abstract: The focus of this thesis is to study dissolved organic carbon composition and reactivity along the Colorado and Green Rivers. Dissolved organic carbon (DOC) in large-scale, managed rivers is relatively poorly studied as most literature has focused on pristine unmanaged rivers. The Colorado River System is the 7th largest in the North America; there are seventeen large dams along the Colorado and Green River. DOC in rivers and in the lakes formed by dams (reservoirs) undergo photo-chemical and bio-degradation. DOC concentration and composition in these systems were investigated using bulk concentration, optical properties, and fluorescence spectroscopy. The riverine DOC concentration decreased from upstream to downstream but there was no change in the specific ultraviolet absorbance at 254 nm (SUVA254). Total fluorescence also decreased along the river. In general, the fluorescence index (FI) increased slightly, the humification index (HIX) decreased, and the freshness index (β/α) increased from upstream to downstream. Photo-oxidation and biodegradation experiments were used to determine if the observed changes in DOC composition along the river could be driven by these biogeochemical alteration processes. In two-week natural sunlight photo-oxidation experiments the DOC concentration did not change, while the SUVA254 and TF decreased. In addition, the FI and ‘freshness’ increased and HIX decreased during photo-oxidation. Photo-oxidation can explain the upstream to downstream trends for TF, FI, HIX, and freshness observed in river water. Serial photo-oxidation and biodegradation experiments were performed on water collected from three sites along the Colorado River. Bulk DOC concentration in all samples decreased during the biodegradation portion of the study, but DOC bioavailability was lower in samples that were photo-oxidized prior to the bioavailability study. The upstream to downstream trends in DOC concentration and composition along the river can be explained by a combination of photo-chemical and microbial degradation. The bulk DOC concentration change is primarily driven by microbial degradation, while the changes in the composition of the fluorescent DOC are driven by photo-oxidation. / Dissertation/Thesis / Masters Thesis Chemistry 2015

abstract: Residents of the United States increasingly support organic and local food systems. New Social Movement theorists have described alternative agriculture as a social movement that transcends social class. Other scholars have critiqued alternative agriculture for catering to a middle-class, white public. Simultaneously, geographers have identified communities across the United States that struggle with reduced access to healthy fruits and vegetables. In some of these neighborhoods, known as “food deserts,” local groups are redefining an inequitable distribution of healthy food as a social injustice, and they have begun initiatives to practice “food justice.” The overarching research questions of this study are: 1) How do communities become food deserts? 2) How do food justice movements crystallize and communities practice food justice? 3) What are the social outcomes of food justice movements? Using an Ecology of Actors framework, this study analyzes the actors and operational scales of three food justice movements in Phoenix, Arizona. A narrative analysis of historical scholarly materials and other artifacts reveals that, for more than a century, some communities have tried to create minority-operated local food systems. However, they were thwarted by racist policies and market penetration of the conventional US food system. Interviews with residents, garden organizers and food justice advocates living and working in the city create a narrative of the present day struggle for food justice. Results of this work show that contemporary residents describe their foodscape as one of struggle, and carless residents rely upon social networks to access healthy food. Garden organizers and gardeners are creating networks of community gardens, market gardens, and informal farmers’ markets. They are actively transforming their communities’ landscapes with sophisticated garden ecology in an intense urban heat island. However, the movement’s continued success may be threatened. Many new Phoenix-based local food coalitions and national alternative agriculture social movements are now working to alter Phoenix’s foodscape. Composed of well-educated professionals, who have adopted a justice-based language around food, these organizations may unintentionally co-opt the local food justice movements. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2015

