Reanalysis of aerial deposition of metals and polycyclic aromatic compounds to snow in the Athabasca Oil Sands Region of Alberta Canada

Sources, spatial-distributions and fluxes of PAH-contaminated dusts in the Athabasca oil sands region

Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) has increased in northern Alberta, Canada, due to industrial development in the Athabasca oil sands region (AOSR). However, the sources, summertime deposition fluxes and associated spatial patterns are poorly characterized, and the magnitude of contamination has not been directly contrasted with comparable measurements around large Canadian cities. PAHs were measured in Sphagnum moss collected from 30 bogs in the AOSR and compared with reference moss collected from various remote, rural and near-urban sites in Alberta and Ontario. At all 39 locations, strong correlations between depositional fluxes of PAHs and accumulation rates of ash (n = 117, r = 0.877, p < 0.001) implied that the main source of PAHs to moss was atmospheric deposition of particles. Average PAH concentrations at near-field AOSR sites (mean [SD], 62.4 [24.3] ng/g) were significantly higher than at far-field AOSR sites (44.9 [20.8] ng/g; p = 0.038) or the 7 reference sites in Alberta (20.6 [3.5] ng/g; p < 0.001). In fact, average PAH concentrations across the entire AOSR (7,850 km2) were approximately twice as high as in London, Ontario, or near petroleum upgrading and major traffic corridors in Edmonton, Alberta. A chemical mass balance model estimated that both delayed petcoke (33 % of PAHs) and fine tailings (38 % of PAHs) were the major sources of PAHs in the AOSR. Over the 2015 summer growing season, we estimate that 101-110 kg of PAHs (on 14,300-17,300 tonnes of PAH-containing dusts) were deposited to the AOSR within a 50 km radius of surface mining. Given that the highest PAH deposition was to the northern quadrant of the AOSR, which includes the First Nations community of Fort MacKay, further dust control measures should be considered to protect human and environmental health in the region.

Atmospheric deposition mapping of particulate elements in the Canadian Athabasca oil sands region

This study used a deposition modeling framework to generate gridded dry, wet, and total (dry + wet) deposition fluxes of 27 particulate elements over the Canadian Athabasca oil sands region and its surrounding areas for the years 2016-2017. The framework employed the element concentrations from the CALPUFF dispersion model outputs that were bias-corrected against measured concentrations, modeled dry deposition velocities, precipitation analysis data, and literature values of element-specific fine mode fractions and scavenging ratios by rain and snow. The annual total deposition (mg/m²/year) of all elements (EM) across the domain ranged from 4.49 to 5450 and the mean and median deposition were 60.9 and 31.0, respectively. Total EM deposition decreased rapidly within a short distance from the oil sands mining area. Annual mean total deposition (mg/m²/year) of EM was 717 in Zone 1 (within 30 km from a reference point, representing the center of the oil sands mining area), 115 in Zone 2 (30-100 km from the reference point), and 35.4 in Zone 3 (beyond 100 km from the reference point). The deposition of individual elements was primarily governed by their respective concentrations and among all elements the annual mean total deposition (μg/m²/year) over the domain varied five orders of magnitude ranging from 0.758 (Ag) to 20,000 (Si). Annual mean dry and wet deposition (mg/m²/year) of EM over the domain were 15.7 and 45.2, respectively. Aside from S, which has relatively lower precipitation scavenging efficiencies, wet deposition was the dominant deposition type in the region contributing from 51% (Pb) to 86% (Ca) of the respective total deposition. Total EM deposition over the domain in the warm season (66.2 mg/m²/year) was slightly higher than that in the cold season (55.6 mg/m²/year). Deposition of individual elements in Zone 1 were generally lower than their deposition at other sites across North America.

Incorporating Industrial and Climatic Covariates into Analyses of Fish Health Indicators Measured in a Stream in Canada’s Oil Sands Region

