Browsing by Department "Environment"

American cutaneous leishmaniasis (CL) is a severely understudied and neglected“disease of poverty” widespread throughout Peru. Transmission dynamics of CL are complex, requiring sandfly vectors and mammalian reservoir hosts to maintain the pathogen in a local environment whereby incidental hosts (people) can become infected. We employed a One-Health approach to understand CL transmission in rapidly changing region of northern Peru. We describe the characteristics of 529 CL positive patients from four participating clinics. Using conditional logistic regression, we assessed risk factors of CL for residents of small urban areas through a matched case-control study with 63 patients who had visited one of the same clinics for CL (cases) or other medical reasons (controls). We later enrolled 343 households as part of a community based study occurring in 15 urban and rural areas of Soritor. We found 256 positive humans (n= 914) as tested via the Montenegro Skin Test; we found 11 positive dogs (n = 236) via an immunofluorescence antibody test. Our results suggest that most- if not all- of CL transmission is occurring in rural areas and that urban women and urban children engage in many high risk activities typically attributed to men. We find evidence that prevalence of past infection is highest among rural residents and men. We believe dogs are unlikely Leishmania reservoirs in either rural or urban settings. It remains unknown if the high number of MST positive children in rural areas is a result of peridomestic or intradomestic transmission.

Nature is under immediate and increasing threat. Tales of destruction and deforestation abound despite the myriad interventions and investments by government bureaucracies, non-government organizations, and private land-owners. As the extinction crisis looms larger and demands on the public purse grow greater, understanding how science becomes policy and policy practice is more important than ever. As a result, and in response to the increasing insularity of conservation biology that has consciously nourished a careful separation of knowledge and action, of scientist and actor, I use this dissertation to navigate the nexus of conservation science, policy, and practice. I employ case studies in forest hydrology and species conservation, as well as cognitive theory, to examine how conservation science becomes policy. I collected field data from Lake Mead National Recreation Area and from the World Bank to explore how policies are translated into practice.

Current assumptions in conservation biology apportions these three separate but equal disciplines - science, policy, and practice - into one greater and two lesser, one that is pure and two that are sticky. But the transmission of knowledge from the Academy to the domains of conservation policy and practice, though difficult, is our mandate. As much as technical competence matters in conservation biology, so too does political literacy. After all, conservation occurs within a dynamic social, political, and institutional landscape. Nonetheless, the current emphasis in conservation biology is on answering questions in the natural sciences and, to a lesser degree, in economics. This focus is important, as is protecting scholarship from the daily pressures of a society that demands quick and ready answers. But scientific data is only one commodity among many that policy-makers and conservation practitioners trade in a tournament of values. Its usefulness lies in the wider social and political environment. Moreover, conservation biology is not simply an applied subset of biology or ecology. It is a mission-driven discipline that dedicates itself to the pursuit of science to save wildlife and wild lands. It encapsulates certain values as axioms. We hold these truths to be self-evident: that the diversity of life matters and that the struggle to end extinctions is meaningful.

Therefore, though conservation science, the design of conservation policies, and the practice of conservation are separate disciplines, they are closely related. For we must understand their different rules of evidence, speak their distinctive languages, and achieve credibility in all three disciplines while maintaining a sense of intellectual integrity in each. This requires respect for their differences as well as recognizing their shared mission in the service of wildlife and wild lands.

According to IPCC estimates, sea levels will rise between .18 and .6 meters by 2100. More recent estimates indicate that actual amounts of sea level rise may be much more, and that 1 meter of sea level rise by 2100 is likely a conservative estimate. These rising sea levels will result not only in more flooding during storm events, but also increased erosion and gradual inundation of coastal property. At the same time, coastal populations in the United States continue to increase rapidly: over half of all Americans live in coastal counties, and at least 25 million more people are expected to move to the coast by 2015. The end result is that human populations, coastal infrastructure, and coastal ecosystems will become increasingly vulnerable to the impacts of climate change. This study examines the political and legal constraints to and opportunities for adaptation to rising sea levels. Using legal and policy analysis and case studies from California, North Carolina and Texas, this study explores the ability of governments to use market tools, land use regulations, and property acquisition to promote adaptation to rising sea levels. Because of market dynamics and political factors including flaws in public risk perception, I conclude that governments who wish to avoid extensive coastal engineering, , can address coastal community vulnerability through a combination of regulations and incentives that spur state and local governments to engage in forward land use planning and other measures to reduce their exposure to sea level rise impacts.

There are currently 22 states with full or partial disclosure requirements for their electricity suppliers. These requirements differ significantly across states, in terms of the specific information content, structure, and presentation, but all have the potential of increasing customers' awareness about the links between their electricity consumption and air emissions, and perhaps create incentives for utilities to reduce those emissions or for customers to reduce their consumption or to switch to a different electricity supplier.

How effective this policy has been is still unclear. The main criterion for effective communication strategies is that they include relevant information for the readers in a usable form. Information needs as well as the ability to process and apply it vary significantly across individuals. However, people are limited in their information-processing capabilities. Policy makers therefore face the trade-off between a large amount of potentially relevant information that ideally needs to be included on the label on the one hand, and decrease in usability as more information is included on the label, on the other.

This paper examines the design, readability and usability of sample labels from 18 different states with information disclosure requirements. The labels are compared and rated according to how they balance the two main dimensions of label design, information content and usability, demonstrating the difficult trade-off between the two. In addition to this, the labels are analyzed along several key aspects: information load, focus on environmental impact, comparability, understandability, and materiality of information. As part of the analysis, measures for these different aspects of label effectiveness are created. The main finding of the analysis is that there are difficult trade-offs between information content and label usability. However, this trade-off can partially be avoided by carefully designing the labels, easing the cognitive burden of users while still conveying relevant information to the decision maker.

The results of the analysis can help evaluate the various existing disclosure policies, and offer approaches to improve upon them. It will also be shown that while preferred levels of information content are incommensurate with maximum usability, certain structures and form elements succeed at making more complex information content easier to use, improving the overall performance of the labels.

Sea turtles, marine mammals and sea birds are vulnerable to higher mortality rates as a direct function of incidental capture (bycatch) in marine fisheries. Their migratory behavior exposes them to multiple fishing gear types and fishing practices and efforts to understand the rates of interaction between these taxa and fishing necessarily entails analysis of data over large spatial areas (ocean-basin) and multiple types of fishing activities. The acquisition the requisite data, however, requires considerable resources and many regions in the world are data-poor with respect to bycatch, including the Wider Caribbean Region (WCR) in the west central Atlantic Ocean basin. This dissertation presents the results of multiple strategies used to assess sea turtle, marine mammal and seabird bycatch in the WCR, with a particular focus on sea turtle bycatch. The research incorporated a synthetic review of the literature, expert consultation, statistical techniques, and geospatial analyses to assess the bycatch seascape for the region. I conclude that sea turtle bycatch in the WRC is significantly linked to turtle rookeries, especially those on the continental land mass and in the southern section of the Caribbean basin, in large part because of the near shore artisanal nature of the fisheries and the importance of these habitats for foraging and reproduction. The limited information on marine mammal bycatch does not permit robust inferences, but it clearly identifies threats to at least one vulnerable marine mammal species, the tucuxi (Sotalia fluviatilis). Information on seabird bycatch was even more limited; the most vulnerable seabird populations occur in the higher latitudes (temperate zones) while the seabird populations in the WCR face significant threats from habitat loss and over-exploitation. This dissertation proposes specific recommendations for improving and advancing the information base for a regional, ecosystem-level management and mitigation of bycatch.

Sustainable water management is needed to ensure quality supplies of our vital water resources in the face of growing human demand for water, high levels of pollution, and increasing spatial and temporal variability associated with climate change. An integrated approach to water management is recommended to address current water challenges, which are often interrelated with other environmental, economic and social issues. Universities and colleges have missions, resources, and contexts that could enable them to lead the process of developing and applying sustainable and integrated water resource management (IWRM). The opportunity to exemplify integrated water management has grown as institutions of higher education have made progress towards incorporating environmental sustainability into teaching, research, and campus operations. This dissertation examines the issue of campus water management at institutions of higher education through a review of campus sustainability literature, a survey of sustainability and facilities managers, and case studies of three campus water-related projects.

Findings from the review of campus sustainability literature and websites suggests water is less of a campus management priority than issues such as energy and climate change; furthermore, where water is addressed, the focus is on water conservation, while water quality management is overlooked. IWRM is not explicitly discussed in the campus sustainability literature reviewed, though principles relevant to IWRM are included in some campus sustainability declarations and programs. Results from the survey substantiate the findings from literature review that water management is less of an institutional priority than energy management and water quality management is often underemphasized in campus management. According to the survey respondents, campus water management at the institutions represented was on average just adequately managed and institutions were minimally prepared to deal with several types of future water problems. Facilities managers tended to rate their institution's water management as slightly more effective compared to sustainability coordinators. Many campuses relied on top-down, engineering based water management approaches, rather than integrated and interdisciplinary water management. Individual initiatives, municipal codes and policies, campus community sustainability awareness, and campus environmental projects served as drivers for more sustainable water management, while budget constrains were a common barrier. Logistic regression analysis of the survey data revealed that institutions featuring stream and wetland restoration projects had greater odds of being described as having a developed watershed plan and taking into consideration multidisciplinary approaches to water management.

Case studies showed that wetland creation and restoration projects can serve as effective teaching and research laboratories for institutions of higher education, but that none of the studied cases fully exemplified IWRM in their operation. Of the three cases studied, the Stream and Wetland Assessment Management Park project at Duke University most closely demonstrated a campus project designed and developed to address water problems in the campus watershed, while also offering an effective outdoor teaching and research laboratory for hundreds of students, professionals, and researchers. The Olentangy River Wetland Research Park case at Ohio State University exemplified the potential for wetland creation and restoration projects to serve as a facility for educating thousands of students and visitors, training dozens of water experts, and influencing wetland and water resource management beyond the campus. The Radford University Stormwater Treatment Wetland Project case illustrated the potential for institutions with limited space and resources to establish effective outdoor teaching laboratories using environmental features already present or in development on campus.

Findings from the review, survey and case studies all point toward the need and opportunity for institutions of higher education to make greater efforts at implementing and promoting sustainable and integrated water resource management. Literature review and survey findings reveal that water is frequently overlooked as environmental resource at universities and colleges, while other environmental issues such as energy, climate change and recycling are prioritized in sustainability plans and efforts. Universities and colleges have made progress addressing water conservation, while water quality and stormwater need further attention and an integrated approach for more effective management.

A cost-effective pathway towards net-zero electric power systems requires an extraordinary deployment of new solar and wind generation assets. This aggressive expansion driving unprecedented investment entails a fundamental understanding of the challenge ahead of us. This dissertation seeks to provide a multidisciplinary perspective of research questions that shine the light on rapid and cost-efficient strategies for the energy transition. Integrating operations research and geospatial analysis methods, the dissertation utilizes a multidisciplinary approach when addressing three questions.

First, the dissertation examines the role of battery energy storage technologies (i.e., utility-scale lithium-ion batteries) on reducing the greenhouse gas emissions of an electric power system while simultaneously achieving a reduction in carbon abatement costs. The study uses a cost-based production model (day-ahead unit commitment and a real-time economic dispatch) to simulate the optimal operation of all the generation resources in the largest vertically-integrated electric service region in the U.S. The study explores a multitude of configurations to identify optimal sizing of battery energy storage systems when paired with utility-scale photovoltaics.

Next, the dissertation studies the effect of incorporating high-resolution data when identifying suitable land for renewable energy projects over a geographically defined region. Using a python-based user-friendly siting tool implemented in ArcGIS Pro to perform suitability and cost analysis of utility-scale photovoltaic projects in North Carolina under three scenarios (representing conditions ranging from favorable to restrictive). The study finds that the land suitable for utility-scale photovoltaics reduces substantially when parcel-level data reflecting local land-use restrictions are incorporated. The study's findings highlight the necessity of integrating detailed land-use data that reflects local regulation (zoning ordinances) into siting models while simultaneously increasing their spatial granularity.

Lastly, the dissertation analyzes the benefits of weatherizing wind power farms enabling their operation under extreme climates (winter storms). The study uses global reanalysis data with operational information from the Electric Reliability Council of Texas (ERCOT) during the 2021 winter storm Uri to simulate a continued operation of wind power farms under low-temperature environments. The study finds that the financial benefits that winterized wind turbines would have received during winter storm Uri would have outweighed the capital costs required to implement ice-accretion mitigation actions (before winter storm URI).

Coastal eutrophication is a complex process that is caused largely by anthropogenic nutrient enrichment. Estuaries are particularly susceptible to nutrient impairment, owing to their intimate connection with the contributing watersheds. Estuaries experiencing accelerating eutrophication are subject to a loss of key ecological functions and services. This doctoral dissertation presents the development and implementation of an integrated approach toward assessing the water quality in the Neuse Estuary following the implementation of the total maximum daily load (TMDL) program in the Neuse River basin. In order to accomplish this task, I have developed a series of water quality models and modeling strategies that can be effectively used in assessing nutrient based eutrophication. Two watershed-level nutrient loading models that operate on a different temporal scale are developed and used to quantify nitrogen loading to the Neuse Estuary over time. The models are used to probabilistically assess the success of the adopted mitigation measures in achieving the 30 % load reduction goal stipulated by the TMDL. Additionally, a novel structure learning approach is adopted to develop a Bayesian Network (BN) model that describes chlorophyll dynamics in the Upper Neuse Estuary. The developed BN model is compared to pre-TMDL models to assess any changes in the role that nutrient loading and physical forcings play in modulating chlorophyll levels in that section of the estuary. Finally, a set of empirical models are developed to assess the water quality monitoring program in the estuary, while also exploring the possibility of incorporating remotely sensed satellite data in an effort to augment the existing in-situ monitoring programs.

