My watch list
my.chemeurope.com  
Login  

Melting snow contains a toxic cocktail of pollutants

07-Apr-2017

hpgruesen; pixabay.com; CC0

With spring finally here and warmer temperatures just around the corner, snow will slowly melt away, releasing us from the clutches of winter. However, that's not the only thing that the melting snow will release. Researchers from McGill University and École de technologie supérieure in Montreal have found that urban snow accumulates a toxic cocktail from car emissions - pollutants that are in turn unleashed into the environment as the weather warms up.

"We found that snow absorbs certain polycyclic aromatic hydrocarbons which are organic pollutants known to be toxic and carcinogenic," says Yevgen Nazarenko, a postdoctoral researcher working with Parisa A. Ariya, professor at McGill's Department of Atmospheric and Oceanic Sciences and Department of Chemistry, and collaborating with Prof. Patrice Seers' team at École de technologie supérieure.

"Understanding how these pollutants interact with the environment, including snow, is crucial if we are to reduce the hundreds of thousands of premature deaths caused by mild air pollution in North America. Worldwide, air pollution claims as many as 8 million lives," says Prof. Ariya, senior author of the group's new study.

The nose knows

In some cases, it doesn't take high-tech equipment to sniff out shifting pollution levels.

"When one goes outdoors in winter, and there is fresh snow, one can sense the air has a different smell--it usually smells 'crisper'. Once the snow has been on the ground for some time, the effect goes away. When the weather warms up, the air acquires yet another smell. This is what led us to wonder about how exactly snow interacts with air pollutants," says Nazarenko.

The scientists analyzed how snow takes up pollutants from car emissions by exposing it to engine exhaust in a frozen glass sphere built in the lab. They found that exhaust is affected differently by the cold and snow depending on the type of fuel injection in the engine.

Exhaust particles altered

The new study also found that snow takes up airborne particulate matter and alters the concentrations of different nanoparticles, the smallest particles found in air pollution. These tiny particles have been linked to numerous health problems. Unexpectedly, colder temperatures and interaction with snow increased the relative presence of smaller nanoparticles in the polluted air above the snow.

Once in the snowpack, air pollutants may undergo chemical transformations that create additional pollutants with different toxicity and carcinogenicity. Some compounds, including more toxic and carcinogenic chemicals, may volatilize back into the air, while others accumulate in the snow and are released with meltwater.

"These releases could lead to a higher short-term concentration of certain pollutants in the air, soil and surface water bodies where the meltwater runs to," worries Nazarenko.

Further studies and environmental monitoring could help identify the most harmful pollutants, which ones should be targeted for reduction in gasoline formulations and in optimization of engines and exhaust treatment technologies, the researchers conclude.

Facts, background information, dossiers
  • polycyclic aromatic…
  • carcinogenicity
  • carcinogens
  • air pollution
  • aerosol particles
More about McGill University
  • News

    Hot 'new' material found to exist in nature

    One of the hottest new materials is a class of porous solids known as metal-organic frameworks, or MOFs. These man-made materials were introduced in the 1990s, and researchers around the world are working on ways to use them as molecular sponges for applications such as hydrogen storage, ca ... more

    From backyard pool chemical to nanomaterial

    Cyanuric acid is commonly used to stabilize chlorine in backyard pools; it binds to free chlorine and releases it slowly in the water. But researchers at McGill University have now discovered that this same small, inexpensive molecule can also be used to coax DNA into forming a brand new st ... more

    A 'printing press' for nanoparticles

    Gold nanoparticles have unusual optical, electronic and chemical properties, which scientists are seeking to put to use in a range of new technologies, from nanoelectronics to cancer treatments. Some of the most interesting properties of nanoparticles emerge when they are brought close toge ... more

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE