Research in the Science Advances journal has published results showing significant deposition of PFAAs from ocean sea spray.

Forever chemicals

Per- and polyfluoroalkyl substances (PFASs) are synthetic organic chemicals found globally in the environment due to their extensive use in various consumer and industrial applications and are often referred to as ‘forever chemicals’. Perfluoroalkyl acids (PFAAs), a subgroup of PFASs, have been detected worldwide in precipitation, often surpassing safety levels for drinking water. Previous studies in the Atlantic Ocean have shown high PFAA concentrations in surface waters of the ocean, decreasing with depth as the chemicals are initially absorbed. Subsequently, these PFAAs are released into the air together with sea spray aerosol (SSA) by bubble bursting.

The new findings were collected from testing ocean samples on a research vessel’s journey from Southampton in the UK to Punta Arenas in Chile in 2019. The results indicate that these substances can become airborne through SSA, and this process may be a significant source of atmospheric PFASs, potentially surpassing other known sources such as direct industrial emissions. The sea spray levels were more than 100,000 times enriched than the relative seawater concentrations. In 2021, it was published that PFASs were found in penguin eggs in Antarctica to polar bears in the arctic. In the examination of the Atlantic Ocean, the authors discovered that the levels of PFASs in the air near the ocean are comparable to levels deposited by other means, suggesting a substantial contribution from the ocean’s spray. The experiments, both in laboratory settings and aboard oceanic vessels, revealed that PFASs have a strong affinity for sea spray particles, particularly larger ones, facilitating their transfer into the atmosphere.

Secondary emission

The authors state “we estimate that the secondary emission of certain PFAAs from the global oceans via SSA emission is comparable to or greater than estimates for the other known global sources of PFAAs to the atmosphere from manufacturing emissions and precursor degradation.”

Ian Cousins, Professor at the Department of Environmental Science and co-author of the study has said “The common belief is that per- and polyfluoroalkyl substances, PFAS, drain from the land into the oceans where they stay to be diluted into the deep oceans over the timescale of decades.”

“But we’ve now demonstrated in multiple studies that there’s a boomerang effect, and some of the toxic PFAS are re-emitted to air, transported long distances and then deposited back onto land.”

The authors note that the presence of natural organic matter in seawater can influence the airborne release of PFASs.

PFASs are found in many household items such as cooking utensils, cleaning products and some hygiene products. The term “forever chemicals” stems from the chemical’s stable and durable nature, making them difficult to remove the environment. Their persistence has also received much attention because of their association with health conditions such as cancers, immune system effects and fertility issues.

Full article: Bo Sha et al., Constraining global transport of perfluoroalkyl acids on sea spray aerosol using field measurements. Sci. Adv. 10, eadl1026(2024). DOI:10.1126/sciadv.adl1026