Sciences de la Terre et de l'environnement // Earth and Environmental Sciences

Permanent URI for this collectionhttps://hdl.handle.net/10393/19590

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Tracking pollution from fur farms using forensic paleolimnology
(2023) Kissinger, Jennifer; Gregory, Braden; Clarkson, Chloe; Libera, Nell; Eickmeyer, David; Kimpe, Linda; Kurek, Josh; Smol, John; Blais, Jules
Eutrophication, which remains one of the greatest threats to water quality worldwide, is particularly acute in agricultural areas. Here we assessed long-term drivers of potential pollution inputs to lakes in southwest Nova Scotia (Canada), a region marked by fur farming (mainly mink) and other agricultural activities. We used a BACI (before-after-control-impact) study design with sediment cores collected from 14 lakes selected based on their proximity to mink farms. We combined economic data, mink faecal samples, and a series of geochemical markers in dated sediment cores, including sterols, δ15N, visible reflectance spectroscopy (VRS)-inferred chlorophyll-a, and heavy metals, to relate changes in sediment geochemistry to the growth of mink farms in the region. Sterol biomarkers (cholesterol and -sitosterol) measured in a range of samples (i.e. mink faeces and feed, aquaculture feed), were elevated where mink farms were located close to each study lake. Mink-related sterols (cholesterol, -sitoserol), δ15N measurements, VRS chlorophyll-a, and heavy metals As, Cu, Sr increased in the 1980s coeval with a ~400% increase of mink farms in the region, especially near Nowlans Lake. Agricultural impacts were subtler in other lakes. Our study expands on prior applications of geochemical fingerprinting in forensic paleolimnology when direct monitoring data are incomplete. This multi-proxy approach has promising applications for environmental pollution assessments in other lake ecosystems experiencing water quality issues.
Paleo-ecotoxicology: What Can Lake Sediments Tell Us about Ecosystem Responses to Environmental Pollutants?
(2017) Korosi, Jennifer B; Thienpont, Joshua R; Smol, John P; Blais, Jules M
The development of effective risk reduction strategies for aquatic pollutants requires a comprehensive understanding of toxic impacts on ecosystems. Classical toxicological studies are effective for characterizing pollutant impacts on biota in a controlled, simplified environment. Nonetheless, it is well-acknowledged that predictions based on the results of these studies must be tested over the long-term in a natural ecosystem setting to account for increased complexity and multiple stressors. Paleolimnology (the study of lake sediment cores to reconstruct environmental change) can address many key knowledge gaps. When used as part of a weight-of-evidence framework with more traditional approaches in ecotoxicology, it can facilitate rapid advances in our understanding of the chronic effects of pollutants on ecosystems in an environmentally realistic, multistressor context. Paleolimnology played a central role in the Acid Rain debates, as it was instrumental in demonstrating industrial emissions caused acidification of lakes and associated ecosystem-wide impacts. "Resurrection Ecology" (hatching dormant resting eggs deposited in the past) records evolutionary responses of populations to chronic pollutant exposure. With recent technological advances (e.g., geochemistry, genomic approaches), combined with an emerging paleo-ecotoxicological framework that leverages strengths across multiple disciplines, paleolimnology will continue to provide valuable insights into the most pressing questions in ecotoxicology.
Simulating diluted bitumen spills in boreal lake limnocorrals - part 2: Factors affecting the physical characteristics and submergence of diluted bitumen
(2021) Stoyanovich, S; Rodríguez-Gil, J R; Hanson, M L; Hollebone, B P; Orihel, D M; Palace, V P; Faragher, R; Mirnaghi, F S; Shah, K; Yang, Z; Blais, J M
We examined the fate and behaviour of diluted bitumen (dilbit) as it weathered for 70 days in freshwater limnocorrals (10 m diameter × 1.5 m depth) installed in a boreal lake to simulate dilbit spills in a natural aquatic environment. We added seven different dilbit spill volumes, ranging from 1.5 to 180 L, resulting in oil-to-water ratios between 1:71,000 (v/v, %) and 1:500 (v/v, %). Volatile hydrocarbons in the dilbit slick decreased rapidly after the dilbit was spilled on the water's surface, and dilbit density and viscosity significantly increased (>1 g mL-1 and >5,000,000 mPa s, respectively). Dilbit sank to the bottom sediments in all treatments, and the time to sinking was positively correlated with spill volume. The lowest dilbit treatment began to sink on day 12, whereas the highest dilbit treatment sank on day 31. Dilbit submerged when its density surpassed the density of freshwater (>0.999 g mL-1), with wind, rain, and other factors contributing to dilbit sinking by promoting the break-up of the surface slick. This experiment improves our ability to predict dilbit's aquatic fate and behaviour, and its tendency to sink in a boreal lake. Our findings should be considered in future pipeline risk assessments to ensure the protection of these important aquatic systems.
