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Full-Text Articles in Physical Sciences and Mathematics

Deglacial And Holocene Environmental Change Recorded In Lake Sediments From The Snowy Mountains, Kosciuszko National Park, Southeastern Australia, Emma J. Mickelson Jan 2024

Deglacial And Holocene Environmental Change Recorded In Lake Sediments From The Snowy Mountains, Kosciuszko National Park, Southeastern Australia, Emma J. Mickelson

WWU Graduate School Collection

The sediment record from Lake Albina, the Snowy Mountains, southeastern Australia suggests significant environmental change mostly reflecting shifts in climate from the LGM through the Holocene. Immediately following deglaciation, approximately 19.4 thousand cal ky BP, Lake Albina experienced cold and/or dry conditions with minimal vegetation in the catchment. Cooler conditions persisted with a slight increase in moisture throughout the Antarctic Cold Reversal (ACR; 14.7-13 cal ky BP) aligning closest with a strengthening of the Atlantic Meridional overturning circulation (AMOC) and a northward shift of the South Westerly Winds (SWW). Between 12.9-9.7 cal ky BP, Lake Albina recorded a climate reversal …


The Biophysical Resilience Capacity Of The Salish Sea’S Tidal Wetlands To Sea Level Rise, Kenna Kuhn Jan 2024

The Biophysical Resilience Capacity Of The Salish Sea’S Tidal Wetlands To Sea Level Rise, Kenna Kuhn

WWU Graduate School Collection

Tidal wetlands offer significant ecosystem services, cultural identity, and economic opportunities, but the impact that projected SLR will have on tidal wetlands in the Salish Sea is not known. In this thesis, I examine the exposure, watershed-scale biophysical resilience capacity, and jurisdictional variation in resilience capacity of the Salish Sea’s tidal wetlands to SLR. I quantify exposure, resilience, and jurisdictional variation using existing spatial data and analysis techniques. I employ a framework for biophysical resilience capacity developed by NOAA and NERRA. This study’s results indicate that there is substantial variation in wetlands area by watershed, from 0 km2 to …


Enhancing The Federal Natural Resource Damage Assessment And Restoration Process Through Bayesian Networks: A Case-Study On The Little Mississinewa River, Indiana, April D. Reed Jan 2024

Enhancing The Federal Natural Resource Damage Assessment And Restoration Process Through Bayesian Networks: A Case-Study On The Little Mississinewa River, Indiana, April D. Reed

WWU Graduate School Collection

The Federal Natural Resource Damage Assessment and Restoration (NRDAR) program gives Tribes and certain government agencies the authority to assess injury to natural resources and to pursue and implement compensatory action for any resources lost or injured due to unlawful releases of chemicals into the environment. This study was centered around the development of a Bayesian network (BN) decision support tool tailored to the needs of NRDAR practitioners. The goal was to design a probabilistic BN tool that could lend quantitative insight into natural resource injury. A case study was used to develop and demonstrate the tool’s functionality and propriety …


Life Cycle Assessment Of A Hemp-Based Thermal Insulation Panel, Kara Davis Jan 2024

Life Cycle Assessment Of A Hemp-Based Thermal Insulation Panel, Kara Davis

WWU Graduate School Collection

Buildings have a monumental impact on the environment and the economy and account for about 40% of energy consumption, greenhouse gas emissions, and materials entering the economy. Life cycle assessment (LCA) is a tool for quantitatively evaluating the environmental impacts of a product throughout its life span commonly applied in the building and construction sector. While past efforts have focused on reducing operational energy and carbon, attention has shifted towards embodied energy and carbon as buildings become more energy efficient. This graduate thesis applies the LCA framework and investigates the life cycle environmental impacts of a hemp-based thermal insulation panel …


Paleomagnetic Determination Of Vertical Axis Block Rotation Near The Doty Fault In Southwestern Washington, Charles Linneman Jan 2023

Paleomagnetic Determination Of Vertical Axis Block Rotation Near The Doty Fault In Southwestern Washington, Charles Linneman

