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Polycyclic Aromatic Hydrocarbons in Atmospheric Fine Particulate Matter: Beyond the Priority Pollutant List
Get PDFAtmospheric fine particulate matter (PM2.5) has been linked to the death of 7 million people per year around the planet. The organic portion of PM2.5 is responsible for increases in oxidative stress, inflammation, mutation and carcinogenesis. Anthropogenic activity releases more organic material into the atmosphere, and has increased the amount of PM2.5 which contains organic aerosol including polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. PAHs are ubiquitous environmental contaminants emitted to the atmosphere through incomplete combustion, which traverse the planet in PM2.5. Protected in PM2.5 by glassy organic aerosol coatings, PAHs undergo long-range atmospheric transport.
Recent studies have shown that PAHs increase the viscosity and atmospheric lifetimes of secondary organic aerosol (SOA) particles formed naturally in the atmosphere, but have not shown the chemical speciation responsible for these trends. This dissertation measured PAH oxidation products formed during SOA formation in the presence of PAH vapor. These SOA particles grew larger, resulting in up to a 600% mass loading increase over SOA formed without PAH vapor present, and had longer atmospheric lifetimes. This indicated that the presences of PAHs during particle growth increases the formation less-volatile organic compounds, which remain condensed in the atmosphere. High-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) showed that SOA particles formed in the presence of PAH vapor had increased signals of mass to charge ratios (m/z) at higher m/z. Other studies have demonstrated a large number of oligomers in SOA which could have the m/z signals measured here, suggesting a synergistic effect on SOA non-volatile compound formation.
In the second part of this dissertation, ambient PM2.5 samples (collected in collaboration with the Swinomish Indian Tribal Community of the Northwest coast of the US State of Washington) were found to contain the same PAH oxidation products measured in our SOA experiments. The presence of these compounds in ambient samples proved the real world application of the experimental data collected in the first part of this dissertation. Along with these oxidation products, measured concentrations of ~130 PAHs in the ambient PM2.5 analyzed in this dissertation were used to assess the air quality of the Swinomish Reservation during different atmospheric conditions. Significant differences in PAH concentrations were found during changes in wind direction, the presence of regional wildfires, and during atmospheric inversions. Excess Lifetime Cancer risk assessment was performed on PM2.5¬ samples to demonstrate that during inversions, the inhalation cancer risk rises to levels above WHO safety guidelines.
The oxidative potential (OP) of atmospheric fine particulate matter (PM2.5) has been linked to the organic content of PM2.5, including polycyclic aromatic hydrocarbons (PAHs). Using the results from individual PAHs in the assay, computational modeling was performed to calculate the free energy of reaction (ΔGrxn) for each PAH in the consumption assay. Significant correlations were found between the DTT50 and the ΔGrxn of subclasses of PAHs, the molecular weight (AMU) of PAHs, the assay response (linear slope), and various physical structural components of the PAHs. While mixtures of the 16 PAHs currently found on the US EPA Priority Pollutant List tested in this study appeared to show an additive mixture effect in the DTT assay, whole mixtures of PAHs prepared to match ambient PM2.5 PAH measurements did not. The compounds in the mixtures appear to either have antagonistic effects, or a non-linear relationship in oxidative potential at the low concentrations measured in PM2.5 samples. Extract measurements were significantly less
This dissertation used advanced aerosol instrumentation, analytical characterization, and chemical assays to demonstrate ways to improve our understanding of PAH fate and transport in the atmosphere, as well as potential impact on human health. The results of this research illustrate both the presence of a large number of PAHs in ambient PM2.5 and their implications on atmospheric lifetimes and PM2.5 exposure induced oxidative stress
On the Topologies of Moduli Spaces of Polygons: A Taxonomic Approach
Get PDFConsider a polygon lying in the Euclidean plane with labeled edge lengths. The moduli space of polygons is the space of all polygons with the same labeled edge lengths, modulo orientation preserving isometries. It is well known that this space is generically a smooth manifold. For certain combinations of edge lengths, however, non-smooth points can arise. We show these points to be isolated, each with a neighborhood homeomorphic to a cone over a product of spheres. We proceed to explicitly compute the homeomorphism types that arise from non-smooth moduli spaces of pentagons. We then turn our attention to the number of different (up to diffeomorphism) smooth manifolds that can arise as moduli spaces of polygons. It is known that, for a fixed number of edges, this number is finite. The exact number is only known up to the case of pentagons, however. We provide a new structure that summarizes the possible manifold topologies of a moduli space of polygons in a directed graph. We then use this structure to provide bounds on the number of diffeomorphism types that can arise as moduli spaces of polygons with no more than eight edges
