Very persistent pollutants in the environment are concentrated in the Arctic, before being released abundantly due to warming. It is a vicious circle between pollution and climate change.
« Chemical pollutants and plastic debris are present in the Arctic Ocean and can be carried into the pack ice “, Recalls Crispin Halsall, a chemist specializing in the environment. With ten other scientists, she is the author of a study published in June 2021 in Environmental Science & Technology and detailed in July 2021 on the Changing Artic Ocean website, at the origin of this research project.
This study focuses on certain types of pollutants in particular: per- and polyfluoroalkylated substances, called PFAS. They are nicknamed “eternal chemicals”, and more formally, they are referred to as persistent organic pollutants. The molecules constituting these substances form a carbon-fluorine bond, one of the strongest in all organic chemistry. Not only are they not biodegradable, but they also have a very long lifespan in the environment.
In the recently published study, the research team explains that these products are “leaking” from the Arctic. This is explained by an environmental vicious circle.
The vicious circle of the circulation of pollutants
PFAS is found in many everyday products to waterproof or fireproof everyday objects or foods. They are found for example in packaging used by fast food, in paints, in certain industries. Overexposure to these pollutants can be harmful to health, and this affects both humans and animals.
The problem is, PFASs tend to leak heavily into the environment: through water or by spilling into the atmosphere before releasing. And the vicious circle is already starting on this point, because this is how fish or food can be exposed to it, before being themselves then consumed by humans.
But another vicious circle is taking place, and it is playing out in the Arctic. PFAS found in the waters tend to concentrate in this region, possibly due to vertical circulation of these products in the ocean. And since PFAS can also be in the atmosphere, snowfall also appears to drop these substances onto arctic sea ice.
Work published in 2021 and led by Crispin Halsall shows that the concentration increases as the salinity of the water increases. Except that climate change involves global warming, which has an impact on the cycles of freezing and thawing of the sea ice, and this disturbance causes particularly salty pockets. Indeed, with warming, there is more “young snow”, which contains more mobile brine (salt). The ” changing nature of sea ice “, with some ” earlier and more irregular thaw periods », Therefore causes areas highly concentrated in salt and pollutants, which are abundantly released during melting.
First of all, this poses a local and immediate problem. These famous pockets release their brine, which contains nutrients that nourish many species at the very base of the region’s marine food chain. But these nutrients now come with the pollutants also released, which are much more concentrated there. The organisms at the base of the chain therefore consume the PFAS, before being themselves consumed by other species, and so on.
As the environmental impact of PFAS becomes clearer, the need for more stringent regulation of these pollutants appears more and more urgent.
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