Bioaerosols: New element in climate mystery

Parisa Ariya’s accidental discovery of the power of bioaerosols to generate rapid and dramatic chemical reactions may change – at the very least alter – the course of climate science.

Ariya, a professor at McGill University’s Department of Atmospheric and Oceanic Sciences, in Montreal (Canada), first made her observation in August 2001, after one of her postdoctoral fellows forgot to close the valve sealing the reaction chamber where an organic compound (containing carbon, oxygen and/or hydrogen) was reacting with ozone (the form of oxygen in the stratosphere that filters out ultraviolet radiation).

By Monday, the organic compound was gone, and several new peaks in the frequency regions for carbohydrates and proteins were found. A sludge had formed on the glass walls of the chamber. What was it? Ariya deduced that airborne micro-organisms in the laboratory had found their way into the chamber, consumed the organic compound and produced new aerosols in their reaction both with the compound and the ozone.

Something told Ariya that such reactions, which would take place all the time in the natural world – given that there are always bioaerosols, living or dead organic compounds in the air, such as dust, bacteria, pollen, leaf dust, viruses – might be significant in understanding climate and climate change. “Fortunately, we didn’t discard it and I was crazy enough to pursue further experiments,” recalls Ariya. “What tipped me to the importance of this accident was the speed and efficiency of the chemical reactions.”

Since beginning her research, Ariya has found that similar to inorganic aerosols, (such as volcanic dust), bioaerosols are capable of forming clouds. She’s examining the role they play in the interfaces between snow and air, snow and water and fog and clouds. She notes that bioaerosols were long suggested to play a role as ice nuclei for cloud formation, yet their impact on driving chemistry and impact of chemical reactions on physics of atmosphere were not considered.

What’s most significant about Ariya’s work is how, until now, no scientist has included bioaerosols in climate research because their numbers were considered insignificant as compared to inorganic aerosols.