PFASが地下水から除去されるまで40年以上かかる可能性(It Could Take Over 40 Years for PFAS to Leave Groundwater)

2024-10-10 ノースカロライナ州立大学(NCState)

＜関連情報＞

• https://news.ncsu.edu/2024/10/it-could-take-over-40-years-for-pfas-to-leave-groundwater/
• https://pubs.acs.org/doi/10.1021/acs.est.4c06697

PFAS製造施設付近の河川に排出される地下水中のPFAS濃度の予測と推定 Forecasting and Hindcasting PFAS Concentrations in Groundwater Discharging to Streams near a PFAS Production Facility

Craig R. Jensen,David P. Genereux,D. Kip Solomon,Detlef R. U. Knappe,and Troy E. Gilmore
Environmental Science & Technology  Published: September 25, 2024
DOI:https://doi.org/10.1021/acs.est.4c06697

Abstract

Per- and polyfluoroalkyl substances (PFAS) are known to be highly persistent in groundwater, making it vital to develop new approaches to important practical questions such as the time scale for future persistence of PFAS in contaminated groundwater. In the approach presented here, groundwater from beneath streambeds was analyzed for PFAS and age-dated using SF₆ and ³H/³He. The results were coupled with groundwater flux measurements in a convolution approach to estimate past and future PFAS concentrations in groundwater discharge to the streams. At our test site near the Cape Fear River (CFR) of North Carolina, PFAS were detected in groundwater up to 43 years old, suggesting that some PFAS entered groundwater immediately or shortly after fluorochemical production began at the nearby Fayetteville Works. Results are consistent with little to no retardation in groundwater for perfluoroethers such as hexafluoropropylene oxide-dimer acid (HFPO–DA) and perfluoro-2-methoxypropanoic acid (PMPA), the two most abundant PFAS, with mean concentrations of 229 and 498 ng/L, respectively. Future PFAS concentrations in groundwater discharge to streams were estimated to remain above current MCL or health advisory levels through at least 2050 or 2060 (using ³H/³He and SF₆, respectively). Recent atmospheric deposition data suggest lower but non-negligible amounts of PFAS may continue to enter groundwater, likely further extending PFAS persistence in groundwater and the adjacent CFR. This approach shows promise for giving an overall perspective on persistence of PFAS in groundwater discharge from a broad contaminated area.