School of Environmental Studies Faculty Publications

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    Radio- and Stable Carbon Isotope Analysis Reveals Minimal Assimilation of Petrogenic Carbon Into an Oligotrophic Freshwater Food Web After Experimental Spills of Diluted Bitumen
    (Elsevier, 2023-04-05) Graves, Stephanie; Mason, Johanna; Rodriguez-Gil, Jose Luis; Seguin, Jonathan Y.; Blais, Jules; Hanson, Mark; Hollebone, Bruce P.; Palace, Vince; Clark, Ian; Cundall, Leah; Layton-Matthews, Daniel; Leybourne, Matthew; Orihel, Diane
    Following an oil spill into water, bacteria can biodegrade petroleum hydrocarbons which could lead to petrogenic carbon assimilation by aquatic biota. We used changes in the isotope ratios of radio- (Δ14C) and stable (δ13C) carbon to examine the potential for assimilation of petrogenic carbon into a freshwater food web following experimental spills of diluted bitumen (dilbit) into a boreal lake in northwestern Ontario, Canada. Different volumes (1.5, 2.9, 5.5, 18, 42, 82, and 180 L) of Cold Lake Winter Blend (a heavy crude blend of bitumen and condensate) dilbit were applied to seven 10-m diameter littoral limnocorrals (approximate volume of 100 m3), and two additional limnocorrals had no added dilbit to serve as controls. Particulate organic matter (POM) and periphyton from oil-treated limnocorrals had lower δ13C (up to 3.2‰ and 2.1‰ for POM and periphyton, respectively) than the control at every sampled interval (3, 6 and 10 weeks for POM and 6, 8 and 10 weeks for periphyton). Dissolved organic and inorganic carbon (DOC and DIC, respectively) had lower Δ14C in the oil-treated limnocorrals relative to the control (up to 122‰ and 440‰ lower, respectively). Giant floater mussel (Pyganodon grandis) housed for 25 days in aquaria containing oil-contaminated water from the limnocorrals did not show significant changes in δ13C values of muscle tissue compared to mussels housed in control water. Overall, the changes in δ13C and Δ14C observed indicated small amounts (up to 11% in DIC) of oil carbon incorporation into the food web. The combined δ13C and Δ14C data provide evidence for minimal incorporation of dilbit into the food web of this oligotrophic lake, suggesting that microbial degradation and subsequent incorporation of oil C into the food web may play a relatively small role in the ultimate fate of oil in this type of ecosystem.
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    Experimental Evidence from the Field that Naturally Weathered Microplastics Accumulate Cyanobacterial Toxins in Eutrophic Lakes
    (Wiley, 2022-09-23) Hataley, Eden K.; Shahmohamadloo, Rene; Ortiz Almirall, Xavier; Harrison, Anna L.; Rochman, Chelsea M.; Zou, Shan; Orihel, Diane
    Freshwater ecosystems with recurring harmful algal blooms can also be polluted with plastics. As such, the two environmental problems may interact. To test if microplastics influence the partitioning of microcystins in freshwater lakes, we examined the sorption of four microcystin congeners to different polymers of commercially available plastics (low-density polyethylene, polyethylene terephthalate, polyvinyl chloride, and polypropylene). We conducted three experiments: a batch sorption experiment in the laboratory with pristine microplastics of four different polymers, a second batch sorption experiment in the laboratory to compare pristine and naturally weathered microplastics of a single polymer, and a 2-month sorption experiment in the field with three different polymers experiencing natural weathering in a eutrophic lake. This series of experiments led to a surprising result: microcystins sorbed poorly to all polymers tested under laboratory conditions (less than 0.01% of the initial amount added), irrespective of weathering, yet, in the field experiment, all polymers accumulated microcystins under ambient conditions in a eutrophic lake (range: 0-84.1 ng/g). Furthermore, the sorption capacity for microcystins differed among polymers in the laboratory experiment yet were largely the same in the field. We also found that the affinity for plastic varied among microcystin congeners, namely more polar congeners demonstrated a greater affinity for plastic than less polar ones. This study improves our understanding of the role of polymer and congener type in microplastic-microcystin sorption, and moreover, provides novel evidence from the field, showing that naturally weathered microplastics in freshwater lakes can accumulate microcystins. Consequently, we caution that microplastics may alter the persistence, transport, and bioavailability of microcystins in freshwaters, which could have implications for human and wildlife health.
