Per- and Polyfluoroalkyl Substances (PFAS) in Street Sweepings

Stormwater discharges affect PFAS occurrence, concentrations, and spatial distribution in water and bottom sediment of urban streams

Per- and polyfluoroalkyl substances (PFAS) are extensively used in urban environments and are, thus, found in urban stormwater. However, the relevance of stormwater as a pathway for PFAS to urban streams is largely unknown. This study evaluated the impact of urban stormwater runoff on PFAS concentrations and spatial distribution in three urban streams affected by stormwater discharges from separate sewer systems. River water was sampled during dry (DW) and wet weather (WW) upstream, immediately downstream, and further downstream of three urbanized areas with separate sewer systems and with and without point sources (i.e. waste water treatment plant, airports). Water samples were analyzed for 34 targeted PFAS compounds and sediment samples for 35 targeted PFAS and 30 PFAS compounds using a total oxidizable precursor assay. The sum of the quantified PFAS concentrations ranged from the reporting limit (RL) to 84.7 ng/L during DW and increased as the streams were affected by WW discharges (0.87 to 102.3 ng/L). The highest PFAS concentrations were found downstream of urban areas and/or point sources (i.e. airports) during WW, indicating a clear contribution from stormwater discharges. A consistent PFAS contribution from the WWTP was observed under both DW and WW conditions. During WW events, concentrations of perfluorooctanesulfonic acid (PFOS) and total PFAS (PFOA equivalents) exceeded the annual average environmental quality standards, which are an established limit of 0.65 ng/L for PFOS and a proposed limit of 4.4 ng/L for total PFAS. Notably, except for the legacy PFAS, PFOS and perfluorooctanoic acid (PFOA), the most frequently quantified PFAS during DW were short-chain. For WW, long-chain perfluorocarboxylic acids (PFCAs) and a precursor, 6:2 Fluorotelomer sulfonic acid (6:2 FTS), were more frequently quantified, suggesting stormwater is a source of these longer-chain and particle-associated PFAS. The detection of unregulated fluorotelomer sulfonates (FTSs) such as 6:2 and 8:2 FTS during WW suggests a need for regulatory action, as these compounds can degrade into more stable PFAS. In sediment, higher concentrations, and a greater variety of PFAS were found at sites with known point sources i.e. airports. Long-chain PFCAs (C7-C13), perfluoroalkyl sulfonates (PFSAs) (C6), and precursors (i.e. N-Ethyl perfluorooctane sulfonamidoacetic acid), were more prevalent in sediments than in the water. Notably, PFOS concentrations in sediment exceeded the lowest Predicted No-Effect Concentration (PNEC) across sites, posing a potential long-term environmental risk, though current PNECs for other PFAS may underestimate such risks. The findings of the study highlight urban stormwater as a source of PFAS to urban streams indicating the need to minimize PFAS sources in the urban environment and to effectively treat stormwater to protect receiving water bodies.

Tunnel wash water in a cold climate: characteristics, ecotoxicological risk, and effect of sedimentation

The characterization of tunnel wash water (TWW) from 12 Norwegian tunnels showed very high concentrations of total suspended solids (TSS), metals, and polycyclic aromatic hydrocarbons (PAHs). Iron (Fe), aluminum (Al), and manganese (Mn) were mainly particle-associated. They are efficiently removed by sedimentation, while the dissolved concentrations of toxic metals like Cu, Zn, and As did not change. Polycyclic aromatic hydrocarbon (PAH) concentration was higher in the dissolved than in the particulate fraction. Sedimentation treatment reduced the particulate share by about 50%. In contrast to metals, the dissolved fraction decreased by about 90% during sedimentation, most probably due to adsorption to particles that are subsequently removed during the process. The concentration levels of 8 out of 16 PAHs, Cu, Zn, and As resulted in a water quality classification of poor or very poor. Acute toxic effects could be expected after short-term exposition. After sedimentation, this was the case for only two PAHs because more harmful compounds with three to six rings were preferably removed. These may adsorb better to particles than PAHs with two rings. No change was observed for the metals. A closer evaluation of secondary treatments of TWW, including conventional technology and mobile solutions, is therefore recommended. Finally, indications for a seasonal pollution variation have been seen, mainly related to the use of salt as a de-icing agent in road maintenance.