Industrial and other human activities in Canada’s oil sands region (OSR) influence the environment. However, these impacts can be challenging to separate from natural stresses in flowing waters by comparing upstream reference sites to downstream exposure locations. For example, health indicators of lake chub (Couesius plumbeus) compared between locations in the Ells River (Upper and Lower) in 2013 to 2015 and 2018 demonstrated statistical differences. To further examine the potential sources of variation in fish, we also analyzed data at sites over time. When fish captured in 2018 were compared to pooled reference years (2013–2015), results indicated multiple differences in fish, but most of the differences disappeared when environmental covariates were included in the Elastic Net (EN) regularized regression models. However, when industrial covariates were included separately in the EN, the large differences in 2018 also disappeared, also suggesting the potential influence of these covariables on the health of fish. Further ENs incorporating both environmental and industrial covariates along with other variables which may describe industrial and natural influences, such as spring or summer precipitation and summer wind speeds and distance-based penalty factors, also support some of the suspected and potential mechanisms of impact. Further exploratory analyses simulating changes from zero and the mean (industrial) activity levels using the regression equations respectively suggest effects exceeding established critical effect sizes (CES) for fish measurements may already be present or effects may occur with small future changes in some industrial activities. Additional simulations also suggest that changing regional hydrological and thermal regimes in the future may also cause changes in fish measurements exceeding the CESs. The results of this study suggest the wide applicability of the approach for monitoring the health of fish in the OSR and beyond. The results also suggest follow-up work required to further evaluate the veracity of the suggested relationships identified in this analysis.

A re-analysis and review of elemental and polycyclic aromatic compound deposition in snow and lake sediments from Canada's Oil Sands Region integrating industrial performance and climatic variables

Much of the research from Canada's oil sands region (OSR) shows contaminants of concern (CoCs) throughout the ambient environment surrounding the industrial facilities. While there are some well-established sources of the CoCs, there is also spatial and temporal variability suggesting activity intensity, changes in technology, types and amounts of fuels combusted at the facilities, and climate may affect the results of deposition studies. This study re-analysed published data on the deposition of elements and polycyclic aromatic compounds (PACs) in snow and the sediments of some lakes by incorporating production data from facilities and climate. Using the Elastic Net (EN) regularized regression, variables describing potential associations between facility-specific activity and climate on the deposition of CoCs were identified. Among the selected variables, the combustion of delayed petroleum coke at the Suncor Basemine was associated with the deposition of CoCs, including elements in snow and in some lakes. Similarly, combustion of petroleum coke at Syncrude Mildred Lake was also identified in some models. In both cases, the effects of petroluem coke combustion are likely associated with the emission and deposition of fly ash. The mass of stored petroleum coke was not selected in snow CoC models, but the speed of the wind was a common driver for PACs. However, the mass of stockpiled petcoke was more closely associated with both elements and PACs in lake sediments. While the potential influence of other variables on the occurrence of CoCs in the OSR was also identified, including the production of crude bitumen and synthetic crude, the use of process and natural gases, temperature, and precipitation, these analyses support much of the earlier work and provides additional nuance. While more work is required, these results suggest facility-specific production and climatic data can be coupled with existing approaches to improve the identification of sources of CoCs in Canada's OSR and practices associated with their release.

A critical review of the ecological status of lakes and rivers from Canada's oil sands region

We synthesize the information available from the peer-reviewed literature on the ecological status of lakes and rivers in the oil sands region (OSR) of Canada. The majority of the research from the OSR has been performed in or near the minable region and examines the concentrations, flux, or enrichment of contaminants of concern (CoCs). Proximity to oil sands facilities and the beginning of commercial activities tend to be associated with greater estimates of CoCs across studies. Research suggests the higher measurements of CoCs are typically associated with wind-blown dust, but other sources also contribute. Exploratory analyses further suggest relationships with facility production and fuel use data. Exceedances of environmental quality guidelines for CoCs are also reported in lake sediments, but there are no indications of toxicity including those within the areas of the greatest atmospheric deposition. Instead, primary production has increased in most lakes over time. Spatial differences are observed in streams, but causal relationships with industrial activity are often confounded by substantial natural influences. Despite this, there may be signals associated with site preparation for new mines, potential persistent differences, and a potential effect of petroleum coke used as fuel on some indices of health in fish captured in the Steepbank River. There is also evidence of improvements in the ecological condition of some rivers. Despite the volume of material available, much of the work remains temporally, spatially, or technically isolated. Overcoming the isolation of studies would enhance the utility of information available for the region, but additional recommendations for improving monitoring can be made, such as a shift to site-specific analyses in streams and further use of industry-reported data. Integr Environ Assess Manag 2022;18:361-387. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

A decadal synthesis of atmospheric emissions, ambient air quality, and deposition in the oil sands region