Urbanization causes myriad changes in watershed processes, ultimately disrupting the structure and function of stream ecosystems. Urban development introduces contaminants (human waste, pesticides, industrial chemicals). Impervious surfaces and artificial drainage systems speed the delivery of contaminants to streams, while bypassing soil filtration and local riparian processes that can mitigate the impacts of these contaminants, and disrupting the timing and volume of hydrologic patterns. Aquatic habitats where biota live are degraded by sedimentation, channel incision, floodplain disconnection, substrate alteration and elimination of reach diversity. These compounding changes ultimately lead to alteration of invertebrate community structure and function. Because the effects of urbanization on stream ecosystems are complex, multilayered, and interacting, modeling these effects presents many unique challenges, including: addressing and quantifying processes at multiple scales, representing major interrelated simultaneously acting dynamics at the system level, incorporating uncertainty resulting from imperfect knowledge, imperfect data, and environmental variability, and integrating multiple sources of available information about the system into the modeling construct. These challenges can be addressed by using a Bayesian modeling approach. Specifically, the use of multilevel hierarchical models and Bayesian network models allows the modeler to harness the hierarchical nature of the U.S. Geological Survey (USGS) Effect of Urbanization on Stream Ecosystems (EUSE) dataset to predict invertebrate response at both basin and regional levels, concisely represent and parameterize this system of complicated cause and effect relationships and uncertainties, calculate the full probabilistic function of all variables efficiently as the product of more manageable conditional probabilities, and includes both expert knowledge and data. Utilizing this Bayesian framework, this dissertation develops a series of statistically rigorous and ecologically interpretable models predicting the effect of urbanization on invertebrates, as well as a unique, systematic methodology that creates an informed expert prior and then updates this prior with available data using conjugate Dirichlet-multinomial distribution forms. The resulting models elucidate differences between regional responses to urbanization (particularly due to background agriculture and precipitation) and address the influences of multiple urban induced stressors acting simultaneously from a new system-level perspective. These Bayesian modeling approaches quantify previously unexplained regional differences in biotic response to urbanization, capture multiple interacting environmental and ecological processes affected by urbanization, and ultimately link urbanization effects on stream biota to a management context such that these models describe and quantify how changes in drivers lead to changes in regulatory endpoint (the Biological Condition Gradient; BCG).

Estuaries interfacing with the land, atmosphere and open oceans can be influenced in a variety of ways by anthropogenic activities. Centuries of overexploitation, habitat transformation, and pollution have degraded estuarine ecological health. Key concerns of public and environmental managers of estuaries include water quality, particularly the enrichment of nutrients, increased chlorophyll a concentrations, increased hypoxia/anoxia, and increased Harmful Algal Blooms (HABs). One reason for the increased nitrogen loading over the past two decades is the proliferation of concentrated animal feeding operations (CAFOs) in coastal areas. This dissertation documents a study of estuarine eutrophication modeling, including modeling of major source of nitrogen in the watershed, the use of the Bayesian Networks (BNs) for modeling eutrophication dynamics in an estuary, a documentation of potential problems of using BNs, and a continuous BN model for addressing these problems.

Environmental models have emerged as great tools to transform data into useful information for managers and policy makers. Environmental models contain uncertainty due to natural ecosystems variability, current knowledge of environmental processes, modeling structure, computational restrictions, and problems with data/observations due to measurement error or missingness. Many methodologies capable of quantifying uncertainty have been developed in the scientic literature. Examples of such methods are BNs, which utilize conditional probability tables to describe the relationships among variables. This doctoral dissertation demonstrates how BNs, as probabilistic models, can be used to model eutrophication in estuarine ecosystems and to explore the effects of plausible future climatic and nutrient pollution management scenarios on water quality indicators. The results show interaction among various predictors and their impact on ecosystem health. The synergistic eftects between nutrient concentrations and climate variability caution future management actions.

BNs have several distinct strengths such as the ability to update knowledge based on Bayes' theorem, modularity, accommodation of various knowledge sources and data types, suitability to both data-rich and data-poor systems, and incorporation of uncertainty. Further, BNs' graphical representation facilitates communicating models and results with environmental managers and decision-makers. However, BNs have certain drawbacks as well. For example, they can only handle continuous variables under severe restrictions (1- Each continuous variable be assigned a (linear) conditional Normal distribution; 2- No discrete variable have continuous parents). The solution, thus far, to address this constraint has been discretizing variables. I designed an experiment to evaluate and compare the impact of common discretization methods on BNs. The results indicate that the choice of discretization method severely impacts the model results; however, I was unable to provide any criteria to select an optimal discretization method.

Finally, I propose a continuous variable Bayesian Network methodology and demonstrate its application for water quality modeling in estuarine ecosystems. The proposed method retains advantageous characteristics of BNs, while it avoids the drawbacks of discretization by specifying the relationships among the nodes using statistical and conditional probability models. The Bayesian nature of the proposed model enables prompt investigation of observed patterns, as new conditions unfold. The network structure presents the underlying ecological ecosystem processes and provides a basis for science communication. I demonstrate model development and temporal updating using the New River Estuary, NC data set and spatial updating using the Neuse River Estuary, NC data set.