abstract: Balancing conservation goals and needs of local residents is always challenging. While some believe protected areas are a safe paradise for wildlife, others suggest that it is shortsighted to ignore the social and economic challenges faced by people who live adjacent to protected areas when addressing conservation objectives. This dissertation explores the link between biodiversity conservation and environmental education programs (EEPs) administered to residents of buffer zones adjacent to three protected areas in the Terai Arc Landscape, Nepal. Using surveys and interviews, this study examined 1) the influence of EEPs on attitudes of local people toward biodiversity conservation; 2) the influence of EEPs on conservation behavior; 3) the responses toward biodiversity conservation of local people residing in buffer zones who have received different levels of EEPs; and 4) the effect of EEPs on wildlife populations within adjacent protected areas. Local people who had participated in EEPs and attended school were more likely to express a positive attitude toward conservation goals than participants who had not participated in EEPs or had the opportunity to attend school. Participation in EEPs and level of education favored expressed behavior toward conservation goals, such as making contributions for conservation or supporting anti-poaching patrols. However, EEP participants and non-participants were equally likely to engage in activities that were at odds with positive conservation behavior, such as collecting fuel wood or killing wildlife to protect their farm or feed their families. A direct comparison of EEPs given by schools versus non-government organizations showed that EEPs were largely ineffective in promoting positive conservation attitudes and behaviors. Despite heavy poaching of charismatic species such as the greater one-horned rhinoceros or tiger over past decades, Nepal recently celebrated ‘zero poaching years’ in 2011 and 2013, largely due to increased anti-poaching enforcement. The relationship between EEPs and the decline in poaching is unclear, although local officials all claimed that EEPs played an important role. These results indicate that current administration of EEPs in Terai buffer zone communities is inadequate, while also providing evidence that properly administrated EEPs may become a valuable investment for these protected areas to achieve long-term success. / Dissertation/Thesis / Doctoral Dissertation Biology 2015

abstract: Six high-production-volume neonicotinoids were traced through a municipal wastewater treatment plant (WWTP) and engineered wetland located downstream, in a study motivated by reports on these insecticides posing threats to non-target invertebrate species and potentially playing a role in the global honeybee colony collapse disorder. An array of automated samplers was deployed in a five-day monitoring campaign and resultant flow-weighted samples were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) using the isotope dilution method. Concentrations in WWTP influent and effluent were 54.7 ± 2.9 and 48.6 ± 2.7 ng/L for imidacloprid, respectively, and 3.7 ± 0.3 and 1.8 ± 0.1 ng/L for acetamiprid, respectively. A mass balance over the WWTP showed no (p=0.09, CI = 95%) removal of imidacloprid, and 56 ± 6% aqueous removal of acetamiprid. In the constructed wetland downstream, a lack of removal was noted for both imidacloprid (from 54.4 ± 3.4 ng/L to 49.9 ± 14.6 ng/L) and acetamiprid (from 2.00 ± 0.03 ng/L to 2.30 ± 0.21 ng/L). Clothianidin was detected only inconsistently in the WWTP and wetland (>2 to 288 ng/L; 60% detection frequency), whereas thiamethoxam (<10 ng/L), thiacloprid (<2 ng/L), and dinotefuran (<180 ng/L) were not detected at all. Thus, imidacloprid and acetamiprid were identified as recalcitrant sewage constituents (estimated U.S. WWTP discharge of 1920- 4780 kg/y) that persist during conventional wastewater treatment to enter U.S. surface waters at potentially harmful concentrations. / Dissertation/Thesis / Masters Thesis Civil and Environmental Engineering 2015

abstract: An understanding of the formation of spatial heterogeneity is important because spatial heterogeneity leads to functional consequences at the ecosystem scale; however, such an understanding is still limited. Particularly, research simultaneously considering both external variables and internal feedbacks (self-organization) is rare, partly because these two drivers are addressed under different methodological frameworks. In this dissertation, I show the prevalence of internal feedbacks and their interaction with heterogeneity in the preexisting template to form spatial pattern. I use a variety of techniques to account for both the top-down template effect and bottom-up self-organization. Spatial patterns of nutrients in stream surface water are influenced by the self-organized patch configuration originating from the internal feedbacks between nutrient concentration, biological patchiness, and the geomorphic template. Clumps of in-stream macrophyte are shaped by the spatial gradient of water permanence and local self-organization. Additionally, significant biological interactions among plant species also influence macrophyte distribution. The relative contributions of these drivers change in time, responding to the larger external environments or internal processes of ecosystem development. Hydrologic regime alters the effect of geomorphic template and self-organization on in-stream macrophyte distribution. The relative importance of niche vs. neutral processes in shaping biodiversity pattern is a function of hydrology: neutral processes are more important in either very high or very low discharge periods. For the spatial pattern of nutrients, as the ecosystem moves toward late succession and nitrogen becomes more limiting, the effect of self-organization intensifies. Changes in relative importance of different drivers directly affect ecosystem macroscopic properties, such as ecosystem resilience. Stronger internal feedbacks in average to wetter years are shown to increase ecosystem resistance to elevated external stress, and make the backward shifts (vegetation loss) much more gradual. But it causes increases in ecosystem hysteresis effect. Finally, I address the question whether functional consequences of spatial heterogeneity feed back to influence the processes from which spatial heterogeneity emerged through a conceptual review. Such feedbacks are not likely. Self-organized spatial patterning is a result of regular biological processes of organisms. Individual organisms do not benefit from such order. It is order for free, and for nothing. / Dissertation/Thesis / Doctoral Dissertation Biology 2015