WWU Graduate School Collection

In this paper I present the results of paleomagnetically derived vertical axis rotations (VARs) of sites in two different flows of the Columbia River Basalt (CRB) – the 16 Ma Sentinel Bluffs member of the Grande Ronde flow and the 12 Ma Pomona Member of the Packsack Lookout – near the Doty fault in southwestern Washington. In two field seasons, I collected 99 cores from 14 sites, 11 in the Grande Ronde flow and three in the Pomona member flow. Of the 227 specimens that I demagnetized, 212 had well-defined magnetic directions. Positive fold and reversal tests results confirm the …


Visual Characteristics Of Walleye Pollock And Chinook Salmon: Modeling Theoretical Visual Space And Target Contrast Of Trawling Materials In The Bering Sea, Rebecca Haehn Jan 2023

Visual Characteristics Of Walleye Pollock And Chinook Salmon: Modeling Theoretical Visual Space And Target Contrast Of Trawling Materials In The Bering Sea, Rebecca Haehn

WWU Graduate School Collection

Walleye pollock (Gadus chalcogrammus) and Chinook salmon (Oncorhynchus tshawytscha) are economic and cultural resources in Alaska. Chinook salmon bycatch is a large concern within the pollock fishery. Current strategies to reduce salmon bycatch include modifying trawl gear by implementing artificial light near or on escapement panels to increase salmon escapement. The visual characteristics of pollock and Chinook salmon were investigated to understand the perception of trawl gear. The visual pigments of each species were measured using microspectrophotometry (MSP). Pollock were dichromats with spectral sensitivity ranging from 449nm–518 nm and Chinook salmon were trichromats with sensitivity ranging …


The Race Toward Carbon Neutral Ecotourism: Leveraging Life Cycle Analysis And Natural Climate Solutions For A Community Adventure Event, Ted Tarricone Jan 2023

The Race Toward Carbon Neutral Ecotourism: Leveraging Life Cycle Analysis And Natural Climate Solutions For A Community Adventure Event, Ted Tarricone

WWU Graduate School Collection

Global tourism is an interconnected framework of multiple industries that is influenced by and has impacts on economic, social, and environmental structures. Currently, tourism accounts for roughly 8% of global greenhouse gas emissions, which is expected to grow with industry expansion. To develop a scalable system for ecotourism assessment, emission reduction, and solutions to meet carbon neutrality, a small (n=3894 participants) adventure relay race named Ski to Sea in Bellingham, WA was studied. A life cycle analysis (LCA) conducted on the race showed similar proportional results to other tourism LCAs, where transport made up over 80% of the 325 tonnes …


Quantifying Channel Change Following Post-Fire Debris Flows In A Steep, Coastal Stream, Big Sur, California, Telemak Olsen Jan 2023

Quantifying Channel Change Following Post-Fire Debris Flows In A Steep, Coastal Stream, Big Sur, California, Telemak Olsen

WWU Graduate School Collection

Debris flows commonly occur following wildfire in steep landscapes, introducing large volumes of sediment to downstream fluvial systems. Fire-related sediment supply perturbations impact channel morphology, and importantly, fragile aquatic and riparian ecosystems downstream of disturbance. The Big Creek watershed drains 57 km2 of steep chaparral and coast redwood forest along California’s Central Coast. Streams in the Big Creek watershed typically exhibit step-pool/cascade morphology and serve as vital spawning habitat for anadromous Steelhead Trout (Oncorhynchus mykiss). In 2020, 97% of the Big Creek watershed burned in the Dolan Wildfire. In January 2021, an atmospheric river event triggered a series of …


Distribution And Mixotrophy Of Cryptophyte Phytoplankton In The Northern Gulf Of Alaska, Megan O'Hara Jan 2023

Distribution And Mixotrophy Of Cryptophyte Phytoplankton In The Northern Gulf Of Alaska, Megan O'Hara

WWU Graduate School Collection

The Northern Gulf of Alaska (NGA) is a productive subarctic marine ecosystem that supports high abundances of plankton, fishes, seabirds, and mammals. Research has shown that this high productivity is primarily controlled by seasonal and spatial heterogeneity in the lower trophic level food web. Marine cryptophytes are a crucial, yet understudied, phytoplankton group in the NGA. Cryptophytes have the capacity for mixotrophy (acquiring energy through photosynthesis and feeding) which can improve trophic transfer efficiency, increase cellular growth rates, and improve retention of nutrients in the water column. Field samples collected in spring, summer, and fall 2021 surveyed the contribution of …


