The current period of human history is considered to be the plastics age due to its versatile characteristics, especially the lightweight, durability and low production cost. Plastics can be manufactured to suit multifarious functions, for example, for personal care products, food/drink storage and medical purposes. Thus, the use of plastics is unavoidable now, finally contributing to the severe pollution worldwide. In 2018 alone, the global plastics production amount has exceeded 359 million tons, around 10% of which ultimately become waste persisting in the environment. When plastic wastes exposed to the sun's radiation, climate change and mechanic abrasion, degradation and fragmentation may occur. Once the size of the fragmentation products is less than 5 mm, they are commonly defined as microplastics (MPs) by the National Oceanographic and Atmospheric Administration. Currently, microplastics have been regarded as the most pervasive environmental pollution problems, not only because of their physical hazards but also due to their interactions with other pollutants in the environment. Pollution can be attributed by the release of additives from MPs, as well as the MPs with adsorbed toxic contaminants. Moreover, MPs additives together with adsorbed chemicals can be easily uptaken by animals, which may cause further propagated effects on the ambient ecosystem. Through the bioaccumulation and biomagnification effect, MPs can even be accumulated in the organisms from different trophic levels and cause serious impacts on aquatic ecology and human health. Despite growing number of evidences that have confirmed the presence and consequential effects of microplastics, researches on microplastic pollution are still lacking. Investigations on occurrence, determination and environmental fate of MPs in aquatic systems are clearly needed. Therefore, the major objective of this study is to elucidate the distribution of MPs in natural environment, to develop novel determination methods to characterize the micro-(nano-)plastics (MNPs), and to study the interactions of MPs with other contaminants in different conditions, as well as their consequential fate in different matrices (e.g. freshwater, cold-blooded intestine, and warm-blooded intestine). The spatial-temporal distribution of the MPs along the Maozhou River was investigated for both the surface water and sediments from 17 sites. Results showed that MPs were widely and unevenly distributed along the river. The MP abundances in dry season ranged from 4.0 ± 1.0 to 25.5 ± 3.5 items·L-1 in water and 35 ± 15 to 560 ± 70 item·kg-1 in sediments, which were relatively higher than those observed in wet season (water: 3.5 ± 1.0 to 10.5 ± 2.5 items·L-1; sediments: 25 ± 5 to 360 ± 90 item·kg-1; p value < 0.05). The dominant types of MPs were identified as: polyethylene (PE, water: 45.0%, sediments: 42.0%), polypropylene (PP, water and sediments: 12.5%), polystyrene (PS, water: 34.5%; sediments 14.5%) and polyvinyl chloride (PVC, water: 2.0%; sediments: 15%). Moreover, metals such as Al, Si, Ca were discovered on the rough surface of the MPs, indicating the interactions between the MPs and the aquatic environment. After obtaining the occurrence of the MPs in the aquatic systems, we proposed an accurate method for MNPs identification and quantification with the employment of the matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). By optimizing the conditions (e.g. the laser energy, matrix, analyte, cationization agent and their ratio), the peaks of PS and polyethylene terephthalate (PET) were successfully identified. A quantitative correlation was built between the normalized signal intensity and ln[polymer concentration], with a correlation coefficient above 0.96 for low-molecular-weight (LM-) polymers and 0.98 for high-molecular-weight (HM-) polymers. Furthermore, two types of environmental MPs samples were prepared, including the particles of an aviation cup as the fresh plastics and the aged MPs extracted from river sediment. By using MALDI-TOF MS, the PS-related micro-(nano-)plastics (in both aviation cup and sediment) consisted of C8H8 and C16H16O oligomers, while the PET-related MNPs (only found in sediment) were identified with compositions of C10H8O4 and C12H12O4. The contents of PS and PET MNPs in sediment were quantified as 8.56 ± 0.04 and 28.71 ± 0.20 mg·kg-1, respectively. Also, the interaction between MPs and bisphenols was investigated. PVC was selected as the representative target because it is comparatively easy to decompose into MPs with the release of additives, especially the bisphenols. The released bisphenols may then be readsorbed by the PVC MPs and cause consequential pollution to the ecosystem. To elaborate on the interactions mechanism, a systematic study was carried out to determine the adsorption mechanisms of five bisphenol analogues (BPA, BPS, BPF, BPB, and BPAF) on PVC MPs. The equilibrium adsorption numbers of the