Research recently published in the journal Science Advances from scientists at the Alfred Wegener Institute and the Helmholtz Centre for Polar and Marine Research (AWI) shows that microplastics are being transported by the atmosphere, in addition to transport via waterways and sediments. The scientists show that microplastics moved over large distances by the atmosphere are appearing all over the world when they are “washed out of the air by precipitation, particularly snow.”
Led by Dr. Melanie Bergmann and Dr. Gunnar Gerdts, the research team analyzed samples of snow from Helgoland, Bavaria, Bremen, the Swiss Alps and the Arctic. They determined that even in the most isolated areas, high concentrations of microplastics were common. Explaining this is easy, comments Dr. Bergmann: "It's readily apparent that the majority of the microplastic in the snow comes from the air.”
We already know from previous studies that the atmosphere is capable of transporting sand and pollen, traveling over 3,500 kilometers from the Sahara Desert to the northeast Atlantic and even the Arctic. Microplastics measure approximately the same size as dust and pollen, and it is therefore plausible that microplastics be transported in the same way by the atmosphere, explain the authors of the study.
In order to count the microplastics, the researchers melt the snow and pour the meltwater through a filter. Following that process, reports Science Daily, “The residue trapped in the filter is then examined with an infrared microscope and depending on the type of plastic, different wavelengths of the infrared light are absorbed and reflected; in this way, an optical fingerprint can be used to determine what type of plastic they've found.” The study found that the highest concentration of microplastics was collected in Bavaria, where up to 154,000 particles of microplastics per liter of snow were recorded. In the Arctic, while much lower in comparison, levels still reached up to 14,400 particles per liter. The classes of plastics recorded ranged from nitrile rubber, acrylates to paint.
Gerdts explains that using the infrared spectroscopy method is more precise other methods. "We've automated and standardized the technique so as to rule out the errors that can creep in when manual analysis is used."
So, what does this mean in terms of microplastic distribution globally? Dr. Bergmann commented that transport by the atmosphere, “…could also explain the high amounts of microplastic that we've found in the Arctic sea ice and the deep sea in previous studies." She says that the team’s findings should beg the question for further investigation, elaborating: "Once we've determined that large quantities of microplastic can also be transported by the air, it naturally raises the question as to whether and how much plastic we're inhaling. Older findings from medical research offer promising points of departure for work in this direction."