The study sheds light on how PFAS ‘forever chemicals’ travel through groundwater.

A family of chemicals that have been used for decades to improve our lives – from non-stick pans to waterproof clothing – are now known as “permanent chemicals” because they don’t break down easily in our environment and pose potential health risks when they build up in our health. Bodies. A new study could improve our understanding of how these chemicals move through groundwater, a team of scientists says.

“These chemicals called PFAS (per- and polyfluoroalkyl substances) are so important that they’ve been used everywhere,” said U.S. Geological Survey researcher Cale Jahn, a doctoral candidate at Penn State. . “Unfortunately, at the small molecular level, they don’t just break down in the natural environment. If they’re released, they can hang around and accumulate in fish and other animals and eventually in us.”

The scientists studied the chemical perfluorooctanesulfonic acid (PFOS) that seeped into groundwater near a former firefighter training center in Center County, Pennsylvania. PFOS is a common ingredient in firefighting foams, and has been used in fire training for decades. At the time, the chemical was not regulated.

PFOS molecules are hydrophobic and bind to organic carbon, and differences in organic carbon in bedrock aquifers can affect concentrations of the chemical in groundwater, the scientists reported in the journal. Ground water.

“Kale’s work highlights the importance of modeling the transport of PFOS and similar compounds in groundwater,” said Kathryn Freeman, professor of geosciences at Ivan Pugh University and Penn State’s Jan advisor, co-author of the paper.

On-site remediation began in the 1990s, and groundwater monitoring has occurred since 2000, including measurements for PFAS and PFOS since 2015.

In the year Data collected between 2015 and 2018 show two concentrations of PFOS in groundwater – one near the training site and another far away, with smaller concentrations between the two hotspots, the scientists said.

Jan said: “It’s interesting that Plum seems to have two ends. “Our goal was to try to figure out what caused that plume to split. It’s often difficult to answer exactly what’s going on in the subsurface. You don’t always get a perfect picture.”

Physical measurements from the site are not responsible for dividing changes in the water table or hydraulic conductivity, how fast water moves underground.

However, the scientists said that the bed samples have a wide variation in organic carbon content. PFOS molecules bind easily to organic carbon and other minerals, so higher levels of contamination can exist in areas with more organic carbon.

“What makes PFAS unique — what makes them important — is their chemical structure, and that’s what makes it difficult to predict their behavior in the environment,” Jahn said. “Pretty much all PFAS are hydrophobic – part of their molecular structure prevents them from being in water, and as a result they bind to organic materials.”

Finding differences in organic carbon or other mineral deposits at the site of a PFAS spill or exposure can help responders better understand where the contamination is concentrated and where to conduct further investigation, the scientists said.

“We’re really trying to limit how much PFAS can escape into the environment, but once it gets there, we have to understand the complexities of limiting its movement with the limited data we collect,” Jahn said. . “This work can give people a starting point to think about pollution elsewhere.”