Matching Items (86)
Description
The ocean sequesters more than 25% of the carbon released by anthropogenic action every year, and oligotrophic oceans, such as the Sargasso Sea, are responsible for about 50% of the global carbon export. Pico- and nano-phytoplankton (cells < 5 µm), mostly unicellular eukaryotes (protists) and cyanobacteria, dominate the primary production in the Sargasso Sea; however, little is known about their contribution to the export of carbon into the deep ocean via sinking particles. The overall goal of this study is to examine the link between growth and grazing rates of pico- and nano-phytoplankton and the carbon export in the Sargasso Sea. I investigate three aspects: 1) how microzooplankton grazing and physical forcing affect taxon-specific primary productivity in this region, 2) how these microbial trophic dynamics impact their contribution to the export of particulate matter, and 3) how much pico-phytoplankton, specifically the pico-cyanobacteria Synechococcus and Prochlorococcus, contribute to the carbon export. I collected seawater samples within the sunlit (euphotic) zone, and sinking particles at 150 m depth using particle traps in the Sargasso Sea during the winter and summer seasons of 2011 and 2012. I conducted dilution experiments to determine the growth and grazing rates of the pico- and nano-phytoplankton community, and used 454 pyrosequencing and quantitative Polymerase Chain Reaction to measure the relative and absolute contribution of these primary producers to the plankton community within the euphotic zone and in the sinking particles. I found that micrograzing controls taxon-specific primary production, and that microbial trophic dynamics impact directly the taxonomical composition of the sinking particles. For the first time, I was able to quantify clade-specific carbon export of pico-cyanobacteria and found that, despite their small size, these tiny primary producers are capable of sinking from the surface to the deeper oceans. However, their contribution to the carbon flux is often less than one tenth of their biomass contribution in the euphotic zone. Our study provides a comprehensive approach to better understand the role of pico- and nano-phytoplankton in the carbon cycle of oligotrophic oceans, and a baseline to study changes in the carbon export in future warmer oceans.
ContributorsDe Martini, Francesca (Author) / Neuer, Susanne (Thesis advisor) / Garcia-Pichel, Ferran (Committee member) / Hartnett, Hilairy (Committee member) / Lomas, Michael (Committee member) / Arizona State University (Publisher)
Created2016
Description
The aboveground surfaces of plants (i.e. the phyllosphere) comprise the largest biological interface on Earth (over 108 km2). The phyllosphere is a diverse microbial environment where bacterial inhabitants have been shown to sequester and degrade airborne pollutants (i.e. phylloremediation). However, phyllosphere dynamics are not well understood in urban environments, and this environment has never been studied in the City of Phoenix, which maintains roughly 92,000 city trees. The phyllosphere will grow if the City of Phoenix is able to achieve its goal of 25% canopy coverage by 2030, but this begs the question: How and where should the urban canopy expand? I addressed this question from a phyllosphere perspective by sampling city trees of two species, Ulmus parvifolia (Chinese Elm) and Dalbergia sissoo (Indian Rosewood) in parks and on roadsides. I identified characteristics of the bacterial community structure and interpreted the ecosystem service potential of trees in these two settings. I used culture-independent methods to compare the abundance of each unique bacterial lineage (i.e. ontological taxonomic units or OTUs) on the leaves of park trees versus on roadside tree leaves. I found numerous bacteria (81 OTUs) that were significantly more abundant on park trees than on roadside trees. Many of these OTUs are ubiquitous to bacterial phyllosphere communities, are known to promote the health of the host tree, or have been shown to degrade airborne pollutants. Roadside trees had fewer bacteria (10 OTUs) that were significantly more abundant when compared to park trees, but several have been linked to the remediation of petroleum combustion by-products. These findings, that were not available prior to this study, may inform the City of Phoenix as it is designing its future urban forests.
