Since They’ve No Place To Go, Plastics End Up in Snow

Advanced analysis techniques have yielded something frightful: super tiny microplastics (or nanoplastics) embedded in freshly fallen snow.


Canada is known for its extreme weather conditions, but this recent forecast from McGill University may be the most alarming yet. Using highly sensitive analysis techniques, a team of scientists from McGill’s Departments of Chemistry and Atmospheric and Oceanic Sciences have found evidence of harmful microplastics in Montreal’s freshly-fallen snow.

Zi Wang, a PhD candidate at McGill, was the first author of the analysis published in Environmental Pollution.

Microplastics are everywhere, but studying them is tricky

Microplastics are tiny pieces of plastic that measure less than 5 millimetres in diameter. They’re found in a number of common household products, but can also be released when larger plastic products break down. Worryingly, studies have shown that we may be ingesting large quantities of microplastics every day, and we still aren’t entirely sure how they’re affecting us.

Given how small these plastic particles are, finding and studying them can be tricky. This is particularly true for the smallest microplastics, which are referred to as nanoplastics and measure less than 1 micrometre in diameter — 5,000 times smaller than the largest microplastics.

Traditional techniques used to study microplastics simply aren’t sensitive enough to analyze micrometre-sized particles. For example, nets or sieves that are used to collect microplastic samples need extraordinarily small filters in order to capture nanoparticles. Many traditional techniques used to analyze microplastics also require the samples to be processed before being analyzed, but Wang and his colleagues wanted to study the microplastics without risking contamination during this pre-processing.

Extremely tiny nanostructures lend a hand

To do this, Wang and his colleagues developed a new type of nanostructure, which is a structure that measures roughly a nanometre, or one billionth of a metre, in size. Their structure was developed in the laboratory, and was composed of sustainable materials such as zinc oxide, titanium oxide, and cobalt which have well-known masses and sizes.

Using these extremely small nanostructures, the team was able to collect and study nanoplastics that had accumulated in Montreal’s freshly-fallen snow. They did this using a nano-structured mass spectrometry technique, which uses light to separate and analyze particles based on their weights.

This technique allowed the scientists to study nanoplastics weighing as little as a picogram, or one trillionth of a gram. At this scale, their measurements were orders of magnitude more sensitive than previous techniques.

The materials Wang and his colleagues used for their lab-constructed nanostructure were particularly well-suited to this type of analysis, in part because they were all readily able to absorb light. This light could then be transferred to the snow samples that were being analyzed, causing the samples to become electrically charged and separated according to their mass. This allowed the team to determine the nanoplastics’ masses, as well as their concentrations.

The materials Wang and his colleagues used are also recyclable, which makes the technique sustainable and environmentally friendly.

“Our hope is that this new technique can be used by scientists in different domains [to] gain key information about the quantity of micro- and nano-plastics in urban environments,” Wang said in a press release.

After analyzing their samples, the team concluded that antifreeze products were the main culprit behind the nanoplastics. These nanoplastics are typically released from antifreeze products into the air, and later picked up by snowflakes as they fall to the ground.

With the snow finally starting to melt in Montreal and other Canadian cities, there’s potential for these nanoplastics to spread into our water and soil as well. Wang’s technique can also access microplastics in water and soil samples, and will help researchers learn more about how microplastics spread throughout our environment.

“Microplastics have been found in […] oceans, sediments, soil, and biological entities,” Wang told The McGill Tribune. “This technique may produce crucial missing information on the fate of micro [or] nanoplastics in various environmental matrices.”

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Emily Deibert is a PhD student in the Department of Astronomy & Astrophysics at the University of Toronto with a passion for science outreach and communication. She earned her HBSc (Astronomy, English, and Mathematics) at the University of Toronto. She is excited about turning scientific research into stories and sharing these stories with the public.