Per- and Polyfluoroalkyl Substances From Firefighting and Domestic Wastewater Remain in Groundwater for Decades Completed

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Contamination of groundwater resources by organic and inorganic chemicals is an issue of national importance because groundwater sources provide drinking water supplies for millions of people in the United States. Poly- and perfluoroalkyl substances (PFASs) are commonly present in the environment because of their widespread use in consumer and industrial applications, such as protective coatings, and as a major component in aqueous film-forming foams. PFASs are widespread groundwater contaminants because they are highly mobile and resistant to microbial and chemical degradation once released into the environment. Understanding how PFASs get into groundwater and how they move in the subsurface is important for understanding human exposure through drinking water consumption.

To address this need, a study was done at the U.S. Geological Survey (USGS) Cape Cod Toxic Substances Hydrology research site on western Cape Cod, Massachusetts, to provide a field-based approach to understand the persistence and transport of PFASs from two independent sources. The sources included a fire training area where foams were used to extinguish fuel fires and infiltration beds where secondarily treated domestic wastewater was applied. A total of 148 groundwater samples and 4 sediment cores were collected from multiple locations along a 1,200-meter-long transect oriented in the direction of the groundwater flow at the study site. Samples were analyzed for a mixture of PFASs by using liquid chromatography-tandem mass spectrometry.

The relative contribution of the two independent PFAS sources was characterized by using state-of-the-science analytical measurements and visualization techniques to examine the PFAS distributions in the complex, overlapping groundwater contamination plumes. Although the fire training area was decommissioned about 30 years ago (1985) and remediated in 1997, and the wastewater facility was decommissioned about 20 years ago (1995), both sites continue to be sources of PFASs to the groundwater.

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This research provides techniques to characterize the fate and transport of the PFASs in plumes emanating from two different types of sources that are widely distributed on the landscape. PFASs have been reported to have a variety of adverse health outcomes, leading the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Understanding the fate and transport of PFASs in groundwater allows water resource and public health managers to identify the risk and minimize exposures of populations to toxic contaminants.

Funding for this joint USGS and Harvard University study was provided by the USGS Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology), the Massachusetts Water Resources Research Center (11 006501 H 01), the William F. Milton Fund, the Harvard Graduate Consortium on Energy and Environment , the John A. Paulson School of Engineering and Applied Sciences TomKat Fund, and the Harvard National Institute of Environmental Health Science Center Grant (P30ES000002).