ContributorsMacNeille, Benjamin C (Author) / Childers, Daniel L. (Thesis advisor) / Garcia-Pichel, Ferran (Committee member) / Cease, Arianne J (Committee member) / Arizona State University (Publisher)
Created2016
Description
The unicellular cyanobacterium Synechocystis sp. PCC 6803 contains a NiFe-type bidirectional hydrogenase that is capable of using reducing equivalents to reduce protons and generate H¬2. In order to achieve sustained H2 production using this cyanobacterium many challenges need to be overcome. Reported H2 production from Synechocystis is of low rate and often transient. Results described in this dissertation show that the hydrogenase activity in Synechocystis is quite different during periods of darkness and light. In darkness, the hydrogenase enzyme acts in a truly bidirectional way and a particular H2 concentration is reached that depends upon the amount of biomass involved in H2 production. On the other hand, in the presence of light the enzyme shows only transient H2 production followed by a rapid and constitutive H2 oxidation. H2 oxidation and production were measured from a variety of Synechocystis strains in which components of the photosynthetic or respiratory electron transport chain were either deleted or inhibited. It was shown that the light-induced H2 oxidation is dependent on the activity of cytochrome b6f and photosystem I but not on the activity of photosystem II, indicating a channeling of electrons through cytochrome b6f and photosystem I. Because of the sequence similarities between subunits of NADH dehydrogenase I in E. coli and subunits of hydrogenase in Synechocystis, NADH dehydrogenase I was considered as the most likely candidate to mediate the electron transfer from hydrogenase to the membrane electron carrier plastoquinone, and a three-dimensional homology model with the associated subunits shows that structurally it is possible for the subunits of the two complexes to assemble. Finally, with the aim of improving the rate of H2 production in Synechocystis by using a powerful hydrogenase enzyme, a mutant strain of Synechocystis was created in which the native hydrogenase was replaced with the hydrogenase from Lyngbya aestuarii BL J, a strain with higher capacity for H2 production. H2 production was detected in this Synechocystis mutant strain, but only in the presence of external reductants. Overall, this study emphasizes the importance of redox partners in determining the direction of H2 flux in Synechocystis.
ContributorsDatta, Īpsitā (Author) / Vermaas, Willem Fj (Thesis advisor) / Garcia-Pichel, Ferran (Committee member) / Rittmann, Bruce (Committee member) / Jones, Anne K (Committee member) / Arizona State University (Publisher)
Created2015
Description
Diarrheal diseases caused by poor water, sanitation and hygiene continue to kill more children in Sub-Saharan Africa's burgeoning informal urban settlements than in any other part of the world. In recent years, Delegated Management Model (DMM), a partnership in which a utility delegates service management to slum residents have been promoted as new models to improve services.
This dissertation examines the benefits of DMM by comparing water services in three informal settlements in Kisumu city, Kenya: two slums where DMM has been implemented, and one, a control, where it has not. In addition, the research examined how school-based hygiene interventions could be designed to improve safe water and hygiene knowledge in urban informal settlements. This study compared outcomes of two approaches to hygiene education, one which combined messages with participatory water testing; the second used hygiene messages alone.
Results of the DMM study showed that DMM implementation had lowered water cost and improved provider accountability. However, unhygienic water collection and handling practices on the part of the service users could contaminate drinking water that was clean at the delivery point, thus preventing the intended health outcomes of DMM from being realized. Results of the hygiene education intervention showed that one week after the inventions, hygiene knowledge among students who received the intervention that combined hygiene messages with participatory water testing was significantly improved. Evaluation of the intervention 12 months after implementation showed that the hygiene knowledge gained was sustained.
The research findings suggest that: i) regular monitoring of water quality at the kiosks is essential to ensure that the DMM model achieves intended health outcomes, ii) sanitation conditions at kiosk sites need to be regulated to meet minimum hygiene standards, and iii) customers need to be educated on safe water collection and storage practices. Finally, school-based hygiene education could be made more effective by including hands-on water testing by students. Making sustainable impact on health and wellbeing of slum residents requires not only building effective partnerships for water delivery, but also paying close attention to the other points of intervention within the water system.
This dissertation examines the benefits of DMM by comparing water services in three informal settlements in Kisumu city, Kenya: two slums where DMM has been implemented, and one, a control, where it has not. In addition, the research examined how school-based hygiene interventions could be designed to improve safe water and hygiene knowledge in urban informal settlements. This study compared outcomes of two approaches to hygiene education, one which combined messages with participatory water testing; the second used hygiene messages alone.
