Little things add up. Look no further than the Arctic: A new study shows that ice samples from the Arctic Ocean contain 12,000 microplastic particles per liter of sea ice, the highest measurement ever taken.
“During our work, we realized that more than half of the microplastic particles trapped in the ice were less than a twentieth of a millimeter wide, which means they could easily be ingested by arctic microorganisms like ciliates, but also by copepods,” says Alfred Wegener Institute (AWI) biologist Dr. Ilka Peeken in a press statement. Copepods are small crustaceans crucial to the underwater food chain, a meal of choice for whales, Alaska pollock, and even other small crustaceans like krill.
Onboard the research vessel Polarstern in the spring of 2014 and the summer of 2015, AWI scientists looked at five different regions of Arctic. They found thousands of pieces of microplastic, a term used to refer to pieces of plastic under five millimeters, or 0.196 inches.
Microplastic gets distributed in a number of ways. It's often released directly into the ocean through the gradual breakdown of larger pieces of plastic, but it can also be released as dust on land. When car tires burn, for example, the dust is filled with pieces of microplastic that can eventually find their way to sea.
To detect microplastic, the AWI researchers relied on a piece of tech known as a Fourier Transform Infrared Spectrometer (FTIR). When infrared radiation passes through a sample, some radiation is absorbed by the sample and some is transmitted. The FTIR then produces a signal, and that signal represents a molecular fingerprint. Particles absorb different wavelengths, so every single piece of microplastic has a unique fingerprint.
“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,” says Gunnar Gerdts, in whose laboratory the measurements were carried out. To their surprise, the scientists found that two-thirds of all particles detected belonged to what they deemed "the smallest of the small": 50 micrometers or less (0.0019 inches).
As for the source, AWI found 17 sources of microplastic. The big contributors were packaging materials like polyethylene and polypropylene, paints, nylon, polyester, and cellulose acetate, primarily used in the manufacture of cigarette filters. Taken as a group, these sources contribute to approximately half of all microplastic in the Arctic.
Peeken says that “no one can say for certain how harmful these tiny plastic particles are for marine life, or ultimately also for human beings.” But they represent a confusing threat to the base of the food chain and when taken in tandem with recent Arctic heatwaves, it's safe to say that the less plastic in the ocean, the better.
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