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- Genre: Academic theses
- Genre: Masters Thesis
- Creators: Arizona State University
- Creators: Grimm, Nancy
- Creators: Sabo, John L
- Member of: Theses and Dissertations
Description
Primary producers, from algae to trees, play a pivotal role in community structure and ecosystem function. Primary producers vary broadly in their functional traits (i.e., morphological, physiological, biochemical, and behavioral characteristics), which determine how they respond to stimuli and affect ecosystem properties. Functional traits provide a mechanistic link between environmental conditions, community structure, and ecosystem function. With climate change altering environmental conditions, understanding this mechanistic link is essential for predicting future community structure and ecosystem function. Competitive interactions and trait values in primary producers are often context dependent, whereby changes in environmental conditions and resources alter relationships between species and ecosystem processes. Well-established paradigms concerning how species in a community respond to each other and to environmental conditions may need to be re-evaluated in light of these environmental changes, particularly in highly variable systems. In this dissertation, I examine the role of primary producer functional traits on community structure and ecosystem function. Specifically, I test a conceptual framework that incorporates response traits, effect traits, and their interaction, in affecting primary producer communities and ecosystem function across different aquatic systems. First, I identified species-specific responses to intensifying hydrologic stressors important in controlling wetland plant community composition over time in an aridland stream. Second, I found that effect traits of submerged and emergent vegetation explained differences in ecosystem metabolism and carbon dynamics among permafrost mire thaw ponds. Next, I examined response-effect trait interactions by comparing two dominant wetland plant species over a water-stress gradient, finding that responses to changes in hydrology (i.e., altered tissue chemistry) in turn affect ecosystem processes (i.e., subsurface CO2 concentration). Finally, I demonstrate how indirect effects of diatom functional traits on water chemistry and ecosystem metabolism help explain disconnects between resource availability and productivity in the Colorado River. By expanding my understanding of how metabolic processes and carbon cycling in aquatic ecosystems vary across gradients in hydrology, vegetation, and organic matter, I contributed to my understanding of how communities influence ecosystem processes. A response-effect trait approach to understanding communities and ecosystems undergoing change may aid in predicting and mitigating the repercussions of future climate change.
ContributorsLauck, Marina Diane (Author) / Grimm, Nancy B (Thesis advisor) / Appling, Alison P (Committee member) / Childers, Dan E (Committee member) / Sabo, John L (Committee member) / Arizona State University (Publisher)
Created2022
Description
Under current climate conditions northern peatlands mostly act as C sinks; however, changes in climate and environmental conditions, can change the soil carbon decomposition cascade, thus altering the sink status. Here I studied one of the most abundant northern peatland types, poor fen, situated along a climate gradient from tundra (Daring Lake, Canada) to boreal forest (Lutose, Canada) to temperate broadleaf and mixed forest (Bog Lake, MN and Chicago Bog, NY) biomes to assess patterns of microbial abundance across the climate gradient. Principal component regression analysis of the microbial community and environmental variables determined that mean annual temperature (MAT) (r2=0.85), mean annual precipitation (MAP) (r2=0.88), and soil temperature (r2=0.77), were the top significant drivers of microbial community composition (p < 0.001). Niche breadth analysis revealed the relative abundance of Intrasporangiaceae, Methanobacteriaceae and Candidatus Methanoflorentaceae fam. nov. to increase when MAT and MAP decrease. The same analysis showed Spirochaetaceae, Methanosaetaceae and Methanoregulaceae to increase in relative abundance when MAP, soil temperature and MAT increased, respectively. These findings indicated that climate variables were the strongest predictors of microbial community composition and that certain taxa, especially methanogenic families demonstrate distinct patterns across the climate gradient. To evaluate microbial production of methanogenic substrates, I carried out High Resolution-DNA-Stable Isotope Probing (HR-DNA-SIP) to evaluate the active portion of the community’s intermediary ecosystem metabolic processes. HR-DNA-SIP revealed several challenges in efficiency of labelling and statistical identification of responders, however families like Veillonellaceae, Magnetospirillaceae, Acidobacteriaceae 1, were found ubiquitously active in glucose amended incubations. Differences in metabolic byproducts from glucose amendments show distinct patterns in acetate and propionate accumulation across sites. Families like Spirochaetaceae and Sphingomonadaceae were only found to be active in select sites of propionate amended incubations. By-product analysis from propionate incubations indicate that the northernmost sites were acetate-accumulating communities.
