The Silent Absorption: How Snow Acts as a Natural Adsorbent for Pollutants”
With winter’s arrival, the unique Silent Absorption properties of snow come into play, contributing to a quieter environment due to its ability to absorb sound. The spaces between snow crystals limit sound wave reflections, creating a natural soundproofing effect. Beyond its acoustic characteristics, snow possesses adsorptive properties, meaning it can adhere to various substances it comes into contact with.
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Silent Absorption
Adsorption involves substances sticking to the surfaces of materials, and snow’s adsorptive nature is responsible for its loosely bound crystalline porous structure and individually shaped flakes with large surface areas. The dynamic transitions between ice and liquid states enable snow to absorb and release pollutants based on prevailing conditions.
As an analytical material chemist specializing in adsorption, my interest lies in understanding how materials like snow adsorb specific substances, particularly persistent organic pollutants (POPs) and vehicular exhaust pollutants.
During winter, snow acts as a superabsorbent, capturing a range of pollutants such as vehicular exhaust particulate matter, POPs, trace metals, and chlorides from road salts. As snow moves or melts, these pollutants often find their way into underground pipes and aquifers.
POPs, including polychlorinated biphenyls, organochlorine pesticides, and perfluoroalkylated substances, are particularly hazardous pollutants, as they remain active for several years before degrading. Snow’s interaction with chemical pollutants from gasoline-powered vehicle exhausts is not well understood, similar to POPs.
In Canadian cities, snow undergoes various movements, such as melting during plowing, transportation on tires or pedestrian shoes, and changes in ground surface pressure and ambient temperature. These factors influence the adsorption rates of chemical pollutants on snow. Research in Québec revealed that snow adsorbs significant amounts of organic pollutants and aerosol particles from exhaust pipes within a short exposure time of 30 minutes, with larger particulate sizes being adsorbed more readily than smaller nanoparticles.
