Perfluoroalkyl substances in a firefighting training ground (FTG), distribution and potential future release

Area of Science:

• Environmental Chemistry
• Contaminant Fate and Transport

Background:

• Firefighting training grounds (FTGs) are significant sources of per- and polyfluoroalkyl substances (PFASs) due to the historical use of aqueous film forming foams (AFFF).
• Understanding the distribution and long-term release of PFASs from these sites is crucial for environmental risk assessment.

Purpose of the Study:

• To investigate the occurrence, distribution, and fate of various PFASs at a contaminated FTG.
• To assess the potential for PFASs to leach from concrete structures into the environment.
• To model the long-term persistence and release kinetics of key PFASs.

Main Methods:

• Sampling and analysis of 15 PFASs and one fluorotelomer sulfonate in concrete from a contaminated FTG.
• Assessment of spatial and vertical distribution of PFASs within the concrete structure.
• Field-based kinetic desorption experiments for PFOS, PFOA, and 6:2FTS.
• Application of a kinetic model incorporating desorption data and estimated rainfall/runoff.

Main Results:

• Perfluorooctane sulfonate (PFOS) was the dominant PFAS on the surface (10–200 μg g⁻¹).
• PFASs were detected up to 12 cm deep in concrete cores, indicating vertical migration, with shorter chains showing higher transport potential.
• Estimated mass load of linear PFOS was over 300 g, totaling 1.7 kg for all analyzed PFASs on the pad.
• Desorption kinetics suggest PFOS release half-life of 25 years, indicating long-term contamination.

Conclusions:

• Contaminated FTG pads act as persistent reservoirs for PFASs.
• The concrete matrix facilitates vertical transport of PFASs, with shorter chains migrating more readily.
• PFASs, particularly PFOS, will continue to be released from these structures for many decades, necessitating long-term management strategies.