Sea turtles have experienced dramatic population declines during the last century as a consequence of direct harvest, by-catch in fisheries, and habitat loss. Despite almost 50 years of partial international protection, several populations of sea turtles are still at imminent risk of extinction. Our knowledge of their complex life histories is still far from complete; these knowledge gaps hinder our ability to provide scientific advice regarding their conservation and management. It is the very complexity of their life histories, which allows them to exploit widely separated habitats during development, often over the course of decades, which makes them inherently difficult to study. I used satellite telemetry (n=60) to investigate the movements and habitat use patterns of juvenile loggerhead (Caretta caretta), green (Chelonia mydas), and Kemp's ridley (Lepidochelys kempii) sea turtles on their summer feeding grounds in North Carolina estuaries. These turtles migrate into and out of the estuarine waters each spring and autumn, encountering a gauntlet of fishing gear on each journey. The by-catch of sea turtles is an important conservation issue in North Carolina, and throughout the world's oceans. I evaluated conservation measures established to reduce the by-catch of sea turtles in Pamlico Sound's autumnal large-mesh gill net fishery for southern flounder (Paralichthys lethostigma), using a spatially explicit predator/prey model. My findings indicated that species-specific habitat preferences contributed to a turtles' risk of encountering fishing gear and that areas of high by-catch are predictable from patterns of overlap between sea turtle habitat use and flounder fishing effort. I then examined how the behavior of green turtles affected their vulnerability to incidental capture in estuarine commercial fisheries. Individual green turtles interact with multiple gears per season as a result of strong site fidelity to habitats also preferred by fishers. Telemetry also allowed me to examine individual variation in movements, habitat use, and site fidelity patterns of juvenile loggerhead turtles, both within the estuary and as the turtles migrated out into the North Atlantic. I used these observations to test the hypothesis of a discrete ontogenetic shift in habitat and diet in juvenile loggerheads. Approximately one-third of large juvenile loggerheads tagged in North Carolina estuaries return to oceanic habitat, sometimes for several years, where they are vulnerable to by-catch in pelagic fisheries. This led me to conclude that the long held notion of a discrete ontogenetic habitat shift between the oceanic and neritic habitat was incorrect for juvenile loggerheads (and possibly also for green turtles). Finally, I explored variation in migratory destinations in these animals through multivariate analyses of carbon and nitrogen stable isotope ratios in blood plasma and red blood cells, and through analysis of sex, genetic, haplotype, body size, and remigration records, and described the trophic niche of these turtles with Bayesian isotope mixing models. Variation in migratory destination (oceanic or neritic habitat) was best described by stable isotope ratios of nitrogen and remigration tendency. Turtles that returned to the open ocean had significantly lower nitrogen ratios than those animals that remained in the neritic zone and their diets retained a substantial contribution of epipelagic prey items. The diet composition of neritic turtles, on the other hand, consisted primarily of estuarine benthic invertebrates during the summertime and autumn foraging season but shifted toward pelagic jellyfish, fish, and Sargassum during the overwintering period. Oceanic turtles likely came from open ocean regions prior to entering the summer foraging grounds while neritic turtles likely overwintered at the edge of the Gulf Stream. The agreement between the dietary compositions and migration patterns between the two groups of turtles suggest that these feeding and habitat use strategies were persistent characteristics in the turtles I sampled. My work has improved our understanding of sea turtle habitats in North Carolina estuaries and identified their migratory destinations and overwintering habitats. I hope that this work lays the groundwork for future studies that will explore how variation in habitat use and feeding strategies are manifested in life history traits that affect fitness directly, such as survivorship, growth rates, stage durations, and fecundity.

Dibenzothiophene (DBT) is a constituent of creosote and petroleum waste contamination, it is a model compound for more complex thiophenes, and its degradation by mixed microbial communities has received little attention. The chemical characteristics, environmental fate and ecotoxicology of DBT degradation products are not well understood. This research investigated DBT degradation in an enrichment culture derived from creosote-contaminated estuarian sediment using a suite of assays to monitor bacterial populations, bacterial growth, degradation products, DBT loss, and toxicity. Ultraviolet (UV) irradiation was evaluated as a sequential treatment following biodegradation. Additionally, to advance SYBR-Green qPCR methodology for characterizing mixed microbial communities, an alternative approach for evaluating qPCR data using a sigmoidal model to fit the amplification curve was compared to the conventional approach in artificial mixed communities. The overall objective of this research was to gain a comprehensive understanding of the degradation of a model heterocyclic PAH, DBT, by a mixed microbial community, particularly within the context of remediation goals.

DBT biodegradation was evaluated in laboratory scale cultures with and without pH control. The microbial community was monitored with 10 primer sets using SYBR-Green quantitative polymerase chain reaction (qPCR). Twenty-seven degradation products were identified by gas chromatography and mass spectrometry (GC/MS). The diversity of these products indicated that multiple pathways functioned in the community. DBT degradation appeared inhibited under acidic conditions. Toxicity to bioluminescent bacteria Vibrio fischeri more than doubled in the first few days of degradation, was never reduced below initial levels, and was attributed in part to one or more degradation products. UV treatment following biodegradation was explored using a monochromatic (254 nm) low-pressure UV lamp. While DBT was not extensively photooxidized, several biodegradation products were susceptible to UV treatment. At higher doses, UV treatment following DBT biodegradation exacerbated cardiac defects in Fundulus heteroclitus embryos, but slightly reduced toxicity to V. fischeri.

This research provides a uniquely comprehensive view of the DBT degradation process, identifying bacterial populations previously unassociated with PAH biodegradation, as well as potentially hazardous products that may form during biodegradation. Additionally, this research contributes to development of unconventional remediation strategies combining microbial degradation with subsequent UV treatment.

The Northern Andes stands as a bastion of unique and narrowly distributed global biodiversity. However, it has also experienced rapid transformation of habitats, posing a serious threat to species in the wild by shrinking their ranges. In this dissertation, I aim to deepen our comprehension of how species react to global changes, pinpointing areas where conservation efforts are lacking and highlighting urgent conservation priorities. Moreover, I demonstrate tangible conservation strategies designed to safeguard vulnerable species, while also prioritizing potential exploration regions to confirm the extent of their ranges.In the first chapter, I assess elevational retreats of nearly 200 range-restricted birds from their lower and upper elevational ranges (Medina et al. 2023). Using abundant crowd-sourced data from the Cornell Lab of Ornithology database, eBird, and the Global Biodiversity Information Facility, I examine whether species shifted their elevational ranges over time by comparing observed versus expected occurrences below a low elevational threshold and above a high elevational threshold for two periods: before and after 2005. I also test for deforestation effects at lower elevations within each species’ distribution ranges. Species’ retreats from lower elevations are ubiquitous and involve a 23–40% decline in prevalence at the lowest elevations. Increases at higher elevations are not consistent. The retreats occur across a broad spectrum of species, from predominantly lowland to predominantly highland. Because deforestation show no relationship with species retreats, I contend that a warming climate is the most parsimonious explanation for such shifts. In the second chapter, I identify priority range-restricted bird species and their conservation hotspots in the Northern Andes (Medina et al. 2024). I employ updated maps of Area of Habitat (AOH), following a protocol I contributed along a set of experts from the Cornell Lab, Birdlife International, and American Bird Conservancy (Huang et al. 2021). In this protocol, I was tasked to build R and Python scripts capable to handle crowd-sourced data and batch-generate habitat maps for a thousand birds across the Americas. With the updated maps of species distribution, I estimate protection within each species’ AOH and for the cumulative distribution of birds. For the latter, I also calculate protection across the elevational gradient. I estimate how much additional protection community lands (Indigenous and Afro-Latin American lands) would contribute if they were conservation-focused. AOHs ranged from 8 to 141,000 km2. I identify four conservation priorities based on cumulative species richness. These priorities are high-resolution mapped representations of Endemic Bird Areas for the Tropical Andes that should be considered critically important. Protected areas cover only 31% of the cumulative AOH, but community lands could add 19% more protection. Sixty-two per cent of the 335 species have ranges smaller than their published estimates, yet IUCN designates only 23% of these as Threatened. Top 50 priority species concentrate in areas of low protection near community lands and at middle elevations where, on average, only 34% of the land is protected. I highlight the importance of collaborative efforts among stakeholders: governments should support private and community-based conservation practices to protect the region with the most range-restricted birds worldwide. Private reserves hold promise for the restoration of degraded landscapes and the protection of fragmented animal populations. In the third chapter, I advocate for the creation and implementation of private reserves as concluded in the previous chapter, drawing upon a case study from the Eastern Andes of Colombia to illustrate their potential. This study examines the rehabilitation efforts spanning four decades within Rogitama, aiming to assess their impact on mammal diversity and composition (Medina et al. 2021). Findings reveal the presence of 22 species, predominantly bats and rodents. These results mirror biodiversity levels akin to those observed in less disturbed areas of the Eastern Cordillera, indicating promising advances in ecosystem recovery within the reserve. I posit Rogitama, as a noteworthy case of successful plant rejuvenation, highlighting its significance in the broader context of biological conservation efforts. I firmly advocate for stakeholders to take heed of this case study as a blueprint for development in Northern Andean regions, where I have previously identified critical conservation gaps and priorities. In the last chapter, I identify species and areas that urgently need exploration to increase knowledge on distribution limits (Medina et al. in prep). I consider the AOH where there is less probability of finding a target species given its closeness to non-detection areas. These non-detection areas have checklists where a target species has yet to be reported. The proportion of species absent from an area over the species present will result in relatively uncertain areas. To define potential exploration sites, I mapped these areas along cumulative AOH for 281 species. I found priority exploration areas (high richness and high relative uncertainty) are relatively small compared to non-priority areas. Since 2000, human impact has penetrated 8% of priority areas and allowed 8% of the areas to be studied. Deforestation has progressively reduced, but some countries are still dealing with it. Protection along the priority regions is low. It is essential that governments devote more efforts to exploring biodiversity to better understand patterns in species distribution and thus develop accurate conservation and management plans.

