Matching Items (26)
Description
With less than seven years left to reach the ambitious targets of the United Nations' 2030 Sustainable Development Goals (SDGs), it is imperative to understand how the SDGs are operationalized in practice to support effective governance. One integrative approach, the water, energy, and food (WEF) nexus, has been proposed to facilitate SDGs planning and implementation by incorporating synergies, co-benefits, and trade-offs. In this dissertation, I conduct three interrelated WEF nexus studies using a sustainability lens to develop new approaches and identify actionable measures to support the SDGs. The first paper is a systematic literature review (2015 – 2022) to investigate the extent to which WEF nexus research has generated actionable knowledge to achieve the SDGs. The findings show that the WEF nexus literature explicitly considering the SDGs mainly focuses on governance and environmental protection, with fewer studies focusing on target populations and affordability. In the second paper, I reframed the water quality concerns using a nexus and systems thinking approach in a FEW nexus hotspot, the Rio Negro Basin (RNB) in Uruguay. While Uruguay is committed to the 2030 Agenda for Sustainable Development, sustainability challenges endure in managing synergies and trade-offs, resulting in strategy setbacks for the sustainable development of food, land, water, and oceans. Reframing the water quality problem facilitated the identification of potential alternative intervention points to support local problem-solving capacity. In the third paper, I conducted semi-structured interviews and examined the meeting transcripts of the RNB Commission to understand local perspectives about how the activities and initiatives taking place in the basin enhance or diminish the overall sustainability. Sustainability criteria for river basin planning and management were operationalized through qualitative appraisal questions. The case of the RNB illustrates the challenges of coordinating the national development agenda to local livelihood. This dissertation advances the WEF nexus and sustainability science literature by shedding light on the implications of the research trend to support the SDGs, as well as reframing and appraising a persistent water quality problem to support sustainable development.
ContributorsOjeda Matos, Glorynel (Author) / White, Dave D (Thesis advisor) / Brundiers, Katja (Committee member) / Garcia, Margaret (Committee member) / Arizona State University (Publisher)
Created2023
Description
Electrochemical technologies emerge as a feasible solution to monitor and treat pollutants. Although electrochemical technologies have garnered widespread attention, their commercial applications are still constrained by the use of expensive electrocatalysts, and the bulky and rigid plate design of electrodes that restricts electrochemical reactor design to systems with poor electrode surface/ volume treated ratios. By making electrodes flexible, more compact designs that maximize electrode surface per volume treated might become a reality. This dissertation encompasses the successful fabrication of flexible nanocomposite electrodes for electrocatalysis and electroanalysis applications.First, nano boron-doped diamond electrodes (BDD) were prepared as an inexpensive alternative to commercial boron-doped diamond electrodes. Comparative detailed surface and electrochemical characterization was conducted. Empirical study showed that replacing commercial BDD electrodes with nano-BDD electrodes can result in a cost reduction of roughly 1000x while maintaining the same electrochemical performance.
Next, self-standing electrodes were fabricated through the electropolymerization of conducing polymer, polypyrrole. Surface characterizations, such as SEM, FTIR and XPS proved the successful fabrication of these self-standing electrodes. High mechanical stability and bending flexibility demonstrated the ability to use these electrodes in different designs, such as roll-to-roll membranes. Electrochemical nitrite reduction was employed to demonstrate the viability of using self-standing nanocomposite electrodes for electrocatalytic applications reducing hazardous nitrogen oxyanions (i.e., nitrite) towards innocuous species such as nitrogen gas. A high faradaic efficiency of 78% was achieved, with high selectivity of 91% towards nitrogen gas.
To further enhance the conductivity and charge transfer properties of self-standing polypyrrole electrodes, three different nanoparticles, including copper (Cu), gold (Au), and platinum (Pt), were incorporated in the polypyrrole matrix. Effect of nanoparticle wt% and interaction between metal nanoparticles and polypyrrole matrix was investigated for electroanalytical applications, specifically dopamine sensing. Flexible nanocomposite electrodes showed outstanding performance as electrochemical sensors with PPy-Cu 120s exhibiting a low limit of detection (LOD) of 1.19 µM and PPy-Au 120s exhibiting a high linear range of 5 µM - 300 µM.
