A recent study revealed that approximately 200 million pounds of toxic substances were released into U.S. waterways in 2020. Although per- and polyfluoroalkyl substances (PFAS) make up only 440 pounds of the total released toxics, the report emphasizes that only 172 out of 12,000 PFAS chemicals must be reported to the EPA’s Toxics Release Inventory (TRI). There is a strong likelihood that PFAS chemicals make up a higher concentration of the total released toxics in our waterways.
What are PFAS?
PFAS are a group of synthetic chemicals that are used in common products like non-stick cookware, water-resistant clothing, fire-fighting foam, and carpeting. These chemicals are often referred to as “forever chemicals” as they are nearly impossible to break down. This is due to their carbon-fluorine bond which is the strongest single bond. Chemicals like PFOA, PFOS, and GenX belong to the parent group of PFAS. The production of perfluorooctanoic acid (PFOA) and perfluoro octane sulfate (PFOS) began in the 1940’s with the invention of non-stick cookware. The production of PFOA and PFOS have since been banned once they were discovered to cause a variety of health issues in humans. Despite the ban of PFOA and PFOS, these chemicals are still persistent in the environment and GenX, along with other PFAS chemicals, are still produced and released into the environment today.
There has been a growing concern of the health and safety of PFAS released into the environment. Their persistence in the environment has resulted in concentrations found in drinking water sources across several municipalities in the United States. In a study conducted by the Environmental Working Group, they found that over 2,800 locations documented a PFAS contamination- they further estimate that over 200 million Americans could have PFAS in their drinking water. These substances are incredibly dangerous as they have been linked to illnesses like liver and kidney cancer, fertility problems, immunosuppression, and diabetes.
PFAS in the Environment
As research into PFAS is new, there are a lot of unknowns about their effect on ecological functions. It has been proven that PFAS can bioaccumulate in fish and wildlife as they do in humans. In laboratory settings, animals exposed to PFAS experienced damage to their livers and immune systems, as well as developmental issues in juvenile stages. It can be assumed that wildlife exposed to considerable amounts of PFAS would experience increased mortality rates overtime.
Bioremediation Strategies
As we know, wetland ecosystems function as filters for the environment by trapping sediment and filtering pollutants from surface waters. There are a few emerging reports that have shown the bioremediation of PFAS using microorganisms and vegetation found in wetlands.
Microorganisms:
As mentioned earlier, PFAS are a persistent contaminant due to their carbon-fluorine bond. Researchers Shan Huang and Peter Jaffé discovered the bacterium Acidimicrobiaceae sp. A6, which is found in New Jersey wetland soils, can break this bond through a reaction called Feammox. Over a course 100 days, the microbe had degraded 60% of the PFOA culture and 50% of the PFOS culture. The applicability of this microbe in wetlands could supply an efficient method to control contaminated soils and groundwater.
Vegetation:
Wetland plants show some of the most unique adaptations to survive in an oxygen deficient environment. A few reports have shown how Juncus sarophorus (Broom Rush), Phragmites australis (Common Reed) and Willows (Genus Salix) can control PFAS contamination through phytoremediation. This environmental engineering tactic is often used for removing metals, sewage, and common wastes from the environment. It is worth noting that most of these experiments were conducted in hydroponic systems. The intention of these studies was to analyze the use of these plants in constructed or floating wetland systems for areas with low levels of PFAS. As more research develops on this subject, it would be interesting to see the comparison of phytoremediation rates between floating/constructed wetlands and natural wetlands.
Sources:
Awad, J., Brunetti, G., Juhasz, A., Williams, M., Navarro, D., Drigo, B., Bougoure, J., Vanderzalm, J., & Beecham, S. (2022). Application of native plants in constructed floating wetlands as a passive remediation approach for PFAS-impacted surface water. Journal of Hazardous Materials, 429. Retrieved from https://doi.org/10.1016/j.jhazmat.2022.128326
HMVT Environmental Solutions. (n.d.). Treatment of PFAS in a constructed wetland using willows. HMVT Environmental Solutions. Retrieved from https://www.hmvt.nl/en/news/treatment-of-pfas-in-a-constructed-wetland-using-willows/
Huang, S. & Jaffé, P. (2019). Defluorination of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS) by Acidimicrobium sp. Strain A6. Environmental Science & Technology, 53, 11410-11419. Retrieved from http://pubs.acs.org/doi/abs/10.1021/acs.est.9b04047
Rumpler, J., Casale, M., Dutzik, T., & Huxley-Reicher, B. (2022). Wasting our waterways: Toxic pollution and the unfulfilled promise of the Clean Water Act. Environment America Research and Policy Center. Retrieved from https://environmentamerica.org/center/resources/wasting-our-waterways/
Zhu, J., Wallis, I., Guan, H., Ross, K., Whiley, H., & Fallowfield, H. (2022). Juncus sarophorus, a native Australian species, tolerates and accumulates PFOS, PFOA and PFHxS in a glasshouse experiment. Science of The Total Environment, 826. Retrieved from https://doi.org/10.1016/j.scitotenv.2022.154184