At a given time, tidal landforms inhabit one of three alternate elevation-determined stable states: salt marsh, sub-tidal platform, or tidal flat. The balance between soil production and sea level rise controls transitions between states. Due to increasing anthropogenic inputs to the carbon and nitrogen cycles, CO2 and nutrient enrichment rates are rising. What effect will this have on the evolution of the tidal landform? The present thesis recognizes that (1) soil production depends on halophyte biomass, (2) nutrient enrichment promotes a shift in biomass production from below- to aboveground thus increasing potential for sediment trapping, and (3) elevated CO2 causes an increase in total biomass production. Through use of point- and one-dimensional models, the present thesis finds that under constant suspended sediment levels equal to 20 kg/m3, (1) nutrient enrichment decreases accretion and increases suspended sediment requirements necessary to maintain accessibility of the salt marsh state, (2) elevated CO2 increases accretion decreases suspended sediment requirements necessary to maintain accessibility of the salt marsh state, and (3) the increase in accretion affected by CO2 addition is greater in magnitude than the decrease affected by nutrient enrichment. Thus we can infer that in a future scenario including increasing CO2, nutrient enrichment, and decreasing suspended sediment concentration, the enhancement effect of CO2 will dominate and a net increase in accretion will occur.

Terrestrial ecosystems, occupying more than 25% of the Earth's surface, can serve as

`biological valves' in regulating the anthropogenic emissions of atmospheric aerosol

particles and greenhouse gases (GHGs) as responses to their surrounding environments.

While the signicance of quantifying the exchange rates of GHGs and atmospheric

aerosol particles between the terrestrial biosphere and the atmosphere is

hardly questioned in many scientic elds, the progress in improving model predictability,

data interpretation or the combination of the two remains impeded by

the lack of precise framework elucidating their dynamic transport processes over a

wide range of spatiotemporal scales. The diculty in developing prognostic modeling

tools to quantify the source or sink strength of these atmospheric substances

can be further magnied by the fact that the climate system is also sensitive to the

feedback from terrestrial ecosystems forming the so-called `feedback cycle'. Hence,

the emergent need is to reduce uncertainties when assessing this complex and dynamic

feedback cycle that is necessary to support the decisions of mitigation and

adaptation policies associated with human activities (e.g., anthropogenic emission

controls and land use managements) under current and future climate regimes.

With the goal to improve the predictions for the biosphere-atmosphere exchange

of biologically active gases and atmospheric aerosol particles, the main focus of this

dissertation is on revising and up-scaling the biotic and abiotic transport processes

from leaf to canopy scales. The validity of previous modeling studies in determining

iv

the exchange rate of gases and particles is evaluated with detailed descriptions of their

limitations. Mechanistic-based modeling approaches along with empirical studies

across dierent scales are employed to rene the mathematical descriptions of surface

conductance responsible for gas and particle exchanges as commonly adopted by all

operational models. Specically, how variation in horizontal leaf area density within

the vegetated medium, leaf size and leaf microroughness impact the aerodynamic attributes

and thereby the ultrane particle collection eciency at the leaf/branch scale

is explored using wind tunnel experiments with interpretations by a porous media

model and a scaling analysis. A multi-layered and size-resolved second-order closure

model combined with particle

uxes and concentration measurements within and

above a forest is used to explore the particle transport processes within the canopy

sub-layer and the partitioning of particle deposition onto canopy medium and forest

oor. For gases, a modeling framework accounting for the leaf-level boundary layer

eects on the stomatal pathway for gas exchange is proposed and combined with sap

ux measurements in a wind tunnel to assess how leaf-level transpiration varies with

increasing wind speed. How exogenous environmental conditions and endogenous

soil-root-stem-leaf hydraulic and eco-physiological properties impact the above- and

below-ground water dynamics in the soil-plant system and shape plant responses

to droughts is assessed by a porous media model that accommodates the transient

water

ow within the plant vascular system and is coupled with the aforementioned

leaf-level gas exchange model and soil-root interaction model. It should be noted

that tackling all aspects of potential issues causing uncertainties in forecasting the

feedback cycle between terrestrial ecosystem and the climate is unrealistic in a single

dissertation but further research questions and opportunities based on the foundation

derived from this dissertation are also brie

y discussed.

Sea turtles are long lived marine species that are currently endangered because their life history and population dynamics hinder them from withstanding modern anthropogenic threats. Worldwide, fisheries bycatch in on the major threats to the survival of sea turtles and that is also the case in the Eastern Pacific. To establish regional conservation priorities for the mitigation of bycatch, it is essential to first obtain a comprehensive picture of the regional sea turtle bycatch situation. This comprehensive analysis was lacking for the Eastern Pacific; therefore one component of this dissertation (the first chapter) is focused on delivering a regional bycatch analysis for the Eastern Pacific. A literature review was conducted to obtain numbers of turtles captured, frequencies, bycatch and mortality rates per species and country in trawl, longline, and gillnet fisheries, and to compile results of mitigation measures. Moreover, estimates for current annual capture rates in trawl fisheries were obtained and compared with population numbers.