This dissertation outlines a method of fabricating self-standing electrodes and provides a pathway of using self-standing electrodes based on polypyrrole and polypyrrole-metal nanocomposites for various applications in wastewater treatment and electroanalytical sensing.
ContributorsBansal, Rishabh (Author) / Garcia-Segura, Sergio (Thesis advisor) / Westerhoff, Paul (Committee member) / Perreault, Francois (Committee member) / Chan, Candace (Committee member) / Arizona State University (Publisher)
Created2023
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
Description
Ultraviolet (UV) radiation is the most well-known cause of skin cancer, and skin cancer is the most common type of cancer in the United States. People are exposed to UV rays when they engage in outdoor activities, particularly exercise, which is an important health behavior. Thus, researchers and the general public have shown increasing interest in measuring UV exposures during outdoor physical activity using wearable sensors. However, minimal research exists at the intersection of UV sensors, personal exposure, adaptive behavior due to exposures, and risk of skin damage. Three studies are presented in this dissertation: (1) a state-of-the-art review that synthesizes the current academic and grey literature surrounding personal UV sensing technologies; (2) the first study to investigate the effects of specific physical activity types, skin type, and solar angle on personal exposure in different outdoor environmental contexts; and (3) a study that develops recommendations for future UV-sensing wearables based on follow-up interviews with participants from the second study, who used a wrist-worn UV sensor while exercising outdoors. The first study provides recommendations for 13 commercially available sensors that are most suitable for various types of research or personal use. The review findings will help guide researchers in future studies assessing UV exposure with wearables during physical activity. The second study outlines the development of predictive models for individual-level UV exposure, which are also provided. These models recommend the inclusion of sky view factor, solar angle, activity type, urban environment type, and the directions traveled during physical activity. Finally, based on user feedback, the third study recommends that future UV-sensing wearables should be multi-functional watches where users can toggle between showing their UV exposure results in cumulative and countdown formats, which is intuitive and aesthetically pleasing to users.
ContributorsHenning, Alyssa Leigh (Author) / Vanos, Jennifer (Thesis advisor) / Johnston, Erik (Thesis advisor) / Frow, Emma (Committee member) / Michael, Katina (Committee member) / Downs, Nathan (Committee member) / Arizona State University (Publisher)
Created2021
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
Limited funding hinders endangered species recovery. Thus, decision makers need to strategically allocate resources to save the most species. Decision science provides guidance on efficient prioritization of conservation actions. However, endangered species recovery cost estimates are incomplete, so decision makers need to understand the implications of different cost estimation approaches. To test how different ways of estimating the expected costs of recovery action influence suggested recovery priorities, I used three different cost estimation scenarios for prioritizing recovery effort for 29 endangered species in Arizona. My scenarios explored “remaining” costs, calculated by subtracting historical spending from recovery plan cost estimates, “average” costs which substituted the average cost for actions in recovery plans, and “micro” and “macro” overlaps accounting for efficiency of costs due to implementing shared recovery actions for species with overlapping ranges. These different methods of estimating costs resulted in different numbers of recovery plans funded. At a representative budget, the macro overlap scenario recommended funding for 97% of plans as compared to 93% of plans under the baseline cost scenario. In contrast, the micro overlap (59%), the average (28%), and remaining (24%) cost estimation approaches all resulted in less plans recommended for funding than the baseline. There were also differences in how individual plans were ranked across the scenarios and variation in species chosen for funding. The order of recovery plans was similar between the baseline and the remaining scenario (WS = 0.833), and the baseline and the average scenario (WS=0.811). The similarity metric is based on the identity of species ranked equally. In contrast, there was less similarity in plan ranking between the baseline, the macro (WS=0.777), and micro (WS=0.442) overlap scenarios. A group of 4 plans remained within the top priority ranks, 5 plans were ranked as high priority for all scenarios except the remaining cost scenario, and 5 plans were consistently ranked as low priority. My results show how cost estimation approaches influence species priority rankings and can be used to help decision makers determine implications when they are exploring options for prioritization.
