Up to 12,000 particles per litre, most small enough for tiny marine organisms to eat, researchers find
The new study suggests that when the Arctic sea ice melts, it will release large amounts of plastic into the Arctic Ocean. (Stefan Hendricks/Alfred Wegener Institute)Alfred Wegener Institute scientist Julia Gütermann, a co-author of the new study, analyzes an Arctic sea ice core for microplastic particles. (Tristan Vankann/AWI)
The concentrations in the ice are hundreds of times higher than any found in seawater so far, even though the researchers didn’t include microfibre particles in their counts, said lead author Ilka Peeken. However, part of that may be that in this study, the researchers measured particles as small as a sixth the width of a human hair — smaller than in previous studies, Peeken said.
Most of the particles are small enough to be eaten by the little marine organisms that live in sea ice, suggesting that high concentrations of microplastics could potentially be entering the Arctic food chain.
The researchers collected five ice core samples over the course of three expeditions aboard the icebreaker Polarstern.(Rüdiger Stein/Alfred Wegener Institute)
“That would also get further up the food chain. That’s why it’s important to know we have small particles there,” Peeken said, adding that the potential health risks are unknown.
The study also suggests that when the ice melts, it will release large amounts of plastic into the Arctic Ocean.
The researchers collected five ice core samples over the course of three expeditions aboard the icebreaker Polarstern.
The highest concentrations of microplastics, about 12,000 particles per litre, were found in an ice floe from the Makarov basin, which is thought to contain frozen water that originated in the northeast Pacific ocean.
That sample contained almost exclusively polyethylene, the plastic found in plastic bags, bottles and packaging, and the researchers suggest that it likely originated from the Great Pacific Garbage Patch, a floating aggregation of 79,000 tonnes of plastic garbage over a 1.6 million square kilometres.
Peeken says not only is it the most common plastic produced worldwide, but it’s also very light.
“I think a lot of other particles might eventually sink in the water column, but this particular one has the tendency to stay afloat.”
A 2009 image provided by the Scripps Institution of Oceanography shows a patch of sea garbage at sea in the Pacific Ocean. That garbage patch is thought to be where a lot of the plastic in the Arctic sea ice comes from.(Mario Aguilera/Associated Press)
Ice floes containing water from Siberia tended to contain more paint from ships and nylon from fishing gear, the study found. That could point to an increase in local sources of plastic as climate change causes the sea ice to melt and opens the Arctic ocean to more ships and fishing.
The researchers are hoping to do a similar analysis on older ice cores to see if the amount of plastic has grown over the past decade, said Peeken.
The samples were collected in Transpolar Drift and the Fram Strait and near northeast Greenland.(Mar Fernandez)
Because there’s no standardized method for measuring microplastics yet, she added, it’s hard to compare different studies at the moment.
However, what’s consistent is the evidence that microplastics from cities far south are being carried by ocean currents and sea ice into the remote Arctic.
“We now know that we have a lot of this human imprint in areas where it certainly doesn’t belong,” Peeken said.
She hopes the research pointing to the routes the plastic is taking will help lead to ways to stop it, through methods like cutting back on the use of plastic and possibly banning certain kinds of plastic products.
“I think it’s important that we change our plastic behaviour and really reduce our plastic imprint.”
Emily Chung covers science and technology for CBC News. She has previously worked as a digital journalist for CBC Ottawa and as an occasional producer at CBC’s Quirks & Quarks. She has a Ph.D. in chemistry.