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    Life under an oil slick: response of a freshwater food web to simulated spills of diluted bitumen in field mesocosms
    (Canadian Science Publishing, 2020-02-17) Cederwall, Jeffrey; Black, Tyler; Blais, Jules; Hanson, Mark; Hollebone, Bruce P.; Palace, Vince; Rodriguez-Gil, Jose Luis; Greer, Charles; Maynard, Christine; Ortmann, Alice; Rooney, Rebecca; Orihel, Diane
    Heavy crude oil transportation over land is increasing, yet the ecological impacts of spills, particularly of diluted bitumen, in freshwater environments remain poorly understood. We simulated spills of diluted bitumen in 1400 L land-based mesocosms containing water and sediments from a boreal, oligotrophic lake and monitored the response of natural planktonic communities over 11 days. Most species of phytoplankton (chrysophytes and dinoflagellates) and zooplankton (copepods and cladocerans) were sensitive to oil, exhibiting >70% overall abundance reductions in response to the spills. Declines in nano- and microphytoplankton were short-lived and began to recover after the oil sank, whereas picophytoplankton and zooplankton populations remained depressed at the end of the experiment. In contrast, oil spills stimulated bacteria known to degrade hydrocarbons, especially Alphaproteobacteria, whereas Gammaprotobacteria (a common marine oil spill bacterial class) increased less. This is the first experiment to examine the effects of diluted bitumen in a multitrophic freshwater community.
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    Haloconduction as a remediation strategy: Capture and quantification of salts excreted by recretohalophytes
    (Elsevier BV, 2019-10-01) Yun, Kassandra B. M.; Koster, Sonja; Rutter, Allison; Zeeb, Barbara A.
    Recretohalophytes employ specialized glands to excrete salt ions onto their tissue surfaces, which then have the potential to be transported away from the plant via wind in a process referred to as ‘haloconduction’. Spartina pectinata and Distichlis spicata were selected to investigate the potential to remediate a cement kiln dust landfill in Bath, ON via salt excretion and haloconduction. Under ideal conditions in the laboratory, measurements of salt excreted by large (>15 shoots and > 50 cm height) plants of each species were 280 ± 164 g/m2 and 164 ± 75 g/m2, respectively, resulting in potential remediation timeframes of 1.4 ± 0.9 and 2.4 ± 1.1 years. Three salt collection methods were developed and installed in the field to test their efficacy for capturing and measuring windborne salt mobilized from plant surfaces. All three methods (two ground-level and one at 260 cm height) were successful in capturing and quantifying airborne salts up to 15 m from the plots. This study is the first to collect and quantify dispersed salt from recretohalophytes and hence confirm the theory of haloconduction, a promising new remediation technology for salt-impacted soils.
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    Modes of Governing Canadian Waste Management: a Case Study of Metro Vancouver’s Energy-From-Waste Controversy
    (2017-06-28) Lougheed, Scott Cameron; Metuzals, Jessica; Hird, Myra J.
    Managing municipal solid waste is a pressing environmental and political concern for Canadian municipalities who bear the primary responsibility for waste management (WM). In 2015, Metro Vancouver’s (MV’s) plans to expand their capacity to expand their WM capacity with energy-from-waste technology was abandoned, despite shrinking landfill space and persistent public opposition to new landfills. Using Bulkeley et al.’s [(2005). Governing municipal waste: towards a new analytical framework. Journal of Environmental Policy and Planning, 7(1), 1–23. doi:10.1080/15239080500251700] ‘modes of governing framework’, we analyse MV’s failed attempt to expand their energy-from-waste capacity to better understand the challenges associated with governing WM in Canada. We argue that a history of downloading responsibility for WM to municipalities, regional districts, and industry has fragmented WM governance, posing a challenge for developing new waste infrastructure. We find that this localization of responsibility is incompatible with contemporary WM challenges. The scalar mismatch between waste’s material impacts and the scale at which waste is managed has resulted in co-dependence and conflict between putatively independent municipalities, regional districts, and private companies. This inhibits higher-level WM coordination while the autonomy of individual municipalities is simultaneously undermined.