Plastics not only pollute oceans and land, and even animals, but new research shows microplastic contamination in the atmosphere – and indeed, the air we breathe. And microplastics are also found in snowfall in the Alps and the Arctic — two of the most “pristine” environments in the world — according to a new study published last week on 14 August in the journal Science Advances (1).
Plastic pollution has become a major global concern. Whereas larger plastics are visibly seen polluting oceans, waterways, and land, these are eventually broken down into smaller fragments called microplastics – minuscule plastic particles that often go undetected. Nonetheless, microplastics are known to pollute the air we breathe, the food we eat and contribute to greenhouse gas emissions. They are found in farmland soils in China as well as rivers, lakes, and oceans in widespread regions as far as the Arctic, and even in the human gut.
Another recent paper published in Nature Geoscience reported the presence of microplastics in remote mountaintops of the Pyrenees (2). However, apart from this, very little research has been done on the transportation of microplastic particles by the atmosphere. Indeed, the authors highlight the “large knowledge gaps” in how these particles are carried further North.
To shed some light on this, the researchers from the Alfred Wegener Institute (AWI) at the Helmholtz Centre for Polar and Marine Research in Germany examined snow samples gathered between 2015–2017 from various regions including Helgoland, Bavaria, Bremen, the Swiss Alps, and the Arctic.
First, they melted the snow and poured it through a filter, then examined residues trapped in the filter using an infrared microscope. Because different plastics absorb different wavelengths, they were also able to identify the type of plastics based on their so-called “optical fingerprint”. By automating the process to some extent, they were able to rule out many of the errors associated with typical manual analysis.
The technique also allowed them to identify particles as small as 0.011 mm, which is less than the width of a human hair. Whereas other studies looked at much larger microplastics and may have, in fact, underestimated actual levels of microplastics in the environment.
The authors found that microplastics are being carried incredible distances to where they are later washed out of the air by precipitation – in particular, snow. At all sites, snow contained high concentrations of microplastics even in remote reaches of the Arctic. They found the highest concentration (154,000 particles per litre) in samples collected near a rural road in Bavaria. But even snow in the remote Arctic contained a significant concentration of microplastic (up to 14,400 particles per litre). Moreover, the type of plastic varied greatly between regions. In the Arctic, these mainly consisted of nitrile rubber (often used in gaskets and hoses), acrylates, and paint.
The authors are now convinced more than ever that a major portion of the microplastic in Europe, and even more so in the Arctic, comes from the atmosphere and snow. And “could also explain the high amounts of microplastic that we’ve found in the Arctic sea ice and the deep sea in previous studies”, says lead author Dr Melanie Bergmann of AWI.
So, exactly how many of these microplastics are we breathing in and how are they affecting human and animal health? Those questions still need to be answered in the future. But these recent studies, at the very least, provide an excellent starting point.
(1) Bergmann, M. et al. White and wonderful? Microplastics prevail in snow from the Alps to the Arctic. Science Advances (2019). DOI: 10.1126/sciadv.aax1157
(1) Allen, S. et al. Atmospheric transport and deposition of microplastics in a remote mountain catchment. Nature Geoscience (2019). DOI: 10.1038/s41561-019-0335-5