Results of the DMM study showed that DMM implementation had lowered water cost and improved provider accountability. However, unhygienic water collection and handling practices on the part of the service users could contaminate drinking water that was clean at the delivery point, thus preventing the intended health outcomes of DMM from being realized. Results of the hygiene education intervention showed that one week after the inventions, hygiene knowledge among students who received the intervention that combined hygiene messages with participatory water testing was significantly improved. Evaluation of the intervention 12 months after implementation showed that the hygiene knowledge gained was sustained.
The research findings suggest that: i) regular monitoring of water quality at the kiosks is essential to ensure that the DMM model achieves intended health outcomes, ii) sanitation conditions at kiosk sites need to be regulated to meet minimum hygiene standards, and iii) customers need to be educated on safe water collection and storage practices. Finally, school-based hygiene education could be made more effective by including hands-on water testing by students. Making sustainable impact on health and wellbeing of slum residents requires not only building effective partnerships for water delivery, but also paying close attention to the other points of intervention within the water system.
ContributorsNzengya, Daniel (Author) / Aggarwal, Rimjhim (Thesis advisor) / Hartwell, Leland (Committee member) / Boone, Christopher (Committee member) / Arizona State University (Publisher)
Created2014
Description
The conflict conditions that afflict the livelihoods of Palestinian residents living in the West Bank are embedded within the population's ability to travel more so than any other routine activity. For Palestinian residents, domestic and international travel is a process of following paths riddled with multiple barriers that are both physical and political. Past studies have done well to paint a clear picture of the harsh transportation landscape in the region. However, less attention has focused on how barriers interact to indirectly and directly affect levels of accessibility and well-being. Additionally, suggested development solutions are rarely capable of being successfully implemented given current political conditions. This dissertation uses a systems approach to understand drivers of accessibility challenges in the West Bank and uses the understanding to propose a method to identify transition strategies that may be presently initiated whilst maintaining the ability to provide adequate benefit. The research question informing the study asks, How do drivers influencing the issue of poor accessibility and well-being in the West Bank persist and interact, and how might solutions be approached? The dissertation approaches the question in four sequential actions that each produces a functional planning deliverable. First, a system map that depicts the drivers and influences to the problem of poor accessibility and well-being is constructed (Chapter 4). Second, a future vision for the transportation system in the West Bank is identified (Chapter 5). Third, the system map and vision are used to assess how conflict conditions affect transition research (Chapter 6). Finally, the previous three deliverables are used to suggest a guide for transition management for transportation development in the West Bank (Chapter 7). Combinations of four different data sets, including an extensive review of published literature, field observations, individual field expert interviews, and group commuter interviews inform the research. Additionally, the Transformational Sustainability Research framework provides a normative base for the steps taken throughout the research. Ultimately, the dissertation presents an interpretation of information that has theoretical and practical application potential in transformational sustainability research and development efforts in the region respectively.
ContributorsAhmad, Omaya Heidi (Author) / Golub, Aaron (Thesis advisor) / Aggarwal, Rimjhim (Committee member) / Saleh Sadaqa, Ahmad (Committee member) / Arizona State University (Publisher)
Created2015
Description
Alfalfa is a major feed crop widely cultivated in the United States. It is the fourth largest crop in acreage in the US after corn, soybean, and all types of wheat. As of 2003, about 48% of alfalfa was produced in the western US states where alfalfa ranks first, second, or third in crop acreage. Considering that the western US is historically water-scarce and alfalfa is a water-intensive crop, it creates a concern about exacerbating the current water crisis in the US west. Furthermore, the recent increased export of alfalfa from the western US states to China and the United Arab Emirates has fueled the debate over the virtual water content embedded in the crop. In this study, I analyzed changes of cropland systems under the three basic scenarios, using a stylized model with a combination of dynamical, hydrological, and economic elements. The three scenarios are 1) international demands for alfalfa continue to grow (or at least to stay high), 2) deficit irrigation is widely imposed in the dry region, and 3) long-term droughts persist or intensify reducing precipitation. The results of this study sheds light on how distribution of crop areas responds to climatic, economic, and institutional conditions. First, international markets, albeit small compared to domestic markets, provide economic opportunities to increase alfalfa acreage in the dry region. Second, potential water savings from mid-summer deficit irrigation can be used to expand alfalfa production in the dry region. Third, as water becomes scarce, farmers more quickly switch to crops that make more economic use of the limited water.
