A new study from Brown University found how pollutants in firefighting foams are distributed in water and surface soil. This could help researchers better predict how pollutants spread from spill and release sites and make their way into drinking water.

Firefighting foams are made of an aqueous film-forming foam (AFFF). They are used to combat fires fueled by highly flammable liquids, like jet fuel. There is a range of per- and polyfluoroalkyl substances (PFAS), including PFOA, PFOS, and FOSA. These substances are linked to cancer, developmental problems and other conditions. PFAs are also known as “forever chemicals” because they are difficult to break down and can lead to long-term contamination of soil and water supplies.

The team wanted to predict how long it will take for PFAS chemicals to reach a body of water or drinking water and how long that body of water will need to be treated to remove the contaminants.

Previous research found that PFAS chemicals tend to accumulate at the interfaces between water and other substances. For example, near the surface of water, PFAS tend to collect at the air-water interference. Prior experiments have shown that this interface activity is only conducted with individual PFAS compounds, but not mix compounds, like firefighting foams.

During their study, the team used a series of lab experiments which proved that firefighting foam mix does behave differently than individual compounds. The foams had a greater affinity for air-water interface than individual compounds. This was two times the interface activity of PFAS alone. This discovery could help researchers model how PFAS compounds migrate from contaminated sites.

The team wanted to come up with basic equations to describe the behavior of compounds in the lab and incorporate those equations into models and apply them in the field. The team’s work so far is the beginning of that process. Researchers hope that this leads to a better understanding of fate and transport of compounds that identify well and waterways that are at risk for contamination and aid in cleaning sites up.

This research was published in Environmental Science and Tech.