bisphenols on PVC MPs are 0.19 ± 0.02 mg/g (BPA), 0.15 ± 0.01 mg/g (BPS), 0.16 ± 0.01 mg/g (BPF), 0.22 ± 0.01 (BPB), 0.24 ± 0.02 mg/g (BPAF), respectively. Intraparticle diffusion modeling (kinetics) divided the adsorption process into three stages: external mass transport, intraparticle diffusion and dynamic equilibrium. The isotherm results showed a better fit of the adsorption to the Freundlich model. Furthermore, the adsorption mechanisms of the five bisphenol analogues were explored intensively, with respect to hydrophobic interaction, electrostatic force and noncovalent bonds. Besides the adsorption process, the transfer and release behaviors of contaminated MPs are of critically importance in the exploration of their role as culprits and/or vectors for the aforementioned toxicity. Therefore, experiments were performed to examine desorption behaviors and cytotoxicity performance of contaminated MPs in aquatic surroundings and intestinal environment after ingestion by organisms (cold-/warm-blooded). The kinetic study showed that the rate of desorption for bisphenols could be enhanced threefold under simulated warm intestinal conditions. The Freundlich isotherms indicated multiple-layer desorption of the bisphenols on the heterogeneous surfaces of PVC MPs. Hysteresis was detected in the adsorption/desorption of bisphenols in a water environment, but no adsorption/desorption hysteresis was observed in the simulated intestinal conditions of warm-blooded organisms. Due to the enhanced bioaccessibility, the desorption results implied that the environmental risk of contaminated PVC MPs might be significantly increased after ingestion at a high bisphenols dosage. Although with different IC50, the five bisphenols released under the intestinal conditions of warm-blooded organisms can cause higher proliferation reduction in fish and human cell lines than the bisphenols released in water. In summary, this study elucidated the spatial-temporal distribution behaviors of MPs, developed effective determination methods for MNPs revealed the interactions mechanisms of MPs with other contaminants, and explored their consequential fate in different environments. The obtained results are helpful of better understanding on the land-based input of MPs from the intensively affected inland waters, realizing the role of microplastics as both source and carrier for emerging organic pollutants, and providing a novel alternative for MPs determination in future studies.

The current period of human history is considered to be the plastics age due to its versatile characteristics, especially the lightweight, durability and low production cost. Plastics can be manufactured to suit multifarious functions, for example, for personal care products, food/drink storage and medical purposes. Thus, the use of plastics is unavoidable now, finally contributing to the severe pollution worldwide. In 2018 alone, the global plastics production amount has exceeded 359 million tons, around 10% of which ultimately become waste persisting in the environment. When plastic wastes exposed to the sun's radiation, climate change and mechanic abrasion, degradation and fragmentation may occur. Once the size of the fragmentation products is less than 5 mm, they are commonly defined as microplastics (MPs) by the National Oceanographic and Atmospheric Administration. Currently, microplastics have been regarded as the most pervasive environmental pollution problems, not only because of their physical hazards but also due to their interactions with other pollutants in the environment. Pollution can be attributed by the release of additives from MPs, as well as the MPs with adsorbed toxic contaminants. Moreover, MPs additives together with adsorbed chemicals can be easily uptaken by animals, which may cause further propagated effects on the ambient ecosystem. Through the bioaccumulation and biomagnification effect, MPs can even be accumulated in the organisms from different trophic levels and cause serious impacts on aquatic ecology and human health. Despite growing number of evidences that have confirmed the presence and consequential effects of microplastics, researches on microplastic pollution are still lacking. Investigations on occurrence, determination and environmental fate of MPs in aquatic systems are clearly needed. Therefore, the major objective of this study is to elucidate the distribution of MPs in natural environment, to develop novel determination methods to characterize the micro-(nano-)plastics (MNPs), and to study the interactions of MPs with other contaminants in different conditions, as well as their consequential fate in different matrices (e.g. freshwater, cold-blooded intestine, and warm-blooded intestine). The spatial-temporal distribution of the MPs along the Maozhou River was investigated for both the surface water and sediments from 17 sites. Results showed that MPs were widely and unevenly distributed along the