This review is part of a series synthesizing peer-reviewed literature from the past decade on environmental monitoring in the oil sands region (OSR) of northeastern Alberta. It focuses on atmospheric emissions, air quality, and deposition in and downwind of the OSR. Most published monitoring and research activities were concentrated in the surface-mineable region in the Athabasca OSR. Substantial progress has been made in understanding oil sands (OS)-related emission sources using multiple approaches: airborne measurements, satellite measurements, source emission testing, deterministic modeling, and source apportionment modeling. These approaches generally yield consistent results, indicating OS-related sources are regional contributors to nearly all air pollutants. Most pollutants exhibit enhanced air concentrations within ~20 km of surface-mining activities, with some enhanced >100 km downwind. Some pollutants (e.g., sulfur dioxide, nitrogen oxides) undergo transformations as they are transported through the atmosphere. Deposition rates of OS-related substances primarily emitted as fugitive dust are enhanced within ~30 km of surface-mining activities, whereas gaseous and fine particulate emissions have a more diffuse deposition enhancement pattern extending hundreds of kilometers downwind. In general, air quality guidelines are not exceeded, although these single-pollutant thresholds are not comprehensive indicators of air quality. Odor events have occurred in communities near OS industrial activities, although it can be difficult to attribute events to specific pollutants or sources. Nitrogen, sulfur, polycyclic aromatic compounds (PACs), and base cations from OS sources occur in the environment, but explicit and deleterious responses of organisms to these pollutants are not as apparent across all study environments; details of biological monitoring are discussed further in other papers in this special series. However, modeling of critical load exceedances suggests that, at continued emission levels, ecological change may occur in future. Knowledge gaps and recommendations for future work to address these gaps are also presented. Integr Environ Assess Manag 2022;18:333-360. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Exploring the Influence of Industrial and Climatic Variables on Communities of Benthic Macroinvertebrates Collected in Streams and Lakes in Canada’s Oil Sands Region

Identifying and tracking the influence of industrial activities on streams and lakes is a priority for monitoring in Canada’s oil sands region (OSR). While differences in indicators are often found in waterbodies adjacent to mining facilities, the confounding influence of natural exposures to bitumen and other stressors can affect the identification of industrial effects. However, recent work suggests metrics of industrial activity at individual facilities, including production and fuel consumption, may be used in site-specific analyses to identify influence of the industry as a whole as well as individual operations. This study further examined the potential relationships between industrial and climatic variables on benthic communities from 13 streams and 4 lakes using publicly available data from the minable region and the Elastic Net (EN) variable selection technique. From the full set of possible industrial and climate variables, the EN commonly identified the negative influence of plant and fuel use of petroleum coke at the Suncor Basemine on benthic communities in streams and lakes. The fuel/plant use of petroleum coke at Suncor likely reflects the emission and regional deposition of delayed coke fly ash. Among the other industrial variables, crude bitumen production at Syncrude Mildred Lake and other facilities, steam injection rates, and petroleum coke stockpiling were also selected for some benthic invertebrate indices at some sites. Land disturbance metrics were also occasionally selected, but the analyses largely support the predominant influence of industrial facilities via (inferred) atmospheric pathways. While climate variables were also commonly selected by EN and follow-up work is needed, this study suggests that integrating industrial performance data into analyses of biota using a site-specific approach may have broad applicability in environmental monitoring in the OSR. More specifically, the approach used here may both resolve the long-standing challenge of natural confounding influences on monitoring the status of streams in the OSR and track the influence of industrial activities in biota below critical effect sizes.

Isotopic Analyses Fingerprint Sources of Polycyclic Aromatic Compound-Bearing Dust in Athabasca Oil Sands Region Snowpack

Fugitive dust associated with surface mining activities is one of the principal vectors for transport of airborne contaminants in Canada's Athabasca oil sands region (AOSR). Effective environmental management requires quantitative identification of the sources of this dust. Using natural abundance radiocarbon (Δ¹⁴C) and dual (δ¹³C, δ²H) compound-specific isotope analysis (CSIA), this study investigated the sources of dust and particulate-bound polycyclic aromatic compounds (PACs) deposited in AOSR lake snowpack. Lower Δ¹⁴C values, higher particulate and PAC loadings, and lower δ¹³C values for phenanthrene and C1-alkylated phenanthrenes/anthracenes (C1-Phen) at sites closer to the mining operations indicated unprocessed oil sand and/or petroleum coke (petcoke-a byproduct of bitumen upgrading) as major sources of anthropogenic fugitive dust. However, a Bayesian isotopic mixing model that incorporated both δ¹³C and δ²H could discriminate petcoke from oil sand, and determined that petcoke comprised between 44 and 95% (95% credibility intervals) of a C1-Phen isomer at lakes <25 km from the heart of the mining operations, making it by far the most abundant source. This study is the first to demonstrate the potential of CSIA to provide accurate PAC source apportionment in snowpack and reveals that petcoke rather than oil sand is the main source of mining-related particulate PACs deposited directly to AOSR lakes.

