The data confirm that microplastics move between continents because the free troposphere acts as an “ultra-fast track” for great distances.
Microplastics, pollutants found even on Everest, the Arctic or in the middle of the ocean, are transported between continents by high-altitude winds, according to a study published Tuesday in the journal Nature Communications.
These residues, of a few millimeters and which come for example from packaging or washing clothes, are of increasing concern to researchers.
Its presence was detected even near the top of Everest, probably coming from the material used by mountaineers.
Other studies revealed that there are microplastics even in the snow of the Alps or the Arctic, as well as in rivers and more remote parts of the oceans.
Microplastics found in the atmosphere of Antarctica
They are also detected in the air, very close to the ground.
But this time, a group of researchers looked for these residues in the “clean” air of altitude, above the clouds.
The scientists – from the National Center for Scientific Research (CNRS) in France, the Grenoble Alpes 2 University and the University of Strathclyde (Scotland) – took samples at the Pic du Midi observatory, at an altitude of 2,877 meters, in the French Pyrenees, between June and October 2017, with a pump that sucked in 10,000 m3 of air per week.
All samples contained microplastics. Although the amounts do not pose an immediate health risk, they are significant for an area that is supposed to be clean and “cannot easily be attributed” to a local source of the contamination, according to the researchers.
To determine the origin of the pollutants, they calculated the trajectory of the different air masses of the samples during the seven days prior to their extraction.
Microplastics found in the stomach contents of boquichicos fish from the Peruvian Amazon
And they found that the pollutants came from the northwest of the African continent, passing through the Mediterranean, North America and the Atlantic Ocean.
The data confirm that microplastics move between continents because the free troposphere, which is the atmospheric zone studied, acts as an “ultrafast pathway” for large distances for the particles, explains Steve Allen, the lead author of the study.
For the researcher, however, the most outstanding finding of the study is the marine origin of a part of these particles.
“That the plastic is dragged from the ocean to such high altitudes shows that there is no storage sink possible, it is going around in a perpetual cycle,” he says.
“It shows that the plastic cannot be sent abroad, because it will come back” in another way, he adds.
Especially because some of the particles analyzed, “are of a size that we can breathe,” adds Deonie Allen, also an author of the study.
These results “show that it is a global problem,” adds the researcher. (I)
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