These results indicate that microbial communities found in poor fen northern peatlands are strongly influenced by climate variables predicted to change under current climate scenarios. I have identified patterns of relative abundance and activity of select microbial taxa, indicating the potential for climate variables to influence the metabolic pathway in which carbon moves through peatland systems.
ContributorsSarno, Analissa Flores (Author) / Cadillo-Quiroz, Hinsby (Thesis advisor) / Garcia-Pichel, Ferran (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Childers, Daniel (Committee member) / Arizona State University (Publisher)
Created2022
Description
Trichloroethene (TCE) and hexavalent chromium (Cr (VI)) are ubiquitous subsurface contaminants affecting the water quality and threatening human health. Microorganisms capable of TCE and Cr (VI) reductions can be explored for bioremediation at contaminated sites. The goal of my dissertation research was to address challenges that decrease the efficiency of bioremediation in the subsurface. Specifically, I investigated strategies to (i) promote improve microbial reductive dechlorination extent through the addition of Fe0 and (ii) Cr (VI) bio-reduction through enrichment of specialized microbial consortia. Fe0 can enhance microbial TCE reduction by inducing anoxic conditions and generating H2 (electron donor). I first evaluated the effect of Fe0 on microbial reduction of TCE (with ClO4– as co-contaminant) using semi-batch soil microcosms. Results showed that high concentration of Fe0 expected during in situ remediation inhibited microbial TCE and ClO4– reduction when added together with Dehalococcoides mccartyi-containing cultures. A low concentration of aged Fe0 enhanced microbial TCE dechlorination to ethene and supported complete microbial ClO4– reduction. I then evaluated a decoupled Fe0 and biostimulation/bioaugmentation treatment approach using soil packed columns with continuous flow of groundwater. I demonstrated that microbial TCE reductive dechlorination to ethene can be benefitted by Fe0 abiotic reactions, when biostimulation and bioaugmentation are performed downstream of Fe0 addition. Furthermore, I showed that ethene production can be sustained in the presence of aerobic groundwater (after Fe0 exhaustion) by the addition of organic substrates. I hypothesized that some lessons learned from TCE Bioremediation can be applied also for other pollutants that can benefit from anaerobic reductions, like Cr (VI). Bioremediation of Cr (VI) has historically relied on biostimulation of native microbial communities, partially due to the lack of knowledge of the benefits of adding enriched consortia of specialized microorganisms (bioaugmentation). To determine the merits of a specialized consortium on bio-reduction of Cr (VI), I first enriched a culture on lactate and Cr (VI). The culture had high abundance of putative Morganella species and showed rapid and sustained Cr (VI) bio-reduction compared to a subculture grown with lactate only (without Morganella). Overall, this dissertation work documents possible strategies for synergistic abiotic and biotic chlorinated ethenes reduction, and highlights that specialized consortia may benefit Cr (VI) bio-reduction.
ContributorsMohana Rangan, Srivatsan (Author) / Krajmalnik-Brown, Rosa (Thesis advisor) / Delgado, Anca G (Thesis advisor) / Torres, César I (Committee member) / van Paassen, Leon (Committee member) / Arizona State University (Publisher)
Created2022
Description
Advanced technology has increased access to Antarctica; consequently, there has been an increase in research and tourism. The production of the new technology and the increased number of individuals visiting can increase the presence of persistent organic pollutants and microplastic within Antarctic soil. Studies have focused primarily on identifying these pollutants in high human impact areas with perhaps an assumption that low human impact areas would have lower concentrations of pollutants. The object of this paper, therefore, was to test the hypothesis that higher concentrations of persistent organic pollutants and microplastic are found in soils collected near research stations and tourist areas, as opposed to sites that are further from stations and have less direct human impact. Soil samples were collected along a 1,500 km transect of the Scotia Arch and Antarctic Peninsula from three high human impact sites and three low human impact sites to compare the concentration of contaminates identified within the soil. The presence and quantities of microplastic were identified using Nile Red and fluorescence microscopy, while gas chromatography-mass spectrometry was used to detect polychlorinated biphenyls, pesticides, polycyclic aromatic hydrocarbons, n-alkane, and phthalates. Although varying contaminate concentration levels were found at all six sights, counter to the hypothesis, there were no clear patterns of increasing pollutants with increasing human activities. These findings could imply that global sources of pollutants can increase local pollutants indicating the best way to solve any pollution problem is through a global lens.