Fluorinated aromatic PBCTF and 6:2 diPAP in bridge and traffic paints

Per- and polyfluoroalkyl substances (PFAS) are reported in residential and commercial paints, but there are no data for paints used in the transportation sector. From 2023 to 2024, 16 traffic paints and 10 bridge paints were collected from Pacific Northwest regional transportation facilities or purchased and analyzed for total fluorine by 19F-nuclear magnetic resonance (NMR) spectroscopy, volatile PFAS by gas chromatography-mass spectrometry (GC-MS), and ionic target and suspect PFAS by liquid chromatography-quadrupole time-of-flight mass spectrometry. The only target PFAS identified was 6:2 fluorotelomer phosphate diester (diPAP) which ranged in concentrations from 0.065 to 13 μg g-1. While 6:2 diPAP is not regulated in paints, it can undergo environmental transformation to act as a source of perfluoroalkyl carboxylic acids. A combination of 19F-NMR and GC-MS was used to quantify and identify the fluorinated aromatic PFAS, parachlorobenzotrifluoride (PCBTF), at concentrations from 440 to 16 000 μg g-1 in bridge paints, thus PCBTF may contribute to work exposure and levels in urban air. Additionally, evolved gas analysis with mass spectrometry and pyrolysis-GC-MS established that the insoluble fraction of paints is not comprised of fluoropolymers. Based on the amount of paint required per kilometer, we estimate up to 0.20-2.30 g 6:2 diPAP per kilometer depending on marking type. Therefore, traffic paint may be a potential source of the PFAS detected in urban runoff.

Leaching of per- and polyfluoroalkyl substances (PFAS) from food contact materials with implications for waste disposal

Leaching of per- and polyfluoroalkyl substances (PFAS) during the post-consumer disposal of food contact materials (FCMs) poses a potential environmental threat but has seldom been evaluated. This study characterized the leaching behavior of PFAS and unidentified precursors from six common FCMs and assessed the impact of environmental conditions on PFAS release during disposal. The total concentration of 21 PFAS ranged from 3.2 to 377 ng/g in FCMs, with PFAS leachability into water varying between 1.1-42.8 %. Increasing temperature promoted PFAS leaching, with leached nine primary PFAS (∑9PFAS) reaching 46.3, 70.4, and 102 ng/L at 35, 45, and 55 ℃, respectively. Thermodynamic analysis (∆G>0, ∆H>0, and ∆S<0) indicated hydrophobic interactions control PFAS leaching. The presence of dissolved organic matter in synthetic leachate increased the leached ∑9PFAS from 47.1 to 103 ng/L but decreased PFBS, PFOS, and 6:2 FTS leaching. The total release of seven perfluorocarboxylic acids (∑7PFCAs) from takeaway food packaging waste was estimated to be 0.3-8.2 kg/y to landfill leachate and 0.6-15.4 kg/y to incineration plant leachate, contributing 0.2-4.8 % and 0.1-3.2 % of total ∑7PFCAs in each leachate type. While the study presents a refined methodology for estimating PFAS release during disposal, future research is needed on the indirect contribution from precursors.

Drivers of change behind the spatial distribution and fate of typical trace organic pollutants in fresh waste leachate across China

