Unexpectedly high levels of microscopic plastic particles have been detected in fresh snow in some of the world’s most isolated areas, underlining the extent of potentially toxic contamination in the earth’s atmosphere.
The first international data on microplastics in snow, collected by the Alfred Wegener Institute in Germany, revealed significant concentrations of the man-made materials even in remote Arctic and Alpine locations. The results, which could have implications for human health, were published in the journal Science Advances.
Plastic ends up in snow through various routes which scientists are just beginning to investigate. Some come from sources on land, ranging from paint particles to tiny fragments of rubber from car tyres wearing down. Some of these find their way into the sea, where they are broken up by the waves and ultraviolet radiation, before being swept up into the atmosphere.
The microplastics are then captured from the air during cloud formation, when particles act as a nucleus around which supercooled droplets can condense, and as the snowflakes are drifting to earth.
“Although there is a huge surge of research into the environmental impact of plastics, there is still so much that we do not know,” said Melanie Bergmann, senior scientist at the Alfred Wegener Institute and a report author.
She noted how scientists were only beginning to investigate the effects of consuming such microscopic materials — an issue that has received little attention — and said there was an “urgent need for research on human and animal health effects focusing on airborne microplastics”.
“Once we have 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 are inhaling,” she said, raising the question of whether breathing in these particles might increase the risk of suffering respiratory and lung diseases.
The quantities of microplastics varied considerably between sampling sites but even snow collected from ice floes in the Arctic between Greenland and Svalbard averaged 1,760 particles per litre of melted snow, with one reaching 14,600 particles per litre. The highest concentration of all, 154,000 particles per litre, was in freshly fallen snow from the Bavarian Alps.
However, the levels of contamination in the snow are considerably higher than those found by other researchers on land-based materials such as dust deposits.
Gunnar Gerdts, another member of the research team, gave two possible reasons for this. “First of all, snow is extremely efficient when it comes to washing microplastic out of the atmosphere.
“Secondly it could be due to the infrared spectroscopy we used, which allowed us to detect even the smallest particles down to a size of 11 micrometres.”
The researchers were able to identify a range of different types of plastic in the snow samples. They included polymers from varnishes and paints used to coat buildings, ships, cars and offshore oil rigs; rubber particles from car tyres; fibres from synthetic clothing; and mass-produced plastics, such as polyethylene, PVC, polystyrene and polycarbonate, which are used in myriad consumer and industrial applications.
Although concern over plastic contamination of the oceans has become a huge environmental issue, research into the way microplastics behave on land and in the atmosphere is still in its infancy.
The US Geological Survey recently released data on plastic contamination of rainfall in the Rocky Mountains, but Ms Bergmann said she was not aware of any systematic international study of microplastics in rain rather than snow.