ContributorsSansonetti, Alice Maria (Author) / Gerber, Leah (Thesis advisor) / Iacona, Gwen (Thesis advisor) / Maas, Amy (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
Prior to COVID-19, tourism was one of the world’s largest and fastest growing industries. Consequently, extensive scholarly research has been conducted on various aspects of tourism. However, the majority of this research has primarily focused on the experiences of tourists, leaving the impacts and dynamics on host destinations, especially in developing countries, relatively understudied. This dissertation examines the dynamics of tourism in Upper Mustang, Nepal. Using a confluence of mixed methods, the three research papers in this dissertation address the gaps in existing literature and provide insights into the complex dynamics of tourism in the region. These studies investigate the effects of COVID-19 on global migratory networks and trans-local kinship relationships, examine the impacts of tourism and power relationships, and analyze the factors that influence tourism-based livelihood diversification. The first paper analyzes migration, mobility, and precarity within the trans-local Himalayan community, particularly in light of the COVID-19’s disruptions. The second paper explores Upper Mustang residents' perspectives on tourism impacts and considers power relationships. The third paper investigates the factors influencing households' decisions to adopt or avoid tourism-based livelihood diversification in Upper Mustang. The findings highlight the dependence of Mustangs' well-being on global migratory networks and trans-local kinship relations. Perceived tourism impacts varied based on geographical location, which defined the presence of tourists. The study reveals an uneven distribution of tourism benefits among the local population, stemming from historical social structures that pre-date tourism. Furthermore, it identifies factors that positively or negatively influence households' choices to diversify their livelihoods into tourism. The research underscores the disruptive nature of migration on the trend of livelihood diversification. Overall, this study contributes to a comprehensive understanding of tourism complexities and effects in the context of Upper Mustang, which are relevant to tourism impacts experienced globally. By addressing multiple dimensions, including migration, power relationship, and livelihood decisions, it sheds light on the intricate dynamics of tourism for the region and connects local tourism to global processes of migration and livelihood change. The research emphasizes the need for a balanced exploration of host destination perspectives and expands knowledge on the impacts of tourism.
ContributorsGurung, Tashi Wongdi (Author) / BurnSilver, Shauna S (Thesis advisor) / Marty Anderies, Marty M (Thesis advisor) / York, Abigail A (Committee member) / Shrestha, Milan M (Committee member) / Arizona State University (Publisher)
Created2023
Description
Precision agriculture (PA) integrating information technology arouses broad interests and has been extensively studied to increase crop production and quality. Sensor probe technology, as one of the PA technologies, provides people with accurate real-time data, which has become an essential part of precision agriculture. Herein a novel microbial sensor probe (MiProbE) is applied to monitor and study the growth of tomatoes (Solanum lycopersicum L.) in real-time at germination and seedling stages. The result showed the raw Miprobe signals present day/night cycles. Alginate-coated probes effectively avoided signal response failure and were more sensitive to the treatments than uncoated probes. The probe signals from successfully germinated tomato seeds and non-germinated seeds were different, and the signal curve of the probe was closely related to the growth conditions of tomato seedlings. Specifically, the rising period of the probe signals coincided with the normal growth period of tomato seedlings. All probes exhibited sudden increases in signal strength after nutrient treatments; however, subsequent probe signals behaved differently: algae extract-treated probe signals maintained a high strength after the treatments; chemical fertilizer-treated probe signals decreased earlier after the treatments; chemical fertilizers and algae extract-treated probe signals also maintained a higher strength after the treatments. Moreover, the relationship between ash-free dry weight and the signal curve indicated that the signal strength positively correlates with the dry weight, although other biological activities can affect the probe signal at the same time. Further study is still needed to investigate the relationship between plant biomass and Miprobe signal.
ContributorsQi, Deyang (Author) / Weiss, Taylor (Thesis advisor) / Penton, Christopher (Committee member) / Park, Yujin (Committee member) / Arizona State University (Publisher)
Created2021
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