There have been growing concerns regarding the health and environmental impacts of trace organic pollutants (TOPs). However, fresh leachate from municipal solid waste (MSW) has been overlooked as a potential reservoir of TOPs. Therefore, we investigated 90 legacy and emerging TOPs in fresh leachate from 14 provinces and municipalities in China. Additionally, the fate and final discharge impacts of TOPs in 14 leachate treatment systems were analyzed. The results revealed that the detection rate of 90 TOPs was over 50 % in all samples. Notably, polychlorinated biphenyls, banned for 40 years, were frequently detected in fresh leachate. The concentration of pseudo-persistent TOPs (105-107 ng/L) is significantly higher than that of persistent TOPs (102-104 ng/L). Spatial distribution patterns of TOPs in fresh leachate suggest that economy, population, climate, and policies impact TOPs discharge from MSW. For example, economically developed and densely populated areas displayed higher TOPs concentrations, whereas warmer climates facilitate TOPs leaching from MSW. We confirmed that waste classification policies were a key driver of the decline in multiple TOPs in leachate. Mass balance analysis shows that the final effluent and sludge from current dominant leachate treatment systems contain refractory TOPs, especially perfluoroalkyl acids, which must be prioritized for control. This paper was the first comprehensive investigation of multiple TOPs in fresh leachate at a large geographic scale. The factors affecting the occurrence, spatial distribution, and fate of TOPs in fresh leachate were revealed. It provides a valuable reference for the establishment of policies for the management of TOPs in MSW and the associated leachate.

Identification and quantification of novel per- and polyfluoroalkyl substances (PFAS) contamination in a Great Lakes urban-dominated watershed

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic organic fluoro-compounds that are oil-, water-, and flame-resistant, making them useful in a wide range of commercial and consumer products, as well as resistant to environmental degradation. To assess the impact of urbanization and wastewater treatment processes, surface water and sediment samples were collected at 27 sites within the Great Lakes in the Lake Huron to Lake Erie corridor (HEC), an international waterway including the highly urbanized Detroit and Rouge Rivers. Samples were analyzed for 92 PFAS via UHPLC-MS/MS. Our previous data in the HEC found the highest amount of PFAS contamination at the Rouge River mouth. In addition to evaluating the input of the Rouge River into the HEC, we evaluated the transport of PFAS into the HEC from other major tributaries. PFAS were detected in both surface water and sediment at all sites in this study, with a total of 10 congeners quantified in all surface water samples and 16 congeners quantified in all sediment samples, indicating ubiquitous contamination. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were pervasive in the HEC as these two compounds were detected in all sites and matrices, often at concentrations above the US EPA's recommended lifetime interim updated health advisories. Surface water samples contained more perfluorohexanoic acid (PFHxA) than any other congener, with average aqueous PFHxA across all surface water samples exceeding the average concentration previously reported in the Great Lakes. Sediment samples were dominated by PFOS, but novel congeners, notably 3-Perfluoropentyl propanoic acid (FPePA), were also quantified in sediment. The Rouge River and other tributaries contribute significantly to the PFAS burden in the HEC including Lake Erie. Overall, our results indicate the need for expanding toxicological research and risk assessment focused on congeners such as PFHxA and PFAS mixtures, as well as regulation that is tighter at the onset of production and encompasses PFAS as a group at a national level.

Sources of per- and polyfluoroalkyl substances in an arid, urban, wastewater-dominated watershed

Per- and polyfluoroalkyl substances (PFAS) enter surface waters from various sources such as wastewater treatment plants, fire-fighting sites, and PFAS-producing and PFAS-using industries. The Las Vegas Wash in Southern Nevada of the United States (U.S.) conveys wastewater effluent from the Las Vegas metropolitan area to Lake Mead, a drinking water source for millions of people in the U.S. Southwest. PFAS have previously been detected in the Las Vegas Wash, but PFAS sources were not identified. In this study, upstream wash tributaries, wastewater treatment effluents, and shallow groundwater wells were sampled in multiple campaigns during dry-weather conditions to investigate possible PFAS sources. Out of 19 PFAS, two short-chain PFAS-perfluoropentanoic acid (48 % of the total molar concentration) and perfluorohexanoic acid (32 %)-comprised the majority of PFAS loading measured in the Las Vegas Wash, followed by perfluorooctanoic acid (9 %). On a mass loading basis, the majority of total measured PFAS (approximately 90 %) and at least 48 % of each specific PFAS in the Las Vegas Wash likely entered via municipal wastewater effluents, of which the main source was likely residential wastewater. One of the drainage areas with a major civilian airport was identified as a potential source of relatively enriched perfluorosulfonic acids to a small wash tributary and shallow groundwater samples. Nonetheless, that tributary contributed at most 15 % of any specific PFAS to the mainstem of the Las Vegas Wash. Total PFAS concentrations were relatively low for the small tributary associated with an urban smaller airport and the lack of flow in the tributary channel immediately downgradient of an Air Force base indicates the smaller airport and base were unlikely significant PFAS sources to the Las Vegas Wash. Overall, this study demonstrated effective PFAS source investigation methodology and the importance of wastewater effluent as a PFAS environmental pathway.