ContributorsCarroll, Kenneth Charles (Author) / Polidoro, Beth (Thesis advisor) / Kinzig, Ann (Thesis advisor) / Ball, Becky (Committee member) / Arizona State University (Publisher)
Created2022
Description
The proliferation of plastic has created a wicked global sustainability challenge. From the extraction of fossil fuels to end-of-life management and pollution, plastic imposes significant negative impacts to human health, economic well-being, and the environment. One proposed solution is to replace conventional plastic with biomass-based plastics and plastic alternatives (BBPAs), such as paper or bio-based plastics. While these products may have advantageous properties, they require biomass as a feedstock. Given the scale of the plastics problem, this biomass demand may be significant. In my dissertation, I evaluate the magnitude of biomass required, and assess the potential impact of this biomass demand on global land use. After examining the scope and the scale of the problem in chapter one, I evaluate the assumptions that have been made regarding the land-use impacts of BBPAs in chapter two. In chapter three, I use a global land-system model (CLUMondo) to evaluate the potential land-use change of large-scale production of BBPAs. In chapter four, I evaluate how certification schemes could be used as a policy tool to mitigate the land-use impacts of bio-based alternatives. I find that the current studies evaluating the land-use impacts of these products make optimistic and unrealistic assumptions regarding land-use. Using a global model, I show how high production scenarios of BBPAs could induce significant land-use change at the global level. Finally, I demonstrate that reliance on certification schemes would likely be insufficient to prevent negative impacts from this scale of land change. Overall, this dissertation suggests that large-scale replacement of plastic with BBPAs could incur significant land-use impacts. Policies designed to mitigate the impacts of plastic need to account for this impact to land-use, lest they risk substituting one global problem for another.
ContributorsHelm, Levi (Author) / Kinzig, Ann (Thesis advisor) / Dooley, Kevin (Committee member) / Turner II, Billie (Committee member) / Verburg, Peter (Committee member) / Arizona State University (Publisher)
Created2023
Description
The prevalence and unique properties of airborne nanoparticles have raised concerns regarding their potential adverse health effects. Despite their significance, the understanding of nanoparticle generation, transport, and exposure remains incomplete. This study first aimed to assess nanoparticle exposure in indoor workplace environments, in the semiconductor manufacturing industry. On-site observations during tool preventive maintenance revealed a significant release of particles smaller than 30 nm, which subsequent instrumental analysis confirmed as predominantly composed of transition metals. Although the measured mass concentration levels did not exceed current federal limits, it prompted concerns regarding how well filter-based air sampling methods would capture the particles for exposure assessment and how well common personal protective equipment would protect from exposure. To address these concerns, this study evaluated the capture efficiency of filters and masks. When challenged by aerosolized engineered nanomaterials, common filters used in industrial hygiene sampling exhibited capture efficiencies of over 60%. Filtering Facepiece Respirators, such as the N95 mask, exhibited a capture efficiency of over 98%. In contrast, simple surgical masks showed a capture efficiency of approximately 70%. The experiments showed that face velocity and ambient humidity influence capture performance and mostly identified the critical role of mask and particle surface charge in capturing nanoparticles. Masks with higher surface potential exhibited higher capture efficiency towards nanoparticles. Eliminating their surface charge resulted in a significantly diminished capture efficiency, up to 43%. Finally, this study characterized outdoor nanoparticle concentrations in the Phoenix metropolitan area, revealing typical concentrations on the order of 10^4 #/cm3 consistent with other urban environments. During the North American monsoon season, in dust storms, with elevated number concentrations of large particles, particularly in the size range of 1-10 μm, the number concentration of nanoparticles in the size range of 30-100 nm was substantially lower by approximately 55%. These findings provide valuable insights for future assessments of nanoparticle exposure risks and filter capture mechanisms associated with airborne nanoparticles.