ContributorsKim, Booyoung (Author) / Muneepeerakul, Rachata (Thesis advisor) / Ruddell, Benjamin (Committee member) / Aggarwal, Rimjhim (Committee member) / Arizona State University (Publisher)
Created2015
Description
Beneficiary participation has become popular in international development generally, and it is an essential feature of sustainable development. But there are diverse definitions of and motivations for using beneficiary participation, and empirical literature on its effects is underdeveloped. This dissertation aims to clarify what beneficiary participation is and whether there is empirical support for claims about its benefits.
I review historical trends in international development that led to the popularity of both sustainable development and beneficiary participation. This review identifies central themes in defining beneficiary participation and motivations for using it.
I also developed a new typology of beneficiary participation based on a literature review of how scholars define beneficiary participation. I found that the main dimensions of beneficiary participation are (1) participants, (2) channels, (3) types of inputs, (4) timing, and (5) goals. By making these dimensions explicit, this work helps researchers and development practitioners more clearly describe the types of beneficiary participation they study, employ, and advocate for.
To contribute to empirical literature about beneficiary participation, I conducted a case-study of two urban development projects in Bhopal, India. I collected data with a structured survey of project beneficiaries in four slums (two slums from each project) and semi-structured interviews with each project's organizers. And project documents provided secondary data on both projects. The results indicate that local elites did not capture a disproportionate share of either project's benefits, at least with respect to individual household toilets. Because project organizers rather than beneficiaries selected households that would receive toilets, both cases serve as counterexamples to the claim that beneficiaries must intensely participate for projects' benefits to be distributed equitably.
Finally, I review academic literature for empirical evidence that supports claims about the advantages of beneficiary participation. There is relatively strong empirical support for the claim that beneficiary participation improves project outcomes, but empirical support for most other claims (i.e., that it helps make projects more efficient, distribute benefits equitably, and sustain project benefits) is weak. And empirical research suggests that one claimed benefit, empowerment, rarely materializes. In general, more empirical research about beneficiary participation is needed.
I review historical trends in international development that led to the popularity of both sustainable development and beneficiary participation. This review identifies central themes in defining beneficiary participation and motivations for using it.
I also developed a new typology of beneficiary participation based on a literature review of how scholars define beneficiary participation. I found that the main dimensions of beneficiary participation are (1) participants, (2) channels, (3) types of inputs, (4) timing, and (5) goals. By making these dimensions explicit, this work helps researchers and development practitioners more clearly describe the types of beneficiary participation they study, employ, and advocate for.
To contribute to empirical literature about beneficiary participation, I conducted a case-study of two urban development projects in Bhopal, India. I collected data with a structured survey of project beneficiaries in four slums (two slums from each project) and semi-structured interviews with each project's organizers. And project documents provided secondary data on both projects. The results indicate that local elites did not capture a disproportionate share of either project's benefits, at least with respect to individual household toilets. Because project organizers rather than beneficiaries selected households that would receive toilets, both cases serve as counterexamples to the claim that beneficiaries must intensely participate for projects' benefits to be distributed equitably.
Finally, I review academic literature for empirical evidence that supports claims about the advantages of beneficiary participation. There is relatively strong empirical support for the claim that beneficiary participation improves project outcomes, but empirical support for most other claims (i.e., that it helps make projects more efficient, distribute benefits equitably, and sustain project benefits) is weak. And empirical research suggests that one claimed benefit, empowerment, rarely materializes. In general, more empirical research about beneficiary participation is needed.
ContributorsKutter, Robert W (Author) / Aggarwal, Rimjhim (Thesis advisor) / Golub, Aaron (Committee member) / Wiek, Arnim (Committee member) / Arizona State University (Publisher)
Created2014
Description
Many acidic hot springs in Yellowstone National Park support microbial iron oxidation, reduction, or microbial iron redox cycling (MIRC), as determined by microcosm rate experiments. Microbial dissimilatory iron reduction (DIR) was detected in numerous systems with a pH < 4. Rates of DIR are influenced by the availability of ferric minerals and organic carbon. Microbial iron oxidation (MIO) was detected from pH 2 – 5.5. In systems with abundant Fe (II), dissolved oxygen controls the presence of MIO. Rates generally increase with increased Fe(II) concentrations, but rate constants are not significantly altered by additions of Fe(II). MIRC was detected in systems with abundant ferric mineral deposition.
