Nontargeted Analysis of Surface and Groundwaters Impacted by Historic PFAS Waste Sites

Per- and polyfluoroalkyl substances (PFAS) make up a
diverse class
of anthropogenic chemicals with widespread industrial and commercial
uses. Historical manufacturing and disposal of PFAS have led to their
introduction to the environment, although only a fraction of existing
PFAS are routinely monitored using targeted analysis methods. Here,
nontargeted analysis was used to investigate the identity and fate
of PFAS present in eight groundwater and nine surface water samples
collected near St. Paul, MN, surrounding two sites that historically
received wastes from a PFAS manufacturer in the 1940–1970s.
A total of 210 PFAS, split across 33 different homologous series,
were identified in surface and groundwater samples both at and downstream
of the two waste sites. Identified compounds included perfluorinated,
polyfluorinated, and unsaturated sulfonic and carboxylic acid species
as well as a variety of sulfonamide and sulfonamido chemistries. PFAS
measured downgradient included legacy perfluorinated sulfonic and
carboxylic acids, as well as their polyfluorinated, unsaturated, keto,
and ether-containing analogs. Two-thirds of the identified PFAS were
unique to the groundwater at one site. The lack of these PFAS at downstream
sites likely reflects dilution below the limit of detection during
downgradient transport. The identified species reveal previously unknown
and substantial ongoing contamination of the watershed due to historic
PFAS manufacturing and waste disposal.