abstract: This study uses the Weather Research and Forecasting (WRF) model to simulate and predict the changes in local climate attributed to the urbanization for five desert cities. The simulations are performed in the fashion of climate downscaling, constrained by the surface boundary conditions generated from high resolution land-use maps. For each city, the land-use maps of 1985 and 2010 from Landsat satellite observation, and a projected land-use map for 2030, are used to represent the past, present, and future. An additional set of simulations for Las Vegas, the largest of the five cities, uses the NLCD 1992 and 2006 land-use maps and an idealized historical land-use map with no urban coverage for 1900. The study finds that urbanization in Las Vegas produces a classic urban heat island (UHI) at night but a minor cooling during the day. A further analysis of the surface energy balance shows that the decrease in surface Albedo and increase effective emissivity play an important role in shaping the local climate change over urban areas. The emerging urban structures slow down the diurnal wind circulation over the city due to an increased effective surface roughness. This leads to a secondary modification of temperature due to the interaction between the mechanical and thermodynamic effects of urbanization. The simulations for the five desert cities for 1985 and 2010 further confirm a common pattern of the climatic effect of urbanization with significant nighttime warming and moderate daytime cooling. This effect is confined to the urban area and is not sensitive to the size of the city or the detail of land cover in the surrounding areas. The pattern of nighttime warming and daytime cooling remains robust in the simulations for the future climate of the five cities using the projected 2030 land-use maps. Inter-city differences among the five urban areas are discussed. / Dissertation/Thesis / Doctoral Dissertation Aerospace Engineering 2015

abstract: This dissertation focused on the development and application of state-of-the-art monitoring tools and analysis methods for tracking the fate of trace level contaminants in the natural and built water environments, using fipronil as a model; fipronil and its primary degradates (known collectively as fiproles) are among a group of trace level emerging environmental contaminants that are extremely potent arthropodic neurotoxins. The work further aimed to fill in data gaps regarding the presence and fate of fipronil in engineered water systems, specifically in a wastewater treatment plant (WWTP), and in an engineered wetland. A review of manual and automated “active” water sampling technologies motivated the development of two new automated samplers capable of in situ biphasic extraction of water samples across the bulk water/sediment interface of surface water systems. Combined with an optimized method for the quantification of fiproles, the newly developed In Situ Sampler for Biphasic water monitoring (IS2B) was deployed along with conventional automated water samplers, to study the fate and occurrence of fiproles in engineered water environments; continuous sampling over two days and subsequent analysis yielded average total fiprole concentrations in wetland surface water (9.9 ± 4.6 to 18.1 ± 4.6 ng/L) and wetland sediment pore water (9.1 ± 3.0 to 12.6 ± 2.1 ng/L). A mass balance of the WWTP located immediately upstream demonstrated unattenuated breakthrough of total fiproles through the WWTP with 25 ± 3 % of fipronil conversion to degradates, and only limited removal of total fiproles in the wetland (47 ± 13%). Extrapolation of local emissions (5–7 g/d) suggests nationwide annual fiprole loadings from WWTPs to U.S. surface waters on the order of about one half to three quarters of a metric tonne. The qualitative and quantitative data collected in this work have regulatory implications, and the sampling tools and analysis strategies described in this thesis have broad applicability in the assessment of risks posed by trace level environmental contaminants. / Dissertation/Thesis / Doctoral Dissertation Civil and Environmental Engineering 2015

abstract: N-Nitrosodimethylamine (NDMA), a probable human carcinogen, has been found in clouds and fogs at concentration up to 500 ng/L and in drinking water as disinfection by-product. NDMA exposure to the general public is not well understood because of knowledge gaps in terms of occurrence, formation and fate both in air and water. The goal of this dissertation was to contribute to closing these knowledge gaps on potential human NDMA exposure through contributions to atmospheric measurements and fate as well as aqueous formation processes. Novel, sensitive methods of measuring NDMA in air were developed based on Solid Phase Extraction (SPE) and Solid Phase Microextraction (SPME) coupled to Gas Chromatography-Mass Spectrometry (GC-MS). The two measuring techniques were evaluated in laboratory experiments. SPE-GC-MS was applicable in ambient air sampling and NDMA in ambient air was found in the 0.1-13.0 ng/m3 range. NDMA photolysis, the main degradation atmospheric pathway, was studied in the atmospheric aqueous phase. Water soluble organic carbon (WSOC) was found to have more impact than inorganic species on NDMA photolysis by competing with NDMA for photons and therefore could substantially increase the NDMA lifetime in the atmosphere. The optical properties of atmospheric WSOC were investigated in aerosol, fog and cloud samples and showed WSOC from atmospheric aerosols has a higher mass absorption efficiency (MAE) than organic matter in fog and cloud water, resulting from a different composition, especially in regards of volatile species, that are not very absorbing but abundant in fogs and clouds. NDMA formation kinetics during chloramination were studied in aqueous samples including wastewater, surface water and ground water, at two monochloramine concentrations. A simple second order NDMA formation model was developed using measured NDMA and monochloramine concentrations at select reaction times. The model fitted the NDMA formation well (R2 >0.88) in all water matrices. The proposed model was then optimized and applied to fit the data of NDMA formation from natural organic matter (NOM) and model precursors in previously studies. By determining the rate constants, the model was able to describe the effect of water conditions such as DOC and pH on NDMA formation. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2016

