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Forever chemicals are released from sea spray

New research suggests that taking a long, deep breath of sea air while standing on the beach may not be such a good idea. When ocean waves break, they release not only aerosolized salts but also other “forever chemicals” that start off dissolved in the seawater and may be far more dangerous. 

The study, published by the American Chemical Society, finds that perfluoroalkyl substances (PFASs) in seawater could become airborne as bubbles pop at the water’s surface, enabling them to enter the atmosphere and travel inland.

PFASs, which include perfluoroalkyl acids (PFAAs), are potentially harmful organic contaminants that were used in industrial processes, food packaging, personal care products and water-repellent coatings. Although their use has been banned in some countries, these compounds are now found worldwide in the atmosphere, in oceans and in living organisms, including humans. PFASs don’t break down easily, which is why they are often referred to as forever chemicals.

A previous study of the transport of PFAAs from seawater into the atmosphere showed that, when bubbles containing PFAAs burst at the surface of saltwater, these persistent compounds are ejected as aerosols – extremely small airborne particles. The study predicted that these contaminants could potentially be transported long distances inland via this process. However, there was no evidence of this from field studies. 

This led the authors of the current study to conduct observations at two coastal locations in Norway, to determine whether PFASs originating in sea spray, were being transported inland. 

They collected more than one hundred 48h aerosol samples between 2018 and 2020, and analyzed these for the presence of 11 different PFAAs, including the possible carcinogens perfluorooctanoic acid and perfluorooctane sulfonic acid. They also tested the air samples for sodium ions (Na+) which are considered to originate in sea spray and therefore indicate that the PFAAs were indeed associated with sea spray aerosols. 

The researchers detected the contaminants in all of the air samples collected. In addition, the levels of individual PFAAs were strongly correlated with the presence of tracer sodium ions, indicating that these organic contaminants were coming from coastal waters and were leaving the ocean with sea spray and travelling inland. The correlations were stronger in the samples from the site at Andøya than they were for Birkenes, which is located further away from the coast. 

The researchers calculated, using their field measurements, that for eight of the PFAAs, there could be 284 to 756 U.S. tons of forever chemicals released globally from the oceans to the air each year, which is higher than previous estimates. 

Based on their field measurements, the researchers conclude that sea spray is an important source of this class of PFASs to coastal communities. They add that because sea spray can travel far distances inland, this is also likely to be a route for PFASs to be transported, and potentially return, to terrestrial regions from the ocean.

The study is published in the ACS journal Environmental Science & Technology.

By Alison Bosman, Staff Writer

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