This regional bycatch used all the information compiled and synthesized to give conservation priorities at the regional level. The review underlines the high bycatch rates in trawls for Costa Rica, Guatemala, and El Salvador and the detrimental impact that these captures could have specially for hawksbill Eretmochelys imbricata due to its reduced population numbers and for green turtle Chelonia mydas due to its highest mortality rate. It also emphasizes the continuous lack of use of TEDs as a bycatch mitigation measure. In longline fisheries, the review identifies the high bycatch rates in pelagic longline fisheries of Costa Rica, Ecuador, and Nicaragua in a global context but given that olive ridley Lepidochelys olivacea is the most common species captured in these countries, it highlights the capture of loggerhead Caretta caretta and leatherback Dermochelys coriacea off Peru and Chile due to their small population numbers. Bottom longlines have high mortality rates compared with pelagic longlines in the region and the review identifies a need for further research in this area due to the scarce information but high mortality rates. The review also noted that some mitigation measures for pelagic longlines like circle hooks and hooks with appendages could bring improvements in the mitigation of bycatch in longline fisheries in the region, there is still considerable work to be done in technology transfer, sea turtle handling, and estimates of post-release mortality rates.

For gillnet fisheries, the most important highlight is how little information exists for the region given the high rates of bycatch for sea turtles in this gear. However, the difficulties of studying bycatch in highly dynamic and artisanal fisheries are recognized as the major impediment for this situation. Nevertheless, the high bycatch rates in areas where sea turtles congregate in high numbers like in foraging grounds for loggerhead in Baja California, Mexico and for greens in Paracas and Sechura, Peru, calls for either gear modifications (which has not been that successful), change of gear, or areas closed for gillnets.

The second half of the dissertation is focused on foraging ecology of oceanic sea turtles in the Southeast Pacific Ocean. Sea turtles in the oceanic stage are the least known stage due to the difficulty of accessing these individuals. However, it is a very important stage in the life cycle and can be critical for the population dynamics of sea turtles as some population models have shown. Therefore, this dissertation is filling a gap in the life cycle of sea turtle populations in the Eastern Pacific.

To study foraging ecology, we used Stable Isotope Analysis (SIA) of turtle tissues as well as potential prey items from the oceanic realm. SIA is a great tool because it gives an integrated view, from days to weeks, of prey from a consumer tissue. SIA also can be used to link consumers to habitats when elements that have spatial trends are used. In chapter two, we investigate the foraging ecology of three species of sea turtles to compare trophic status and to observe if spatial patterns were shown in the SIA signatures of sea turtles. To our knowledge this is the first study employing SIA to research the ecology of three species of sea turtles from the same time and space. Our results show that spatial patterns in delta15N and delta13C were observed in sea turtle's tissues as correlations with latitude. We also found that loggerhead's signatures differed significantly from green and olive ridleys, especially in terms of delta15N. Loggerheads had higher values of delta15N and also a wider nitrogen trophic niche. Greens and olive ridleys were similar in isotopic nitrogen values but they were significantly different in carbon. When analyzing a smaller group of animals captured in a more restricted area, nitrogen differences were not found which suggests that latitudinal spatial patterns play an important role in the nitrogen signature. On the contrary, carbon signatures still differed among turtles in the restricted area which suggest that the inshore-offshore trend is strong and made us conclude that loggerheads are restricted to oceanic areas but that greens and olive ridleys could be using both coastal and oceanic areas.

In chapter three, we conduct a mixing model analysis using the Bayesian program SIAR to identify the most important prey items for green, olive ridley, and loggerhead off Peru. Also, we wanted to identify the contribution of longline baits in the diet of oceanic turtles. The analysis was restricted to the central zone of our study area to avoid spatial trends in nitrogen. To use as sources in the model, we collected potential prey items offshore Peru during trips on longline fishing vessels and obtained their stable isotope signatures. Results from our mixing models show that for greens and olive ridleys, crustaceans, mollusks, and coastal Ulva (indicator of coastal prey) were the only important food items. In the case of greens, crustaceans had a very high proportional contribution and due to the fact that nitrogen values of crustaceans were the lowest ones among the sources it seems that greens would be eating in a lower trophic level. The importance of coastal Ulva for greens and olive ridleys is a confirmation of our findings from chapter two where we suggest that these two species could be using oceanic as well as coastal areas.

Results for loggerheads showed cnidarians, mollusks, mackerel and squid bait as foraging items and highlights the differences among this species and the other two. The lack of importance of coastal Ulva again suggests that loggerheads remain only in oceanic areas off Peru. Moreover, the importance of mackerel and squid, the most common longline baits, suggests this species is the one interacting the most with longline fisheries and that cumulative effect of multiple interactions could have a detrimental effect in this population.

Since their creation, the multilateral development banks have accumulated performance records that include both substantial successes and stunning failures. Nowhere have their performance records been more mixed and controversial than with respect to environmental management issues. The multilateral development banks have financed projects that are widely considered to be environmental disasters, but have also financed projects that successfully included best practice environmental mitigation measures. They have wasted hundreds of millions of dollars financing unsuccessful environmental protection programs, while at the same time they have supported programs that contributed to the rapid development of environmental management capacity in less-developed countries. The purpose of this dissertation is to explore when and why monitoring and evaluation can prompt the multilateral development banks to move away from poor performing projects and towards high performing projects.

This type of performance-based allocation has been repeatedly highlighted as a key element in the successful delivery of development assistance. To test when the multilateral development banks practice performance-based allocation, I assembled a team that coded environmental performance information from 960 project evaluations, 174 program evaluations, and 74 civil society complaints. I use the resulting data to model when four multilateral development banks - the World Bank, Asian Development Bank, Inter-American Development Bank, and African Development Bank - make performance-based allocation decisions about environmentally-risky and environment-improving operations. In addition, I visited the headquarters of each of these organizations and conducted interviews with 54 staff members about the processes that are in place to use monitoring and evaluation information as part of decision-making.

I find that the establishment of monitoring and evaluation systems at the MDBs has not created incentives for staff to practice performance-based allocation. Instead, performance information influences allocation decisions when it helps MDB staff approve future projects more quickly. It does so by helping staff identify development projects that are likely to face significant delays due to the inability of the borrowing country to manage negative environmental impacts and to identify the borrowing countries that are likely to successfully implement environment-improving operations.

