Contaminated groundwater in parts of North Carolina may take more than 40 years to flush out harmful chemicals known as PFAS, according to a recent study from North Carolina State University. The findings highlight the persistent threat posed by per- and polyfluoroalkyl substances (PFAS) in Cumberland and Bladen counties, with significant implications for residents and ecosystems reliant on local water sources.
The study, published in Environmental Science & Technology, used a combination of groundwater sampling, age-dating tracers, and groundwater flow models to predict the longevity of PFAS contamination in groundwater that discharges into tributaries of the Cape Fear River. This water source supplies both private wells and public water systems downstream, particularly in and around Wilmington.
Study Findings: PFAS in Groundwater Up to 43 Years Old
The researchers collected groundwater samples from two watersheds near the Fayetteville Works fluorochemical plant, a facility associated with PFAS contamination. Testing revealed that groundwater contained PFAS as old as 43 years. Concentrations of two common PFAS chemicals, hexafluoropropylene oxide-dimer acid (HFPO−DA) and perfluoro-2-methoxypropanoic acid (PMPA), were especially high, averaging 229 nanograms per liter (ng/L) and 498 ng/L, respectively.
For context, the U.S. Environmental Protection Agency (EPA) has set a maximum contaminant level (MCL) of 10 ng/L for HFPO-DA in public drinking water, meaning the detected levels are far above what is considered safe.
The Long-Term Threat to Groundwater and Surface Water
David Genereux, a professor at NC State and the study’s lead researcher, emphasized the scope of the problem. “There’s a huge area of PFAS contaminated groundwater—including residential and agricultural land—which impacts the population in two ways,” he explained. Over 7,000 private wells in the area are affected, meaning thousands of people may be using water tainted with these chemicals.
Additionally, PFAS-contaminated groundwater discharges into tributaries of the Cape Fear River, further spreading the chemicals downstream. This not only poses a risk to local well users but also to residents in Wilmington and surrounding areas who rely on the river for drinking water.
Modeling PFAS Persistence: A Multi-Decade Problem
The study’s modeling efforts forecast that natural groundwater flow alone will take decades to flush out the PFAS currently present in the system. The “high emission years” of PFAS contamination, which the researchers define as the period from 1980 to 2019, left significant levels of the chemicals in the soil and groundwater. As Genereux noted, “It could take decades for natural groundwater flow to flush out groundwater PFAS still present from the ‘high emission years.'”
Moreover, this timeline could be even longer if PFAS chemicals are trapped in clay layers or other low-permeability areas underground, slowing their movement toward surface water. The research suggests that even in a best-case scenario where no new PFAS enters the environment, the contamination from past decades could persist in the groundwater for another 40 years.
Air Emissions and Ongoing Contamination
While air emissions of PFAS have significantly decreased since 2019, they have not stopped entirely. The researchers suggest that ongoing atmospheric deposition, although much reduced, could still be contributing to the PFAS levels in groundwater. This means the contamination may not just be a legacy problem but one that continues to evolve, albeit at a slower pace.
Future Directions: Impact on Private Wells and Health Outcomes
Looking ahead, the research team plans to refine their models to better predict future PFAS levels in individual drinking water wells. They also hope to work with toxicologists to examine how past PFAS exposure correlates with health outcomes in affected communities. This could help clarify the long-term health risks posed by PFAS contamination and guide mitigation efforts.
Conclusion: A Slow Path to Recovery
The NC State study underscores the complexity of dealing with PFAS contamination, which has already seeped deep into the groundwater and will continue to affect water quality for decades to come. With high levels of these chemicals found in both private wells and water discharging into tributaries, the people of Cumberland and Bladen counties—and those downstream—are likely to face a prolonged challenge in managing this contamination.
Reverse Osmosis and Water Conditioners: Solutions for PFAS-Contaminated Water
For homeowners in contaminated areas, reverse osmosis (RO) filtration systems offer a reliable way to remove PFAS from drinking water. These systems force water through a semi-permeable membrane, effectively filtering out most contaminants, including PFAS. Whole-home water conditioners, while not specifically designed for PFAS, can also help reduce other impurities and protect household plumbing from corrosion, offering an additional layer of protection for water quality. In areas with severe PFAS contamination, a combination of reverse osmosis and whole-home water conditioners may be necessary to safeguard against health risks.
Source: Phys.org
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