Polycyclic aromatic compounds (PACs) in the Canadian environment: Ambient air and deposition

Polycyclic aromatic compounds (PACs) in Canadian air and deposition were examined at the national scale for the first time in over twenty-five years. Air concentrations spanned four orders of magnitude, and were highest near industrial emitters and lowest in the Arctic. Declines in unsubstituted PAHs were observed at locations close to industrial facilities that had reduced emissions, but trends elsewhere were modest or negligible. Retene concentrations are increasing at several locations. Ambient concentrations of benzo[a]pyrene exceeded Ontario's health-based guideline in many urban/industrial areas. The estimated toxicity of the ambient PAC mixture increased by up to a factor of six when including compounds beyond the US EPA PAHs. Knowledge of PAC deposition is limited to the Laurentian Great Lakes and Athabasca Oil Sands regions. The atmosphere remained a net source of PAHs to the Great Lakes, though atmospheric inputs were decreasing with halving times of 26-30 years. Chemical transport modelling substantially overestimated wet deposition, but model performance is unknown for dry deposition. Sources from Asia, Europe and North America contributed to Arctic and Sub-Arctic concentrations, whereas transboundary or long-range transport have not been assessed outside Canada's north. Climate-related impacts from re-emission and forest fires were implicated in maintaining air concentrations in the high Arctic that were not consistent with global emissions reductions. Industrial emission decreases were substantial at the national scale, but their influence on the environment was limited to areas near relevant facilities. When examined through the lens of ambient levels at the local scale, evidence suggested that contributions from residential wood combustion and motor vehicles were smaller and larger, respectively, than those reported in national inventories. Future work aimed at characterizing PACs beyond the EPA PAHs, improving measurement coverage, elucidating deposition phenomena, and refining estimates of source contributions would assist in reducing remaining knowledge gaps about PACs in Canada.

Polycyclic aromatic compounds (PACs) in the Canadian environment: Sources and emissions

Twenty-five years after the first look at polycyclic aromatic compounds (PACs) in Canada, this article presents current knowledge on Canadian PAC emission sources. The analysis is based on national inventories (the National Pollutant Release Inventory (NPRI) and the Air Pollutant Emissions Inventory (APEI)), an analysis of Canadian forest fires, and several air quality model-ready emissions inventories. Nationally, forest fires continue to dominate PAC emissions in Canada, however there is uncertainty in these estimates. Though forest fire data show a steady average in the total annual area burned historically, an upward trend has developed recently. Non-industrial sources (home firewood burning, mobile sources) are estimated to be the second largest contributor (∼6-8 times lower than forest fires) and show moderate decreases (25%-65%) in the last decades. Industrial point sources (aluminum production, iron/steel manufacturing) are yet a smaller contributor and have seen considerable reductions (90% +) in recent decades. Fugitive emissions from other industrial sources (e.g. disposals by the non-conventional oil extraction and wastewater sectors, respectively) remain a gap in our understanding of total PAC emissions in Canada. Emerging concerns about previously unrecognized sources such as coal tar-sealed pavement run-off, climate change are discussed elsewhere in this special issue. Results affirm that observations at the annual/national scale are not always reflective of regional/local or finer temporal scales. When determining which sources contribute most to human and ecosystem exposure in various contexts, examination at regional and local scales is needed. There is uncertainty overall in emissions data stemming in part from various accuracy issues, limitations in the scope of the various inventories, and inventory gaps, among others.

Long-term spatial and temporal trends, and source apportionment of polycyclic aromatic compounds in the Athabasca Oil Sands Region