Contaminants Of Emerging Concern In Puget Sound: Screening, Prioritization, And Estrogenic Mixture Response Assessment, Maya Faber Jan 2023

Contaminants Of Emerging Concern In Puget Sound: Screening, Prioritization, And Estrogenic Mixture Response Assessment, Maya Faber

WWU Graduate School Collection

Contaminants of emerging concern (CECs) are chemicals used in daily life, such as pharmaceuticals, personal hygiene products, steroids, pesticides, and flame retardants. The environmental occurrence and toxicology of CECs are poorly characterized, and they are generally unregulated. Traditional toxicological approaches rely on in vivo methods to test whole organisms for apical endpoints, including survival, reproduction, and growth. This is time-consuming and costly, both financially and in terms of laboratory animal well-being, limiting ecotoxicological data for CECs. To overcome this challenge, we are utilizing alternative approaches, including New Approach Methodologies (NAMs), to perform a screening-level evaluation of CECs present in Puget …


Using Chemical Zoning In Minerals To Understand Magmatic Processes At Augustine Volcano, Alaska, Sloane Kennedy Jan 2023

Using Chemical Zoning In Minerals To Understand Magmatic Processes At Augustine Volcano, Alaska, Sloane Kennedy

WWU Graduate School Collection

The eruption behavior of a volcano is intrinsically linked to magmatic evolution. Augustine Volcano is an active stratovolcano in the Aleutian Arc (AK, USA), showing stratigraphic evidence that eruptions before 1,800 C.E. were more explosive, producing thick pumice deposits, compared to the six eruptions observed in the last 200 years. Tephra B, an understudied ~400-year-old pumice fall unit, represents the last more explosive style eruption at Augustine - making it ideal for studying how changes in magmatic evolution can result in changes in eruption style. For this thesis, I used textural zoning patterns and chemical variations (major and trace elements) …


Modeling The Effects Of Projected Climate Warming On Stream Temperatures In The Stillaguamish River Basin, Emily Esther Gebheim Smoot Jan 2023

Modeling The Effects Of Projected Climate Warming On Stream Temperatures In The Stillaguamish River Basin, Emily Esther Gebheim Smoot

WWU Graduate School Collection

The Stillaguamish River is a snow-and-rain mixed basin and the fifth largest river in the Puget Sound basin. Elevations in the 1700 km2 Stillaguamish River basin reach roughly 2000 m and historically a snowpack is sustained above 1000 m. Snowmelt in the basin is important for sustaining spring and summer streamflow and buffering stream temperatures. Stream temperature increases are of significant concern because of the threatened Chinook salmon (Oncorhynchus tshawytscha) population.

I reexamined projected stream temperatures in the Stillaguamish River by forcing the coupled Distributed Hydrology Soil Vegetation Model and River Basin Model with dynamically downscaled meteorological …


Activity And Selectivity Of Class B Sortase Enzymes, Sophie Jackson Jan 2023

Activity And Selectivity Of Class B Sortase Enzymes, Sophie Jackson

WWU Graduate School Collection

Gram-positive bacteria attach many proteins to their cell walls via sortase enzymes. Sortases are cysteine transpeptidases and are grouped into 6 classes, A-F. Sortase enzymes, particularly sortase A from Staphylococcus aureus, have been used extensively for in vitro protein ligations. Here, we investigate substrate-binding in sortase A from Streptococcus pyogenes. In addition, class B sortases are typically overlooked for research and development due to low in vitro activity and incomplete knowledge of substrate specificity. Here, we investigate the activity of class B sortases from Bacillus anthracis (baSrtB), Clostridioides difficile (cdSrtB), Listeria monocytogenes (lmSrtB), and Staphylococcus aureus (saSrtB). Of these, …


Selectivity And Structure Of Chimeric Loop Swaps In Sh2 Domains, Sarah N. Smith Jan 2023

