Environmental Science & Technology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2748
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Item Soils Developed in Freshwater Marl Sediments in The Hagerstown (Great) Limestone Valley(1993) Shaw, Joey N.; Rabenhorst, Martin C.; Agronomy; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)Certain calcareous soils occupying alluvial landscape positions in the Hagerstown (Great) limestone valley of western Maryland have developed from highly calcareous ( 60-100g/100g) marl sediments of Holocene age which range in depth from .5m to over 8m. These marlderived soils have a high pH ( 7. 5-8. 5) , low bulk density, and high porosity (0.5 to 0.6). The carbonate in the marl was developed from inorganic and biogenic processes. The marl was formed in now extinct ponds which had inundated alluvial landscape positions during parts of the Holocene period. Certain algae capable of accumulating carbonate internally and externally developed the majority of the marl. Pedogenic processes have transformed the marl sediments into highly calcareous Mollisols. The presence of buried surface horizons and coarse (> fine sand) carbonate forms render classification of these soils problematic. The coarse carbonate forms were mainly biogenic deposits, but these carbonates have been altered sufficiently by coating with pedogenic carbonate to identify calcic horizons. The drainage class is difficult to interpret as a result of the gleyed appearance of the marl sediments (chroma <3) and the high pH of these soils which inhibits Fe oxide reduction. Most of the marl-derived soils (70%) are better drained than the previous classification indicates. These soils have been mapped in the Great Valley in units named for the warners series (fine-silty, carbonatic, mesic Fluvaquentic Haplaquolls) and the Massenet ta series (fine-loamy, carbonatic, mesic, Fluvaquentic Hapludolls). However, proper classification may place these soils in the Typic Calciudolls subgroup. Some soils originally mapped in the very poorly drained Dunning units are very poorly drained marl-derived soils.Item Eutrophication, Hypoxia and Trophic Transfer Efficiency in Chesapeake Bay(2002) Hagy, James Dixon III; Boynton, Walter R.; Environmental Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Coastal eutrophication is a global problem that has contributed to loss of estuarine habitats and potentially decreased fisheries production. Hypoxia is often observed in eutrophic estuaries where it can be an important cause of habitat loss. This study utilized a suite of empirical analyses to examine key linkages relating coastal eutrophication to hypoxia, trophic structure, and trophic transfer efficiency in Chesapeake Bay (CB), USA. A salt- and water-balance model, or "box" model, was developed to quantify large-scale physical transport for CB, an input to many subsequent analyses. Historical ( 1950-1999) dissolved oxygen (DO) data for CB showed that moderate hypoxia (DO<2.0 mg1^-1) increased ~3-fold, modulated by spring river flow. Severe hypoxia (DO<0.7 mg1^1) occurred only in high flow years during 1950-1967, but was present annually since 1968. Analysis using tree-structured regression showed that hypoxia was the most important factor determining patterns of macrobenthic biomass in Chesapeake Bay. Carbon budgets showed that, where habitat quality was poor, macrobenthic biomass was much less than could be supported by the organic carbon supply. In these cases, even dramatic reductions in carbon supply would not be expected to limit benthic production and by extension, trophic transfers to upper trophic levels via the benthos. The effect of eutrophication and hypoxia on trophic structure and trophic transfer efficiency were examined by estimating trophic flow networks for three regions of CB during summer. In addition, a series of "rules" were described and used to infer the trophic flow network for a "restored" middle CB from historical data, comparative ecological relationships and mass balance constraints. Excessive carbon now through bacteria was the most pronounced symptom of eutrophication in the modern mid Bay. The microbial food web transferred organic matter to trophic levels comparable to large piscivorous predators, maintaining average trophic transfer efficiency, even as the fraction of primary production transferred to top predators decreased. In the restored Bay, increased macrobenthic production shifted metabolic activity away from the microbial food web, increasing the potential trophic transfer to fish by 7-fold, even as total primary production decreased to 63% of the current average.Item Pueraria