We investigated the spatio-temporal trends of polycyclic aromatic compounds (PACs) deposition in the Athabasca Oil Sands Region (AOSR) between 2008 and 2017, and applied source apportionment tools to assess sources using snowpacks. Estimated PAC mass deposition was significantly correlated with crude oil production (R² = 0.48, p = 0.03), and increased between 2008 and 2017. Loadings of alkylated PACs c1-, c2-fluorenes/pyrenes and c1-, c3-benzo[a]anthracenes/chrysenes/triphenylenes significantly increased at mid-field sites (25-50 km from central industrial reference site, AR6) (Mann-Kendall, p < 0.05) reflecting physical expansion of the AOSR. The distance from emission sources was important in the deposition of PACs, including the distance from AR6 (R² = 0.69-0.91), nearest petcoke storage (R² = 0.77-0.88), 0.89) and upgrader stack (R² = 0.56-0.61). Source apportionment PAC distribution profiles of the source materials (petcokes, oil sand ores, road dust) did not show unique matching profiles with the snowpacks. However, the minimal presence of retene in petcokes and an abundance of benzo[ghi]fluoranthene in road dust was observed, and suggests potential for these compounds as chemical markers in distinguishing sources. Furthermore, correlations between PACs and selected metal(loid)s in the AOSR snowpacks were assessed to infer potential common sources. Significant positive (p < 0.05) correlations between metal(loid)s enriched in bitumen (vanadium, molybdenum, nickel) and PACs, at near to mid-field (0-50 km from AR6) sites suggests common sources or similar transfer and fate processes. The results of our study convey data necessary for monitoring studies in the constantly developing AOSR, advance our knowledge of PACs profiles in source materials (including the much less studied alkylated PACs and dibenzothiophenes), which will be valuable for other studies related to oil pollution, urban run-off and forest fires. PACs mass deposition increasing between 2008 and 2017 coincident with crude oil production, and retene and benzo[ghi]fluoranthene show potential in distinguishing AOSR sources.

PM2.5-Bound Polycyclic Aromatic Hydrocarbons: Sources and Health Risk during Non-Heating and Heating Periods (Tangshan, China)

Exposure to polycyclic aromatic hydrocarbons (PAHs) may lead to adverse health risks. To understand the potential sources and carcinogenic risks of PAHs in Tangshan, 40 PM_2.5 samples were collected for analysis of eighteen PM_2.5-bound PAHs during non-heating period and heating period. The results display a significant variation. The median concentration of ∑₁₈PAHs during the heating period (282 ng/m³) was higher than during the non-heating period (185 ng/m³). Especially, the median concentration of Benzopyrene (BaP) during the heating period (61.6 ng/m³) was 16.9-fold that during the non-heating period (3.64 ng/m³). It exceeded BaP annual average limit of China (1 ng/m³). Diagnostic ratios (DRs) and principal component analysis (PCA) both indicated that vehicle emissions and coal and biomass combustion were the dominant contributors of PAHs pollution in Tangshan. The incremental lifetime cancer risk (ILCR) of three age groups (children, teenagers, and adults) ranged from 2.56 × 10⁻⁶ to 5.26 × 10⁻⁵ during the entire sampling periods. The 95% risk values of adults exceeded 10⁻⁴ during the heating periods, indicating a potential health risk from PAHs.

Forest health effects due to atmospheric deposition: Findings from long-term forest health monitoring in the Athabasca Oil Sands Region

Oil sands developments release acidifying compounds (SO₂ and NO₂) with the potential for acidifying deposition and impacts to forest health. This article integrates the findings presented in the Oil Sands Forest Health Special Issue, which reports on the results of 20 years of forest health monitoring, and addresses the key questions asked by WBEA's Forest Health Monitoring (FHM) Program: 1) is there evidence of deposition affecting the environment?, 2) have there been changes in deposition or effects over time?, 3) do acid deposition levels require management intervention?, 4) what are major sources of deposited substances? and 5) how can the program be improved? Deposition of sulphur, nitrogen, base cations (BC), polycyclic aromatic compounds and trace elements decline exponentially with distance from sources. There is little evidence for acidification effects on forest soils or on understory plant communities or tree growth, but there is evidence of nitrogen accumulation in jack pine needles and fertilization effects on understory plant communities. Sulphur, BC and trace metal concentrations in lichens increased between 2008 and 2014. Source apportionment studies suggest fugitive dust in proximity to mining is a primary source of BC, trace element and organic compound deposition, and BC deposition may be neutralizing acidifying deposition. Sulphur accumulation in soils and nitrogen effects on vegetation may indicate early stages of acidification. Deposition estimates for sites close to emissions sources exceed proposed regulatory trigger levels, suggesting a detailed assessment of acidification risk close to the emission sources is warranted. However, there is no evidence of widespread acidification as suggested by recent modeling studies, likely due to high BC deposition. FHM Program evolution should include continued integration with modeling approaches, ongoing collection and assessment of monitoring data and testing for change over time, and addition of monitoring sites to fill gaps in regional coverage.