Selectivity And Structure Of Chimeric Loop Swaps In Sh2 Domains, Sarah N. Smith

WWU Graduate School Collection

SH2 (Src Homology 2) domains are protein domains that bind to phosphorylated tyrosine residues within cell signaling cascades. They have been found to play a role in certain cancers and immunological disorders. Despite their importance in cell signaling and medical relevance, the structural basis of the various selectivity classes of SH2 domains is only partially understood. Previous research found that the EF and BG loops of the domains contribute to forming the peptide binding pocket, and thus impact their selectivity. To further understand the role of these loops in selectivity, we engineered chimeric SH2 domains by swapping the EF and …


Connections Between Eruption Style And Magmatic Reservoir Evolution: Insights From Augustine Volcano, Alaska, Usa, Mahinaokalani G. Robbins Jan 2023

Connections Between Eruption Style And Magmatic Reservoir Evolution: Insights From Augustine Volcano, Alaska, Usa, Mahinaokalani G. Robbins

WWU Graduate School Collection

At a single volcano, eruptive behavior can change through time as the plumbing system evolves. Augustine Volcano, a frequently active intermediate stratovolcano in the Alaska-Aleutian arc (USA), is an ideal setting to investigate magma reservoir processes due to its frequent modern and Holocene eruption history. Its most recent 2006 CE eruption included mixed effusive and moderately explosive (VEI 3) events and has been studied in detail. Proximal fall deposits from this eruption were generally mixed fine ash to lapilli with variable thickness, but typically ~5 cm on the island (Wallace et al., 2010). The Pre-contact “Tephra M” was deposited by …


Development Of Silk Microparticles Capable Of Bioluminescence, Monique Berg Jan 2023

Development Of Silk Microparticles Capable Of Bioluminescence, Monique Berg

WWU Graduate School Collection

The use of silk microparticles (µPs) as drug delivery devices has gained attention due to slow degradation properties, mild preparation conditions, and advantageous biocompatibility. However, little research has been done on where these particles go once injected. To expand these studies, the goal for this work is to create bioluminescent silk µPs that can be tracked in vivo. Here several methods are demonstrated for preparing bioluminescent silk µPs containing Nanoluciferase (NLuc) and/or its substrate furimazine (FZ). In this study, silk µPs were formed using a salting-out procedure. The first method involved non-specific adsorption of NLuc and non-specific adsorption of FZ …


Impact Of Riverbank Lupine (Lupinus Rivularis) On Grand Fir (Abies Grandis) Ectomycorrhizal Symbioses, Andrew Labay Jan 2023

Impact Of Riverbank Lupine (Lupinus Rivularis) On Grand Fir (Abies Grandis) Ectomycorrhizal Symbioses, Andrew Labay

WWU Graduate School Collection

Lupine (Lupinus rivularis) is used in the revegetation of coarse sediments surrounding the Elwha basin in Washington State due to its ability to improve soil conditions. Previous research illustrated that seeding lupine with conifers increased growth and foliar nitrogen, however, decreased ectomycorrhizal (ECM) root colonization, an important symbiosis for conifers used in restoration. We hypothesized the observed decrease in ECM may be due to lupine increasing soil nitrogen, negating the need for a fungal symbiont. To investigate this, we explored the interaction between lupine and ECM colonization of grand fir (Abies grandis) in both a field …


Learning From Traditional Ecological Knowledge: Paralytic Shellfish Toxins In Butter Clams, Jackelyn Garcia Jan 2023

Learning From Traditional Ecological Knowledge: Paralytic Shellfish Toxins In Butter Clams, Jackelyn Garcia

WWU Graduate School Collection

Anthropogenic forcing of marine ecosystems is disproportionately impacting Indigenous food systems and the health of coastal Indigenous communities. With increasing harmful algal events, there is rising concern for access and health of coastal communities who rely on shellfish for commercial, food, subsistence, and ceremonial harvest. In the U.S West Coast, the dinoflagellate Alexandrium spp. may produce paralytic shellfish toxins, which can cause shellfish to become toxic and is of especial concern. While recent research has led to greater awareness of the risks associated with paralytic shellfish toxins (PSTs), the concern for harmful algae is not new. Coastal Indigenous communities have …


