The invisible fingerprint of industry in the Athabasca region and its environmental implications
In the vast boreal forests of northeastern Alberta, Canada, lies one of the world's largest industrial developments—the Athabasca oil sands. This region, larger than some European countries, contains an estimated 178 billion barrels of natural bitumen, representing one of the planet's most significant petroleum reserves3 . While the economic benefits have been substantial, scientists have uncovered a more concerning story unfolding in the very air that surrounds these massive operations—a story of invisible chemicals known as polycyclic aromatic compounds (PACs) that may pose risks to both ecosystem and human health.
PACs represent a broad class of widespread environmental contaminants that include polycyclic aromatic hydrocarbons (PAHs) and their derivatives6 . These complex chemicals emerge not only from natural sources like forest fires but also from industrial processes involving fossil fuels.
What makes PACs particularly concerning is their persistence in the environment and their documented potential to cause harm—some are known carcinogens, while others can damage immune and reproductive systems6 . In the Athabasca Oil Sands Region (AOSR), the combination of massive-scale bitumen mining, extraction, and upgrading processes has created a perfect environment for PAC release into the atmosphere, making this region a living laboratory for understanding how industrial activity can alter our air quality.
Polycyclic aromatic compounds exist all around us, but rarely do we encounter them in the concentrations found in petroleum-rich regions undergoing intensive development. These chemicals are composed of multiple interconnected aromatic rings and can be divided into several categories:
The basic structures consisting solely of carbon and hydrogen atoms
PAHs with additional alkyl groups attached
Structures containing nitrogen, oxygen, or sulfur within the ring framework6
While much regulatory attention has historically focused on only 16 "priority pollutant" PAHs identified by the U.S. Environmental Protection Agency, emerging research suggests this approach is insufficient. Many alk-PAHs are actually more toxic and mutagenic than their parent compounds, yet ambient concentration guidelines for these derivatives have yet to be established3 .
The health concerns associated with PAC exposure are particularly worrying. The National Toxicology Program notes that some PACs are known carcinogens, and animal experiments have shown that certain compounds in this class can cause damage to the immune and reproductive systems6 . The reality, however, is that people are rarely exposed to single PACs—instead, they encounter complex mixtures whose combined effects are poorly understood, creating a significant knowledge gap that scientists are working to address.
Between 2011-2015, scientists conducted a comprehensive air monitoring study in the Athabasca region to better understand the scope and distribution of PAC contamination3 . This research marked a significant advancement in environmental monitoring by expanding beyond the conventional 16 PAHs to measure an unprecedented 110 different PACs in the atmosphere.
Air samples were collected at three sites within the minable area of the AOSR, strategically chosen at varying distances from major industrial facilities, plus one urban comparison site in Edmonton.
Researchers gathered air samples over 24-hour periods using high-volume active samplers, following the National Air Pollution Surveillance program protocol.
The team employed sophisticated analytical techniques to identify and quantify both gaseous and particulate-phase PACs, including 24 unsubstituted PAHs, 86 alk-PAHs, and dibenzothiophenes (DBTs).
This expansive approach allowed scientists to create a detailed picture of not just how much PAC pollution existed, but how it varied across space and time, and which specific compounds were most prevalent.
| Site Code | Location | Proximity to Industry | Primary Monitoring Purpose |
|---|---|---|---|
| AMS 11 | Near main operations | Closest | Assess maximum industrial impact |
| AMS 13 | Within minable area | Intermediate | Measure intermediate exposure |
| AMS 14 | Within minable area | Farthest | Establish baseline concentrations |
| Edmonton | Urban center | Distant (comparison) | Compare with urban pollution sources |
The findings from this extensive monitoring effort revealed a clear pattern: PAC concentrations increased steadily with decreasing distance to the main oil sands operations. The highest concentrations were measured at site AMS 11, located closest to the primary industrial facilities, while the lowest levels were found at AMS 13, the most distant of the three AOSR sites3 .