abstract: Constructed treatment wetlands (CTW) have been a cost-efficient technological solution to treat different types of wastewater but may also be sources of emitters of methane (CH4) and nitrous oxide (N2O). Thus, my objective for this dissertation was to investigate CH4 and N2O fluxes via multiple pathways from the Tres Rios CTW located in Phoenix, AZ, USA. I measured gas fluxes from the CTW along a whole-system gradient (from inflow to outflow) and a within-marsh gradient (shoreline, middle, and open water sites). I found higher diffusive CH4 release in the summer compared to spring and winter seasons. Along the whole-system gradient, I found greater CH4 and N2O emission fluxes near the inflow compared to near the outflow. Within the vegetated marsh, I found greater CH4 emission fluxes at the vegetated marsh subsites compared to the open water. In contrast, N2O emissions were greater at the marsh-open water locations compared to interior marsh. To study the plant-mediated pathway, I constructed small gas chambers fitted to Typha spp. leaves. I found plant-mediated CH4 fluxes were greater near the outflow than near the inflow and that CH4 fluxes were higher from lower sections of plants compared to higher sections. Overall, Typha spp. emitted a mean annual daily flux rate of 358.23 mg CH4 m-2 d-1. Third, using a 30-day mesocosm experiment I studied the effects of three different drydown treatments (2, 7, 14 days) on the fluxes of CH4 and N2O from flooded CTW soils. I found that CH4 fluxes were not significantly affected by soil drydown events. Soils that were dry for 7 days shifted from being N2O sources to sinks upon inundation. As a result, the 7-day drydown soils were sinks while the 14-day drydown soils showed significant N2O release. My results emphasize the importance of studying ecological processes in CTWs to improve their design and management strategies so we can better mitigate their greenhouse gas emissions. / Dissertation/Thesis / Doctoral Dissertation Biology 2017

abstract: Whale watching has been hailed by environmental non-governmental organizations like Greenpeace and the International Fund for Animal Welfare as a responsible form of tourism that has the potential to enhance conservation outcomes for cetaceans, while also supporting the economic development of coastal communities. Tourism research suggests that while it is possible for whale watching to provide these benefits, it may also have considerable costs to members of host communities and cetaceans. My dissertation sought to gather data on the economic, ecological, and social impacts of whale watching in the Caribbean in order to evaluate the industry's performance in the region. My project thus took the form of three sub-projects. The first used an ordinary least squares analysis to examine the relationship between Caribbean country characteristics and whale watching expenditures. This analysis showed that a country's level of development changes the strength of correlations, that mass tourism development is negatively associated with whale watching profits, and that cetacean biodiversity and whale watching regulations designed to protect cetaceans both had positive relationships with the whale watching industry. In the second sub-project, I developed an index of Caribbean cetacean vulnerability to the negative impacts of whale watching with a traditional literature review informed by systematic methods. The index illustrated that both target and non-target species had vulnerabilities, and that regulations addressing these issues in the Caribbean were lacking overall. Considerable gaps in data were also identified. Finally, I used qualitative interviews in Dominica and the Dominican Republic to gather information on resident perceptions of whale watching. This analysis revealed overall positive perceptions of the industry in both countries, but also uncovered considerable levels of social conflict surrounding whale watching. Taken together, the results of my study suggest that better regulatory structures, investment in the local community, and efforts to maximize cooperation are needed in order for the Caribbean whale watch industry to better serve local communities, while mitigating its impacts on cetaceans. / Dissertation/Thesis / Doctoral Dissertation Environmental Social Science 2017