Short-lived Photofission Product Yields and Analytical Methods for Nuclear Forensic Application
Get PDFThe evaluated nuclear data widely used in computational tools suffer from inaccuracies and large relative uncertainties, particularly with respect to short-lived and low-yield fission products. The existing data are often based on nuclear models, and limited experimental measurements of these fission product yields have been performed. This work seeks to validate and improve, where applicable, the current fission product yield data in the ENDF library using experimental measurements, particularly for the photofission of ²³⁸U and ²³²Th.
Much of the measurable fission products would have decayed away in experiments that require sample transfer from the linear accelerator to an auxiliary detection setup, resulting in low count rates and large uncertainty in the calculated yield of fission products for those that are short-lived (half-life of less than 50 s). A high-purity germanium detector and a pneumatic transfer system were employed for measurements of short-lived fission products, collecting data between accelerator irradiation and counting cycles. These experiments resulted in measured cumulative fission product yields for ²³⁸U and ²³²Th at bremsstrahlung X-ray endpoint energies of 8, 14, and 20 MeV. These are reported with their excitation energies to allow for reliable comparison among other experimental data sets
Deschutes River Salmonid Risk of Enteronecrosis in a Changing Climate
Get PDFCeratonova shasta is an obligate endoparasite of salmonid fish that is endemic to the Pacific Northwest of North America. The parasite has a complicated lifecycle with two distinct spore stages and two obligate hosts, a salmonid and a freshwater annelid. Myxospores released from infected salmonid hosts, infect Manayunkia occidentalis (freshwater annelid), and actinospores released from infected annelid hosts infect salmonids. C. shasta infects multiple salmonid species, and genetically distinct strains (genotypes I, II and 0) vary in specificity and virulence in their respective fish hosts. In the Deschutes River, OR, high pre-spawn mortality in Spring Chinook salmon has been associated with genotype I. Genotypes 0 and II are also present but have not been associated with disease. Previous studies on the Deschutes River showed that C. shasta exhibits temporal variability with onset (first date of detection of >1 spore/L) typically occurring in late spring and peak densities occurring in summer. However, it was not clear whether there were differences in timing of genotypes’ onsets and peaks. To explore this question, I used water sampling data from 2015-2019, qPCR, and genotyping to describe the temporal distributions of genotypes (Chapter 2). I observed that genotype I had the earliest onset (late spring) and peak (late spring-early summer), while genotype 0 was primarily detected in mid-late summer, and genotype II was primarily detected in late summer-fall. To further study temporal dynamics of each genotype, I back-calculated hypothetical infection dates for the annelid hosts based on thermal development units (Chapter 2). I found evidence that adult Fall Chinook Salmon correlated with genotype I onsets and adult Spring Chinook Salmon run size correlated with genotype I peaks. Genotypes 0 and II correlations were less robust, but data suggested adult Steelhead and Rainbow trout were contributors of genotype 0, and Coho correlated with genotype’s II onset while adult and juvenile Sockeye correlated to its peak. Using linear models, I tested how peak discharge, total number of fish host during a year, and mean temperature during last 200 dd of development within the annelid host were related to the genotypes’ peaks (Chapter 2). I found that the temperature model explained the majority of the variation in peak sizes (R2>0.5 in all models), while fish host run size and peak discharge explained less variation, and not at all sites. In Chapter 3 I explored relationships between spatial distribution of C. shasta and M. occidentalis, including the prevalence of C. shasta infection in M. occidentalis. I used spatial surveys from 2018-2020 and simple correlations. I observed correlations between spatial distribution of C. shasta and its annelid host in spring surveys: Sites having high densities of C. shasta also had high densities of C. shasta-infected M. occidentalis. In addition, densities of M. occidentalis were correlated with prevalence of C. shasta infection in annelid hosts in spring surveys but these relationships were undetectable in late summer surveys suggesting targeted habitats (e.g., spawning sites in spring surveys) may be important.