The rates of microbial and abiological iron oxidation were determined in a variety of cold (T= 9-12°C), circumneutral (pH = 5.5-9) environments in the Swiss Alps. Rates of MIO were measured in systems up to a pH of 7.4; only abiotic processes were detected at higher pH values. Iron oxidizing bacteria (FeOB) were responsible for 39-89% of the net oxidation rate at locations where biological iron oxidation was detected. Members of putative iron oxidizing genera, especially Gallionella, are abundant in systems where MIO was measured. Speciation calculations reveal that ferrous iron typically exists as FeCO30, FeHCO3+, FeSO40 or Fe2+ in these systems. The presence of ferrous (bi)carbonate species appear to increase abiotic iron oxidation rates relative to locations without significant concentrations. This approach, integrating geochemistry, rates, and community composition, reveals biogeochemical conditions that permit MIO, and locations where the abiotic rate is too fast for the biotic process to compete.
For a reaction to provide habitability for microbes in a given environment, it must energy yield and this energy must dissipate slowly enough to remain bioavailable. Thermodynamic boundaries exist at conditions where reactions do not yield energy, and can be quantified by calculations of chemical energy. Likewise, kinetic boundaries exist at conditions where the abiotic reaction rate is so fast that reactants are not bioavailable; this boundary can be quantified by measurements biological and abiological rates. The first habitability maps were drawn, using iron oxidation as an example, by quantifying these boundaries in geochemical space.
The rates of microbial and abiological iron oxidation were determined in a variety of cold (T= 9-12°C), circumneutral (pH = 5.5-9) environments in the Swiss Alps. Rates of MIO were measured in systems up to a pH of 7.4; only abiotic processes were detected at higher pH values. Iron oxidizing bacteria (FeOB) were responsible for 39-89% of the net oxidation rate at locations where biological iron oxidation was detected. Members of putative iron oxidizing genera, especially Gallionella, are abundant in systems where MIO was measured. Speciation calculations reveal that ferrous iron typically exists as FeCO30, FeHCO3+, FeSO40 or Fe2+ in these systems. The presence of ferrous (bi)carbonate species appear to increase abiotic iron oxidation rates relative to locations without significant concentrations. This approach, integrating geochemistry, rates, and community composition, reveals biogeochemical conditions that permit MIO, and locations where the abiotic rate is too fast for the biotic process to compete.
For a reaction to provide habitability for microbes in a given environment, it must energy yield and this energy must dissipate slowly enough to remain bioavailable. Thermodynamic boundaries exist at conditions where reactions do not yield energy, and can be quantified by calculations of chemical energy. Likewise, kinetic boundaries exist at conditions where the abiotic reaction rate is so fast that reactants are not bioavailable; this boundary can be quantified by measurements biological and abiological rates. The first habitability maps were drawn, using iron oxidation as an example, by quantifying these boundaries in geochemical space.
ContributorsSt Clair, Brian (Author) / Shock, Everett L (Thesis advisor) / Anbar, Ariel (Committee member) / Garcia-Pichel, Ferran (Committee member) / Hartnett, Hilairy (Committee member) / Arizona State University (Publisher)
Created2017
Description
Large-scale land acquisition (LaSLA), also called "land grabbing" refers to the buying or leasing of large tracts of land, especially in Sub-Saharan Africa (SSA) by foreign investors to produce food and biofuel to send back home. Since 2007, LaSLA has become an important development issue due to the opportunities and threats for SSA countries. LaSLA has the potential to create local jobs, transfer technology, build infrastructure, and modernize SSA's agriculture. Nonetheless, it can also aggravate food insecurity, perpetuate corruption, degrade ecosystems, cause conflicts, and displace local communities. What drives LaSLA, what are its impacts on local people, and under what circumstances can we consider it as just and ethical?
