Researchers from North Carolina State University used historical and current pine needle samples to trace the presence and concentrations of over 70 different types of PFAS in six N.C. counties from 1961 to the present. The findings are a snapshot of the evolution of PFAS in the state over a 50-year period. Why pine needles?
“They’re everywhere in the state and free, so it’s very easy to sample numerous locations and time points without having to build and retrieve expensive sampling equipment,” says Erin Baker, associate professor of chemistry at NC State and co-corresponding author of the work.
As for the needles themselves, the waxy coating that protects them from the elements also acts as an efficient trap for airborne contaminants such as PFAS. And since pine trees drop their needles on an annual schedule, researchers can be certain about the points in time they’re looking at when they take samples.
Baker, NC State colleague Scott Belcher, and Ph.D. candidate and lead author Kaylie Kirkwood obtained 60 pine needle samples from sites in Durham, Wayne, Cumberland, Robeson, Onslow and Brunswick counties.
For historical comparison, they used 15 pine needle samples from the NC State and Duke University herbaria, looking specifically at samples from those same counties dated from 1961 to the present.
“We were focused primarily on locations we have modern data for, as well as locations that are associated with PFAS, like airports, firefighter training sites and chemical plants like the Chemours facility,” says Belcher, an associate professor of biology at NC State and co-corresponding author of the research. “We took samples at those sites and at sites three to 11 miles away for comparison.”