river. The MP abundances in dry season ranged from 4.0 ± 1.0 to 25.5 ± 3.5 items·L-1 in water and 35 ± 15 to 560 ± 70 item·kg-1 in sediments, which were relatively higher than those observed in wet season (water: 3.5 ± 1.0 to 10.5 ± 2.5 items·L-1; sediments: 25 ± 5 to 360 ± 90 item·kg-1; p value < 0.05). The dominant types of MPs were identified as: polyethylene (PE, water: 45.0%, sediments: 42.0%), polypropylene (PP, water and sediments: 12.5%), polystyrene (PS, water: 34.5%; sediments 14.5%) and polyvinyl chloride (PVC, water: 2.0%; sediments: 15%). Moreover, metals such as Al, Si, Ca were discovered on the rough surface of the MPs, indicating the interactions between the MPs and the aquatic environment. After obtaining the occurrence of the MPs in the aquatic systems, we proposed an accurate method for MNPs identification and quantification with the employment of the matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). By optimizing the conditions (e.g. the laser energy, matrix, analyte, cationization agent and their ratio), the peaks of PS and polyethylene terephthalate (PET) were successfully identified. A quantitative correlation was built between the normalized signal intensity and ln[polymer concentration], with a correlation coefficient above 0.96 for low-molecular-weight (LM-) polymers and 0.98 for high-molecular-weight (HM-) polymers. Furthermore, two types of environmental MPs samples were prepared, including the particles of an aviation cup as the fresh plastics and the aged MPs extracted from river sediment. By using MALDI-TOF MS, the PS-related micro-(nano-)plastics (in both aviation cup and sediment) consisted of C8H8 and C16H16O oligomers, while the PET-related MNPs (only found in sediment) were identified with compositions of C10H8O4 and C12H12O4. The contents of PS and PET MNPs in sediment were quantified as 8.56 ± 0.04 and 28.71 ± 0.20 mg·kg-1, respectively. Also, the interaction between MPs and bisphenols was investigated. PVC was selected as the representative target because it is comparatively easy to decompose into MPs with the release of additives, especially the bisphenols. The released bisphenols may then be readsorbed by the PVC MPs and cause consequential pollution to the ecosystem. To elaborate on the interactions mechanism, a systematic study was carried out to determine the adsorption mechanisms of five bisphenol analogues (BPA, BPS, BPF, BPB, and BPAF) on PVC MPs. The equilibrium adsorption numbers of the bisphenols on PVC MPs are 0.19 ± 0.02 mg/g (BPA), 0.15 ± 0.01 mg/g (BPS), 0.16 ± 0.01 mg/g (BPF), 0.22 ± 0.01 (BPB), 0.24 ± 0.02 mg/g (BPAF), respectively. Intraparticle diffusion modeling (kinetics) divided the adsorption process into three stages: external mass transport, intraparticle diffusion and dynamic equilibrium. The isotherm results showed a better fit of the adsorption to the Freundlich model. Furthermore, the adsorption mechanisms of the five bisphenol analogues were explored intensively, with respect to hydrophobic interaction, electrostatic force and noncovalent bonds. Besides the adsorption process, the transfer and release behaviors of contaminated MPs are of critically importance in the exploration of their role as culprits and/or vectors for the aforementioned toxicity. Therefore, experiments were performed to examine desorption behaviors and cytotoxicity performance of contaminated MPs in aquatic surroundings and intestinal environment after ingestion by organisms (cold-/warm-blooded). The kinetic study showed that the rate of desorption for bisphenols could be enhanced threefold under simulated warm intestinal conditions. The Freundlich isotherms indicated multiple-layer desorption of the bisphenols on the heterogeneous surfaces of PVC MPs. Hysteresis was detected in the adsorption/desorption of bisphenols in a water environment, but no adsorption/desorption hysteresis was observed in the simulated intestinal conditions of warm-blooded organisms. Due to the enhanced bioaccessibility, the desorption results implied that the environmental risk of contaminated PVC MPs might be significantly increased after ingestion at a high bisphenols dosage. Although with different IC50, the five bisphenols released under the intestinal conditions of warm-blooded organisms can cause higher proliferation reduction in fish and human cell lines than the bisphenols released in water. In summary, this study elucidated the spatial-temporal distribution behaviors of MPs, developed effective determination methods for MNPs revealed the interactions mechanisms of MPs with other contaminants, and explored their consequential fate in different environments. The obtained results are helpful of better understanding on the land-based input of MPs from the intensively affected inland waters, realizing the role of microplastics as both source and carrier for emerging organic pollutants, and providing a novel alternative for MPs determination in future studies.

