In 2014, scientists clad in thick neon orange suits stepped off a research vessel and visited five different patches of pristine-looking Arctic sea ice. As these researchers discovered, the blinding white ice in the remote north looks awfully pure, but its appearance is deceiving.
After removing cores of ice from the frozen ground, the research team found it contained up to 12,000 tiny to microscopic bits of plastic, some from cigarette filters, some from paint, and others that were degraded pieces of common litter. The amount of plastic found was over double the numbers previously seen in Arctic sea ice.
The research, published Tuesday in Nature Communications, shows that Arctic sea ice doesn't just temporarily trap plastic pollution; the drifting and melting ice cover can also transport this microscopic litter to other oceans, where it melts and enters a new food web.
"In many ways, plastics have stopped surprising us," Jennifer Lavers, a research scientist at the University of Tasmania's Institute for Marine and Antarctic Studies, said in an interview. "We now know that plastics are ubiquitous. They're found from the surface to the deepest depths," she said. Lavers was not involved in the new study.
It's not as if there's been a sudden spike in the amount of plastic particles in the Arctic ocean — it's been accumulating there for decades. Rather, the researchers used a more precise method of observing all the plastic fragments in the ice, even pieces just one-sixth the width of a human hair (11 micrometers).
Scientists taking samples of a melt pond on Arctic sea ice.
Image: Alfred Wegener Institute/ M.Fernandez
This ability to see an unprecedented number of microplastics in the ice was still somewhat eye-opening for researchers.
"Overall we were surprised by these high numbers, although, by using this approach, we discovered plastic particles that were only 11 micrometers across, which might partly explain the extremely high numbers we found," Ilka Peeken, a marine biologist at the Alfred Wegener Institute's Helmholtz Center for Polar and Marine Research and lead author of the study, said in an email.
The researchers used a specialized camera to peer into the sea ice and identify microplastic particles, two-thirds of which were thinner than a human hair. Specifically, the team employed an infrared spectrometer, which involves shooting an invisible type of light (infrared) into the ice sample and then analyzing the wavelengths that bounce back off the particles. Each type of plastic reflects a different "fingerprint" of light, telling scientists what type of plastics were trapped in the ice.
About half the plastics were of the same six types, which included packing materials, a material used to make cigarette filters (cellulose acetate), paints, and nylon.
There were two major sources of microplastic pollution, and the first is well known: the Great Pacific Garbage Patch.
Although it's not so much a "patch" as it is an area with lots of floating litter, it's undoubtedly huge, and growing. The patch is now over twice the size of Texas and is rich in the most common type of plastic, called polyethylene. This sturdy plastic was abundant in some ice floes, so the team suspects these Garbage Patch particles drifted by Alaska through the tempestuous Bering Strait and into the Arctic, where they ultimately froze into the ice.
The German research icebreaker Polarstern traveling through the central Arctic Ocean.
Image: Alfred Wegener Institute/ R.Stein
The paint and nylon particles, though, are believed to come from Siberian seas in the Arctic itself. The paint likely comes from thick-hulled vessels and the nylon from fishing nets. "These findings suggest that both the expanding shipping and fishing activities in the Arctic are leaving their mark," Peeken said.
As the Arctic continues to experience record warmth and historic lows in sea ice cover — both in summer and winter — more of the sea becomes navigable, and accordingly, new shipping lanes open up. This means more shipping traffic — and more microplastic pollution.
The Arctic Ocean is connected to both the Pacific and Atlantic Oceans, as well as regional seas, making the fate of liberated plastics from melting ice a key question for scientists to answer. Peeken suspects the plastics will have various fates.
One of these, she said, is sinking to the sea floor. Algae and bacteria tend to stick to the small plastics, weighing them down. Researchers have already found high concentrations of plastics embedded in sea floors around the world. But this doesn't mean the plastics get sequestered down there for good. Sea creatures commonly eat off the sea floor, so plastics could still enter the food web after sinking.
Or, said Peeken, marine creatures could simply swallow floating plastics after the ice melts, and the plastics could then be incrementally passed up the food chain.
Scientists prepare an Arctic sea-ice core for microplastic analysis.
Image: Alfred Wegener Institute/ T.Vankann
It's clear how large plastic debris harms, and can kill, sea life. In February, for instance, a dead sperm whale washed up onto a Spanish beach. Inside the whale's stomach, scientists found 64 pounds of trash, which they believe caused a deadly internal inflammation.
Microplastics, however, have the potential to harm anything that eats, not just the largest denizens of the ocean.
"Microplastics have opened the floodgates," said Lavers. Everything from tiny, shrimp-like krill to massive whales are now at risk, she said.
"Wildlife has been adapted to identify things in the ocean," said Lavers. "And if they can see it, they can eat it."
It's not fully understood, though, how microplastics might harm marine or human life, said Peeken. So far, the research is inconsistent, and as is common, more needs to be done.
Peeken noted that fish exposed to microplastics have shown behavioral disorders and inflammatory reactions in muscle tissue. But other research showed no effect on marine life, as the small plastics just passed through the animals, she said.
Still, Lavers said this is no excuse to ignore the growing plastic pollution problem. Plastic never goes away, but just continues to break down into smaller pieces. For this reason, even individual actions, like throwing away a plastic bottle, are consequential. That bottle, she said, can become 10,000 imperceptible particles, floating in the sea.
"Just because you can’t see it, doesn't mean it's not there," she said.