The liver is a primary target for toxicants and/or their metabolites. Selected fish species now serve as model organisms for laboratory investigations of toxic responses in the liver. One such model is the Japanese medaka (Oryzias latipes), a small freshwater teleost with a robust history of usage in liver and biliary toxicity studies. The structural components of the medaka hepatobiliary system have been well-described by recent studies in two- and three-dimensional contexts, but efforts to characterize the molecular mechanisms underlying critical medaka liver functions during normalcy remain sparse. This dearth of information makes it difficult to definitively characterize toxic responses in this model organism. A crucial transcription factor underlying proper hepatobiliary function in both mammalian and non-mammalian species is the farnesoid X receptor alpha (FXRα), a member of the nuclear receptor superfamily that plays a key role in bile acid homeostasis. This dissertation describes the function of medaka fxrα during both normalcy and toxicity.

To achieve this overall objective, in vitro techniques were first employed to study the function of medaka fxrα. Two isoforms of fxrα that differ in the AF1 domain, Fxrα1 and Fxrα2, were isolated from liver cDNA and are the result of alternative splicing of one gene locus. Fxrα2 responded significantly to C24 bile acids and the synthetic FXRα agonist GW4064. On the other hand, Fxrα1, despite having an identical ligand-binding domain to that of Fxrα2, showed no response to any agonists tested by transient transactivation assays. Furthermore, Fxrα2 interacted with nuclear receptor coactivators PGC-1α and SRC-1 in mammalian two-hybrid assays while Fxrα1 did not. These findings point to a significant importance of the AF1 domain to overall receptor structure and function.

Following in vitro functional characterization, in vivo experiments using medaka larvae were performed to determine fxrα's function during normalcy. Quantitative, real-time PCR data demonstrated that Fxrα1 is highly expressed in adult liver, while Fxrα2 is expressed predominantly in gut. Fxrα1's expression was higher than Fxrα2 in embryos and larvae at all developmental timepoints tested. In vivo exposures of medaka hatchlings to GW4064 at various doses significantly altered expression of defined FXRα targets, including: bile salt export protein (BSEP), small heterodimer partner (SHP), and cytochrome P450 7A1 (CYP7A1). Surprisingly, numerous sublethal hepatic alterations to hepatocytes and bile preductular epithelial cells (BPDECs) were observed following exposure to GW4064; alterations included: lipid accumulation, glycogen depletion, mitochondrial swelling and rupture of mitochondrial membranes, disruption of endoplasmic reticulum, and apoptosis. Significant lipid accumulation, as revealed by oil red O whole mount staining of larvae, was also noted at lower doses of GW4064. These findings were the first observations of sublethal hepatotoxicity of GW4064; to date, no studies in the mammalian literature reported alterations following its administration.

Because of studies in the mammalian literature that demonstrated alleviation of cholestatic injury induced via the classic hepatotoxicant α-naphthylisothiocyanate (ANIT) by GW4064, it was originally hypothesized that a similar finding would be observed in medaka coexposed to these compounds. However, because of GW4064's ability to induce sublethal hepatic alterations in medaka, it was anticipated that its coadministration with ANIT would result in enhanced toxicity rather than alleviation as described in rodent models. However, despite the sublethal alterations induced by 1 uM GW4064, alleviation of toxicity following exposure to 15 uM ANIT was observed. Surprisingly, reduction of GW4064's toxicity was also observed in larvae exposed to both compounds. These investigations of fxrα function are an important and essential component in furthering our understanding of hepatobiliary toxicity in small aquarium fish models of human liver disease. These collective findings have created molecular underpinnings necessary for understanding medaka hepatobiliary function during normalcy and toxicity.

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used in a wide array of products and applications (e.g., nonstick cookware, waterproof and water-repellent textiles, firefighting foam). Following their decades of use, PFAS have garnered concern as “forever chemicals” due to their extreme persistence in the environment and in humans. PFAS have further elicited concern because they have been linked to adverse health effects in humans, and their huge number (over 12,000 different chemicals) and complex chemistry make them very challenging to analyze and study for exposure and toxicology. Two particular PFAS chemicals, perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), are drinking water contaminants that can be found in the blood of the vast majority of people. PFOA and PFOS are also linked to toxic effects like kidney and testicular cancer, increased blood cholesterol, and reproductive outcomes. These two chemicals are being phased out of use and federal drinking water standards are likely upcoming. However, the replacements for these two chemicals are much less well-characterized, and many of these newer, replacement PFAS chemicals can be found in the environment of North Carolina due (at least in part) to industrial pollution.

The overarching goal of this dissertation was to characterize the potential exposure and health effects of PFAS in North Carolina communities. The surface water and drinking water in some areas of North Carolina have been found to be contaminated with PFAS; however, there are additional routes of PFAS exposure beyond drinking water, such as ingestion of house dust or placental transfer during pregnancy. This dissertation explores various routes of PFAS exposure and better characterizes the specific PFAS analytes that can be found in North Carolina and the concentrations in which they are present. Additionally, this dissertation evaluates this exposure and potential associations with some adverse health outcomes in a few North Carolina communities.

In Chapter 2, the relationships between PFAS exposure during pregnancy and birth outcomes are explored. This chapter includes data on PFAS concentrations in placenta samples from 120 participants in Durham, North Carolina and evaluates the subsequent associations between placental PFAS exposure and birth outcomes (e.g., infant birth weight, gestational age). A total of 11 PFAS were measured in placental tissues collected in 2010-2011, and the compounds PFOS, PFOA, PFNA, and PFDA were detected in all placenta samples. A few placental PFAS were associated with birth outcomes. The most striking result was that placental PFOS was associated with changes in birth weight, but the direction of change depended on the sex of the infant. For male infants, placental PFOS was associated with lower birthweight, and in female infants, placental PFOS was associated with higher birthweight.

In Chapter 3, the exposure to PFAS through drinking water is evaluated in a community with known PFAS water contamination. This chapter includes data on PFAS concentrations in blood serum and drinking water samples from 49 participants in Pittsboro, North Carolina. The community receives its drinking water from the Haw River, a part of the Cape Fear River watershed. Blood and water samples were collected at two different timepoints to explore temporal variability in contamination. This community was found to have blood levels of PFAS about two to four times higher than the U.S. average. This chapter also includes results on the associations between PFAS blood level and clinical chemistry measurements, such as serum lipids, as indicators of health. Negative associations were found between serum PFOS and PFHxA with decreased electrolytes and decreased liver enzymes. Positive associations were found between serum PFOA and PFHxS with increased total cholesterol and increased non-HDL cholesterol.