Occurrence, Concentration, and Distribution of 35 PFASs and Their Precursors Retained in 20 Stormwater Biofilters

Current knowledge about the fate and transport behaviors of per- and polyfluoroalkyl substances (PFASs) in urban stormwater biofilter facilities is very limited. C5-14,16 perfluoroalkyl carboxylic acids [perfluorinated carboxylic acids (PFCAs)], C4,8,10 perfluoroalkanesulfonic acids (PFSAs), methyl-perfluorooctane sulfonamide acetic acid (MeFOSAA, a PFSA precursor), and unknown C6-8 PFCA and perfluorooctanesulfonic acid precursors were frequently found in bioretention media and forebay sediments at Σ35PFAS concentrations of <0.03-19 and 0.064-16 μg/kg-DW, respectively. Unknown C6-8 PFCA precursor concentrations were up to ten times higher than the corresponding PFCAs, especially at forebays and biofilters' top layer. No significant trend could be attributed to PFAS and precursor concentrations versus depth of filter media, though PFAS concentrations were 2-3 times higher in the upper layers on average (significant difference between the upper (0-5 cm) and deepest (35-50 cm) layer). PFASs had a similar spatial concentration distribution in each filter media (no clear difference between short- and long-chain PFASs). Commercial land use and organic matter were important factors explaining the concentration variations among the biofilters and between the sampling depths, respectively. Given the comparable PFAS accumulations in deeper and superficial layers and possible increased mobility after precursor biotransformation, designing shallow-depth, nonamended sand biofilters or maintaining only the top layer may be insufficient for stormwater PFAS management.

Crowdsourcing citizens for statewide mapping of per- and polyfluoroalkyl substances (PFAS) in Florida drinking water

Per- and polyfluoroalkyl substances (PFAS) are a class of persistent chemicals that have been associated with a diverse array of adverse environmental and human health related effects. In addition to a growing list of health concerns, PFAS are also ubiquitously used and pervasive in our natural and built environments, and they have an innate ability to be highly mobile once released into the environment with an unmatched ability to resist degradation. As such, PFAS have been detected in a wide variety of environmental matrices, including soil, water, and biota; however, the matrix that largely dictates human exposure to PFAS is drinking water, in large part due to their abundance in water sources and our reliance on drinking water. As Florida is heavily reliant upon water and its varying sources, the primary objective of this study was to survey the presence of PFAS in drinking water collected from taps from the state of Florida (United States). In this study, 448 drinking water samples were collected by networking with trained citizen scientists, with at least one sample collected from each of the 67 counties in Florida. Well water, tap water, and bottled water, all sourced from Florida, were extracted and analyzed (31 PFAS) using isotope dilution and ultra-high-performance liquid chromatography - tandem mass spectrometry (UHPLC-MS/MS). Overall, when examining ∑PFAS: the minimum, maximum, median, and mean were ND, 219, 2.90, and 14.06 ng/L, respectively. The data herein allowed for a comparison of PFAS in drinking water geographically within the state of Florida, providing vital baseline concentrations for prospective monitoring and highlighting hotspots that require additional testing and mitigation. By incorporating citizen scientists into the study, we aimed to educate impacted communities regarding water quality issues and solutions.