ContributorsZhang, Zhaobo (Author) / Herckes, Pierre (Thesis advisor) / Westerhoff, Paul (Committee member) / Shock, Everett (Committee member) / Fraser, Matthew (Committee member) / Arizona State University (Publisher)
Created2023
Description
Flowering phenology offers a sensitive and reliable biological indicator of climate change because plants use climatic and other environmental cues to initiate flower production. Drylands are the largest terrestrial biome, but with unpredictable precipitation patterns and infertile soils, they are particularly vulnerable to climate change. There is a need to increase our comprehension of how dryland plants might respond and adapt to environmental changes. I conducted a meta-analysis on the flowering phenology of dryland plants and showed that some species responded to climate change through accelerated flowering, while others delayed their flowering dates. Dryland plants advanced their mean flowering dates by 2.12 days decade-1, 2.83 days °C-1 and 2.91 days mm-1, respectively, responding to time series, temperature, and precipitation. Flowering phenology responses varied across taxonomic and functional groups, with the grass family Poaceae (-3.91 days decade1) and bulb forming Amaryllidaceae (-0.82 days decade1) showing the highest and lowest time series responses respectively, while Brassicaceae was not responsive. Analysis from herbarium specimens collected across Namibian drylands, spanning 26 species and six families, revealed that plants in hyper-arid to arid regions have lower phenological sensitivity to temperature (-9 days °C-1) and greater phenological responsiveness to precipitation (-0.56 days mm-1) than those in arid to semi-arid regions (-17 days °C-1, -0.35 days mm-1). The flowering phenology of serotinous plants showed greater sensitivity to both temperature and precipitation than that of non-serotinous plants. I used rainout shelters to reduce rainfall in a field experiment and showed that drought treatment advanced the vegetative and reproductive phenology of Cleome gynandra, a highly nutritional and medicinal semi-wild vegetable species. The peak leaf length date, peak number of leaves date, and peak flowering date of Cleome gynandra advanced by six, 10 and seven days, respectively. Lastly, I simulated drought and flood in a greenhouse experiment and found that flooding conditions resulted in higher germination percentage of C. gynandra than drought. My study found that the vegetative, and flowering phenology of dryland plants is responsive to climate change, with differential responses across taxonomic and functional groups, and aridity zones, which could alter the structure and function of these systems.
ContributorsKangombe, Fransiska Ndiiteela (Author) / Throop, Heather (Thesis advisor) / Sala, Osvaldo (Committee member) / Vivoni, Enrique (Committee member) / Pigg, Kathleen (Committee member) / Hultine, Kevin (Committee member) / Kwembeya, Ezekeil (Committee member) / Arizona State University (Publisher)
Created2023
Description
Climate change is one of the most pressing issues facing humanity, and cities are likely to experience many of the most dangerous effects of climate change. One way that cities aim to adapt to become more resilient to climate change is through the provision of locally produced ecosystem services: the benefits that people get from nature. In cities, these ecosystem services are provided by diverse forms of urban ecological infrastructure (UEI): all parts of a city that include ecological structure and function. While there is a growing body of research touting the multifunctionality of UEI and an increasing number of cities implementing UEI plans, there remain important gaps in understanding how UEI features perform at providing ecosystem services and how the local social-ecological-technological context affects the efficacy of UEI solutions. Inspired by the need for cities to adapt to become more resilient to climate change, this dissertation takes an interdisciplinary approach to understand how diverse UEI features and their ecosystem services are perceived, provided, and prioritized for current and future climate resilience. The second chapter explores how a diverse group of local actors in Valdivia, Chile perceives the city’s urban wetlands and identifies common trade-offs in the perceived importance of different ecosystem services from the wetlands. The third chapter demonstrates species-level differences and trade-offs between common street trees in Phoenix, Arizona in their ability to provide the ecosystem services of both local climate regulation and stormwater regulation. The fourth chapter compares how participatory scenarios from nine cities across the United States and Latin America vary in the degree to which they incorporate UEI and ecosystem services into future visions. The fifth chapter returns focus to Phoenix and illustrates dominant perspectives on the prioritization of ecosystem services for achieving climate resilience and how those priorities change across temporal scales. The dissertation concludes with a synthesis of the previous chapters and suggestions for future urban ecosystem services research. Combined, this dissertation advances understanding of ecosystem services from UEI and highlights the importance of considering trade-offs among UEI features in order help achieve more just, verdant, and resilient urban futures.