In Chapter 4, the effects and toxicokinetics of PFAS in a pregnant rabbit model are evaluated. This chapter includes data from an animal study of 21 pregnant rabbits provided with drinking water that is representative of the PFAS exposure observed in Pittsboro, North Carolina. Rabbits were exposed to this environmentally-relevant mixture of ten different PFAS during and before pregnancy. After exposure, the wastes and tissues were evaluated to measure the PFAS concentration that accumulated. This provided information on where PFAS are distributed in the body after exposure. The liver of the pregnant rabbit was also evaluated to determine if there was an increase in lipids in the liver, or any changes in liver lipid metabolism. For this study, few differences were noted between treated animals and control animals, indicating that the environmentally-relevant dose had little effect on pregnant rabbits. However, due to the lack of PFAS accumulation in blood, tissue, or in wastes, it is likely that the dose of PFAS given through drinking water was too low.

In Chapter 5, the levels of PFAS in indoor house dust were evaluated. This chapter includes data on PFAS concentrations in indoor dust from 184 homes in Durham, North Carolina, as well as 49 fire stations across the U.S. and Canada. House dust and fire station dust PFAS concentrations were then evaluated for associations with characteristics of the building (e.g., square footage, amount of carpeting, age of building construction). Levels of precursor PFAS, such as fluorotelomer alcohols, were typically higher in dust than the perfluoroalkyl acids. This study, along with previous literature, shows that the legacy PFAS in dust has been decreasing, but the precursor PFAS has been increasing in U.S. house dust. Few associations were found between building characteristics and dust PFAS. However, one notable result was that higher 8:2 FTOH was found in dust from buildings with more carpeting, indicating that carpets may be an important source of exposure to fluorotelomer alcohols (possibly from stain-proofing treatment).

Collectively, this dissertation provides important information on the potential exposure and health effects of PFAS in North Carolina communities.

Azobenzene disperse dyes are the fastest-growing category of commercial dyestuffs, accounting for 70% of the 9.9 million tons of industrial dye colorants used annually. Azobenzene disperse dyes are intended to be applied to synthetic fabrics such as polyester, nylon, and acrylic; however, azo dyes may also be used in cosmetic products such as hair dyes, and in fashion accessories such as leather goods. Recently, our group and others have detected azobenzene disperse dyes in dust particles collected from the indoor environment, and raising concerns about the release of these chemicals from products and human exposure. Although extensive literature characterizes these chemicals as toxic contaminants in aquatic environments, to date there exists little data on levels, exposures, and hazards associated wit exposures to azobenzene disperse dyes in the indoor environment. The presence of these dyes in the indoor environment is concerning. House dust is a sink for many contaminants that leach out or off-gas from products in the home. Due to children’s unique behaviors (e.g. crawling and hand to mouth activity) they have higher exposure to chemicals associated with dust. Azobenzene disperse dyes are implicated in literature as potentially allergenic: they are known to be present in clothing that elicits allergic reactions such as skin sensitization. Therefore, it is of crucial importance to support research that seeks to characterize children’s exposure in the home environment, and evaluate the in vitro effects of azobenzene disperse dyes. The hypothesis of this research dissertation is that azobenzene disperse dyes are prevalent in dust collected from the indoor environment at concentrations of concern for human health. In the first aim of this thesis research, azobenzene disperse dyes were characterized in commercial mixtures and in children’s polyester clothing. Azo dyes were first purified from dyestuffs by Soxhlet extraction and flash chromatography and then analyzed using ultra-high-performance liquid chromatography (UHPLC) coupled with high resolution mass spectrometry (HRMS), as well as by 1H and 13C NMR for structural elucidations. Nineteen total azobenzene dyes were detected in dyestuffs via a non-targeted analysis approach, including Disperse Blue 79:1, Disperse Blue 183:1, Disperse Orange 44, Disperse Orange 73, Disperse Red 50, Disperse Red 73, and Disperse Red 354. Samples of children's polyester clothing (n=X) were then analyzed via UHPLC-HRMS. In clothing, 21 azobenzene disperse dyes were detected, 12 of which were confirmed and quantified via reference standards. Individual dyes in apparel were quantified at concentrations up to 9230 μg dye/g shirt, with geometric means ranging 7.91–300 μg dye/g shirt. Total dye load in apparel was quantified at up to 11,430 μg dye/g shirt. This research supported the development of reference standards and library mass spectra for azobenzene disperse dyes previously absent from standard and spectral libraries. This study was the first to confirm and quantify these azo compounds in children’s products, facilitating a more robust understanding of sources of azobenzene disperse dyes in the indoor environment. The second aim of this thesis research investigated the presences and quantities of azobenzene disperse dyes and related compounds in indoor house dust (n=188) collected from homes in Durham, NC. Using a targeted approach, we quantified 12 azo disperse dyes and quantified at least one dye in every house dust sample. Detection frequencies ranged from 11% to 89%; of the dyes that were detected in at least 50% of the samples, geometric mean levels ranged from 32.4 to 360 ng/g. HRMS suspect screening analysis identified an additional eight azobenzene compounds in dust that are present at high relative abundances. This study indicates that azo disperse dyes and related compounds are ubiquitous in the indoor environment. To support quality assurance and control during the analysis, a house dust Standard Reference Material (NIST SRM 2585) was extracted and analyzed with the samples. Based on the detection and abundance of azo dyes in SRM 2585, which was prepared from hundreds of dust samples collected in the mid 1990s, azo dye levels in the indoor environment may be increasing over time. To our knowledge, this is the most comprehensive quantitative study of azo disperse dyes in house dust to date. Future studies are needed to quantify additional dyes in dust, particularly those identified here via suspect screening, and to examine exposure pathways of dyes in the indoor environment where children are concerned. The third aim of this thesis research examined the binding reactivity of azobenzene disperse dyes to nucleophilic peptide residues in order to understand their potential reactivity as electrophilic allergenic sensitizers. The Direct Peptide Reactivity Assay (DPRA) was utilized via both a spectrophotometric method and a high-performance liquid chromatography (HPLC) method. Dyes isolated from the commercial dyestuffs, and several potential transformation products, were tested. All dyes were found to react with nucleophilic peptides in a dose-dependent manner with pseudo-first order (kobserved) activity, but overall to react more potently with cysteine than with lysine: EC10 values for cysteine binding were determined as low as 0.005mM and pseudo-first order rate constants as high as 0.04 hr-1 (as observed for Disperse Blue 79:1). Observed rate constants were correlated to metrics of structural features such as Hammett constants and electrophilicity indices, indicating that binding reactivity may be related to structural properties of azobenzene disperse dyes. In addition to examining dyes, the reactivity of extracts of polyester shirts were also examined; shirt extracts with high relative abundances of azobenzene disperse dyes were observed to induce greater peptide reactivity. Results suggest that azobenzene disperse dyes may function as immune sensitizers, and that clothing containing azobenzene disperse dyes may pose risks for skin sensitization. Collectively, this thesis research suggests that azobenzene disperse dyes are common in clothing, and appear to be near ubiquitous in house dust. Given their reactivity in vitro, this may present health consequences, particularly for young children.