Microplastics have been discovered ubiquitously in marine environments. While their accumulation is noted in seagrass meadows, much work is required to understand microplastic accumulation patterns and mechanisms in this ecosystem, as well as microplastic impacts on seagrass plants and their associated epiphytic and sediment communities. We pursue this effort by quantifying microplastic densities in seagrass blades, sediments, and nearby water columns across nine sites in coastal Massachusetts and exploring their relationships to morphological and anthropogenic variables. Further, we synthesize the potential impacts microplastics have on relevant seagrass plant, epiphyte, and sediment processes and functions. Microplastics were found ubiquitously at all sites regardless of proximity to anthropogenic interference, with plant epibiont density influencing their accumulation on seagrass blades, and bulk density influencing accumulation within sediments. Literature review revealed that microplastics may harm seagrass ecosystems via physical obstruction of epiphytic and plant surfaces, nutrient cycle and sediment characteristic alteration, and sediment organism ingestion, with all impacts exacerbated by seagrasses high trapping efficiency. As microplastics become a permanent and increasing member of seagrass ecosystems it will be pertinent to direct future research towards continuing to explore their impacts and patterns behind their accumulation. / 2023-09-28T00:00:00Z

Limited research on microplastics makes it increasingly difficult to measure the potential dangers of their toxicological effect on humans and the environment. Today, evidence has revealed that microplastics have been located in highly remote areas of the world. There are few studies that examine the movement of microplastics within urban landscapes and even fewer that observe different communities within cities. To this end, a study was devised that utilized filtration, dehydration, and Laser Direct Infrared Spectroscopy to monitor drinking water microplastics found in residential buildings across different communities. Houses and apartments of low and high-income at different distances from the nearest water treatment plant were considered. Comparisons between format differences between housing units were made possible by creating a ratio between rent and the square footage of the unit. Samples were extracted from kitchen faucets for their high impact on cooking and human consumption. While there was no significant difference between distance, income level, and building structure some factors had a stronger influence on microplastic count than others. Using a general linear model, it was found that distance had the greatest effect on microplastic count followed by building type and then income levels. The greater the distance from a water treatment plant the fewer microplastics one was exposed to. Microplastics were found to be more abundant in apartments as opposed to houses. A weak positive correlation between income level and the number of microplastics was found but was not significant enough to state that income played a role in microplastic count. This is interpreted as microplastics having no discrimination on one’s socioeconomic status. As everyone, no matter their background is affected by microplastics, it is recommended that more research be conducted in order to confirm whether other building types and other factors have an influence on microplastic exposure.

The broad use of plastics has resulted in the increase in both production and consequent plastic pollution in the environment. Microplastics, defined as particles &lt; 5 mm, is of special interest because of its wide existence in environment and potential hazards to our ecosystem. The degradation of microplastics can be studied using Fourier Transform Infrared spectroscopy (FTIR), where the optical absorption of different functional groups in a molecule can be detected and used for identification. By studying the change in intensity or peak area of certain functional groups (such as carbonyl, hydroxyl, or vinyl) in the spectrum, the degradation of microplastics can be quantified. In the past decades, carbonyl index (intensity or area change of carbonyl group in FTIR spectra), has been applied as a quantitative probe to monitor the extent of plastics degradation. However, the analysis of FTIR spectra requires expertise and comparison between different reports are often difficult due to non-standardized methods. Therefore, an automated method is urgently needed to ease the difficulty. This project has developed a program that automates and standardizes the analysis of the spectrum. The program calculates an index by using specified area under the band corresponding to a functional group peak and a reference peak. By comparing the indexes over time, degradation can be quantified. Additionally, poly(vinyl chloride) (PVC) particles were subjected to a heterogeneous photo-Fenton process for 116 hours to obtain data of microplastics degradation. Both optical imaging and FTIR were used to characterize the degradation of PVC, on aspects of size reduction and band changes, respectively. The obtained FTIR data were fed into the developed program to calculate carbonyl index, and the result suggests a degradation of the PVC particles. This implies that the program can effectively reduce the time of analysis for researchers and evaluate and/or calculate the degradation of plastics.