Unsubstituted PAHs at AMS 11
Alkylated PAHs at AMS 11
All Dibenzothiophenes at AMS 11
Perhaps the most significant discovery was the overwhelming predominance of alkylated PACs over parent PAHs in the region's air. At the most impacted site (AMS 11), the median concentration of alk-PAHs was 97 ng/m³, compared to just 8.8 ng/m³ for unsubstituted PAHs. Similarly, dibenzothiophenes (including both non-alkylated and alkylated forms) showed median concentrations of 12 ng/m³3 . This pattern is particularly concerning given that many of these alk-PAHs are known to be more toxic than their parent compounds.
| PAC Category | AMS 11 (Highest Impact) | AMS 13 (Lowest Impact) | Edmonton (Urban Comparison) |
|---|---|---|---|
| Unsubstituted PAHs | 8.8 | 1.4 | Not reported |
| Alkylated PAHs | 97.0 | 5.0 | Not reported |
| All Dibenzothiophenes | 12.0 | 0.4 | Not reported |
The research also uncovered distinct seasonal variations, with winter months showing significantly higher PAC concentrations—a pattern attributed to increased emissions from industrial heating processes and more stable atmospheric conditions that limit pollutant dispersion during colder periods3 .
An unexpected aspect of the study emerged when researchers had the opportunity to measure PAC emissions during the massive Richardson Backcountry wildfire in May-June 2011, which burned approximately 5,800 km² of boreal forest near the oil sands operations3 . This natural disaster provided a unique opportunity to distinguish between industrial and pyrogenic (fire-related) PAC sources.
While wildfires certainly contribute PACs to the atmosphere, they have a different chemical signature than industrial emissions.
The abundance of alk-PAHs relative to parent PAHs served as a chemical fingerprint pointing specifically to petrogenic sources.
The findings revealed that while wildfires certainly contribute PACs to the atmosphere, the chemical signature of industrial emissions was distinct and dominant near oil sands facilities. The abundance of alk-PAHs relative to parent PAHs served as a chemical fingerprint pointing specifically to petrogenic (petroleum-derived) sources rather than combustion processes3 . This distinction is crucial for regulatory agencies working to identify pollution sources and implement targeted control measures.
Studying PACs in the environment requires specialized approaches and materials. Here are some of the key tools and methods scientists employ in this critical research:
| Tool/Method | Function | Application in PAC Research |
|---|---|---|
| High-Volume Active Samplers | Collect gaseous and particulate air samples over extended periods | 24-hour integrated sampling of PACs in ambient air |
| Gas Chromatography-Mass Spectrometry | Separate and identify individual chemical compounds | Detection and quantification of specific PACs in complex environmental samples |
| Molecular Sieves | Remove water from solvents and samples | Maintaining dry conditions to prevent PAC degradation during analysis |
| Schlenk Line Techniques | Handle air-sensitive compounds without contamination | Processing samples under inert atmosphere to preserve chemical integrity |
| Diagnostic Ratio Analysis | Identify pollution sources based on chemical patterns | Distinguishing between petrogenic, pyrogenic, and biogenic PAC sources |
The persistent presence of PACs in the Athabasca region's atmosphere carries significant implications for both environmental and human health. Studies have documented these chemicals in various components of the ecosystem, including rivers and streams where elevated methylmercury has been found—a compound toxic to nervous systems1 . Wildlife studies have detected PACs in terrestrial animals, with evidence of ecosystem-wide contamination3 .
PACs have been detected throughout the ecosystem, from waterways to terrestrial animals, indicating widespread contamination.
Researchers have documented pollutants including benzo(a)pyrene, a potent mutagen and carcinogen linked to birth defects, organ damage, and genetic damage, in the Athabasca River watershed1 .
Perhaps most concerning is the potential for human health impacts. The proximity of Indigenous communities and workers to these industrial operations raises urgent questions about chronic exposure risks.
Recognizing these concerns, Canada implemented an expanded air monitoring network for PACs in the AOSR through the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring signed in 20123 . This program represents a significant step toward better understanding the scope and impact of industrial emissions.
As production in the oil sands continues—reaching 3.05 million barrels per day in 2018—the need for comprehensive monitoring and effective mitigation strategies becomes increasingly urgent3 . While the Canadian government has implemented requirements for companies to refill old pit mines and plant trees, the fundamental challenges of PAC emissions and their persistence in the environment remain.
The silent story of PACs in the oil sands region serves as a powerful reminder that our industrial activities leave invisible fingerprints on the environment—fingerprints that science must work to decipher before their full impact is written into the health of ecosystems and human populations.
As research continues to evolve, each new discovery adds another piece to this complex puzzle, bringing us closer to understanding the true cost of our energy choices and guiding us toward more sustainable solutions for the future.