An explicit review and proposal of an integrated framework system to mitigate the baffling complexities induced by road dust-associated contaminants

Road dust-associated contaminants (RD-AC) are gradually becoming a much thornier problem, as their monotonous correlations render them carcinogenic, mutagenic, and teratogenic. While many studies have examined the harmful effects of road dust on both humans and the environment, few studies have considered the co-exposure risk and gradient outcomes given the spatial extent of RD-AC. In this spirit, this paper presents in-depth elucidation into the baffling complexities induced by both major and emerging contaminants of road dust through a panorama-to-profile up-to-date review of diverse studies unified by the goal of advancing innovative methods to mitigate these contaminants. The paper thoroughly explores the correlations between RD-AC and provides insights to understand their potential in dispersing saprotrophic microorganisms. It also explores emerging challenges and proposes a novel integrated framework system aimed at thermally inactivating viruses and other pathogenic micro-organisms commingled with RD-AC. The main findings are: (i) the co-exposure risk of both major and emerging contaminants add another layer of complexity, highlighting the need for more holistic framework strategies, given the geospatial morphology of these contaminants; (ii) road dust contaminants show great potential for extended prevalence and severity of viral particles pollution; (iii) increasing trend of environmentally persistent free radicals (EPFRs) in road dust, with studies conducted solely in China thus far; and (iv) substantial hurdle exists in acquiring data concerning acute procedural distress and long-term co-exposure risk to RD-ACs. Given the baffling complexities of RD-ACs, co-exposure risk and the need for innovative mitigation strategies, the study underscore the significance of establishing robust systems for deep road dust contaminants control and future research efforts while recognizing the interconnectivity within the contaminants associated with road dust.

Investigating the sources and fate of per- and polyfluoroalkyl substances (PFAS) in food waste compost

Composting municipal food waste is a key strategy for beneficially reusing methane-producing waste that would otherwise occupy landfill space. However, land-applied compost can cycle per- and polyfluoroalkyl substances (PFAS) back into the food supply and the environment. We partnered with a pilot-scale windrow composting facility to investigate the sources and fate of 40 PFAS in food waste compost. A comparison of feedstock materials yielded concentrations of ∑PFAS under 1 ng g-1 in mulch and food waste and at 1380 ng g-1 in leachate from used compostable food contact materials. Concentrations of targeted ∑PFAS increased with compost maturity along the windrow (1.85-23.1 ng g-1) and in mature stockpiles of increasing curing age (12.6-84.3 ng g-1). Among 15 PFAS quantified in compost, short-chain perfluorocarboxylic acids (PFCAs) - C5 and C6 PFCAs in particular - led the increasing trend, suggesting biotransformation of precursor PFAS into these terminal PFAS through aerobic decomposition. Several precursor PFAS were also measured, including fluorotelomer carboxylic acids (FTCAs) and polyfluorinated phosphate diesters (PAPs). However, since most targeted analytical methods and proposed regulations prioritize terminal PFAS, testing fully matured compost would provide the most relevant snapshot of PFAS that could be land applied. In addition, removing co-disposed food contact materials from the FW feedstock onsite yielded only a 37 % reduction of PFAS loads in subsequent compost, likely due to PFAS leaching during co-disposal. Source-separation of food contact materials is currently the best management practice for meaningful reduction of PFAS in food waste composts intended for land application.

Examining the effectiveness of municipal street sweeping in removing road-deposited particles and metal(loid)s of respiratory health concern

