Browsing by Author "Ross, Matthew S."
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- ItemCharacterization of microplastics and anthropogenic fibers in surface waters of the North Saskatchewan River, Alberta, Canada(2021) Bujaczek, Taylor; Kolter, Sheldon; Locky, David; Ross, Matthew S.Microplastics are globally ubiquitous contaminants, but quantitative data on their presence in freshwater environments are sparse. This study investigates the occurrence, composition, and spatial trends of microplastic contamination in the North Saskatchewan River flowing through Edmonton, Alberta, the fifth largest city in Canada. Surface water samples were collected from seven sites throughout the city, upstream and downstream of the city, and near potential point sources (i.e., a wastewater treatment plant). Samples were spiked with fluorescent microbeads as internal standards and extracted by wet peroxide oxidation and density floatation. Microplastics were found in all samples, ranging in concentration from 4.6 to 88.3 particles·m−3 (mean = 26.2 ± 18.4 particles·m−3). Fibers were the dominant morphology recovered, and most were of anthropogenic origin and chemically identified as dyed cotton or polyester by Raman microspectroscopy. The majority of fragments were identified as polyethylene or polypropylene. No upstream to downstream differences were found in concentration, size distribution, or morphological composition suggesting nonpoint sources of microplastics to the river. This study represents one of the first investigations into the occurrence of microplastics in the freshwater environment in western Canada and will provide a baseline for future studies.
- ItemDifferential protein expression during growth on model and commercial mixtures of naphthenic acids in Pseudomonas fluorescens Pf-5(2021) McKew, Boyd A.; Johnson, Richard; Clothier, Lindsay; Skeels, Karl; Ross, Matthew S.; Metodiev, Metodi; Frenzel, Max; Gieg, Lisa M.; Martin, Jonathan W.; Hough, Michael A.; Whitby, CorinneNaphthenic acids (NAs) are carboxylic acids with the formula (CnH2n+ZO2) and are among the most toxic, persistent constituents of oil sands process-affected waters (OSPW), produced during oil sands extraction. Currently, the proteins and mechanisms involved in NA biodegradation are unknown. Using LC-MS/ MS shotgun proteomics, we identified proteins overexpressed during the growth of Pseudomonas fluorescens Pf-5 on a model NA (4′-n-butylphenyl)- 4-butanoic acid (n-BPBA) and commercial NA mixture (Acros). By day 11, >95% of n-BPBA was degraded. With Acros, a 17% reduction in intensity occurred with 10–18 carbon compounds of the Z family −2 to −14 (major NA species in this mixture). A total of 554 proteins (n-BPBA) and 631 proteins (Acros) were overexpressed during growth on NAs, including several transporters (e.g., ABC transporters), suggesting a cellular protective response from NA toxicity. Several proteins associated with fatty acid, lipid, and amino acid metabolism were also overexpressed, including acyl-CoA dehydrogenase and acyl-CoA thioesterase II, which catalyze part of the fatty acid beta-oxidation pathway. Indeed, multiple enzymes involved in the fatty acid oxidation pathway were upregulated. Given the presumed structural similarity between alkyl-carboxylic acid side chains and fatty acids, we postulate that P. fluorescens Pf-5 was using existing fatty acid catabolic pathways (among others) during NA degradation.
- ItemEstimated discharge of microplastics via urban stormwater during individual rain events(2023) Ross, Matthew S.; Loutan, Alyssa; Groeneveld, Tianna M.; Molenaar, Danielle; Kroetch, Kimberly; Bujaczek, Taylor; Kolter, Sheldon; Moon, Sarah; Huynh, Alan; Khayam, Rosita; Franczak, Brian C.Urban stormwater runoff is an important pathway for the introduction of microplastics and other anthropogenic pollutants into aquatic environments. Highly variable concentrations of microplastics have been reported globally in runoff, but knowledge of key factors within urban environments contributing to this variability remains limited. Furthermore, few studies to date have quantitatively assessed the release of microplastics to receiving waters via runoff. The objectives of this study were to assess the influence of different catchment characteristics on the type and amount of microplastics in runoff and to provide an estimate of the quantity of microplastics discharged during rain events. Stormwater samples were collected during both dry periods (baseflow) and rain events from 15 locations throughout the city of Calgary, Canada’s fourth largest city.
- ItemParticulate matters: student-led air quality research in the third-year environmental chemistry classroom and the field(2018) Hilts, Robert; Gao, Sherry; Ross, Matthew S.; Styler, Sarah A.The article reports on a student-led air quality research in the third-year environmental chemistry classroom and the field. Topics discussed include environmental chemistry course offered at the University of Alberta; impact of particulate matter on environment; and impact of oxidation of precursor emissions and industrial processes in the formation of particulate matter.