Microplastic (MP) pollution is ubiquitous in the aquatic environment. Though their properties are known to vary considerably, these particles are typically 1–5,000 μm in size and irregular in shape. Research suggests that MPs pose a significant hazard to aquatic ecosystems, lead to negative economic consequences, and may cause adverse human health effects. The effluents of municipal wastewater treatment plants (WWTPs) comprise a significant source of MPs, containing < 1 MP/L to > 440 MPs/L. Pursuant to the large volumes of wastewater processed, estimated daily effluxes can exceed one billion MPs/day in some WWTPs. Membrane technologies, like those used in some tertiary wastewater treatment applications, appear well-positioned to mitigate releases of MPs. However, research directly characterizing the performance of membranes in these applications is lacking. The studies in this work address this knowledge gap. To this end, irregularly-shaped MPs were produced in a novel milling/sieving process. Ultrafiltration and microfiltration membranes were challenged to these MPs suspended in secondary effluent wastewater to elucidate their fouling behaviour under realistic solution conditions. Subsequently, MPs milled/sieved from a fluorescently-labelled plastic feedstock were utilized in microfiltration experiments. Bulk MP concentrations in samples were easily measured using a plate reader to quantify MP rejection. Improving upon this technique, a new protocol involving a flow cytometer was developed, enabling the identification of individual fluorescent MPs in filtration samples, even when complex solutions chemistries were used. A culminating investigation was performed to bridge a gap in the literature between studies considering small-scale laboratory filtration phenomena and observations of large-scale WWTPs. Thus, the performance of a hollow fiber crossflow microfiltration module was evaluated in the filtration of wastewater containing MPs. Overall findings suggest that incidences of fouling by MPs can be managed via periodic cleaning processes, and the well-informed selection/operation of membrane technologies can contribute to high MP removal efficiencies (> 99%) in tertiary wastewater applications. / Thesis / Doctor of Philosophy (PhD) / The term "microplastics" (MPs) is used to describe microscopic plastic particles. Recent investigations have reported these MPs in lakes, rivers, and oceans across the globe. These reports are concerning as other studies demonstrate that MP pollution can be hazardous to aquatic life, yet the potential effects of MPs on human health remain largely unknown. Many MPs originate from municipal wastewater treatment plants (WWTPs) which discharge large numbers of these particles into the aquatic environment. Researchers often recommend the use of membranes as a barrier to prevent MPs from leaving in the final treated wastewater. This work seeks to assess that recommendation. Assessments of the effectiveness of membranes at withholding MP particles in wastewater are performed over various conditions. The propensity of MPs to interfere with the desired output of treated wastewater is also measured. Overall, findings indicate that carefully designed and operated membranes processes can be well-suited to this application.