Stereoselective Synthesis Of (+)- And (-)-Cananodine, Haley Holliday Jan 2023

Stereoselective Synthesis Of (+)- And (-)-Cananodine, Haley Holliday

WWU Graduate School Collection

Natural products are an important class of molecules utilized in traditional medicine and inspire drug design in medicinal chemistry. Cananga odorata, a tree commonly known as ylang-ylang, contains natural products known to positively benefit health, and specifically promote liver health. One alkaloid isolated from Cananga odorata, cananodine, possesses cytotoxic properties, specifically against hepatocellular carcinoma (HCC). HCC is the most common type of liver cancer, with one million diagnoses projected by 2025 globally. Cananodine is a member of the guaipyridine alkaloid family, a class of compounds that feature a substituted pyridine bonded to a seven-membered ring. The first enantiomer …


New Synthetic Methods Based On Silicon-Tethered Nucleophilic Addition Reactions, Alexie W. Clover Jan 2023

New Synthetic Methods Based On Silicon-Tethered Nucleophilic Addition Reactions, Alexie W. Clover

WWU Graduate School Collection

With the recent discovery of an iodine mediated rearrangement of diallylsilanes, we set out to investigate a similar fluorine mediated rearrangement, aimed at introducing a new method for synthesizing organofluorine compounds. Interest in incorporating fluorine into organic molecules has grown significantly in recent years, primarily for medicinal applications. Since certain fluorination methods require the use of mCPBA, a common epoxidizing reagent, control experiments were performed on the reaction of several diallylsilanes with mCPBA, anticipating that a competing epoxidation of the diallylsilanes might occur. It was found that the formation of the hydroxy ester occurred through a regioselective epoxide opening from …


Using Qm/Mm Methods To Explore Sortase Enzyme Intermediates, Kinetics, And Stability, Kyle Whitham Jan 2023

Using Qm/Mm Methods To Explore Sortase Enzyme Intermediates, Kinetics, And Stability, Kyle Whitham

WWU Graduate School Collection

Biochemistry has seen advancements in methods and understanding of the inner workings of proteins, yet biochemists struggle to see real time reaction pathways of protein intermediates. This is where computational chemistry comes in and fills in the holes in knowledge through the use of Quantum Mechanical (QM) models. QM chemistry alone does not give results in a reasonable timescale to predict protein chemistry in a reasonable amount of time. Computational chemistry methods such as Quantum mechanical (QM)/ Molecular Mechanical (MM) (QM/MM), allow us to split the in-silico system into two regions that utilize a fast MM force field region and …


Generations Of Stewards: Re-Indigenizing Youth Leadership, Learning, And Conservation Education, Drew Slaney Jan 2023

Generations Of Stewards: Re-Indigenizing Youth Leadership, Learning, And Conservation Education, Drew Slaney

WWU Graduate School Collection

My thesis is an exploratory case study into epistemologies (or worldviews) supported by organizations and agencies that develop outdoor conservation and education programs for Native youth called Native Youth Stewardship Programs (NYSPs). This subject relies on the content developed by Medin and Bang (2014) who state that an under-representation of Indigenous peoples in Science, Technology, Engineering, and Mathematics (STEM) fields is largely the result of epistemological conflicts between educators and Indigenous students. I hypothesize that there is a considerable epistemological difference between the conservation entities developing programs to engage Native youth. These differences may create significant barriers with youth recruitment, …


U-Pb Zircon Geochronology And Structure Of Regional Blueschist Units In The Easton Metamorphic Suite, Northwest Cascades, Wa, Katherine Lang Jan 2023

U-Pb Zircon Geochronology And Structure Of Regional Blueschist Units In The Easton Metamorphic Suite, Northwest Cascades, Wa, Katherine Lang