Paleolimnology can provide the missing long-term perspective in ecotoxicology research
(2017) Korosi, Jennifer B; Thienpont, Joshua R; Smol, John P; Blais, Jules M
In-situ bitumen extraction associated with increased petrogenic polycyclic aromatic compounds in lake sediments from the Cold Lake heavy oil fields (Alberta, Canada)
(2016) Korosi, Jennifer B; Cooke, Colin A; Eickmeyer, David C; Kimpe, Linda E; Blais, Jules M
Most future growth in the Alberta bituminous sands will be based on thermal in-situ recovery technologies. To date, however, most attention on the environmental effects of bitumen recovery has focused on surface mining in the Athabasca region. Recent uncontrolled bitumen flow-to-surface incidents (FTS; appearance at the surface of bitumen emulsions from deep subsurface recovery zones) reported at the Cold Lake heavy oil fields highlight the need to better understand the potential role of in-situ extraction as a source of contaminants to landscapes and surface waters. We analyzed sediment cores from a lake located ∼2 km away from a recent bitumen FTS incident to provide a long-term perspective on the delivery of metals, polycyclic aromatic compounds (PACs), and polychlorinated biphenyls (PCBs) to surface freshwaters, and to assess whether the onset of local in-situ bitumen extraction can be linked to contaminant increases in nearby lakes. An increase in alkyl PACs coincided with the onset and expansion of commercial in-situ bitumen extraction, and multiple lines of evidence indicate a petrogenic source for recent alkyl PAC enrichment. However, no coincident increase in vanadium (enriched in bitumen) occurred that would suggest the source of petrogenic PAC enrichment is direct input of bituminous particles. Our results show that, similar to surface mining in the Athabasca region, activities associated with in-situ extraction can increase the burden of petrogenic PACs in nearby lakes, but many questions still remain regarding the exact sources and pathways of PACs into the environment. Given that more than 80% of Alberta's bitumen reserves can only be accessed using in-situ technologies, we recommend that this be made a research priority.
Integrated analysis of petroleum biomarkers and polycyclic aromatic compounds in lake sediment cores from an oil sands region
(2021) Salat, Alexandre P J; Eickmeyer, David C; Kimpe, Linda E; Hall, Roland I; Wolfe, Brent B; Mundy, Lukas J; Trudeau, Vance L; Blais, Jules M
We examined polycyclic aromatic compounds (PACs) and petroleum biomarkers (steranes, hopanes, and terpanes) in radiometrically-dated lake sediment cores from the Athabasca oil sands region (AOSR) and the Peace-Athabasca Delta (PAD) region in Alberta (Canada) to determine whether contributions from petroleum hydrocarbons have changed over time. Two floodplain lakes in the PAD (PAD 30, PAD 31) recorded increased flux of alkylated PACs and increased petrogenic (petroleum-derived) hydrocarbons after ∼1980, coincident with a decline of sediment organic carbon content and a rise of bulk sedimentation rate, likely due to increased Athabasca River flow. A large expansion of upstream oilsands mining, upgrading, and refining may also have contributed to the observed shift to more petrogenic hydrocarbons to sediments since the 1980s. Alkylated PAC flux increased in the floodplain lake analyzed within the AOSR (Saline Lake) since the 1970s-1980s, coincident with a sharp rise in sediment organic carbon content and increased contributions of petrogenic hydrocarbons. These changes identify increased supply of petrogenic PACs occurred as Athabasca River floodwaters waned, and may implicate aerial contributions of petrogenic hydrocarbons from oilsands activity. PACs and petroleum biomarkers (steranes, hopanes, and terpanes) in sediment cores from Saline Lake, PAD 30 and PAD 31 revealed a predominance of petrogenic hydrocarbons in these lakes. In contrast, we recorded minimal petrogenic hydrocarbons in the reference lakes outside the surface minable area of the AOSR and PAD (Mariana Lake and BM11), though we noted slight increases in petrogenic contributions to modern (2010-2016) sediments. We show how a combined analysis of PACs and petroleum biomarkers in sediments is useful to quantify petrogenic contributions to lakes with added confidence and highlight the potential for petroleum biomarkers in lake sediment cores as a novel and effective method to track petroleum hydrocarbons in lake sediment.
