Record microplastic rate in the Arctic Ocean
Researchers have found up to 12 000 particles per liter frozen in the pack ice.
THE WORLD 25.04.2018 By Sylvie Burnouf
Up to 12 000 microplastic particles per liter: the figure is so huge that we can hardly believe it, but this is what researchers from the Alfred-Wegener Institute found for polar and marine research (AWI, Germany) by melting sea ice samples taken from the Arctic zone.
On board the Polarstern, their ice-breaking research vessel, they conducted three expeditions between 2014 and 2015, collecting ice cores along the transpolar drift (a major ocean current in the Arctic) and the Strait of Fram (at the junction between the central Arctic and the North Atlantic) to characterize the content and composition of microplastics.
Their results, published in the 24 April in Nature Communications, are staggering: none of the five areas analyzed were virgin contaminants. Like frozen cocktails, ice packs contained residues of seventeen kinds of plastics, including polyethylene and polypropylene (used especially in packaging), paint, cellulose acetate (from cigarette), nylon and polyester. With a total of 1 100 12 000 microdebris per liter of chilled water - rates well above those found elsewhere, although some methodological differences limit direct comparisons.
Seventh continent
These particles were carried there by the sea currents, explain the researchers. And, "With global plastic production around 300 million tonnes per year, it's no wonder there's no more spared area," says Johnny Gaspéri, lecturer at the Water, Environment and Water Laboratory. urban systems (LEESU, University Paris-Est-Créteil).
The pack ice then accumulates, whether at the beginning of its formation or when it expands as it drifts with the arctic currents. In fact, depending on the sampling zone, the composition in microplastics varied, and their provenance also. Using satellite data coupled with thermodynamic ice-pack formation models, biologists were able to trace the path of their samples and identify potential sources of pollution.
For example, the high levels of polyethylene observed in some areas of the Arctic could, they say, come from the seventh continent, the gigantic mass of plastic floating in the Pacific Ocean. As for the paint and nylon residues, it appears that they result from local pollution linked to human activity - in particular from the decomposition of the painted hulls of boats and fishing nets - suggesting that the development of these activities in the Arctic "leaves traces", according to the terms of Ilka Peeken, the first author of the study.
If microplastics are defined by a size smaller than five millimeters, two-thirds of those taken during expeditions of the Polarstern measured at most one twentieth of a millimeter. "This means that they could easily be ingested by Arctic microorganisms, such as ciliates or copepods [the major component of zooplankton]," says Ilka Peeken.
What are the environmental and health impacts? Research on the subject is in its infancy. For now, "no one can say for sure how tiny these plastic particles are likely to be dangerous to marine life, any more than one can know for humans," says Ilka Peeken.
However, complete Françoise Amélineau, biologist at the Littoral Institute Environment and Societies (LiEnSs, University of La Rochelle), we know that "plastics tend to fix pollutants" and that there is a phenomenon of "biomagnification" by which the concentration of pollutants increases at each stage of the food chain. Especially since the "frozen" microplastics do not remain trapped in the pack ice: they end up being released after a few years. With, in one way or another, a probable return to our countries.
http://www.lemonde.fr/pollution/article ... 52666.html