Per- and Polyfluoroalkyl Substance (PFAS) Transport from Groundwater to Streams near a PFAS Manufacturing Facility in North Carolina, USA

We
quantified per- and polyfluoroalkyl substance (PFAS) transport
from groundwater to five tributaries of the Cape Fear River near a
PFAS manufacturing facility in North Carolina (USA). Hydrologic and
PFAS data were coupled to quantify PFAS fluxes from groundwater to
the tributaries. Up to 29 PFAS were analyzed, including perfluoroalkyl
acids and recently identified fluoroethers. Total quantified PFAS
(ΣPFAS) in groundwater was 20–4773 ng/L (mean = 1863
ng/L); the range for stream water was 426–3617 ng/L (mean =
1717 ng/L). Eight PFAS constituted 98% of ΣPFAS; perfluoro-2-(perfluoromethoxy)­propanoic
acid (PMPA) and hexafluoropropylene oxide dimer acid (GenX) accounted
for 61%. For PFAS discharge from groundwater to one tributary, values
estimated from stream water measurements (18 ± 4 kg/yr) were
similar to those from groundwater measurements in streambeds (22–25
± 5 kg/yr). At baseflow, 32 ± 7 kg/yr of PFAS discharged
from groundwater to the five tributaries, eventually reaching the
Cape Fear River. Given the PFAS emission timeline at the site, groundwater
data suggest the abundant fluoroethers moved through the subsurface
to streams in ≪50 yr. Discharge of contaminated groundwater
may lead to long-term contamination of surface water and impacts on
downstream drinking water supplies. This work addresses a gap in the
PFAS literature: quantifying PFAS mass transfer between groundwater
and surface water using field data.