Road dust is a demonstrated source of urban air pollution. Given this, the implementation of street sweeping strategies that effectively limit road dust accumulation and resuspension should be a public health priority. Research examining the effectiveness of street sweeping for road dust removal in support of good air quality has been limited to date. To address this, the study aimed to assess the use of a regenerative-air street sweeper to efficiently remove road dust particles and metal(loid)s in size fractions relevant for respiratory exposure in Toronto, Canada. As part of this, the mass amounts, particle size distribution and elemental concentrations of bulk road dust before and after sweeping at five arterial sites were characterized. Sweeping reduced the total mass amount of thoracic-sized (<10 µm) road dust particles by 76 % on average. A shift in the size distribution of remaining particles toward finer fractions was observed in post-sweeping samples, together with an enrichment in many metal(loid)s such as Co, Ti and S. Overall, the mass amounts of metal(loid)s of respiratory health concern like Cu and Zn were greatly reduced with sweeping. Traffic volume and road surface quality were predictors of dust loadings and elemental concentrations. Road surface quality was also found to impact street sweeping efficiencies, with larger mass amounts per unit area collected post-sweeping where street surfaces were distressed. This study demonstrates that street sweeping using advanced technology can be highly effective for road dust removal, highlighting its potential to support air quality improvement efforts. The importance of tailoring sweeping service levels and technologies locally as per the quality of road surface and traffic patterns is emphasized. Continued efforts to mitigate non-exhaust emissions that pose a respiratory health risk at their source is essential.

Occurrence of traffic related trace elements and organic micropollutants in tunnel wash water

Substantially polluted tunnel wash water (TWW) is produced during road tunnel maintenance. Previous literature has reported the presence of trace elements and polycyclic aromatic hydrocarbons (PAHs). However, it was hypothesized that other organic pollutants are present, and more knowledge is needed to prevent environmental harm. This study reveals for the first time the presence of four short- and 17 long-chained per- and polyfluoroalkyl substances (PFASs), three benzothiazoles (BTHs), six benzotriazoles (BTRs), four bisphenols, and four benzophenones in TWW from a Norwegian road tunnel over a period of three years. Concentrations of PAHs, PFASs, BTHs, and BTRs were higher than previously reported in e.g., road runoff and municipal wastewater. Trace elements and PAHs were largely particulate matter associated, while PFASs, BTHs, BTRs, bisphenols, and benzophenones were predominantly dissolved. 26 of the determined contaminants were classified as persistent, mobile, and toxic (PMT) and are of special concern. It was recommended that regulations for TWW quality should be expanded to include PMT contaminants (such as PFPeA, PFBS, BTR, and 4-OH-BzP) and markers of pollution (like 2-M-BTH, 2-OH-BTH, and 2-S-BTH from tire wear particles). These findings highlight the need to treat TWW before discharge into the environment, addressing both, particulate matter associated and dissolved contaminants.

Evaluation of per- and polyfluoroalkyl substances (PFAS) released from two Florida landfills based on mass balance analyses

Per- and polyfluoroalkyl substances (PFAS) have been found at high levels within landfill environments. To assess PFAS distributions, this study aimed to evaluate PFAS mass flux leached from disposed solid waste and within landfill reservoirs by mass balance analyses for two full-scale operational Florida landfills. PFAS mass flux in different aqueous components within landfills were estimated based on PFAS concentrations and water flow rates. For PFAS concentration, 26 PFAS, including 18 perfluoroalkyl acids (PFAAs) and 8 PFAA-precursors, were measured in samples collected from the landfills or estimated based on previous studies. Flow rates of aqueous components (rainfall, evapotranspiration, runoff, stormwater, groundwater, leakage, gas condensate, and leachate) were evaluated through the Hydrologic Evaluation of Landfill Performance model, water balance, and Darcy's Law. Results showed that the average PFAS mass flux leached from the solid waste standardized by area was estimated as 36.8 g/ha-yr, which was approximately 1 % to 3 % of the total amount of PFAS within the solid waste. The majority of PFAS leached from the solid waste (95 % to 97 %) is captured by the leachate collection system, with other aqueous components representing much smaller fractions (stormwater system at 3 % to 5 %, and gas condensate and groundwater at < 1 %). Also, based on the results, we estimate that PFAS releases will likely occur at least over 40 years. Overall, these results can help prioritize components for waste management and PFAS treatment during the anticipated landfill release periods.

