Wind plays a role in carrying microplastics (MPs, shreds of plastic less than five millimeters long) to both the snowy streets of European cities and remote areas of the Arctic Ocean. The high concentrations found in snow samples from disparate regions suggest microplastics—which may contain varnish, rubber, or chemicals used in synthetic fabrics—cause significant air pollution.

Previous studies have shown that microplastics may contribute to lung cancer risk, highlighting an urgent need to further assess the health risks of inhaling them.

To better understand how microplastics travel so far, which has been a question, researchers from the Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung In Germany used an imaging technique to analyze snow samples collected between 2015 and 2017 from floating ice in the Fram Strait, a passage between Greenland and Svalbard to the Arctic Ocean. They visited five ice floes by ship-based helicopters or dinghies during three expeditions.

For comparison, the researchers investigated samples from the remote Swiss Alps and the City of Bremen in northwest Germany.

They observed that while concentrations of microplastics in Arctic snow were significantly lower than the concentrations in European snow, the levels of this pollutant in the far North were still substantial.

The highest proportion of MPs in the total natural and synthetic particle load was found in snow from Ice Floe 1 (88%), followed by Bavaria 2 (67%) and Ice Floe 9 (37%). There was no significant difference in the proportion of MP particles from European and Arctic snow (Mann-Whitney U test: W = 170, P = 0.59). The composition varied considerably with 19 different polymer types found in total ranging between 2 (Ice Floe 4) and 12 types (Bavaria 2) per sample.

The number of polymers per sample was significantly higher in European (mean, 8.63 ± 0.80) compared with Arctic (mean, 5.14 ± 0.79) samples (Mann-Whitney U test: W = 123, P = 0.013).

Acrylates/polyurethanes/varnish/lacquer (hereafter varnish) occurred most frequently (17 samples), followed by nitrile rubber (16 samples), polyethylene (PE), polyamide, and rubber type 3 (13; ethylene-propylene-diene rubber). The polymer composition of samples from Europe and the Arctic was significantly different [permutational multivariate analysis of variance (PERMANOVA): pseudo-F = 2.43, P = 0.006]. The dissimilarity in the polymer composition from European and Arctic samples was 67% and caused primarily by much higher abundances of polyamide, varnish, rubber type 3, nitrile rubber, ethylene-vinyl-acetate, and PE in European samples. By contrast, polystyrene, polyvinyl chloride (PVC), polycarbonate, polylactic acid, and polyimide occurred exclusively in Arctic snow.

—Bergmann et al.

Most of the particles were in the smallest measurable size range of less than 11 micrometers; such particles are more likely to be picked up by atmospheric transport, the authors say.

Because most studies currently focus on particles larger than 200 or 300 micrometers, measuring smaller particles remains important, in order to realistically assess microplastics' environmental toll. The high amounts of microplastics in snow, as reported here, suggest that atmospheric transport and deposition could represent a significant pathway for these materials to places far afield, the authors say.

Resources

• Melanie Bergmann, Sophia Mützel, Sebastian Primpke, Mine B. Tekman, Jürg Trachsel, Gunnar Gerdts (2019) “White and wonderful? Microplastics prevail in snow from the Alps to the Arctic” Science Advances doi: 10.1126/sciadv.aax1157