One particularly disconcerting consequence of our huge plastic pollution problem is that we really have no idea where the stuff can end up. The latest locale to surprise scientists looking into such matters is the Arctic Circle, who say that snow falling on this frigid, remote part of the world is bringing tiny fragments of plastic along for the ride.

Sea water, drinking water, human stool and the bellies of sea turtles are just a few of the places we know microplastics can now be found. These minuscule shreds of plastic are the result of larger pieces washing into the sea and being broken down by the forces of the ocean, creating an almost immeasurable mass of microscopic waste that is proving incredibly hard to track.

Last year, scientists at Germany's Alfred Wegener Institute (AWI) published research describing unexpected quantities of microplastics lodged in Arctic sea ice. The findings, based on ice samples retrieved during Arctic expeditions between 2014 and 2015, shed new light on the way microplastics move through the marine environment.

Now the institute's latest research has revealed they can take an aerial route, too. These findings stem from another round of analysis, this time on snow samples collected from remote reaches of the Arctic, along with other locations including the Swiss alps and remote parts of Germany.

The snow taken from the Arctic contained up to 14,400 pieces of microplastic per liter (0.26 gal), while samples collected in rural parts of Bavaria, Germany contained as much as 154,000 pieces. The scientists say the plastic particles originally came from a diverse range of sources including paints, car tires and nitrile rubber often used in gaskets and hoses.

So how does plastic become one with snow, of all things? The findings tie into research published earlier in the year in Nature Geoscience, in which scientists found that microsplastics fine enough to become airborne had been transported via the atmosphere and blown into pristine, untouched corners of the French Pyrenees mountains. Another exit strategy, it appears, is to be washed out of the atmosphere by precipitation such as snow.

This method of atmospheric travel hasn't been studied in depth, but the revelation that it can transport huge amounts of microplastic sheds new light on what we know about plastic contamination of the environment. For one, the scientists posit that it may be a significant factor in the discovery of microplastics in the Arctic sea ice last year. It also begs the question, if microplastics can be so easily swept up and blown across the Earth, how much might we be breathing in? These are the kinds of questions the scientists will seek to answer with further research.

"To date there are virtually no studies investigating the extent to which human beings are subject to microplastic contamination," says Melanie Bergmann, leader of the research team. "But once we've determined that large quantities of microplastic can also be transported by the air, it naturally raises the question as to whether and how much plastic we're inhaling. Older findings from medical research offer promising points of departure for work in this direction."

The new research was published in the journal Science Advances.

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