Microplastics, those pervasive relics of modern times, have invaded seemingly every part of the planet today, including rain over the Rocky Mountains and the most remote reaches of the Arctic. Scientists have been puzzling over how this flood of pollution makes its way to such distant locations far from the urban centers where it’s generated. A new study finds a surprising route for the tiny particles—they’re ferried aloft to fall in the Arctic as snow.
“Substantial” amounts of plastic fragments and fibers are landing atop ice floes in the Fram Strait—an unpopulated expanse of ocean between Greenland and the Norwegian Arctic archipelago of Svalbard—reports the study, published today in Science Advances.
Scientists from Germany’s Alfred Wegener Institute for Polar and Marine Research and the Swiss Institute for Snow and Avalanche Research measured microplastics in snow samples from this remote location during research cruises from 2015-17, and found levels they conclude could only have fallen from the sky. The study raises concerns about how much microplastics contaminate the atmosphere, posing a potential health risk to people and animals that breathe them in.
“I think the exposure pathway for us, the main exposure pathway, may be the air that we breathe,” says Melanie Bergmann, a marine ecologist with the Alfred Wegener Institute and lead author on the new paper.
Although it’s remote, the Arctic is far from pristine, with much of the world’s pollution eventually making its way there. Bergmann and her colleagues had been studying plastics on the Arctic sea floor since 2002. Over the past decade or so, they noticed huge increases in the amount they were seeing, including a tenfold rise at one station.
So they started to look for microplastics in the Arctic water column. Copious amounts turned up everywhere they looked. In deep sea sediments, they found about 6,000 particles in every 2.2 pounds of mud. Sea ice was even more laden—as much as 12,000 particles per 34 ounces of melted ice, according to Bergmann. And other researchers found that Arctic surface waters had the highest microplastics concentrations of all the world's oceans.
"We asked ourselves, where does it all come from?" says Bergmann.
The biggest load, studies suggest, is ferried north by the Gulf Stream and strong Atlantic currents. Most of it likely started off in Northern Europe.
But Bergmann and colleagues wondered whether the atmosphere posed another transportation route for microplastics. Researchers in France and China had found plastic particles in the air near cities. And a recent study found deposits in a part of the Pyrenees so remote that they must have drifted airborne over the mountains. Could microplastics be catching rides on the wind and landing far to the north as snow?
It turns out they are, says Bergmann. Snow samples from ice floes in the Fram Strait had surprisingly high concentrations of microplastics. One spot, close to the middle of the passage, had 14,000 particles per 34 ounces. The average across all samples was 1,800 particles.
For comparison, the researchers also analyzed snow near urban sites in Germany and the Alps. While the microplastics measured in those samples were considerably higher, with an average of 24,600 particles per 34 ounces, the study concluded that the amount found in the Arctic is still substantial and shows significant atmospheric contamination.
“Basically microplastic is everywhere,” says Bergmann. “Aerial transport is the pathway to transport microplastic to the remotest parts of our planet.”
And this means the atmosphere may be a key source of exposure for humans and animals.
“Microplastic is in the air, and it's not unlikely that we also inhale some of it,” says Bergmann.” And part of this may actually make it into our lungs."
Plastics are literally everywhere
The new study drives home the reality of microplastics traveling in the atmosphere, said Jennifer Provencher, head of the wildlife health unit for the Canadian Wildlife Service who studies the impacts of plastics in Arctic ecosystems and was not involved with the study.
“The message I'm often trying to communicate to people, specifically people who live in the middle of the continent away from a large water body, is that there's so much information about, you know, garbage patches and turtles with straws up their nose, all of that stuff, that people think that plastic pollution is a middle-of-the-ocean problem,” says Provencher.
“And the more we work on this, the more we are learning that it's not a middle-of-the-ocean problem. It's a water body problem. It's a terrestrial problem, it's an air problem, it's a tropical problem, it's an Arctic problem,” she says.
But Provencher worries less about the threat that inhaling microplastics poses to wildlife than about contaminated snow dumping its plastics load into waterways. “From an ecosystem perspective,” she says, “we're much more concerned about what happens when that snow melts and often enters the aquatic environment.”
University of Toronto microplastics researcher Chelsea Rochman, who did not take part in the study, says she was surprised at first to learn that the particles were being transported in the atmosphere.
“But, when we take a step back and see the big picture,” she says, “we know that this is not novel for other persistent contaminants.”
The Arctic has long been a sink for pollutants like flame retardants and pesticides, which spiral northward on ocean and wind currents.
“Now that we know that microplastics cycle in the atmosphere too,” Rochman says, “maybe we should not be so surprised they are entering the Arctic this way as well.”
Is it hurting us?
The science on the health impacts of microplastics is still evolving.
“For human health, we currently know very little,” says Rochman. “There is a lot of concern because we know we are exposed… For wildlife, we know that microplastics enter every level of the food chain in aquatic ecosystems.”
Laboratory studies find some physical and chemical effects from microplastics exposures, but the findings vary by plastic type, shape and size.
“More research is needed to fully understand health effects,” says Rochmann.
The health impacts of inhaled microplastics are even less known, Bergmann said.
Even worse may be the threat from airborne nanoplastics—so small they’re essentially invisible and about which almost nothing is known so far.
"They may actually enter cells,” says Bergmann. “So we may have a big problem."