I concluded that abiotic variables (temperature) were correlated with C shasta dynamics (timing of onset and peak spore release) and both biotic and abiotic variables were associated with the magnitude of C. shasta genotype peaks in the Deschutes River below the dams. I recommend conducting more annelid surveys along with C. shasta surveys that target M. occidentalis habitats stratified throughout the lower basin to better understand how their distribution and densities affect the risk of C. shasta for salmonids. Furthermore, annelid host surveys should be conducted in June or July so they correspond with the periods of peak C. shasta densities
Designing and Evaluating a User Interface for Multi-Robot Furniture
Get PDFA chair, once placed, will stay put until moved. Or will it? With the rise of technology being embeddable into everyday objects, what if that chair could move itself? Such robotic furniture has been featured in advertisements, art, and Human-Robot Interaction (HRI) research. Existing methods for operating robotic furniture have been limited to commands at a low level of abstraction which limits the number of furniture robots usable at once as the operator becomes overwhelmed. This thesis explores how user interfaces can support the needs of human operators and interaction partners for arranging multi-robot furniture by iterating an interface for operating three chair robots (ChairBots) over two experiments. The first explores multi-robot furniture in a needfinding experiment to derive user-centric requirements. These requirements included a screen-based modality, autonomy, and geometric (i.e., spatial furniture-specific) intelligence. Requirements were met by implementing high-level affordances, and precise motion on the ChairBots. The second experiment extended the screen-based interface to enable tele-operation over the internet and refined affordances to three diverse levels of abstraction. This iteration of the interface was evaluated in a novelly remote user study wherein participants arranged the ChairBots in a simulated multi-phase event. Participants were able to arrange the ChairBots successfully proving the utility of a screen-based interface, and affordances at diverse levels of abstraction. Insights from this research can be used by future designers of multi-robot furniture and HRI researchers alike
An Empirical Analysis of Climate and Risk on Rural Productive Lands
Get PDFEfficient and effective climate policies require cost estimates supported by empirical analysis at multiple spatial scales. Fine-scale spatial analysis of climate impacts for rural land markets represents a gap in the current climate change economics literature. In this dissertation I estimate relationships between climate, risk and parcel-level land values for rural land markets across the state of Oregon. With these estimates I explore the effect of climate change on the value of private forestland, the relationship between wildfire risk, climate, and public forest management, and the effect of natural and human-caused shoreline change along estuaries and tidal rivers on Oregon’s coastline.
Chapter 1 estimates a parcel-level forest Ricardian price function for productive timberland across Oregon State. These estimated marginal effect of climate on forestland value are then linked with future climate projections to analyze the overall effect and spatial pattern of climate change on private forestland value. Results indicate climate damages will vary across the state, with warmer and wetter forests increasing in value and colder, drier forests decreasing in value. This study presents the first empirical assessment of climate’s effect on individual forestland parcels in the United States and provides foundational empirical evidence of climate’s heterogeneous effect on timber land values.
