Aqueous film-forming foams (AFFFs), containing per- and polyfluoroalkyl substances (PFASs), are released into the environment during response to fire-related emergencies. Repeated historical applications of AFFF at military sites were a result of fire-fighter training exercises and equipment testing. Recent data on AFFF-impacted groundwater indicates that ∼25% of the PFASs remain unidentified. In an attempt to close the mass balance, a systematic evaluation of 3M and fluorotelomer-based AFFFs, commercial products, and AFFF-impacted groundwaters from 15 U.S. military bases was conducted to identify the remaining PFASs. Liquid chromatography quadrupole time-of-flight mass spectrometry was used for compound discovery. Nontarget analysis utilized Kendrick mass defect plots and a "nontarget" R script. Suspect screening compared masses with those of previously reported PFASs. Forty classes of novel anionic, zwitterionic, and cationic PFASs were discovered, and an additional 17 previously reported classes were observed for the first time in AFFF and/or AFFF-impacted groundwater. All 57 classes received an acronym and IUPAC-like name derived from collective author knowledge. Thirty-four of the 40 newly identified PFAS classes derive from electrochemical fluorination (ECF) processes, most of which have the same base structure. Of the newly discovered PFASs found only in AFFF-impacted groundwater, 11 of the 13 classes are ECF-derived, and the remaining two classes are fluorotelomer-derived, which suggests that both ECF- and fluorotelomer-based PFASs are persistent in the environment.
Aqueous film-forming foams (AFFFs) are proprietary mixtures containing hydrocarbon surfactants and per-and polyfluoroalkyl substances (PFASs) that are used to extinguish hydrocarbonbased fuel fires. There is limited information on hydrocarbon surfactants in AFFFs and AFFF-contaminated groundwater even though hydrocarbon surfactants are more abundant (5−10% w/w) than PFASs (0.9− 1.5% w/w) in AFFFs. Eight commercial AFFFs manufactured between 1988 and 2012 and 10 AFFF-contaminated groundwaters collected from near source zones of fire-fighter training areas were analyzed for suspect hydrocarbon surfactants by liquid chromatography quadrupole time-of-flight mass spectrometry. A suspect list and a homologous series detection computational tool, enviMass, were combined to screen for hydrocarbon surfactants. Nine classes of hydrocarbon surfactants were detected in AFFFs including octylphenol polyethoxylates, linear alcohol ethoxylates, ethoxylated cocoamines, alkyl ether sulfates, alkyl amido dipropionates, linear alkyl benzenesulfonates, alkyl sulfates, and polyethylene glycols. Of those, six were also found in groundwater along with diethanolamines and alkyl amido betaines, which were not found in the eight archived AFFFs. This indicates that although aerobically biodegradable, hydrocarbon surfactants likely persist in groundwater due to anaerobic aquifer conditions. To the best of our knowledge, this is the first screening for hydrocarbon surfactants in AFFFs and in AFFFcontaminated groundwater.
Urban-use pesticides
are of increasing concern as they are widely
used and have been linked to toxicity of aquatic organisms. To assess
the occurrence and treatment of these pesticides in stormwater runoff,
an approach combining field sampling and watershed-scale modeling
was employed. Stormwater samples were collected at four locations
in the lower San Diego River watershed during a storm event and analyzed
for fipronil, three of its degradation products, and eight pyrethroids.
All 12 compounds were detected with frequency ranging from 50 to 100%.
Field results indicate pesticide pollution is ubiquitous at levels
above toxicity benchmarks and that runoff may be a major pollutant
source to urban surface waters. A watershed-scale stormwater model
was developed, calibrated using collected data, and evaluated for
pesticide storm load and concentrations under several management scenarios.
Modeling results show that enhanced stormwater control measures, such
as biochar-amended biofilters, reduce both pesticide storm load and
toxicity benchmark exceedances, while conventional biofilters reduce
the storm load but provide minimal toxicity benchmark exceedance reduction.
Consequently, biochar amendment has the potential to broadly improve
water quality at the watershed scale, particularly when meeting concentration-based
metrics such as toxicity benchmarks. This research motivates future
work to demonstrate the reliability of full-scale enhanced stormwater
control measures to treat pollutants of emerging concern.
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