Tracking the history of cultural eutrophication in High Arctic waterbodies
(2020) Gallant, Lauren; Kimpe, Linda; Hargan, Kathryn; Blais, Jules
Human activities can greatly affect the chemical and biological composition of High Arctic lakes that otherwise receive only sparse inputs from their watersheds and airsheds. Here we present a study of three High Arctic waterbodies in which wastewater from an airport was released over the span of several decades. Using sediment cores from these waterbodies, we reconstructed the history of wastewater inputs using a multiproxy approach consisting of sterols, stanols, metals, and stable isotopes of carbon and nitrogen. This multi-proxy approach showed good concordance between 15N, coprostanol (a stanol specific to human fecal sources), cholesterol, and cholestanol, which tracked the known history of human wastewater deposition to this High Arctic environment. Concentrations of plant derived sterols, such as campesterol and sitosterol, increased at the time of wastewater input, presumably due to increased plant growth stimulated by wastewater nutrients. Metal(loid)s normalized to titanium showed copper and lead tracked the input of wastewater into R-12, while arsenic, cadmium, chromium, nickel, and zinc increased more than 15 years after the onset of wastewater input. These results demonstrated the ability of sterols and stanols to reconstruct the historical presence of humans in High Arctic locations within the last 80 years and provided compelling evidence that these paleolimnological approaches may be used to track occupation of Arctic peoples beyond the last century.
Fate of polycyclic aromatic compounds from diluted bitumen spilled into freshwater limnocorrals
(2022) Stoyanovich, S; Yang, Z; Hanson, M; Hollebone, B P; Orihel, D M; Palace, V; Rodriguez-Gil, J R; Mirnaghi, F; Shah, K; Blais, J M
Diluted bitumens (dilbits) are produced by mixing highly viscous bitumen with lighter petroleum products to facilitate transport. The unique physical and chemical properties of dilbit may affect the environmental fate and effects of dilbit-derived chemical compounds when spilled. To further explore this, we monitored experimental spills of Cold Lake Winter Blend (CLWB) dilbit for 70 days in limnocorrals installed in a freshwater boreal lake. A regression design with 2 controls and 7 treatments was used to assess the fate and behaviour of polycyclic aromatic compounds (PACs) as they partitioned from the dilbit into the air, water column and sediments. Treatments ranged from 1.5 to 180 L of CLWB, resulting in oil:water ratios ranging between 1:71000 to 1:500 (v:v). We began to detect elevated concentrations of PACs as early as 6 h post-addition in the air, 12 h post-addition in the water column, and 15-28 d post-addition in the sediments. By the end of the experiment, concentrations of PACs had largely declined in the water column but remained elevated in the sediments. Our results demonstrate that under conditions typical of temperate boreal lakes, only a small proportion of PACs from dilbit enters the aquatic system, but even so, may produce concentrations of ecotoxicological concern, especially in the sediments, which is the ultimate sink for dilbit-derived PACs.