In Chapter 2 I extend the Ricardian Forestry model developed in Chapter 1 to empirically estimate the effect of climate change and fire risk on private forest land values in Oregon based on spatial proximity to publicly managed forests. I explore a policy scenario in which public forests are managed like private forests in order to mitigate the effects of increasing fire risk under climate change. I find a significant risk effect of proximity to public forests, but one that varies spatially across the state based on local precipitation levels. Altering public forest management has positive benefits for adjacent private forests, but these benefits also vary spatially with precipitation. My novel dataset allows empirical analysis of this issue, evidence of which is currently missing from the climate change economics literature. In addition, this work provides a framework with which to evaluate how changes in public forest management effect the value of adjacent private forestland. This is an important policy question in the West, where catastrophic fire seasons are becoming the norm and limited management budgets must be allocated between often competing priorities.
In Chapter 3 I exploit the discontinuous risk between shoreline and nearshore parcels to estimate the implicit price of shoreline for agricultural and rural single-family residential land markets on Oregon’s estuaries and tidal rivers. Using this functional link, I simulate the land market effect of natural and human-caused shoreline change on land markets adjacent to estuary and near-coastal shorelines in Tillamook county, Oregon. I find a negative shoreline premium for both agricultural and single-family residential land markets near estuarine and freshwater coastal shorelines, but one that is small when considering the total economic effect of shoreline change on these land markets. This is the first empirical assessment of estuary restoration on West Coast land markets, providing foundational empirical evidence for the economic relationship between marine habitat restoration and human systems. Parcel-level analysis also allows for spatially explicit economic impact assessment, providing valuable information conspicuously missing from current restoration policy. This is also the first analysis exploring the relationship between sea level rise risk and near-coastal land values in Oregon and provides a starting framework with which to explore these effects on near-coastal land markets
Drivers of Deconstruction: An Analysis of Dam Removal in the United States
Get PDFThe goal of this thesis is to identify the factors which have most significantly contributed to historical dam removals in the United States. The trend of increased dam removals over time is specifically analyzed for evidence that increased scarcity of environmental goods and services is motivating dam removals. A theoretical model is presented to explain how dam removal is consistent with maximization of social welfare and to hypothesize the direction of the effects for variables which are believed to contribute to changes in the relative price of environmental goods. The empirical estimation is conducted using a time series dataset of characteristics of dams both removed and not removed between 1969 and 2016. The dataset is an aggregation of the American River’s Dam Removal Database and the U.S. Army Corps of Engineers National Inventory of Dams, with additional explanatory variables added using geospatial identifiers. Using a logit regression, the effect of explanatory variables are estimated to identify which factors have most motivated past dam removals. The results of this analysis provide evidence that dam-specific characteristics and federal regulations are most significantly influencing dam removal decisions. Evidence that increases in the relative value of environmental goods and services have contributed to dam removals was inconclusive. Overall, this analysis suggests that removals are decided on an individual basis depending on the specific attributes of the dam under consideration
Structural Response of High-Performance Fiber-Reinforced Cementitious Composites: Evaluation, Simulation, and Sensitivity Analysis
No full textThe constitutive behavior of high-performance fiber-reinforced cementitious composites (HPFRCCs) under mechanical loading is characterized by significant tensile properties that play an essential role in the structural response of several applications in structural engineering. The significance of tensile properties of HPFRCCs in structural engineering is the focus of three manuscripts presented as part of this dissertation, which focus on (1) experimental evaluation of the tension and cyclic constitutive behavior of high-performance fiber-reinforced cementitious composites considering the impact of using different fiber types and fiber content; (2) development and implementation of a validated uniaxial numerical model for simulation of the uniaxial monotonic and cyclic constitutive behavior of fiber-reinforced cement-based composites; and (3) development of a multistage extreme condition sensitivity analysis of the response of an HPFRCC reinforced concrete column due to material parameter uncertainties.
In the research work presented in the first manuscript, a testing jig and a testing procedure are developed to evaluate the response of HPFRCCs under monotonic tension loading, cyclic tension-only loading, and cyclic tension-compression loading. The experimental design included development and testing of ten different mixtures to study the effect of using two different fiber types (polyvinyl alcohol [PVA] and twisted steel fibers), varying fiber volume fractions, and varying mixture hybridization on several mechanical properties, including peak tensile strength, toughness, energy absorption capacity during hardening and softening stages, as well as strength degradation, stiffness degradation, and toughness degradation under cyclic response. The data obtained in the research work presented in the first manuscript are employed in the development of the numerical model in the subsequent work performed in this dissertation.