WWU Graduate School Collection

The Easton metamorphic suite of the Northwest Cascades Thrust System (NWCS) is a well-preserved subduction accretion complex in Washington State. The regional blueschist units of the Easton metamorphic suite include the Mt. Josephine semi-schist, Darrington Phyllite, and Shuksan greenschist/blueschist and all are interpreted to have accreted after the onset of Jurassic subduction beneath North America. This study uses zircon U-Pb geochronology, structure, and field observations to test the regional correlations between units in the Easton metamorphic suite and address models for the timing of subduction accretion along the North American margin in the Late Jurassic – Early Cretaceous. The results …


Investigating Kīlauea’S 2018 Offshore Lava Emplacement Through Hydroacoustic Data, Olana Costa Jan 2023

Investigating Kīlauea’S 2018 Offshore Lava Emplacement Through Hydroacoustic Data, Olana Costa

WWU Graduate School Collection

The 2018 eruption of Kīlauea Volcano produced an unprecedented volume of lava, creating 3.5 km2 of new land on Hawai`i’s Big Island (Soule et al., 2021). Lava expelled from the Ahu`aila`au vent (originally called Fissure 8) traveled ~13 km to where it entered the ocean. Over half of the lava erupted in 2018 was emplaced offshore where it produced four new submarine lava deltas (Soule et al., 2021). In response to the eruption, a network of 12 ocean-bottom seismometers (OBS) with attached hydrophones was deployed on Kīlauea’s submarine south flank. Ten of the instruments successfully recorded data from July …


A Characterization Of Hyporheic Temperatures With Applications For Salmon Habitat Restoration In A Thermally Impaired River, Sydney Jantsch Jan 2023

A Characterization Of Hyporheic Temperatures With Applications For Salmon Habitat Restoration In A Thermally Impaired River, Sydney Jantsch

WWU Graduate School Collection

This thesis project is part of an ongoing study assessing the effectiveness of a potentially innovative habitat restoration strategy for Pacific salmon in thermally impaired rivers. This strategy uses engineered log jams (ELJs) to create pockets of cool-water refuge by forming deep scour pools and promoting localized upwellings of shallow subsurface (i.e., hyporheic) water. This project seeks to characterize the relationship between hyporheic temperature and overlying surface stream temperature to elucidate the extent to which hyporheic upwellings can deliver cool water to ELJ-formed pools during the summer low-flow season. Among six sites within a 2.7 km-long study reach on the …


Value Mapping And The Community Wildfire Protection Planning Process In Entiat, Wa, Katharine Kiendl Jan 2023

Value Mapping And The Community Wildfire Protection Planning Process In Entiat, Wa, Katharine Kiendl

WWU Graduate School Collection

Community Wildfire Protection Plans (CWPP) offer benefits for communities effected by wildfire risk and ignitions. CWPP’s serve several functions; they develop interlocal agreements between agencies that provide wildfire response and management, they develop hazard mitigation and wildfire education programs, and they define areas as wildland urban interface (WUI). The CWPP drafting process can impact the resources available to a wildfire risk community. However, despite the impact to communities effected by wildfire, CWPP planning is considered a categorical exclusion under the National Environmental Policy Act (NEPA) allowing CWPP’s to be developed without public review. Given that community plans with public participation …


Does Sediment Supply Impact The Threshold For Initial Sediment Motion In Natural, Gravel Bedded Streams?, Emily Loucks Jan 2023

Does Sediment Supply Impact The Threshold For Initial Sediment Motion In Natural, Gravel Bedded Streams?, Emily Loucks

WWU Graduate School Collection

Sediment transport in river channels control channel morphology, streamflow, and benthic ecosystems. Predicting sediment transport rates through a channel is required for sediment management for stream restoration and aquatic habitat assessment. The critical Shields stress (τ*c), is a dimensionless parameter used in sediment transport models that characterizes the river bed surface shear stress required to initiate sediment motion. The τ*c is typically assumed constant in transport models, yet compilations of field data have shown that τ*c can vary wildly, causing sediment transport models to over- or under-predict fluxes by an order of magnitude or more. Understanding …


The Economic And Emissions Reduction Potential Of Air Source Heat Pumps As A Replacement For Natural Gas And Electric Resistance Space Heating In The Contiguous United States, Joshua Schraer Jan 2023

The Economic And Emissions Reduction Potential Of Air Source Heat Pumps As A Replacement For Natural Gas And Electric Resistance Space Heating In The Contiguous United States, Joshua Schraer

