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

Abstract

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).

Keywords: Air quality; Atmosphere; Deposition; Emissions; Oil sands.

Figure 1

Map of the oil sands region showing (as of 2019) continuous air‐monitoring stations (AMS), deposition monitoring sites (only sites using ion exchange resin [IER] collectors are shown), and the boundaries of each oil sands region (Athabasca, Cold Lake, and Peace River). Airshed organizations that operate these monitoring stations are shaded in different colors to show their respective boundaries

Figure 2

Conceptual model showing sources, air pollutants, pathways, and impacts, published between 2009 and 2019. The bracketed numbers in each box correspond to the paper count for each topic. Note that papers considering multiple topics are counted once under each relevant category. This conceptual model was adapted from models developed in the OSMP Integration Workshops (Swanson, , 2019b)

Figure 3

Gridded emission inventories at a 2.5 × 2.5 km resolution in Northern Alberta for (A) SO₂, (B) NOx, (C) NH₃, and (D) PM₁₀ in tonnes/year. Emission data are adapted from Zhang et al. (2018)

Figure 4

Percent contribution of source factors to (A) PM_2.5 mass and (B) PM_10–2.5 mass, identified by positive matrix factorization (PMF). Citations for each study appear on the x‐axis, along with notes that explain the differences between multiple results reported in a single study

Figure 5

Percent contribution of source factors to (A) ∑PACs or ∑PAHs loading and (B) ∑TEs loading identified by positive matrix factorization (PMF) or the chemical mass balance (CMB) model. Citations for each study appear on the x‐axis, along with notes that explain the differences between multiple results reported in a single study

Figure 6

Model‐measurement fusion deposition for (A) total S in kg m⁻² year⁻¹, (B) total N in kg m⁻² year⁻¹, (C) total base cations in eq ha⁻¹ year⁻¹, and (D) ratio of total base cation to anion (unitless)