Sources, Fate, and Detection of Dust-Associated Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS): A Review

The occurrence of sand and dust storms (SDSs) is essential for the geochemical cycling of nutrients; however, it is considered a meteorological hazard common to arid regions because of the adverse impacts that SDSs brings with them. One common implication of SDSs is the transport and disposition of aerosols coated with anthropogenic contaminants. Studies have reported the presence of such contaminants in desert dust; however, similar findings related to ubiquitous emerging contaminants, such as per- and poly-fluoroalkyl substances (PFAS), have been relatively scarce in the literature. This article reviews and identifies the potential sources of dust-associated PFAS that can accumulate and spread across SDS-prone regions. Furthermore, PFAS exposure routes and their toxicity through bioaccumulation in rodents and mammals are discussed. The major challenge when dealing with emerging contaminants is their quantification and analysis from different environmental media, and these PFAS include known and unknown precursors that need to be quantified. Consequently, a review of various analytical methods capable of detecting different PFAS compounds embedded in various matrices is provided. This review will provide researchers with valuable information relevant to the presence, toxicity, and quantification of dust-associated PFAS to develop appropriate mitigation measures.

Concentrations of perfluoroalkyl and polyfluoroalkyl substances before and after full-scale landfill leachate treatment

Many consumer and industrial products, industrial wastes and dewatered sludge from municipal wastewater treatment plants containing per- and polyfluoroalkyl substances (PFAS) are disposed of in landfills at the end of their usage, with PFAS in these products leached into landfill leachates. On-site leachate treatment is one possible method to reduce PFAS in leachates. Many landfills are equipped with on-site leachate treatment systems, but few full-scale facilities have been systematically evaluated for PFAS concentration changes. The objective of this study was to evaluate a cross-section of full-scale on-site landfill treatment systems to measure changes in PFAS concentrations. Leachate samples were collected before and after treatment from 15 facilities and were evaluated for 26 PFAS, including 11 perfluoroalkyl carboxylic acids (PFCAs), 7 perfluoroalkyl sulfonic acids (PFSAs), and 8 perfluoroalkyl acid precursors (PFAA-precursors). Transformation of precursors was evaluated by the total oxidizable precursor (TOP) assay. Results showed no obvious reductions in total measured PFAS (∑26PFAS) for on-site treatment systems including ponds, aeration tanks, powdered activated carbon (PAC), and sand filtration. Among evaluated on-site treatment systems, only systems fitted with reverse osmosis (RO) showed significant reductions (98-99 %) of ∑26PFAS in the permeate. Results from the TOP assay showed that untargeted PFAA-precursors converted into targeted short-chain PFCAs increasing ∑26PFAS in oxidized samples by 30 %, on average. Overall, results of this study confirm the efficacy of RO systems and suggest the presence of additional precursors beyond those measured in this study.

Micropollutants in Urban Runoff from Traffic Areas: Target and Non-Target Screening on Four Contrasted Sites

Although runoff from trafficked urban areas is recognized as a potentially significant pathway of micropollutants, runoff pollution remains poorly documented, except for relatively few historical pollutants such as some metals and hydrocarbons. Therefore, in this work, road and parking lot runoff from four sites with contrasting traffic levels were analyzed for a very broad spectrum of molecules and elements. A total of 128 pollutants and micropollutants were monitored, including inorganic (n = 41) and organic (n = 87) pollutants. Both the dissolved and particulate phases were considered. For a reduced number of samples, non-targeted screening by high-resolution mass spectrometry (HRMS) was carried out. For targeted screening, the contamination profiles were quite homogeneous, but the concentrations significantly differed between the different sites. Sites with the highest traffic density exhibited the highest concentrations for polycyclic aromatic hydrocarbons (PAHs), some traffic-related metals, alkylphenols and phthalates. Overall, for most micropollutants, the parking lot runoff exhibited the lowest concentrations, and the specificity of this site was confirmed by its HRMS fingerprint. Non-target screening allowed the sites to be discriminated based on the occurrence of specific compounds. Unlike the results of targeted screening, the HRMS intra-site variability was lower than its inter-site variability. Unknown substances were tentatively identified, either characteristic of each site or ubiquitous of all samples.