In the second manuscript, a new mathematical model is proposed to simulate the uniaxial constitutive behavior of HPFRCCs for use in monotonic or cyclic analyses of finite element models consisting of nonlinear elements that make use of fiber sections. The model is computerized in C++ programing language and then integrated into the OpenSees, which is a finite element software that is widely used in the research community for many engineering applications. The model implementation is verified and validated successfully with respect to experimental data obtained from manuscript one as well as other available literature.
Lastly, in the third manuscript, the influence of uncertainties in HPFRCC material parameters on the structural behavior of reinforced HPFRCC columns is assessed. A multistage extreme condition sensitivity analysis is employed as the technique for conducting the study. The study is conducted in two phases (i) sensitivity analysis at the material level to assess the sensitivity of HPFRCC constitutive response on energy dissipation capacity, and (ii) evaluation of the sensitivity of the flexural response of a reinforced HPFRCC column with respect to several significant model parameters that characterize the HPFRCC behavior. For both phases of the sensitivity analysis, the HPFRCC material model parameter statistics are obtained from data in experimental work presented in manuscript one and from other published research work available in the literature
Exploration of Simultaneous Anammox and Denitrification (SAD) Biofilm Processes for Nitrogen Removal
Get PDFAnammox (anaerobic ammonium oxidation) bacteria are capable of providing low-cost nitrogen removal for numerous types of wastewaters. However, low growth rates cause long startup-times and inhibition by oxygen and metabolic substrates necessitate close process control to maintain performance. Incorporation of Simultaneous Anammox and Denitrification (SAD) into constructed wetlands could provide high efficiency nitrogen removal for lower capital investment. Herein, the feasibility of this process is examined. First, gravel, Waldport basalt, and K2 plastic media are evaluated as possible surfaces for the promotion of growth and attachment of anammox bacteria. Second, process control of partial denitrification by multiple soil isolates is examined both in batch tests and fixed bed columns to determine the required carbon loading. Third, woodchips are examined is a fixed bed column to determine whether these are a suitable carbon source for this application
Water Governance in Afghanistan
Get PDFEnsuring long term water security is the essential pathway towards development, prosperity, and stability in Afghanistan. However, the country is faced with water challenges that can be ascribed to governance failure at multiple levels of governance rather than to the resource base itself. Hence, studying the water governance system in Afghanistan is crucial, and assessment of the existing system is the first step. To date, there has been no systematic study to benchmark and diagnoses the strengths and weaknesses of the existing water governance system. The current study addressed this gap by analyzing and assessing water governance in Afghanistan qualitatively and quantitively at multiple levels, using the OECD water governance principles and indicators framework. The thesis answered to the following questions:
1- How can the analysis of a developing country contribute to further developing the OECD water governance indicators framework?
2- How is the performance of the Afghanistan water governance system against OECD water governance principles?
3- What are the strengths and weaknesses of the Afghanistan water governance system?
The OECD water governance principles and indicators framework applied well in the Afghanistan context and provided a holistic and better analytical framework for the study.
Qualitatively using existing literature and semi-structured interviews, the OECD water governance principles well captured the strengths and weaknesses of the existing water governance system at multiple levels of governance. The analyses showed that the existing water governance system in Afghanistan is weakly functioning against all the twelve OECD water governance principles.
Similarly, quantitively using surveys, the OECD indicators framework well benchmarked the robustness of the existing governance system. The quantitative assessment also confirmed that the existing water governance system is poorly functioning against OECD principles. The system is suffering from either shortage or weak implementation and functioning of water governance frameworks, institutions, and mechanisms. Most of the indicators either do not exist or not implemented in the current water governance system. None of the 36 indicators are fully functioning