Record levels of microplastics – most of which are microscopically small – have been discovered in Arctic sea ice, according to a new study published in Nature. Ice samples from the Arctic Ocean contained as many as 12,000 microplastic particles per liter of ice. Now, a team of scientists believe they’ve traced the trash to two origins.
Over the course of three expeditions in 2014 and 2015, the team gathered ice samples from five separate regions along an area that transports sea ice from the Central Arctic to the North Atlantic. An infrared spectrometer, which hits the plastic particles with infrared light and analyzes the different wavelengths reflected back, allowed scientists to identify the makeup and composition of the microplastics. In doing so, the ice showed “heavy contamination”.
“Using this approach, we also discovered plastic particles that were only 11 micrometers across. That’s roughly one-sixth the diameter of a human hair, and also explains why we found concentrations of over 12,000 particles per liter of sea ice – which is two to three time higher than what we’d found in past measurements,” said researcher Gunnar Gerdts in a statement.
Particle densities varied in each sample and were not distributed evenly throughout the core. Using their compositional makeup and location in the ice core, the scientists were able to trace where the plastics came from.
Ice floes in the pacific waters of the Canadian Basin contained particularly high concentrations of a kind of plastic found in packaging material called polyethylene. The researchers believe these plastics are migrating from the “Great Pacific Garbage Patch” after being pushed along the Bering Strait and into the Arctic Ocean.
In the shallow Siberian seas, the scientists found particles from ship paint as well as nylon waste from fishing nets. Here, they suggest expanding shipping and fishing industries are “leaving their mark” in the Arctic.
“We traced back the journey of the ice floes we sampled and can now safely say that both the region in which the sea ice is initially formed and the water masses in which the floes drift through the Arctic while growing, have an enormous influence on the composition and layering of the encased plastic particles,” said researcher Ilka Peeken.
A total of 17 different types of microplastics – tiny particles that slough off of everyday materials – were found in the sea ice, including plastics used in vehicle parts (polypropylene), clothing (nylon), and cigarette filters (cellulose acetate).
“The sea ice binds all this plastic litter for two to a maximum of eleven years – the time it takes for ice floes from the marginal seas of Siberia or the North American Arctic to reach the Fram Strait, where they melt,” said Peeken.
It’s not clear yet whether the plastic particles are released into the Arctic or if they’re transported farther south with ocean currents, but the researchers say it’s entirely possible algae and bacteria colonize the plastic and sink it to deeper waters.