Extracts from Dated Lake Sediment Cores in the Athabasca Oil Sands Region Alter Ethoxyresorufin-O-deethylase Activity and Gene Expression in Avian Hepatocytes
(2021) Salat, Alexandre P J; Williams, Kim L; Chiu, Suzanne; Eickmeyer, David C; Kimpe, Linda E; Blais, Jules M; Crump, Doug
Increases in oil sands mining operations in the Athabasca oil sands region have resulted in increased concentrations of polycyclic aromatic compounds (PACs) and heavy metals in aquatic systems located near surface mining operations. In the present study, sediment cores were collected from 3 lakes with varying proximity to surface mining operations to determine the differences in PAC concentrations. Sediment cores were separated into 2 sections-current mining (top; 2000-2017) and premining (bottom; pre-1945)-and extracts were prepared for in vitro screening using a well-established chicken embryonic hepatocyte (CEH) assay. Concentrations and composition of PACs varied between sites, with the highest ∑PACs in Saline Lake, 5 km from an active oil sands mine site. The proportion of alkylated PACs was greater than that of parent PACs in the top sediment sections compared with the bottom. Ethoxyresorufin-O-deethylase activity in CEH permitted the ranking of lake sites/core sections based on an aryl hydrocarbon receptor-mediated end point; mean median effect concentration values were lowest for the top cores from Saline Lake and another near-mining operations lake, referred to as WF1. A ToxChip polymerase chain reaction (PCR) array was used to evaluate gene expression changes across 43 target genes associated with numerous toxicological pathways following exposure to top and bottom sediment core extracts. The 2 study sites with the greatest ∑PAC concentrations (Saline Lake and WF1) had the highest gene expression alterations on the ToxChip PCR array (19 [top] and 17 [bottom]/43), compared with a reference site (13 [top] and 7 [bottom]/43). The avian in vitro bioassay was useful for identifying the toxicity of complex PAC extracts associated with variably contaminated sediment cores, supporting its potential use for hotspot identification and complex mixture screening. EnvironToxicol Chem 2021;40:1883-1893. © 2021 SETAC.
Assessing the contribution of combustion-derived contaminants to a remote subarctic environment from traffic on the Tibbitt to Contwoyto winter road (Northwest Territories, Canada)
(2016) Korosi, Jennifer B; Eickmeyer, David C; Thienpont, Joshua R; Palmer, Michael J; Kimpe, Linda E; Blais, Jules M
Remote mining operations in Canada's Northwest Territories and Nunavut are supported by a 600 km winter road, which spans the transition from subarctic boreal forest in Yellowknife to low Arctic tundra. Each year, thousands of truckloads of fuel, large equipment, and other heavy loads are hauled up the winter road. We investigated whether diesel emissions from commercial truck traffic is a major source of metals and polycyclic aromatic compounds (PACs) to aquatic ecosystems along the winter road. In March 2014, at the end of the hauling season, we collected integrated snow samples, water, and sediment from nine lakes located along the winter road, as well as from six lakes located within the city of Yellowknife. Examination of PAC composition and diagnostic ratios in snow samples showed that wildfires are an important source of PACs to lakes along the winter road, while anthropogenic sources are more prevalent in snow from Yellowknife lakes. Concentrations of PACs, including those associated with diesel emissions, were variable in snow, water, and sediment across all sites. The highest concentrations of PACs in snow were reported in winter road lakes located in the subarctic boreal forest, where forest fires are common. No compositional differences were observed for PACs in sediment and water samples between Yellowknife and winter road lakes. We did not observe any evidence of metal contamination in snow collected along the winter road, and metal concentrations in snow from winter road sites were consistently lower than Yellowknife sites. Our results show that a high contribution of PACs from natural sources can obscure potential contributions from diesel traffic emissions along the winter road.
Paleoecotoxicology: Developing methods to assess the toxicity of lake sediment records influenced by legacy gold mining
(2022) Cheney, Cynthia; Pothier, Martin; Thomas, Philippe J; Sarma, Sailendra Nath; Poulain, Alexandre J; Blais, Jules M
The contamination of lakes by industrial emissions is an issue of international concern. Traditional paleolimnology examines sedimentary micro-fossils to infer the biological response to natural and anthropogenic stressors over time. Here, we calculate a theoretical biological effect for historic sediment sections using Probable Effect Concentration Quotient (PEC-Q) and arsenic specific quotient methods and develop novel time-constrained sediment toxicity test methods using a cultured Daphnia sp. combined with a whole cell microbial biosensor to assess the toxicity of past industrial contamination with modern testing methods. These methods were developed using sediments collected from Pocket Lake (Northwest Territories, Canada), a lake known to have exhibited a significant ecological shift following input from nearby gold smelter emissions during the mid 20th century. We then applied these methods to near-, mid-, and far-field sites to assess the response of Daphnia sp. to varying contaminant load. Daphnia sp. mortality exposed to dated sediments indicated a strong concordance with the timing of mining activities, and a strong concordance with PEC-Q and arsenic specific toxicity quotients. In contrast, a decrease in Daphnia mortality was observed during pre-, and post-mining periods when the contaminant burden was lower. Initial assessments of bioavailability using a microbial biosensor indicated that arsenic in porewater is 72-96% bioavailable, and limited evidence that oxidative stress may contribute to the Daphnia sp. toxic response. These results indicate that lake sediment archives can be used to infer missing biomonitoring data in sites of legacy anthropogenic influence, which will be useful for those seeking to conduct cost-effective and efficient preliminary environmental risk assessments.
