Although plastic bottles and bags can travel far and cause environmental damage, it’s the microplastics -- tiny particles sometimes too small to see -- that have invaded every corner of the planet.
Marine biologist Melanie Bergmann of the Alfred Wegener Institute, in Germany, first started noticing an alarming increase in plastic and other pollutants on the Arctic Ocean floor about a decade ago. Since then, she and her team also found that the amount of microplastics in the Arctic seafloor has increased as much as 23-fold in 12 years.
Since then, one question has remained in her mind: How do all these microplastics make it so far north? To answer that question, she looked at snow.
Snow can trap particles in the atmosphere as it forms, so microplastics in snow may indicate a windblown origin. Bergmann and her team collected snow from floating ice sheets in the Fram Strait -- a passage between Greenland and Svalbard -- during polar expeditions from 2015 to 2017. For comparison, they also collected fresh snow in the Alps and urban areas in Europe. In the lab, they thawed the samples, filtered the water and studied the size and materials using a highly accurate imaging technique.
The scientists found microplastics smaller than 100 microns in all but one of the 22 one-liter samples. Snow near urban places or roadways contained the highest number of microplastic particles (154,137 in one sample from the Bavarian Alps), but samples from the Arctic also contained a significant number of them (as high as 14,400 in one). Although Bergmann expected some microplastics to show up in the Arctic snow, “I did not expect such high numbers,” she said.
Scientists have also found microplastics in the air of cities in India, China and France, and in the French Pyrenees mountain range. Other studies have found that other particles, such as pollen, can reach the Arctic through the air. So, it makes sense that the microplastics Bergmann and her team found were transported to the north through wind currents. “I'm sure that they come from the atmosphere,” she said.
The new study adds to the mounting evidence that microplastics are now ubiquitous, which "makes me sad," Bergmann said. She thinks much more research needs to be done to understand the pollutants' effects on wildlife, our food and our own health.
“I do wonder why people don't worry,” she said. “This is where we live.”
The scientists described their findings in a paper published online today in Science Advances.