lobata Willd. (Ohwi) kudxa: Limitations to Sexual Reproduction(1983) Abramovitz, Janet Naomi; Teramura, Alan H.; Botany; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)The success of kudzu, Pueraria lobata Willd. (Ohwi), as a weedy invader in the southeastern United States is a result of its rapid growth rate, high leaf area index and ability to reproduce vegetatively. Populations at three sites near College Park, Maryland varied in their growth and reproduction, leaf area index, specific leaf weight, vine elongation rates, raceme density and seed production and dispersal. Soil characteristics, air temperature, humidity and photosynthetically active radiation (PAR) were measured at each site. The site which had the greatest vegetative productivity received significantly higher levels of PAR. Virtually no flowers or seeds were produced at the other two sites. At the site which produced a large number of flowers, successful sexual reproduction was limited by insufficient pollinator service during some periods of the season and low germination and seedling survivorship. Measurements of specific leaf weight, leaf area index, biomass, raceme production and seed set suggest that kudzu is a sun adapted plant. Even though it is capable of establishing itself in habitats of low or moderate irradiance, a greater ability for sexual reproduction was apparent in sun populations versus no sexual reproduction was apparent in sun populations versus no sexual reproductive success in populations occurring in shaded habitats. While its primary mode of reproduction is vegetative, successful sexual reproduction may occur despite several limiting factors.Item Using behavior change and social-ecological frameworks to inform riparian forest buffer outreach in the Maryland Upper Potomac watershed(2019) Boone, Hannah; Pavao-Zuckerman, Mitchell; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Land in the Maryland Upper Potomac watershed is predominantly privately held. Watershed restoration efforts seek to improve water quality through the implementation of riparian forest buffers. However, those efforts rely on aggregated actions of the individuals within the watershed, and adoption rates for the past decade have been below annual targets. An understanding of outreach strategies that promote riparian forest buffer adoption in a complex social-ecological system is needed. Employing qualitative methods, we integrated social-ecological and behavior change frameworks to better understand riparian forest buffer outreach and adoption in the Maryland Upper Potomac watershed. We conducted nineteen interviews with key stakeholders, followed by a quantification of main findings through landowner and practitioner questionnaires. Findings demonstrate that there is no “one size fits all” strategy. Rather, riparian forest buffer outreach needs interpersonal connections between landowners and practitioners to build trust and account for context-specific ecological feedbacks. There is opportunity to further reinforce riparian forest buffers through activities that demonstrate and leverage norms, impacting adoption through social feedbacks.Item High Quality Biosolids: Assessment of Nitrogen Mineralization and Potential for Improving Highway Soils(2019) Zhu, Chenglin; Felton, Gary K; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Biosolids production is increasing with increase in human population. Over the years, the quality of biosolids has been improving with the upgrading of most wastewater treatment plants (WWTP) as dictated by a need to meet discharge limits in receiving water bodies. Applying biosolids to agricultural soils to improve crop production has been practiced for decades. With increased regulation on land application in agricultural lands, biosolids industry has been exploring ways to use biosolids in specific situations such as highway roadside soils to improve soil properties. Roadside soils are known to be compacted and contaminated due to vehicular traffic and typically have low organic matter and nutrients. The objective of this study was to investigate the efficacy of high quality biosolids (i.e. Bloom) to improve soil physical and chemical properties. Results showed that Bloom and its mixture can significantly improve soil bulk density and hydraulic conductivity. Bloom-amended soils had a higher nitrogen mineralization rate than the control (2.45 times faster in simulated roadside soil and 1.21 times faster in agricultural soil) and compost amended soil. Further, soils amended with cured Bloom had relatively slower N mineralization than those applied with uncured Bloom since the curing process