Determining the effects of past gold mining using a sediment palaeotoxicity model
(2020) Cheney, Cynthia L; Eccles, Kristin M; Kimpe, Linda E; Thienpont, Joshua R; Korosi, Jennifer B; Blais, Jules M
Ore processing techniques used in Yellowknife's largest mining operation, Giant Mine, is responsible for the atmospheric release of approximately 20,000 t of particulate arsenic trioxide and other heavy metal(loids). This rapid deposition of heavy metal(loids) may have caused ecological disturbances to aquatic food webs. Here we use 210Pb and 137Cs dated lake sediment cores from 20 lakes within a 40 km radius of Yellowknife to examine the spatial-temporal distribution of arsenic, antimony and lead. Further, we model the toxicity of the sediment to aquatic biota pre-, during, and post-mining using palaeotoxicity modelling, enrichment factor assessment, and comparisons to national sediment quality guidelines. We found that metal(loid) profiles in sediment peaked during the height of mining operations. These peak metal(loid) concentrations were highest in lakes near the mine's roaster stack, and decreased with distance from the historic mine. Palaeotoxicity modelling of lake sediment archives indicate that there is no significant difference in the mean predicted toxicity of pre- and post-mining samples (p = 0.14), however mining activities in the region significantly increased the predicted toxicity of sediments to aquatic organisms during mining operations (p < 0.001). In the years since roasting processes ceased, the mean palaeotoxicity of all lakes has decreased significantly (p < 0.05), indicating a projected pattern of biological recovery. Importantly, some lakes remain at an elevated risk, indicating that aquatic ecosystems in Yellowknife may continue to have lingering effects on aquatic biota despite the closure of the mine two decades ago.
A bat guano deposit in Jamaica recorded agricultural changes and metal exposure over the last > 4,300 years
(2020) Gallant, Lauren; Grooms, Chris; Kimpe, Linda; Smol, John; Bogdanowicz, Wieslaw; Stewart, Stefan; Clare, Elizabeth; Fenton, Brock; Blais, Jules
Bats are excellent ecological indicators because they are long-lived, globally distributed, and show predictable responses to environmental stressors. Unaltered bat guano deposits, although rare, can serve as environmental archives to reveal changes in dietary patterns over millennial time scales. We inferred changes in agricultural and industrial practices using a continuous 4,300-year-old bat guano deposit from Jamaica. Cadmium, mercury, lead, and zinc increased during the Industrial Revolution, (which began in ca. 1760), a period characterized by elevated emissions of metals to the atmosphere. Beginning in the early 20th century, decreases in 206Pb/207Pb isotopes tracked the history of leaded gasoline use. Metal concentrations in the bat guano deposit exceeded those recorded in two nearby lake sediment cores from Jamaica. Carbon, nitrogen, and sulfur stable isotope profiles in bat guano tracked the agricultural history of Jamaica, specifically the introduction of nitrogen fertilizers, sugarcane, and possibly fungicides. Bat populations are under stress globally, and such intact guano deposits provide potentially critical information on long-term changes in their food source and exposure to metals.
