Oil Sands Alchemy: NOx Emissions and Limestone Dust Drive Boreal Forest Carbon Sequestration.

Quad bear cubs and sow living at major oil sands mining facility confirms that regional NOx emissions are boosting ecosystem primary productivity.

Sixteen years ago, I was fresh out of graduate studies from the University of Calgary and had but a year under my belt working on environmental impact assessments for an engineering consultancy company based out of Calgary, when I was laid off as soon as the Great Recession hit in October 2008.

Within a month, I had an interview for a position with Suncor Energy as an environmental research specialist and by January 2009, I was relocated to Fort McMurray as part of Suncor’s massive investment in two large tailing pond reclamation projects.

Note that I grew up in northern Saskatchewan, Yukon and central British Columbia, so I was more than familiar with living dabb-smack in the middle of the Canadian Boreal Forest.

Come spring, the first observations that I made were the constant fine dust precipitation that required me to wash my truck weekly and the lush dense green forests that surrounded Fort McMurray.

The source of the dust was obvious.

Fort McMurray is located less than 30 km south of the Suncor and Syncrude mining operations

Keep in mind that common heavy-haulers in the oil sands mining sector are over 1 million pounds fully loaded and travel in excess of 40 miles per hour on dirt roads. Suncor alone moves well over a million tonnes of ore and overburden every day and there are a total of four large open pit mines along the Athabasca River valley where bitumen containing ore deposits are covered by a thin layer of overburden and soil.

What also caught my attention in the summer of 2009 was the frequent sightings of sow black bears with triples and quadruplet cubs in tow, or cow moose with twins and triplets that I noticed within the region.

Having grown up in a family with extensive experience in ranching, big game outfitting and trapping, I knew that this could mean only one thing.

High quality forage was in abundance.

As a junior scientist, I was totally enthralled.

The burning question I had was what was causing this high productivity?

My eureka moment came one day while enjoying a coffee break at work, standing on a second storey balcony of my ATCO trailer office complex overlooking the heavy-hauler route on the opposite side of the Athabasca River that connects Suncor’s Millennium mining operation, to its ore processing and bitumen extraction plants.

While I was over 3 km away, I was still close enough to observe the large dust plume following the convoy of some 200 heavy-haulers that would often extend well over 1 km into the atmosphere before being displaced horizontally by higher speed winds and moving off into the distance as far as the eye could see.

At that moment, I realized that nitrogen oxides (NO_x) emissions from mining equipment and other combustion sources within the region must be reacting with mining-dust emissions and sunlight to form nitrate fertilizer, that was then depositing all over the regional landscape.

Bear in mind, NO_x emissions from mining operations in Canada are heavily regulated in terms of emissions control, verification and reporting. However, the shear number of combustion sources within the region results in NO_x emissions that are on par with large metropolitan cities like Toronto or Vancouver.

When I went to my boss with my exciting hypothesis, I was immediately reminded that this was not why I was hired and that I should focus on my tailing pond reclamation pilot project.

This hardly deterred me.

After some fancy salesmanship, I convinced my Management Team and Legal Affairs to approve and fund a site-wide baseline environmental sampling campaign for an altogether unrelated project that had been handed over for me to manage.

I knew that the data I obtained would inadvertently provide me with the evidence required to test my fertilization hypothesis.

Six years later, I had my confirmation and somehow convinced Suncor Corporate Communications to allow me to present my findings at the Air & Waste Management Association conference in Long Beach, California in 2014.

What we found was that the calcium carbonate used in the construction of heavy-hauler roads was functioning as the key ingredient in this regional fertilization effect. As shown in the illustration below, a thin veneer of low grade bitumen ore (aka B-Spec) is used as paving material over a foundation of limestone materials. As shown the the XRD analysis data, over 50% of the mineralogy of common heavy hauler roads is limestone (i.e., basic mineral).

Furthermore, we found that rainfall within the oil sands mining region was slightly alkaline. This was surprising given rainfall is naturally slightly acidic (pH < 7) due to equilibrium with atmospheric CO2 (forming carbonic acid pKa = 5.5), which commonly becomes even more acidic when elevated NO_x emissions (forming nitric acid) are present.

Below is a map of the Wood Buffalo Environmental Association’s (WBEA) regional air monitoring station (AMS) network along the Athabasca River, together with rain and dust (RD) sampling locations dispersed across Suncor’s oil sands mining and upgrading facility.

Note the congestion of AMS between the communities of Fort McMurray and Fort McKay, together with the remote (AMS8) station located to the north of the community called Fort Chipewyan.

As the 10 year average WBEA precipitation pH data shows, rain fall is on average neutral within Suncor’s industrial facility (AMS12), which is a full 1.5 logarithmic units higher (more basic) than the baseline pH of 5.5 at AMS near Fort Chipewyan to the north. Fort Chipewyan’s 10 year average pH is exactly what is expected for a location not influenced by anthropogenic NOx emissions and is directly proportional to tropospheric CO2 concentrations.

But, when we looked at regional rainfall water chemistry, we found that alkalinity, nitrate and calcium were the highest near oil sands mining operations and these parameters dissipated as a function of distance from the source of the dust and NO_x emissions.

This trend was especially noticeable in rain water samples collected within Suncor oil sand’s facility (below).

The results from my on-site surveillance conducted during my tenure at Suncor Oil Sands is shown in the table below, together with the facility map to aid the eye in locating where a given RD sampling station is located relative to the upgrader and Millennium Pit.

See how RD3 and RD4 demonstrate that Ca, HCO3, NO3 and pH are the highest near the Millennium Mine open pit?

Thus, my co-author and I established the basis to claim that calcium carbonate (a weakly basic mineral) dust was neutralizing the acidifying potential of NO_x emissions and that the reaction by-product was calcium nitrate fertilizer.

Note that our work confirmed the research of Dale Vitt et al who demonstrated that elevated nitrogen deposition rates were causing dominant peat forming plant species to grow 3 times faster near the Steepbank River (cover image), that runs through Suncor’s mine site than at remote locations. What Dale didn’t consider was that these elevated nitrogen deposition rates are not accompanied by acidified rainfall.

In other words, the Athabasca Boreal Forest is sequestering carbon at a rate proportional to NO_x emissions.

Let me re-emphasize this punch line here by stating that oil sands industrial emissions of CO2 are being offset by their concurrent emissions of NOx. With some estimates placing the typical carbon to nitrogen ratio in Boreal Forests at 100 : 1 and sector wide NOx emission estimates ranging from 20,000 to 30,000 tonnes per year, there is significant sequestration potential here just waiting to be leveraged by an innovative politician and corporate lawyer.

This is not a topic that I suspect we will hear anyone in the mainstream media or in politics acknowledging anytime soon - as we all know, industrial activity can only be negative.

So while open-pit oil sands mining operations may look like Mordor in the short term, these operations are also positively impacting the biological productivity of the surrounding ecosystems, extending many kilometers outside of the temporarily impacted mine sites.