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Polyfluoroalkyl and perfluoroalkyl (PFAS) substances are known as “permanent chemicals” because they do not break down naturally in the environment. Today, a new study reveals that the increasing rate of melting Arctic ice is leaking more of these chemicals into the environment.
PFAS are not native to the Arctic, but they are settling there – they are used in all kinds of man-made products and processes, from pizza boxes to the mousse used to fight fires. . Once released into the atmosphere, they are often trapped in arctic sea ice.
This is nothing new. But in a disturbing new study by chemists at Lancaster University in the UK, it appears that the concentrations of PFAS in bulk sea ice are closely related to the salinity of the water. So the brighter the sea, the more concentrated these permanent chemicals.
The problem is as the planet heats up, the melting and freezing cycles form pockets of very salty seawater, packing the PFASs in tiny pools. Eventually, these highly concentrated chemicals are released into the general circulation.
“The changing nature of sea ice, with earlier and more erratic thaw periods, could alter the processing and release of pollutants alongside key nutrients, which in turn affects the biota at the base of the food chain. marine, “says environmental chemist Crispin Halsall of Lancaster University in the UK.
PFAS are known to be toxic to humans and animals, which is why their release into the food chain is of such concern. Previous studies have linked them to problems such as liver damage and problems with fetal growth.
Previous research had shown that the concentrations of PFAS in surface seawater near melting arctic sea ice were up to twice as high as comparable readings taken in the North Sea.
According to another study published recently, it appears that many of these chemicals arrive via snowfall above the ice.
To study in more detail how these chemicals are likely to be released, the team used an artificial sea ice chamber to conduct controlled experiments that measured the movement of chemicals between water and ice during the phase changes.
Initially, when the ice melts, the water carries a large percentage of the salts dissolved in it.
The team found that not only did this portion also contain a large amount of PFAS, but that it was largely made up of shorter-chain varieties. Later, when the melt water was cooler, the PFAS chains were a bit longer.
Long periods of thaw in the Arctic release this brine and cause it to mix more regularly with snowmelt water – perhaps the source of these increased concentrations of contamination, the researchers say.
The problem is, we now see the Arctic Ocean dominated by one-year-old ice – replacing the older ice that has formed over many years. This young ice contains a lot of mobile brine which can interact with snow and further concentrate PFAS contaminants.
And this is an immediate problem for organisms in direct contact with ice – organisms at the bottom of the Arctic food chain – which often nibble the brine channels of the pack ice to which they are connected, and will now be exposed to more of them. . chemical.
The study is part of the Effects of Ice Stressors and Pollutants on the Arctic marine Cryosphere (EISPAC) project, led by organizations from the UK and Germany. The team calls for further restrictions on the use of PFAS in the future.
“More controlled experiments, as well as careful observational field studies, are now needed to understand these complex but potentially important processes, particularly with respect to chemical exposure to organisms at the base of the marine food web.” , conclude the researchers.
The research was published in Environmental sciences and technologies.
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