will decrease organic matter (OM) content and facilitate the loss of N as ammonium. The take home message is that bloom is more effective than inorganic fertilizer in terms of improving soil physical properties for roadside soils and bloom mixed with sand and sawdust is more effective than pure bloom. Bloom addition can significantly increase soil organic nitrogen mineralization. Further study and analysis will be needed to conclude on the effect of deer compost on soil physical properties and the mineralization rate of Orgro amended soil.Item INCREASING EFFICIENCY AND SUSTAINABILITY OF WASTE-TO-ENERGY SYSTEMS USING BIOCHAR FOR HYDROGEN SULFIDE CONTROL AND LIFE CYCLE ASSESSMENT(2019) Choudhury, Abhinav; Lansing, Stephanie; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The research aim was to increase energy production efficiency and reduce the environmental impacts of waste-to-energy technologies, specifically anaerobic digestion (AD) of dairy manure (DM) and combustion of poultry litter (PL). The first objective was co-digestion of DM with gummy vitamin waste (GVW) to increase methane (CH4) yield. The GVW co-digestion treatments significantly increased CH4 yield by 126% - 151% compared to DM-only treatment and significantly decreased the H2S concentration in the biogas by 66% - 83% compared to DM-only. The second objective was understanding the effect of hydrogen sulfide (H2S) scrubber management, operation, and maintenance parameters on H2S removal efficiency. Even though the capital and operating costs for the two H2S scrubbing systems in this study were low (< $1500/year), they showed ineffective performance due to insufficient air injection, substitution of proprietary iron oxide-based H2S adsorbents for cheaper alternatives, and the lack of dedicated operators. The third objective was adsorption of H2S using Fe-impregnated biochar as a substitute for activated carbon (AC). Fe-impregnation of biochar led to a 4.3-fold increase in the H2S adsorption capacity compared to AC. When compared to unimpregnated biochars, Fe-impregnation led to an average 3.2-fold increase in the H2S adsorption capacity. The fourth objective was in-situ use of biochar in AD to remove H2S. In-situ biochar addition at the highest dose (1.82 g biochar/g manure total solids (TS)) resulted in an average H2S removal efficiency of 91.2%. Biochar particle size had no significant effect on H2S reduction. In-situ addition of Fe-impregnated biochar resulted in an average H2S removal efficiency of 98.5%. The fifth objective was a life cycle assessment (LCA) of a PL fluidized bed combustion (FBC) system. The LCA assessment showed that heating poultry houses using heat obtained from the combustion of PL in the FBC system had 32% lower climate change potential (CCP) compared to use of propane for heating poultry houses. However, analyzing the FBC system under a net positive electrical output scenario resulted in 66% less impact on CCP and a 48 – 98% reduction in environmental impacts compared to the previous scenario with net electricity input.Item Anthropogenic disturbance alters plant and microbial communities in tidal freshwater wetlands in the Chesapeake Bay, USA(2019) Gonzalez Mateu, Martina; Yarwood, Stephanie A; Baldwin, Andrew H; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Tidal freshwater wetlands are often found near urban centers, and as a result of human development they are subject to multiple environmental stressors. Increases in nutrient runoff, sedimentation, and hydrologic alterations have had significant impacts on these systems and on the ecosystem services they provide. One of the consequences of these stressors is the expansion of invasive species that can affect native biodiversity and the many biogeochemical processes that are key to wetland ecosystem function. This research looked at how human activities affect microbial communities in tidal freshwater wetlands, and explored various aspects of an invasive plant’s ecology in the Chesapeake Bay. In our first study, we found that microbial community composition differed along a rural to urban gradient and identified microbial taxa that were indicators of either habitat. Rural sites tended to have more methanogens and these were also indicators in these system, whereas in urban systems nitrifying bacteria were the main indicator taxa. This study suggested that urban wetlands have different microbial communities and likely different functions than those in rural areas, particularly concerning nitrogen and contaminant removal. Our second study looked at management of an invasive lineage of Phragmites australis which is commonly found in wetlands impacted