Simulating diluted bitumen spills in boreal lake limnocorrals - Part 1: Experimental design and responses of hydrocarbons, metals, and water quality parameters
(2021) Rodriguez-Gil, Jose Luis; Stoyanovich, Sawyer; Hanson, Mark L; Hollebone, Bruce; Orihel, Diane M; Palace, Vince; Faragher, Robert; Mirnaghi, Fatemeh S; Shah, Keval; Yang, Zeyu; Black, Tyler A; Cederwall, Jeffrey; Mason, Johanna; Patterson, Samuel; Timlick, Lauren; Séguin, Jonathan Y; Blais, Jules M
Large-scale, in-lake enclosures (limnocorrals) were used to simulate spills of diluted bitumen (dilbit) in a boreal lake. In this study we use these simulated spills, which covered a range of sizes (oil:water ratio) representative of the upper 25% of onshore crude oil spills in North America (2008-2019), to assess the fate of dilbit-derived hydrocarbons and metals as well as the impacts of the spills on standard water quality parameters. The systems were monitored over 70 days following the application of dilbit amounts ranging between 1.5 and 179.8 L into 10-m diameter, ~100 m3 limnocorrals. The concentration of total petroleum hydrocarbons (TPH) in the water column increased rapidly over the first two weeks reaching a plateau that ranged between 200 μg/L and 2200 μg/L for the lowest and highest treatment respectively. The concentration of total polycyclic aromatic compounds (PACs) also increased over the first two weeks, prior to a slow decrease until day 70. The maximum measured concentrations in the highest treatment were 2858 ng/L for the sum of all 46 quantified PACs, 2716 ng/L for alkylated PACs and 154 ng/L for the 16 EPA priority PAHs. The concentrations of PACs in the sediment increased continuously over the study in the three highest treatments with maximum observed concentrations of 189 ng/g for ΣPAC46, 169 ng/g for ΣPACalk. No significant treatment-related changes in the 16 EPA priority PAHs were observed in the sediment. Of the 25 metals quantified in the water column, only manganese, molybdenum, and vanadium displayed a significant treatment effect with increases of 280, 76 and 25% respectively in the total fraction. These results can help us understand and predict the fate of oil-derived contaminants following a spill and characterize the exposure of freshwater organisms living within them. These results should help inform the risk assessment of future dilbit transportation projects.
Sterols and Stanols Preserved in Pond Sediments Track Seabird Biovectors in a High Arctic Environment
(2016) Cheng, Wenhan; Sun, Liguang; Kimpe, Linda E; Mallory, Mark L; Smol, John P; Gallant, Lauren R; Li, Jinping; Blais, Jules M
Seabirds are major vertebrates in the coastal ecosystems of the Canadian High Arctic, where they transport substantial amounts of marine-derived nutrients and pollutants from oceans to land by depositing guano and stomach oils to their nesting area, which often includes nearby freshwater ponds. Here we present novel indicators for evaluating the impact of seabirds on freshwater ecosystems. The ratio of cholesterol/(cholesterol + sitosterol) in pond sediments showed significant enrichment near a nesting colony of northern fulmars (Fulmarus glacialis) and was significantly correlated with ornithogenic enrichment of sediment as determined by sedimentary δ(15)N. The sterol ratio was also correlated with several bioaccumulative persistent organic pollutants (POPs), suggesting its usefulness in tracking biovector enrichment of contaminants. Human-derived epicoprostanol was also analyzed in the sediments, and its relationship with an abandoned, prehistoric camp was recorded, suggesting its potential as a tracer of prehistoric human activities in the Arctic. Sterols and stanols preserved in sediments appear to be useful geochemical tools that will inform our understanding of migratory species and the presence of prehistoric human populations in the Arctic, and possibly other animal populations.
Using stable water isotope composition (δ18O and δ2H) to track the interannual responses of Arctic and tropical Andean water bodies to rising air temperatures
(2022) Michelutti, Neal; Hargan, Kathryn; Kimpe, Linda; Smol, John; Blais, Jules
Lakes in the Arctic and tropical Andes are experiencing some of the largest temperature increases on the planet with coeval marked limnological changes, but little data exist on water balance parameters from these regions. Here, we present a unique data set of water stable isotope composition (δ18O and δ2H) from a suite of 49 waterbodies in the Canadian Arctic (Resolute Bay, Cornwallis Island, and Cape Herschel, Ellesmere Island) and the tropical Andes (Cajas National Park, Ecuador) spanning various years from 2009 to 2016. We show that an increase in air temperature over the study period resulted in evaporative enrichment of water isotopes in most Arctic sites highlighting the significance of evaporative losses to small Arctic ponds during the prolonged ice-free summers now experienced in this part of the world. Exceptions include some Arctic waterbodies that received abundant snowmelt and large, ice-covered lakes less prone to evaporation. Data from the Andean lakes indicated evaporative effects were minimal due to abundant precipitation. These data, in combination with limnological records and paleolimnological research from each region, provide a holistic view on how freshwater ecosystems are responding to recent warming in climatically sensitive Arctic and Andean environments.