To examine what drives LaSLA, I used country level data from 2005 to 2013 on economic conditions, natural resources, business practices, and governance to estimate LaSLA models. I find that LaSLA increases with increasing government effectiveness, land prices, and the ease of doing business, and decreases with stronger regulatory regimes. To assess LaSLA's impacts on local people, I conducted a comparative case study in Tanzania. I compare changes in peoples' livelihood between treatment villages (those experiencing LaSLA) and control villages (those without LaSLA projects). The results show that under current practices, the risks of LaSLA outweigh the benefits to local livelihoods, yet there are potential benefits if LaSLA is implemented correctly.
To philosophically examine whether LaSLA can be considered just and ethical, I apply John Rawls' theory of justice. The analysis indicates that from both procedural and distributive justice perspective, LaSLA currently fails to satisfy Rawlsian principles of justice. From these analyses, I conclude that if implemented correctly, LaSLA can produce a win-win outcome for both investors and host countries. I suggest that strong governance, rigorous environmental and social impact assessment, and inclusion of local people at all levels of LaSLA decision making are critical for sustainable and equitable outcomes.
To examine what drives LaSLA, I used country level data from 2005 to 2013 on economic conditions, natural resources, business practices, and governance to estimate LaSLA models. I find that LaSLA increases with increasing government effectiveness, land prices, and the ease of doing business, and decreases with stronger regulatory regimes. To assess LaSLA's impacts on local people, I conducted a comparative case study in Tanzania. I compare changes in peoples' livelihood between treatment villages (those experiencing LaSLA) and control villages (those without LaSLA projects). The results show that under current practices, the risks of LaSLA outweigh the benefits to local livelihoods, yet there are potential benefits if LaSLA is implemented correctly.
To philosophically examine whether LaSLA can be considered just and ethical, I apply John Rawls' theory of justice. The analysis indicates that from both procedural and distributive justice perspective, LaSLA currently fails to satisfy Rawlsian principles of justice. From these analyses, I conclude that if implemented correctly, LaSLA can produce a win-win outcome for both investors and host countries. I suggest that strong governance, rigorous environmental and social impact assessment, and inclusion of local people at all levels of LaSLA decision making are critical for sustainable and equitable outcomes.
ContributorsNkansah-Dwamena, Ernest (Author) / Kinzig, Ann (Thesis advisor) / Minteer, Ben (Committee member) / Perrings, Charles (Committee member) / Gabagambi, Damian (Committee member) / Aggarwal, Rimjhim (Committee member) / Arizona State University (Publisher)
Created2017
Description
What happens to community-based institutions (CBIs) when persistent out-migration changes the socio-demographic structures in the community? This question needs exploration in the context of increasing urbanization in the developing countries, where a substantial population depends on forests for subsistence livelihoods. In pursuance of this question, Almora district in India provided the necessary conditions of high out-migration, and the presence of oldest surviving CBIs of forest management (locally called as Van Panchayats or VPs). Framing the research question as social resilience of VPs amidst high out-migration, a representative sample of six VPs in Almora was investigated. Factors considered crucial to social resilience were analyzed by using qualitative and quantitative techniques on primary data collected through household surveys (n=111) and secondary data from authentic sources. Results, organized by three levels of analysis, highlight: 1) community - low participation, particularly of women, in proceedings of VPs, and a transition away from forest-based livelihoods; 2) institutional (VPs) - low adaptability to changes in gendered composition and a shift away from the community-specific needs; and, 3) policy - reduced use and access of forest resources for the community, and curtailed autonomy of VPs. The findings suggest that out-migration is one among the multiple factors, and its impacts on VPs are mediated by the broader political economy around VPs, thus obviating a linear causal relationship. Therefore, the findings arguably inform policy and future research by highlighting linkages between diverse contextual factors at the regional and community level, and the points of concern for social resilience of VPs, with particular focus on out-migration.
ContributorsPrateek, Gautam (Author) / Knopf, Richard (Thesis advisor) / Aggarwal, Rimjhim (Committee member) / Kelman, Candice Carr (Committee member) / Mobarakeh, Behrang Forroughi (Committee member) / Arizona State University (Publisher)
Created2017