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Microplastics in Arctic sea ice

Microplastics have been found inside tiny bits of algae that live under the Arctic sea ice. That’s bad news. Photos: Environ. Sci. Technol. 2023, 57, 17, 6799-6807

The Inertia

By now, you’re certainly aware of the scourge of plastic we’ve cluttered our planet with. The stuff is everywhere, from our blood to the deepest reaches of the ocean. Well, here’s another place scientists found them: inside algae growing under the sea ice in the Arctic.

It’s estimated that there are somewhere around 170 trillion bits of plastic pollution floating around at sea, and despite our (meager) efforts to stop the bleeding, that number is ticking up every day. Microplastics are tough to get rid of, and they can do weird things to us and other animals, like disrupt hormones and even cross the brain/blood barrier in mice in a handful of studies. The bigger bits have been killing sea life like whales for a long time now, and the problem is getting worse. Although a bunch of whales full of plastic is a little more eye-catching than micro-bits stuffed into algae, the micro-bits in the algae is a very bad sign.

The algae researchers were studying is called Melosira arctica. It’s found, as I mentioned, under the Arctic sea ice, and it’s extraordinarily important. There are a ton of tiny little creatures that rely on it for food. And, since the food chain is exactly what it sounds like, bigger creatures eat those creatures, then bigger ones eat those and bigger and bigger and so on and so forth until they reach us. And those microplastics that are inside the algae? Well, they end up as part of the very long chain.

microplastics in the food chain

Here’s how microplastics work in the food chain that they’re not supposed to be a part of. Graphic: Environ. Sci. Technol. 2023, 57, 17, 6799-6807

The team of researchers that found the plastic-laden algae took samples from the Arctic Circle a few years ago, back in 2021. They were studying how the melting sea ice — which is full of microplastics, too — was affecting the algae in the area. They scooped up some Melosira arctica along with a bit of the sea water it was living in, then took a very close look. What they saw was pretty shocking.


“After analyzing the samples using Raman and fluorescence microscopy, the team found that all of them contained microplastics in concentrations ranging from 13,000 to 57,000 microplastics per cubic meter within the ice algae,” wrote IFLScience. “In the seawater that was also sampled, the concentrations were from 1,400 to 4,500 microplastics per cubic meter. The algae had around ten times more microplastic particles than the surrounding seawater. Of the total microplastic particles that were found, 94 percent of them were 10 micrometers or smaller in size.”

It’s likely that the composition of the algae is what lead to the high number of microplastics.

“The filamentous algae have a slimy, sticky texture, so it potentially collects microplastic from the atmospheric deposition on the sea, the sea water itself, from the surrounding ice and any other source that it passes,” Deonie Allen, who works at the University of Canterbury and Birmingham University, said in a statement. “Once entrapped in the algal slime they travel as if in an elevator to the seafloor, or are eaten by marine animals.”


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