A thesis submitted to the School of Graduate Studies in partial fulfilment of the requirements for the degree of Master of Science in the graduate academic unit of Biology / Microparticles enter aquatic environments through many sources, including wastewater treatment plants (WWTPs), but their uptake by aquatic organisms is poorly understood. Freshwater bivalves accumulate multiple contaminants, making them potential bioindicators for MP pollution. This study aims to understand the abundance and characteristics of microparticles that accumulate in wild bivalves. Samples were collected from 5 locations along the Grand River (Ontario, Canada) in 2021-2022, including 3 municipal WWTPs where both an upstream and downstream site were sampled. At each site, fingernail clams (Sphaeriidae, n=5 composite samples), flutedshell mussels (Lasmigona costata, n=10), and surface water (n=3) were sampled. Within the mussels, the gill, digestive gland, and hemolymph tissues were targeted and compared. Microparticles were isolated and quantified via stereomicroscopy but have not yet been confirmed as plastic; as such, they will be referred to herein as microparticles. Fibers were the dominant morphology and clear, blue, and black were the most common colours, but there were some differences among sites and sample types. Most microparticles were between 80 μm and 1 mm in length. Fingernail clams contained the highest microparticle counts per mass of tissue at 35.5 ± 29.4 microparticles/g, mussel tissues ranged from 4.3 ± 4.2 microparticles/mL to 6.5 ± 8.1 microparticles/g, and water samples contained the lowest counts at 0.0055 ± 0.0028 microparticles/mL. Elevated microparticle counts at downstream sites were only seen in mussel gills and not other bivalve tissues. Surface water samples did not show elevated counts downstream of the WWTPs and microparticle exposures were similar across sites. This study provides baseline data for future monitoring and informs toxicity studies to fully assess the risk of microparticles to vulnerable freshwater bivalves and other aquatic organisms. It also suggests microparticles in freshwater bivalves are coming from sources in addition to WWTPs and are ubiquitous in the Grand River. / Thesis / Master of Science (MSc) / Microplastics are found in nearly every environment, especially freshwater ecosystems. These plastics come from a variety of sources, and this study focuses on assessing the characteristics of microparticles in freshwater clams and mussels (bivalves) that have been exposed to municipal wastewaters. Bivalves and water samples were collected from 5 locations along the Grand River (Ontario, Canada) in 2021-2022, and microparticles were extracted and analyzed from each sample. Fibers were the most abundant type of microparticle, with colours consisting mostly of clear, blue, and black. Clams had the highest number of microparticles per mass of tissue collected and the lowest counts were found in water samples. Higher microparticle counts were only seen in one (mussel gill) of the four tissues from bivalves collected downstream of wastewater outfalls. This study provides baseline data on microparticle characteristics in freshwater bivalves and will guide future studies on the toxicity of microparticles to these animals.

An increasing number of Americans identify bottled water as their preferred water source to meet household needs, despite additional expenses and less stringent quality reporting requirements. Previous studies note perceptions of poor water quality and/or distrust in public water authorities as the primary drivers of bottled water use. Examinations of Safe Drinking Water Act (SDWA) violation data validate these perceptions and highlight the increased prevalence of drinking water disparities in rural, low-income communities. This effort aims to assess in-home and bottled drinking water throughout rural Central Appalachia: a documented water inequity hotspot. To evaluate the uses, perceptions, motivations, expenditures, and quality related to in-home and bottled water sources, 24 homes in three different Central Appalachian counties were recruited to complete household surveys. Concurrently, 23 in-home (11 municipally and 12 privately sourced), 11 brands of bottled water, and four roadside spring samples identified as preferred drinking water sources were collected and analyzed for regulated (bacteria, inorganic ions) and emerging (per-and polyfluoroalkyl substances (PFAS), microplastics) contaminants via Standard Methods and compared to Safe Drinking Water Act (SDWA) standards (if applicable). The majority of respondents viewed their in-home water quality as satisfactory or less due to negative organoleptic perceptions (taste, odor, appearance). In-home and roadside spring water quality generally aligned with poor perceptions: coliform bacteria, E. coli, aluminum, iron, manganese, and sodium were detected at concentrations above United States Environmental Protection Agency (USEPA) standards and guidelines. Approximately 71 percent of homes reported bottled water as their primary drinking water source. Bottled water samples did not exceed any USEPA health-based regulations. The presence of inorganic ions contaminants varied greatly across the 11 brands of bottled water assessed, and within brand variability was noted in one bottled water brand purchased at two different