed a gradual reduction of wave attenuation over time, as well as increased sediment export from the coast. When oysters were included in the modeling, on the other hand, wave dampening and sediment retention were preserved through the time. Laboratory experiments showed oyster-reef breakwaters in emergent or near-emergent conditions produced higher drag coefficient compared to gray structures, resulting in greater dissipative features. Higher water levels simulated in our experiments produced less reliable results that will require further investigation. This thesis supports oysters for coastal protection, and emphasizes the positive aspects of NNBF regarding wave attenuation and sediment retention in the face of climate changes and SLR. However, challenges encountered during field studies underlined the importance of environmental and biogeochemical conditions (such as water level, aerial exposure, temperature and seasonality) for oyster reefs’ establishment, growth and survivability. Future restoration plans involving oysters in coastal defense should definitely take these environmental and biogeochemical aspects into account, in order to properly protect the coast in the face of climate changes and SLR, while also providing many other useful ecosystem services for the environment. The coupling between oysters and breakwaters may represent a valuable and effective methodology to protect our coast over a changing climate and a rising sea, where optimal conditions for oysters’ survivability occur and are maintained over time.Item CHARACTERIZATION OF LEACHABLE DISSOLVED ORGANIC MATTER FROM BIOSOLIDS AND IMPLICATIONS FOR NUTRIENT RELEASES, MODELING, AND EMERGING CONTAMINANTS(2019) Fischer, Sarah Jane; Torrents, Alba; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Treated wastewater residuals are utilized as a soil amendment to recycle nutrients to agricultural soils. Due to international application, biosolids are also a significant source of anthropogenic dissolved organic matter (DOM) to the environment. The first contribution of this dissertation characterized DOM and nitrogen mineralization rates of anaerobically digested (AnD) biosolids with variable pre-treatments, such as the thermal hydrolysis pretreatment coupled to anaerobic digestion (THP-AnD). There was not strong evidence that differently pretreated-AnD material had largely different aerobic inorganic nitrogen releases when incubated in a sandy loam soil. Variable pools of DOM decayed in soil treatments over time. Biosolids-DOM was then characterized from a greater representation of full-scale stabilization processes including (i) limed stabilization (LT), (ii) aerobic digestion (AeD), and (iii) anaerobic digestion (AnD). These different final stabilization processes produced substantially different leachates characterized by organic carbon content, size-exclusion chromatography, and fluorescence spectroscopy. Traditional optical metrics previously defined for aquatic DOM did not consistently capture fluorescence maxima of the anthropogenic material. Therefore, boundary-based excitation emission matrix (EEM) analyses were re-defined based on local fluorescence maxima. Novel parallel factor analysis (PARAFAC) and spectral database comparisons confirmed that biosolids-DOM contain both common high energy stimulated components and low energy stimulated components that are unique to digested leachates. The third research contribution applied fluorescence suppression experiments to measure interactions of halogenated ECs with contrasting biosolids-DOM types. Despite digested biosolids-DOM containing different humic acid-like or fulvic acid-like signatures than limed leachates, antimicrobial triclocarban and industrial compound 2-4 dichlorophenol suppressed similar high energy fluorescent signatures in all biosolids-DOM. This suggests TCC and 2-4 DCP electronically interacts with smaller aromatic compounds, such as amino acids, and this interaction is not unique to DOM from different waste stabilizations. This study contributes to future bioavailability assays modeling complex effects of leachate quality on halogenated contaminants. This thesis also confirmed the presence of dehalogenating microbes in the anaerobic microbial community structure of a THP-AD system. These results contribute to on-going work assessing solids treatments, where halogenated emerging contaminants can be dehalogenated before land application. This work advances understanding of biosolids DOM leachates, modeling EEM data, and fate of ECs during full-scale solids treatment processes.Item A BIODEGRADABLE POT TECHNIQUE, AND EMERGY ANALYSIS TO IMPROVE RESTORATION OUTCOMES OF POTAMOGETON PERFOLIATUS L.