Oil sands removal as suspended matter slingshot

Bitumen fumes produce more organic aerosols than previously thought

View of an oil sands mining facility in Canada - hydrocarbon bottoms rise from the processing piles and ponds - largely invisible. © Environment Canada
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Large-scale contamination: The extraction of oil sand not only contaminates the immediate environment, the rising vapors also lead to the formation of huge clouds of organic suspended matter. The Canadian mining areas alone are already one of the largest sources of such particulate matter in North America - with potentially far-reaching consequences for the environment and climate, as Canadian researchers report in the journal "Nature".

Since classical oil deposits are scarce, so-called unconventional deposits are being explored and exploited in many parts of the world. These include oily sands, which are already being mined in the Canadian provinces of Alberta and Saskatchewan on a large scale. By hot water, steam and various catalysts while the oil is separated from the bitumen.

However, this oil extraction has serious environmental consequences: The open pit not only destroys the landscape, poisonous hydrocarbons and acids from the mining areas also contaminate soils and waters tens of kilometers away, as researchers noted in 2013.

Using a test aircraft, the researchers took air samples near the facilities. © Environment Canada

Source of organic suspended matter

Now, John Liggio of the Canadian Environmental Protection Agency and his colleagues are warning of another, far-reaching consequence of oil sands extraction: the release of massive amounts of particulate matter, so-called secondary organic aerosols. These arise when ascending organic gases react with the oxygen in the air and are thereby oxidized. This forms fine dust-like suspended matter.

The number of such secondary aerosols produced by oil sands extraction has now been researched for the first time. They flew with test aircraft over the oil reduction areas of Canada and analyzed the thereby taken at different points of the suspended clouds clouds of air. display

Exhaust plume like a megacity

The result: Even 120 kilometers away from the mining areas, the aerosol cloud was clearly detectable in the prevailing wind direction. The concentration of organic suspended matter was around twelve micrograms per cubic meter, despite the prolonged spread and dilution of the cloud. "This suggests a significant rate of formation of these aerosols inside the cloud, " the researchers report.

Destroyed landscape: view into an open pit for oil land reclamation. Environment Canada

"The rate of production of organic aerosols is comparable to the exhaust plume of megacities like New York and Paris and is higher than for example about Tokyo, " said Liggio and his colleagues. According to their calculations, 45 to 84 tonnes of organic suspended matter are formed each day in the Canadian oil extraction areas. "This makes the lsande one of the largest sources of anthropogenic organic aerosols in North America, " say the researchers.

Bitumen fumes as a source

Chemical analyzes confirmed that these suspended solids actually originate from the gases released during oil degradation. "More than 90 percent of the suspended matter in the cloud had been freshly formed from oil sand emissions, " the scientists report. "Their mass spectrum is almost identical to that of particulate matter produced by the oxidation of bitumen vapors in laboratory experiments."

These vapors are released because the tar-containing components of the oil are separated from the sand by hot water followed by further heating. Many volatile hydrocarbons evaporate. "The impact on air quality from such fumes could be far more serious and widespread than previously thought, " the researchers warn.

"A worldwide problem"

And the Canadian oil sands are just the beginning: "So far, heavy oil and bitumen account for around ten percent of global earth production, but their share is growing, " say the researchers. It is estimated that nine billion trillion barrels of oil are still stored in such deposits worldwide. As the scientists report, Venezuela is already planning to exploit its Orinoco oil and the US has already started mining bitumen deposits in Utah.

"This problem is therefore not confined to Canada, " warn Liggio and his colleagues. "In light of the current trend towards the exploitation of unconventional oil, we urgently need further research to gauge the scale of this potentially global problem." (Nature, 2016; doi: 10.1038 / nature17646)

(Nature, 26.05.2016 - NPO)