locations. PFAS compounds were detected in both in-home and bottled water samples, though at relatively low levels. Microplastic particles were found in all samples, regardless of source. Statistical analyses revealed significantly higher concentrations of all contaminants in point-of-use samples compared to bottled water, except total microplastic particle count. Bottled water is a safe drinking water source for those without access to or confidence in their in-home drinking water, though associated time and financial burdens are considerable. / Master of Science / An increasing number of Americans regularly choose bottled water over tap water as their preferred water source. Previous studies claim this is because of poor home tap water quality and/or distrust in public water sources. This study aims to understand tap and bottled drinking water quality and opinions in rural West Virginia and Kentucky, where unavailable and/or unsafe tap water has been reported. Through partnerships with nonprofits in West Virginia and Kentucky, 24 homeowners were interviewed about their household water sources, uses, perceptions, motivations, and expenses. Water samples were also collected from homes, locally purchased bottled water, and other sources, including roadside springs. These samples were analyzed for regulated (bacteria, metals, nutrients) and emerging (per-and polyfluoroalkyl substances (PFAS), microplastics) contaminants and compared to federally enforceable standards for safety and aesthetics (if applicable). The majority of participants described their in-home water quality as satisfactory or poor due to unpleasant taste, odor, and appearance. This finding aligned with in-home water quality results, which found coliform bacteria, E. coli, aluminum, iron, manganese, and sodium levels above United States Environmental Protection Agency (USEPA) standards and guidelines. Most homes (71 percent) reported bottled water as their primary drinking water source. While bottled water samples did not exceed any USEPA health-based standards or guidelines, homeowners reported spending an average of $68–80/month and driving up to 1 hour and 45 minutes to buy it. Emerging contaminants (PFAS and microplastics) were detected in all bottled and tap-water samples at relatively low levels. Therefore, although bottled water is a safe drinking water source for those without access to or confidence in their tap water, having to regularly purchase it represents a significant household burden.

Annually, it is estimated that 82 million tons of global plastic waste is either mismanaged or littered, bypassing waste management practices. This mismanagement causes the permeation of plastic debris into the environment, which then undergoes natural degradation processes. These degradation processes result in the proliferation of miniscule plastic particles known as microplastics. Due to the inherent proximity to sources of anthropogenic waste, concerns of microplastic pollution and its impact on freshwater ecosystems have recently increased. Until recently, microplastic research has primarily been focused on the toxicological affects felt by an individual organism rather than the intricate interactions that occur between taxa. Only focusing on the individual toxicological impact turns a blind eye on the communities that maintain ecosystem health and stability. To that end, our experiment was unique as it will be the first study assessing the impact of a freshwater symbiosis, as symbioses in the scope of toxicokinetic studies have primarily been dominated by that of terrestrial and marine relationships. This knowledge gap is a serious concern as its argued freshwater systems are more contaminated, than that of other aquatic habitats. To address this knowledge gap, we conducted mesocosm-based exposure-response assays, exposing the crayfish-branchiobdellidan symbiosis to microplastics of fibrous, microsphere, and tire wear particle morphologies while varying symbiont densities. We used the crayfish-branchiobdellidan model system in our study due to its amenability to laboratory monitoring and manipulation. The crayfish C. appalachiensis, common in the Virginia New River Basin, served as hosts to obligate ectosymbiotic annelids in the order Branchiobdellida. Previous research, using the crayfish-branchiobdellidan symbiosis demonstrated that the interaction is a cleaning symbiosis, where hosts benefit from reduced gill fouling while symbionts benefit from increased resource availability. We observed the physical and behavioral changes of the crayfish-branchiobdellidan symbiosis over a 172-day chronic exposure assay. Our results show, crayfish hosts with higher symbiont densities experienced decreased physical growth when exposed to microplastics compared to the control. This alteration in host growth was the result of increased antagonistic symbiont behavior in the form of gill tissue consumption. Our results suggest microplastics caused a reduction in epibiont abundance, thus decreasing symbiotic resource availability. This reduction in resources resulted in a shift of context dependency, thus increasing parasitic symbiont behavior. This study demonstrates microplastics have the capability to shift symbiotic context from a mutualism to a parasitism. / Master of Science / Every year, due to improper waste management, approximately 82 million