An ~1,100-year record of human and seabird occupation in the High Arctic inferred from pond sediments
(2021) Cheng, Wenhan; Kimpe, Linda; Mallory, Mark; Smol, John; Blais, Jules
Seabirds in the Canadian Arctic congregate in large colonies producing oases of biological productivity and diversity in coastal regions. Here we examine sterols, stanols, and stable isotopes (15N, and 13C) in three 14C-dated pond sediment cores near a large seabird colony and archeological site on Devon Island, showing historical occupation by the seabirds and an ancient human (Thule or Norse) settlement over ~1,100 years. Coprostanol in the sediment records captures the presence of humans at ca. 1150 CE, followed by their abandonment of the site by ca. 1300 CE. Seabird presence at this site after ca.1200 CE is indicated by increases in δ15N and cholesterol/sitosterol. Seabird population expansion is observed after ca. 1600 CE in δ15N and cholesterol/sitosterol profiles, coinciding with European whaling activities that expanded in the 17th-19th centuries. Our study provides insights to human and seabird occupation in the High Arctic to inform archeological and conservation efforts.
Risk management in carbon capture and geological storage: insights from a structured expert elicitation
(2019) Larkin, Patricia; Gracie, Robert; Shafiei, Ali; Dusseault, Maurice; Sarkarfarshi, Mirhamed; Aspinall, Willy; Krewski, Daniel
With a focus on risk management (RM) in injection and storage for carbon capture and geological sequestration (CCS), an expert elicitation of scientific judgements quantified collective uncertainty ranges for a number of difficult environmental and human health risk challenges. Results suggest similarities and differences in opinions, an outcome that may be reflective of both the newness and the complexity of this technology. A suitable monitoring period was estimated at about a century; however, uncertainty was three orders of magnitude, with an upper (5th percentile) value of almost 1,000 years. For selected low probability high impact georisks, only site selection and monitoring were considered ‘very’ effective RM options. Monitoring, well integrity studies, emergency response plan, automatic emergency shut down system and training were considered ‘very’ or ‘extremely’ effective in managing two risks more directly related to human health. Experts responded with a wide uncertainty spread for a regulated threshold of minor, major and catastrophic leakage. A companion paper discusses elicitation findings for issues related to risk assessment.
Uncertainty in risk issues for carbon capture and geological storage: findings from a structured expert elicitation
(2019) Larkin, Patricia; Gracie, Robert; Shafiei, Ali; Dusseault, Maurice; Sarkarfarshi, Mirhamed; Aspinall, Willy; Krewski, Daniel
Carbon capture and geological storage (CCS) is identified within the portfolio of mitigation options for climate change. Each value chain activity of large scale integrated projects (capture, transport, injection and storage) includes uncertainties and hence potential risks with respect to both environmental and human health protection. With a focus on injection and storage, a structured elicitation of international experts provides quantified judgements and uncertainties and understanding of relative risk of CCS activities. In the 0–50 year, 51–499 year and >500 year time periods, the expert panel suggested an almost equal likelihood of storage leakage occurring, with a marked decrease from minor to major to catastrophic leakage (approximately >1 in 30; 1 in 103; 1 in 104, respectively); for the same time periods, the judgement of likelihood for major leakage that would result in measurable negative effects on human health or the environment was the same (approximately 1 in 103). Insights could stimulate further scientific deliberations about the reliable and effective deployment of this complex and interdisciplinary technological process. A companion paper discusses complementary findings for issues in CCS risk management.
Ensuring health and environmental protection in hydraulic fracturing: A focus on British Columbia and Alberta, Canada
(2018) Larkin, Patricia; Gracie, Robert; Dusseault, Maurice; Krewski, Daniel
Unconventional natural gas resources recovered using hydraulic fracturing (HF) is contributing to national energy self-sufficiency and could be a significant factor in the global transition to a low carbon economy. Using an integrated risk management framework, we conduct a comparative analysis of practices and review recommendations of a regulatory, economic, advisory, community-based, or technological nature for British Columbia and Alberta, Canada. Lessons learned from international assessments of risk issues are also considered. Overall, there is much less emphasis on potential impacts on human health than on the environment. The analysis also identifies a need for a strong and adequately resourced regulatory framework that works in concert with enhanced technological requirements; evidence-based emissions standards; regulated and/or community-based setbacks and buffer zones; operational surveillance, reporting, and disclosure of value-chain activities in an accessible and transparent way; community participation in the development of these mechanisms; and provision for legacy sites. Economic options such as performance-based taxes and fees, industry-funded studies, the role of carbon taxes, and cost allocations to protect or improve determinants of health are the least advanced option. This analysis provides support for the development of a risk management policy agenda with respect to broad and persistent HF risk management issues.

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