(2018) Zinecker, Elizabeth Kirsten; Kangas, P. C.; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Potamogeton perfoliatus (L.) (P. perfoliatus), is a species of submersed aquatic vegetation (SAV) in mesohaline Chesapeake Bay that provides important ecosystem services but has been in decline. Efforts to restore its populations have met with mixed success. While the challenges to healthy SAV growth such as inadequate light for photosynthesis, poor water quality, and site disturbance have been well documented, studies using microcosms have failed to specifically examine other factors such as propagule type and seed storage duration, source population, plant growth response to a fully characterized substrate, and planting techniques, for the duration of an entire simulated growing season. Also, no studies have conducted an environmental cost accounting to assess the sustainability of a given restoration approach. This research investigated the growth and reproductive responses of P. perfoliatus propagules to various substrates and planting techniques; and conducted an emergy analysis case study, a type of environmental cost accounting, to compare two restoration techniques. P. perfoliatus net primary productivity and reproductive potential was highest when grown in sediment cores taken from SAV beds (~1.0gDW/m2/day, 18% stems with inflorescences), with peat/oyster shell being the next most desirable substrate choice for propagation (~0.86 gDW/m2/day, 4% stems with inflorescences). Seeds grown in biodegradable pots grew no differently than seeds grown in control polyethylene pots, or seeds planted by hand onto the bare sediment surface of the microcosm, (although hand-planting required multiple attempts to keep buoyant, germinated seeds in place). Seeds grown from harvests four years apart also showed no differences in yield (~0.56 gDW/m2/day). Biodegradable pots lost on average 60 percent of their mass over 12 weeks, and degraded more in brackish vs. fresh SAV bed sediments in the field. Emergy analysis indicated that planting seed-filled biodegradable pots resulted in 97% more area (m2) SAV bed restored than hand transplanting sods, and was more ecologically sustainable. These results indicate that appropriate substrates for propagation and restoration sites, and the ability to securely place propagules in the sediment, may be critical to P. perfoliatus establishment and success, thereby enhancing SAV habitat in Chesapeake Bay.Item Temporal Trends of and Influence of Storage Methods on Concentrations of Perfluoroalkyl Substances in Limed Municipal Wastewater Biosolids(2014) Armstrong, Dana Lynne; Torrents, Alba; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Perfluoroalkyl substances (PFASs) are a classification of anthropogenic chemicals used in a variety of consumer and industrial products. Compounds from two PFAS subgroups, perflurocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs) are known to be persistent and have been detected in environmental and biotic samples worldwide. While long-chain PFCAs and PFSAs have been in a phase-out process within the United States and some have been regulated in Europe, these compounds have continued to be produced in developing countries. The sustained use of PFCA and PFSA compounds in consumer products, as well as the ability of some PFASs to degrade into these compounds, has led to their presence in the wastewater treatment (WWT) process. This study analyzes archived limed biosolids from a municipal WWT plant for temporal trends of 8 PFCAs and 4 PFSAs over an eight year period. This study also compares storage methods to determine influence on PFCA concentrations.Item The Impact of Cool Roofs in Different Climatic Regions: A Quantitative Empirical Analysis(2014) Petry, Kimberly Johanna; McIntosh, Marla S; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This research investigated regional climate differences and weather impacts on the effectiveness of cool roofs. In most US climate zones, cool roofs can reduce energy consumption because they reflect more sunlight and heat than standard roofs. Since temperatures are expected to increase in many regions, cool roofs may offer greater energy and cost savings than currently estimated. Energy consumption by Department of Energy (DOE) Research Laboratory buildings across the US with cool and standard roofs were assessed using metered energy datasets collected from 2003-2013. Statistical tests were conducted to compare differences in energy consumption of buildings between cool and standard roofs at sites in different climatic regions. In order to better understand the effectiveness of cool roof technologies in a future that is expected to become increasingly warmer, data collected from weather stations near each DOE site were used to interpret the potential influences of weather patterns on cool roof energy savings. This research confirmed that cool roofs do reduce energy consumption, especially at sites with warmer summers and milder winters. Regression analyses of energy consumption and temperature data were conducted to identify associations between air temperatures and heating and cooling degree-days with seasonal energy consumption. While the energy consumption of buildings with cool roofs was generally less than buildings with standard roofs, the differences in energy consumption varied depending on building use and building size.