tons of global plastic waste ends up in the environment. Once in the environment, this plastic waste naturally breaks down into tiny particles known as microplastics. Recently, there's been growing concern about how these microplastics affect freshwater habitats. One particular worry is the impact that this contaminant can have on the relationships between different organisms living in freshwater environments. Currently, multiple scientific experiments have studied the effects of microplastics on marine and land-based organismal relationships, however, none have studied the effect of microplastics on freshwater organismal relationships. To explore this, we used the relationship of crayfish and a type of worm called Branchiobdellida, due to their close, prolonged relationship commonly found in nature. These Branchiobdellida worms live on the outside of crayfish and keep the gills of the crayfish clean by consuming any matter that has grown or lodged itself on the gill filaments. As such, the worms rely on the crayfish as a home and means of collecting food. Depending on food availability, this relationship can be mutually beneficial for both the crayfish and worm. Due to the worm's reliance of the crayfish and the mutually beneficial relationship they facilitate, the crayfish-branchiobdellidan relationship is known as a symbiosis. To best understand how microplastics affect the crayfish-branchiobdellidan symbiosis, we conducted experiments where we exposed crayfish with varying numbers of worms to a controlled dosage of microplastics for a prolonged period of time within artificial environments called mesocosms. Each microplastic dosage contained different types of microplastics, that mimicked the type and amount commonly found in nature. We found that crayfish with higher worm densities grew less when exposed to microplastics compared to those not exposed to microplastics. We also noticed that when microplastics were present, the worms exhibited more aggressive behavior, like consuming the gills of the crayfish. Based on assays which measured the number of resources accessible to the symbionts, our findings suggest that microplastics reduce the resource availability to the worms, which then triggers a change in their relationship with the crayfish host. Instead of being helpful, the worms start behaving more like parasites when exposed to microplastic. Ultimately, this study shows that microplastics can change the way different organisms interact, turning a beneficial symbiosis into a harmful one.

In the northeast Pacific, salmon are an integral part of ecology, economics and culture. Nearshore areas, where juvenile salmon reside upon leaving their natal streams, are important habitat during a critical time where growth can determine overall survivorship. With the rise in human development in coastal areas, these valuable habitats are becoming increasingly modified, however, the ecological ramifications are not fully understood. This study focuses on two types of anthropogenic influence including shellfish aquaculture, which modifies intertidal areas by adding structures such as intertidal fencing and anti-predator nets, and plastic marine pollution in the form of microplastics. We beach seined at sites within an area extensively modified for shellfish aquaculture (Baynes Sound) to examine juvenile salmon abundance, condition, feeding intensity and prey at aquaculture and non-aquaculture areas. In addition, we also beach seined, and along the east coast of Vancouver Island to determine the incidence of microplastics in juvenile Chinook salmon and their nearshore environments. No significant differences were found between areas in the abundance, diets, condition or feeding intensity of juvenile Coho and Chinook. Chum had different prey and a higher condition and feeding intensity at aquaculture sites, suggesting that species such as Chum feeding on more benthic prey items have a higher probability of being impacted by shellfish aquaculture modifications and in this case we observed positive effects. Microplastic analysis showed juvenile Chinook salmon contained 1.15 1.41 (SD) microplastics per individual while water and sediment samples had 659.88 520.87 microplastics m-3 and 60.2 63.4 microplastics kg-1 dry weight, respectively. We found no differences in microplastic concentrations in juvenile Chinook and water samples among sites but observed significantly higher concentrations in sediment at our Deep Bay site compared to Nanaimo and Cowichan Bay. These differences may be due to site bathymetry and oceanographic differences facilitating settlement at the Deep Bay site and/or may be a result of differential plastic sources in the area including shellfish farming and a marina. Shellfish aquaculture had negligible or positive effects on juvenile salmon abundance, diet, condition and feeding intensity and Chinook microplastic concentrations were relatively low compared to literature values. Although fitness consequences and ecosystem-wide implications must be addressed in the future, it appears shellfish aquaculture and microplastics are not immediate threats to juvenile Pacific salmon along the east coast of Vancouver Island at this time. However, continued monitoring programs and larger-scale studies should be implemented as shoreline modification and plastic use continues to increase. / Graduate / 2017-08-14