Lichens are all around us in the Athabasca Oil Sands Region. A natural partnership between algae and fungi, these tiny organisms inhabit the nooks and crannies of the natural world. You may find a spongy grey carpet of them covering the forest floor, on exposed rock faces encrusted in bright orange swirls, or swaying in the breeze from jack pine twigs.
Lichens have a remarkable ability to accumulate airborne pollutants. This makes them ideal bio-monitors for tracking air emissions. Lichens are the original air pollution sentinels, out on nature’s landscapes!
At the Wood Buffalo Environmental Association (WBEA), we use lichens to track and measure the fate of airborne pollutants as they are dispersed from natural and industrial sources over the Athabasca Oil Sands Region. What’s more, chemical fingerprinting techniques can actually pinpoint the source of air pollutants found in the lichens.
WBEA Executive Director, Dr. Kevin Percy, says of the work, “In essence, WBEA can trace an air pollutant found in a lichen hanging on a jack pine tree north of Fort McMurray back to the source activity which generated that pollutant. In this way, WBEA is fine-tuning the understanding of how pollutants travel away from sources and are deposited onto the landscape in our region.”
WBEA has conducted two major lichen collecting campaigns with associated analyses. In 2011, we sampled for sulphur, nitrogen, and trace elements, and in 2014, we looked for polycyclic aromatic hydrocarbons (PAHs).
In the 2011 study, WBEA analyzed lichens collected from 359 sites throughout our 68,000-km2 northeastern Alberta air shed. The lichen sampling sites were up to 160 km away from oil sands industrial operations, and stretched all the way into Saskatchewan.
WBEA mapped concentrations of 41 trace elements, along with sulphur and nitrogen, and determined their emission origins. In 2012, our analyses were published in the peer-reviewed book, Alberta Oil Sands: Energy, Industry and the Environment.
We associated chemical fingerprints from natural and industrial (obtained with WBEA industry-member cooperation) emission sources with concentrations of the same fingerprint measured in the lichens. Six source types were found to contribute air pollutants to the lichens in the following proportions:
- 15% – Oil sands mine ore and processed sources, such as bitumen and petroleum coke.
- 23% – Combustion sources, including industrial stacks and mine fleets.
- 19% – Tailings sand dust from tailings pond banks at oil sands mining operations.
- 15% – Mine haul road and limestone quarry dust from industrial oil sands operations.
- 15% – Urban and general man-made contributions from Fort McMurray and other regional human activity.
- 7% – Lichen site-related influences, such as elevation and lichen physiology.
- Only 6% of the variability in regional lichen elemental concentrations could not be explained by the receptor model results.
In 2014, WBEA built on the success of the earlier lichen study, using the same techniques to examine another important group of air pollutants, polycyclic aromatic hydrocarbons (PAHs). Lichenologist, Dr. Keith Puckett, ECOFIN, and WBEA Field Biologists, Natalie Bonnell and Evan Magill, collected lichens at 121 regional sites, as detailed on the following map.
The collection sites were accessible only by helicopter, requiring many hours of flight over the remote reaches of the Wood Buffalo Region.
A team of scientists worked with WBEA to analyze the lichens for PAHs. The team was led by (pictured left to right), Dr. Joe Graney, Binghamton University, NY, USA, the late Dr. Sagar Krupa, University of Minnesota, MN, USA, and Dr. Matt Landis, Integrated Atmospheric Solutions, Research Triangle Park, NC, USA.
WBEA shipped the samples to clean scientific labs in North Carolina, New York, and Michigan for intricate and extensive analysis, including the use of two-dimensional time-of-flight mass spectrometry.
What do the results tell us?
- We compared the Athabasca Oil Sands Region’s ambient and lichen PAH concentrations to similar international studies. Our findings suggested that airborne PAHs across the Athabasca Oil Sands Region occur at levels similar to, or lower than, global PAH levels in both urban and rural environments.
- Mining operations and fugitive dust (pictured, below left) contribute the highest PAH and inorganic element concentration levels in lichens.
- The impacts of fugitive dust are limited to distances of about 25 km away from active oil sands mining operations.
Lichen monitoring is a key tool in tracking the fate of pollutants as they travel from sources out onto the Athabasca Oil Sands Region’s landscapes. WBEA’s data will be used to support Environmental Impact Assessments (EIA) that inform regional stakeholders and decision-makers about the connections between air emissions and their environmental effects.