Study finds microplastic fibers can travel as far as the stratosphere

How far microplastics travel in the atmosphere depends critically on the shape of the particles, according to a recent study by scientists at the University of Vienna and the Max Planck Institute for Dynamics and Self-Organization in Göttingen . Although spherical particles settle quickly, microplastic fibers can travel up to the stratosphere.

In a new article published in the journal Environmental science and technologyResearchers say additional studies are urgently needed to investigate the possible influence of microplastics on the atmosphere.

Microplastic particles can be found in the most remote corners of our planet. For some places, such as glaciers and ice caps in the Arctic, atmospheric transport is the only feasible route. However, it is puzzling how fairly large microplastics, mostly resembling fibers, could have ended up in such places, even though atmospheric transport models predict that such large particles fall from the atmosphere nearby. from their source.

The study by an interdisciplinary group of scientists from the University of Vienna, Austria, and the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, approached this puzzle via a innovative combination of laboratory experiments and model simulations. The researchers first experimentally determined how quickly microplastic fibers settle in the atmosphere and found that the fibers settle much more slowly than spheres of the same mass.

Lack of data on microplastic fibers in the air

Mohsen Bagheri of the Max Planck Institute for Dynamics and Self-Organization, who supervised the laboratory experiments, comments: “Surprisingly, there are almost no data in the literature on the dynamics of microplastic fibers when they settle in the air. largely because of the challenges of conducting controlled, reproducible experiments on such small particles in the air. Thanks to advances in 3D printing at submicron resolution and the development of a new experimental setup allowing the tracking of individual microplastics in the air, we have been able to enrich this knowledge. gap and improve existing models in this study.

The researchers then implemented a model describing the sedimentation process of non-spherical particles in a global atmospheric transport model. The differences from spherical particles were dramatic: fibers with a length of up to 1.5 mm could reach the most remote places on Earth in the model, while the model showed that spheres of the same mass s were located much closer to plastic source regions.

Daria Tatsii from the Department of Meteorology and Geophysics at the University of Vienna, first author of the study, says: “With the new laboratory experiments and modeling analysis, we are certainly reducing the uncertainties regarding the atmospheric transport of fibers and can finally explain it via modeling. why microplastics reach very remote regions of the planet. An important result of the study is that our analysis is applicable not only to microplastics, but also to any other particles such as volcanic ash, mineral dust, pollen, etc.

Fibers could impact even the stratosphere

Another finding is that, in the model, plastic fibers could reach much higher heights in the atmosphere than spheres of the same mass. Andreas Stohl, from the University of Vienna, who led the study, comments: “This could have implications for cloud processes and even stratospheric ozone, as it seems possible that microplastic fibers are abundant in the upper troposphere and could even reach the stratosphere. For example, we cannot exclude that the chlorine contained in these particles is harmful to the ozone layer.

“However, at present we do not even know how much plastic, or in what sizes and shapes, is released into the atmosphere, nor do we know what happens to it in the extreme conditions of the upper troposphere and stratosphere. We are missing very basic data. But given the dramatic increase in global plastic production, we need to be vigilant.”

Despite all the uncertainties, one thing is clear from the article: the often peculiar shapes of microplastic particles must be taken into account when studying their environmental impact.