ContributorsElser, Stephen Robert (Author) / Grimm, Nancy (Thesis advisor) / Berbés-Blázquez, Marta (Committee member) / Cook, Elizabeth (Committee member) / McPhillips, Lauren (Committee member) / York, Abigail (Committee member) / Arizona State University (Publisher)
Created2022
Characterization and Manipulation of Microbiomes From Arid Landfills for Improved Methane Production
Description
Environmentally harmful byproducts from solid waste’s decomposition, including methane (CH4) emissions, are managed through standardized landfill engineering and gas-capture mechanisms. Yet only a limited number of studies have analyzed the development and composition of Bacteria and Archaea involved in CH4 production from landfills. The objectives of this research were to compare microbiomes and bioactivity from CH4-producing communities in contrasting spatial areas of arid landfills and to tests a new technology to biostimulate CH4 production (methanogenesis) from solid waste under dynamic environmental conditions controlled in the laboratory. My hypothesis was that the diversity and abundance of methanogenic Archaea in municipal solid waste (MSW), or its leachate, play an important role on CH4 production partially attributed to the group’s wide hydrogen (H2) consumption capabilities. I tested this hypothesis by conducting complementary field observations and laboratory experiments. I describe niches of methanogenic Archaea in MSW leachate across defined areas within a single landfill, while demonstrating functional H2-dependent activity. To alleviate limited H2 bioavailability encountered in-situ, I present biostimulant feasibility and proof-of-concepts studies through the amendment of zero valent metals (ZVMs). My results demonstrate that older-aged MSW was minimally biostimulated for greater CH4 production relative to a control when exposed to iron (Fe0) or manganese (Mn0), due to highly discernable traits of soluble carbon, nitrogen, and unidentified fluorophores found in water extracts between young and old aged, starting MSW. Acetate and inhibitory H2 partial pressures accumulated in microcosms containing old-aged MSW. In a final experiment, repeated amendments of ZVMs to MSW in a 600 day mesocosm experiment mediated significantly higher CH4 concentrations and yields during the first of three ZVM injections. Fe0 and Mn0 experimental treatments at mesocosm-scale also highlighted accelerated development of seemingly important, but elusive Archaea including Methanobacteriaceae, a methane-producing family that is found in diverse environments. Also, prokaryotic classes including Candidatus Bathyarchaeota, an uncultured group commonly found in carbon-rich ecosystems, and Clostridia; All three taxa I identified as highly predictive in the time-dependent progression of MSW decomposition. Altogether, my experiments demonstrate the importance of H2 bioavailability on CH4 production and the consistent development of Methanobacteriaceae in productive MSW microbiomes.
ContributorsReynolds, Mark Christian (Author) / Cadillo-Quiroz, Hinsby (Thesis advisor) / Krajmalnik-Brown, Rosa (Thesis advisor) / Wang, Xuan (Committee member) / Kavazanjian, Edward (Committee member) / Arizona State University (Publisher)
Created2022
Description
In arid and semiarid areas of the southwestern United States and northwestern México, water availability is the main control on the interactions between the land surface and the atmosphere. Seasonal and interannual variations in water availability regulate the response of water and carbon dioxide fluxes in natural and urban landscapes. However, despite sharing a similar dependance to water availability, landscape characteristics, such as land cover heterogeneity, landscape position, access to groundwater, microclimatic conditions, and vegetation functional traits, among others, can play a fundamental role in modulating the interactions between landscapes and the atmosphere. In this dissertation, I study how different landscape characteristics influence the response of water and carbon dioxide fluxes in arid and semiarid urban and natural settings. The study uses the eddy covariance technique, which calculates the vertical turbulent fluxes within the boundary layer, to quantify water, energy, and carbon dioxide fluxes within local patches. Specifically, the study focused on three main scopes: (1) how vegetation, anthropogenic activity, and water availability influence carbon fluxes in four urban landscapes in Phoenix, Arizona, (2) how access to groundwater and soil-microclimate conditions modulate the flux response of three natural ecosystems in northwestern México during the North American monsoon, and (3) how the seasonal hydrologic partitioning in a watershed with complex terrain regulates the carbon dioxide fluxes of a Chihuahuan Desert shrubland. Results showed a differential response of landscapes according to their land cover composition, access to groundwater or functional traits. In Chapter 2, in urban landscapes with irrigation, vegetation activity can counteract carbon dioxide emissions during the day, but anthropogenic sources from the built environment dominate the carbon dioxide fluxes overall. In Chapter 3, across an elevation-groundwater access gradient, low elevation ecosystems showed intensive water use strategies linked to a dependance to shallow or intermittent access to soil moisture, while a high elevation ecosystem showed extensive water use strategies which depend on a reliable access to groundwater. Finally, in Chapter 4, the mixed shrubland in complex terrain showed an evenly distributed bimodal vegetation productivity which is supported by an abundant water availability during wet seasons and by carry-over moisture in deeper layers of the soil during the dry season. The results from this dissertation highlight how different forms of water availability are responsible for the activity of vegetation which modulates land surface fluxes in arid and semiarid settings. Furthermore, the outcomes of this dissertation help to understand how landscape properties regulate the flux response to water availability in urban and natural areas.
ContributorsPerez Ruiz, Eli Rafael (Author) / Vivoni, Enrique R (Thesis advisor) / Sala, Osvaldo E (Committee member) / Throop, Heather L (Committee member) / Whipple, Kelin X (Committee member) / Yepez, Enrico A (Committee member) / Arizona State University (Publisher)
Created2021