Groundwater impacted by fire-fighting foams

Fires resulting from plane crashes are fought using aqueous film-forming foams (AFFF) that are formulated to act quickly by spreading a film of water over the burning fuel that subsequently extinguishes the fire. The first evidence that these foams later contaminate groundwater is scheduled to appear in the August 15 issue of the peer-reviewed journal Environmental Science & Technology, published by the American Chemical Society, the world's largest scientific society.

Until now, the fate of AFFF released to the environment at fire-training facilities and emergency response sites was unknown, says Jennifer A. Field, Ph.D., of Oregon State University. Commercial AFFF mixtures are proprietary in nature, Field says, but they are known to contain fluorocarbon- and hydrocarbon-based surfactants. Field developed an analytical method for measuring the amount of perfluorocarboxylated surfactants in ground water, and then monitored groundwater at military bases in Florida and Nevada that had fire-training facilities which were no longer in use. Concentrations were detected at these sites ranging from 0.1 to 7.1 parts per million. Samples with some of the higher concentrations actually foamed.

Unfortunately, Field notes, the stability of the fluorocarbon surfactants that makes them good choices for high-temperature applications such as fire-fighting has the negative effect of making them resistant to degradation in the environment. The components measured are thought to be only minor components of the original fire-fighting foams, so that the actual amount of fluorinated constituents of AFFF in contaminated groundwater is likely much higher, according to Field.

The work is the first to detect the AFFF components in groundwater, but virtually nothing is known about their behavior in the environment, she says. The surfactants associated with fire training activities may also occur with other pollutants, such as fuel components and solvents, so the AFFF surfactants may affect the transport and biodegradation of other contaminants.

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