by nitrogen enrichment. We evaluated the effects of different C:N ratios on the competitive ability of this lineage and a native North American lineage. Even though carbon addition did not improve the native’s competitive ability, we identified facilitative interactions when both lineages were growing together. This suggests that native and invasive Phragmites might coexist if there are no additional disturbances to the system. Our last study focused on plant-fungal interactions, and found that both Phragmites lineages benefitted from inoculation with fungal endophytes under salt stress. These results suggest that studies of plant-fungal interactions can yield insights into mechanisms of invasion, and could be further investigated in native wetland plants susceptible to increased salt stress following sea-level rise. Our results provide insights into plant and microbial ecology in the Chesapeake Bay’s tidal freshwater wetlands, and improve our understanding of the invasion process and management strategies of Phragmites australis.Item BLOOM BIOSOLIDS: WHAT IS THEIR MICROBIAL COMMUNITY AND HOW DO THEY AFFECT SOIL AND PLANT HEALTH?(2019) Baballari, Eni; Yarwood, Stephanie; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Biosolids are rich in nutrients and organic matter, and are known to improve and maintain productive soils and stimulate plant growth. D.C. Water’s new Class A biosolids product, Bloom, was evaluated for its impact on plant and soil health. Using molecular tools, Bloom was examined for the presence of functional genes that would indicate the presence of microbes capable of improving plant growth (i.e.nitrifiers, N- fixers). Using greenhouse and laboratory experiments, we determined Bloom’s effect on plant growth, carbon and nitrogen cycling. Bloom has both nitrifying and N-fixing microbes, but their gene numbers vary depending on the stage of production. We show that plants, such as cucumber and tomato, grown in soil amended with Bloom produce more leaves and stems and have higher aboveground biomass, and soybeans produced more bean pods. Lastly, we found that N-mineralization is higher in soil amended with Bloom, even after one growing season, providing increased nutrients.Item SOIL ORGANIC CARBON IN MID-ATLANTIC REGION FOREST SOILS: STOCKS AND VERTICAL DISTRIBUTION(2019) Colopietro, Daniel John; Weil, Ray R; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Soil contains the largest terrestrial pool of organic carbon (Boschi et al., 2018) and temperate forest soils have been a major sink for atmospheric carbon; however, determining the size of the soil organic carbon stock can be problematic. Sampling practices vary for sampling depth, and determining the density of the soil. The aforementioned standard practices need to be revised if the size of SOC stocks are to be accurately quantified, to establish a global SOC baseline. A soil monitoring of 414 forested sites within 11 national parks in the National Capital Region (Schmit, 2014) was conducted over 10 years. Samples were collected from the leaf litter and each soil horizon to 1 meter depth. Soil bulk density (Db) was determined by the core method for the A horizons, and proxy Db values were investigated for the subsoil. The vertical distribution of SOC concentration and stocks were evaluated with respect to soil order, physiographic region/landform, drainage class and parent material.Item SPATIAL AND TEMPORAL VARIANCE OF MICROBIAL WATER QUALITY IN TWO MARYLAND IRRIGATION PONDS(2019) Kierzewski, Rachel Annette; Hill, Robert; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Farm ponds must be regularly sampled for Escherichia coli (E. coli) concentrations to evaluate the health risks of using pond water for irrigation. However, no guidance is available regarding sampling locations and/or irrigation pump placement. We hypothesized that there exists spatial and/or temporal patterns of E. coli concentrations across ponds. To test this hypothesis, we sampled two irrigation ponds in Maryland biweekly during the summers of 2016 and 2017. Results from data analysis of mean relative differences and Spearman correlation coefficients are presented. Empirical orthogonal functions indicated spatial patterns of Log E. coli concentrations were temporally maintained. More sample variance existed over time in the pond interiors versus near shore locations. Furthermore, larger patterns of sample variance existed within the spatial analysis variance versus the temporal analysis variance over both ponds for this study. Therefore, the spatio-temporal E. coli variance may have significant impacts on sampling and pump intake locations.