Microscopic fragments of plastic have invaded the farthest reaches of the sea, from the depths of the Mariana Trench to the freezing waters off Antarctica. Now, researchers have found that such microplastics have polluted the Pyrenees mountains, expanding plastic’s dominion to previously unknown heights.
Prior studies have shown that microplastics, which can be ingested and inhaled by humans—and which may lead to reproductive issues in some marine mollusks—can rise up into the atmosphere and drop back to solid ground in the cities they come from. But scientists thought these plastics couldn’t travel very far from their urban sources.
To find out just how far they can go, the researchers collected particles falling from the sky in dust, rain, and snow for 5 months at the Bernadouze meteorological station in the Pyrenees mountains in southwestern France—100 kilometers from the nearest city.
To their horror, the authors found plastics, predominantly the kind from the single-use packaging used in shipping. From their sample, they determined that each day, an average of 365 plastic particles sifted down from above into the square meter surface of the collection device. If comparable quantities of airborne microplastic fall across the rest of the country, the researchers estimate roughly 2000 tons of plastic blanket France each year, they report today in Nature Geoscience.
Computer simulations corroborated the notion that the plastic fragments, films, and fibers collected could have originated in cities, suggesting the microplastics floated at least 100 kilometers before falling back to Earth. But researchers say these tiny particles may travel much farther. Dust particles from the Sahara Desert, for example, have been found in the Pyrenees, even though they are twice as large and twice as heavy as the microplastics found in the study.
Pieces of plastic small enough to sail into the atmosphere are virtually impossible to clean up, say the researchers, suggesting the only viable solution is to produce less in the first place. Until then, the researchers plan to keep up their detective work—tracking the airborne microplastics all the way back to their source.