WWU Graduate School Collection

It is widely believed that to reduce CO2 emissions the best strategy is to electrify everything, decarbonize the grid, and improve energy efficiency. This research looks specifically at the use of air source heat pumps (AHP) as a tool to reduce the CO2 emissions of heating energy in the residential sector. The landscape of residential energy use is complicated by a broad range of factors. We compare AHP, natural gas (NG), and electric resistance (ER) heating using data from energy prices, temperature, appliance efficiency, building efficiency and marginal emissions data from 2019 as well as modeled data of …


Impact Of Carbonaceous And Inorganic Nanomaterial Chemistry On Polymer Additive Release From Weathered Epoxy Composites, Haley Sefi-Cyr Jan 2023

Impact Of Carbonaceous And Inorganic Nanomaterial Chemistry On Polymer Additive Release From Weathered Epoxy Composites, Haley Sefi-Cyr

WWU Graduate School Collection

Nanomaterials (NMs) are small (< 100 nm), reactive, chemical species that can often be used as polymer fillers to improve mechanical strength and slow the degradation of polymer nanocomposites (PNCs). Polymers can undergo physical and chemical weathering which can result in increased release of polymer additives and non-polymerized monomers from the polymer matrix. This project aimed to study how NM chemistry and environmental weathering impacts the release and transformation of relevant PNC systems. Bisphenol A diglycidyl ether (BADGE) PNCs were synthesized containing titanium dioxide (TiO2), multi-walled carbon nanotubes (MWCNT), or graphene oxide (GO) NMs. These composites were subjected to either simulated or natural weathering conditions to quantify and characterize their capacity to leach endocrine-disrupting chemicals. Environmental variables, including temperature and ultra-violet (UV) light, were investigated for their impact on additive release. Fourier-transform infrared spectroscopy and Raman microscopy were used to characterize the PNCs which were leached in water for one to five days at 25, 45, or 65 °C. The degree of weathering also varied from no weathering, outdoor weathering, or simulated weathering using UV light. Leachates were analyzed using high-performance liquid chromatography quadrupole time-of-flight mass spectrometry to quantify release of bisphenol A (BPA), tert-butylphenol (TBP), and nonylphenol (NP). There were significant differences between NM types for PNCs weathered outdoors and leached at 25 °C for 24 h, however only TBP was detected in the leachate. When compared to the blank epoxy, GO PNCs leached significantly less in the UV and in May outdoor weathered experiments, MWCNT PNCs leached significantly less when weathered outdoors in May and June, and TiO2 PNCs leached significantly less when UV weathered. Each of the NMs has potential to decrease TBP release through sorption or photodegradation. The carbonaceous NMs (GO and MWCNT) may sorb TBP, inhibiting its release, while TiO2 may photodegrade TBP. The unweathered PNCs leached the most TBP, followed by UV weathered, and then outdoor weathered. A possible explanation for this is photodegradation of TBP by UV light in the UV- and outdoor-weathered experiments leading to removal of TBP prior to leaching. Future experiments should include additional sorption trials and long-term natural weathering with microplastic generation to further explore the release and degradation mechanisms.


Modeling 21st Century Peak Flows In The Nooksack River Basin In Northwestern Washington State Using Dynamically-Downscaled Global Climate Model Projections, Evan A. Paul Jan 2023

Modeling 21st Century Peak Flows In The Nooksack River Basin In Northwestern Washington State Using Dynamically-Downscaled Global Climate Model Projections, Evan A. Paul

WWU Graduate School Collection

The Nooksack River in northwestern Washington State provides freshwater for agriculture, municipal, and industrial use and serves as a vital habitat for endangered salmon, a resource that is of cultural and economic importance to the Nooksack Indian Tribe and the surrounding region. As more landscape becomes exposed to rain rather than snow and heavy winter precipitation events intensify (i.e., atmospheric rivers), peak flows and sediment delivery to streams will increase due to rapid runoff, resulting in salmon habitat degradation and increased flood risk. Thus, anticipating the effect of climate change on peak flows is crucial for salmon habitat restoration efforts …