- ItemPhotodegradation of bitumen-derived organics in oil sands process-affected water(2020) Challis, Jonathan K.; Parajas, Angelique; Anderson, Julie C.; Asiedu, Evelyn; Martin, Jonathan W.; Wong, Charles S.; Ross, Matthew S.The chemical composition of water-soluble organics in oil sands process-affected water (OSPW) is primarily composed of natural constituents of bitumen that are solubilized and concentrated during aqueous extraction of oil sands. OSPW organics are persistent and acutely toxic, and a leading remediation strategy is long-term ageing in end-pit lakes, despite limited data available on its photochemical fate. Here, direct photolysis of whole OSPW, or of its constituent fractions, was examined at environmentally relevant wavelengths (>290 nm) in bench-top studies. Changes in the chemical profiles of whole OSPW, acid- (AEO), and base-extractable organics (BEO) were characterized by liquid chromatography with ultra-high resolution mass spectrometry in negative (−) and positive (+) ionization modes. Following 18 d of irradiation, photolysis reduced the total ion intensity in all samples in both modes. The most photo-labile species included the O2−, O3−, O4−, O2S−, and O4S− chemical classes, which were depleted in whole OSPW by 93–100% after only 5 d. In positive mode, detected species were more recalcitrant than those detected in negative mode, with an average reduction across all heteroatomic classes of 75 ± 11.0% after 18 d. Estimated environmental half-lives for heteroatomic classes ranged from 57 d (O4S−) to 545 d (O3N+), with a greater recalcitrance for classes detected in positive mode compared to negative mode. Under field conditions in end-pit lakes, natural photolysis may be an important mechanism for effective OSPW remediation, and we suggest that future end-pit lakes be shallow to maximize light penetration and natural photolysis in ageing OSPW.
- ItemRepeated ethanol exposure increases anxiety-like behaviour in zebrafish during withdrawal(2019) Krook, Jeffrey T.; Duperreault, Erika; Newton, Dustin; Ross, Matthew S.; Hamilton, TrevorZebrafish (Danio rerio) are quickly becoming an important model organism in behavioural neuroscience and drug addiction research. Conditioned place preference studies show that drugs of abuse produce responses in zebrafish that are similar to mammalian animal models. Repeated administration of ethanol in zebrafish results in withdrawal-induced behavioural responses that vary with dose and exposure duration, requiring additional investigation. Here, we examine the effects of ethanol withdrawal on anxiety-like behaviours in adult zebrafish after a 21-day ethanol dosing schedule at either 0.4% or 0.8%. Anxiety-like behaviour was measured with the novel object approach test; this test involves placing a fish in a circular arena with a novel object in the centre and observing the amount of exploration of the object. We found increased anxiety-like behaviour during ethanol withdrawal. This study adds to the growing body of literature that validates the zebrafish as a model organism in the field of behavioural neuroscience and addiction.
- ItemSilicone wristbands as personal passive samplers: assessing exposure to organophosphate flame retardants(2020) Molenaar, Danielle; Ross, Matthew S.Organophosphate flame retardants (OPFRs) are used as additives in a variety of industrial and commercial products, such as furniture and electronics, to meet fire resistance standards. However, OPFRs have been associated with health effects, including neurotoxicity, hormonal changes, and cancer; therefore, insight into levels of exposure is necessary for health and risk assessments. An individual’s exposure to OPFRs can be measured using silicone wristbands as passive samplers, which make use of the tendency for a chemical to equilibrate between the solid phase (the sampler) and air to measure personal exposure to contaminants over time. Because OPFRs are frequently used in electronics, this study aimed to examine correlations between electronic use and personal exposure to OPFRs. Silicone wristbands were cleaned to remove surface contaminants, and then deployed to participants to wear for one week. Following deployment, the adhered compounds were extracted and analyzed using gas chromatography-mass spectrometry. While deployed, participants filled out a questionnaire indicating their weekly electronic use, which was used to draw correlations between electronics and exposure to OPFRs. The median concentration of OPFRs on wristbands were found to be about 6300ng/wristband, with high variability between individual wristbands. This project will be one of the first in Canada to use silicone wristbands as personal samplers to address exposure to OPFRs in relation to electronic use, and thus will prove useful in risk assessment due to the increasing use of electronics in society.
- ItemSupplemental information: photodegradation of bitumen-derived organics in oil sands process-affected water(2020) Challis, Jonathan K.; Parajas, Angelique; Anderson, Julie C.; Asiedu, Evelyn; Martin, Jonathan W.; Wong, Charles S.; Ross, Matthew S.Supplementary material consists of figures and tables.