Dispersion and stratification of Per-and polyfluoroalkyl substances (PFAS) in surface and deep-water profiles: A case study of the Biscayne Bay area

Evidence of the occurrence, detection, and ecotoxicity studies of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in aqueous environments

Perflorochemicals (PFCs), among which are the most commonly detected perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), are persistent emergent contaminants of concern in recent times. These compounds have been reported for their cytotoxicity, genotoxicity, carcinogenicity, immunotoxicity, and developmental toxicities. Meanwhile, they have been detected in diverse matrices such as soil, sediment, and, surprisingly, in serum and even breastmilk. Worrisomely, these compounds are detected in drinking water across the globe, aquaculture water, and other surface waters. Thus, it was important to appraise the studies conducted on PFOS and PFOA to provide an overview of the environmental status of contamination regarding them. The present review article sought to provide insights into the occurrence patterns and ecotoxic effects of both pollutants in the water ecosystems within five continents of the world. Based on the information gathered in this article, the ∑ P F O S concentration (ng/L) within the five continents is in the order Europe > Asia > Africa > North America > South America, while the ∑ P F O A level (ng/L) is in the order Europe > Asia > South America > Africa > North America. The study also investigated the previous works that have been conducted regarding the diverse elimination technologies employed for the removal of these pollutants from the aqueous environments, with plasma combined with surfactant process being the most efficient. Generally, studies on PFOS/PFOA are still scanty when compared to those on pharmaceuticals and personal care products (PPCPs), especially in North America. The information gathered in this study could be useful in establishing thresholds of PFOA and PFOS environmental levels and be adopted by appropriate authorities as safety guidelines.

Per- and polyfluoroalkyl substances (PFAS) composition and distribution in surface water of the Miccosukee Indian Reservation, Everglades and tributaries in the coastal environment of Miami, Florida

PFAS have a well-documented history of adverse human health effects and have been detected in both urban environments and remote rural areas. In this study, PFAS concentrations were monitored in canals discharging into Biscayne Bay (Miami, FL) and compared to the surface water in canals and marshes within the Miccosukee Indian Reservation of Everglades National Park to assess PFAS contamination levels in urban and rural environments. Solid phase extraction was performed on 250 mL water samples using Strata-AW-XL cartridges, followed by liquid chromatography tandem mass spectrometry. The sum of PFAS concentrations ranged between 30.1 and 153 ng/L along the Miami canals. PFAS have been detected for the first time in the Miccosukee Indian Reservation, with levels ranging from 3.94 to 40.1 ng/L. The most abundant compounds were perfluorooctanesulfonate (PFOS) with a mean concentration of 15.2 ± 9.72 ng/L, perfluoro-n-pentanoic acid (PFPeA, mean = 10.2 ± 7.73 ng/L), perfluoro-n-butanoic acid (PFBA, mean = 10.7 ± 7.87 ng/L), and perfluoro-n-hexanoic acid (PFHxA, mean = 7.38 ± 5.16 ng/L). In the Everglades samples, 48 % of the total compounds identified were PFBA and 15 % was PFOS, while in the canals, 25 % was PFOS, 16 % PFPeA, and 14 % PFBA. The land uses of the area that could be contributing to PFAS concentrations are the production of textiles and stain resistant products, metal plating and finishing facilities, aqueous film forming foams, and various wastewater entering the watershed.

Exploring per- and polyfluoroalkyl substance distribution in Arctic wastewater treatment lagoons and natural wetlands: First record in Nunavik, Canada

Per- and polyfluoroalkyl substances (PFAS), as emerging and bioaccumulative contaminants, are widely present in water and wastewater systems. Municipal wastewater effluents serve as pathways for PFAS to enter aquatic environments. This study monitors the PFAS in wastewater treatment lagoons, nearby wetlands and bay in a Canadian Arctic community. Eight out of the 40 targeted PFAS were detected in samples collected from raw wastewater, wastewater treatment lagoons, natural wetlands, and Ungava bay. The total PFAS concentrations were in the ranges of 45.9-56.1 ng/L in wastewater treatment lagoons, 36.6-70.8 ng/L in natural wetlands and measured at 7.3 ng/L in the bay. The most prevalent and frequently detected PFAS were 6:2 FTS, PFHxA, and PFNA. At all sites, short-chain PFAS concentrations surpassed long-chain PFAS. Short-chain PFAS peaked at 267.01 ng/L (79.74%), while long-chain PFAS totaled 67.83 ng/L (20.26%). The estimated yearly mass flow rate of total PFAS into the environment through lagoon effluent was 2.33 g/year. The conducted environmental risk assessment for both the effluent of the wastewater treatment lagoons and the three downstream natural wetlands suggests that the risks associated with all PFAS under study posed minimal ecological risk, though long-term evaluation is needed. In conclusion, the findings of this research provide further information on PFAS pollution through wastewater in Arctic regions and may, as such, guide the development of comprehensive regulations to safeguard both human health and the environment, thereby mitigating potential future risks.

Assessing Bivalves as Biomonitors of Per- and Polyfluoroalkyl Substances in Coastal Environments

Per- and polyfluoroalkyl substances (PFAS) are widely used chemicals that enter coastal ecosystems through various pathways. Despite the ecological and economic significance of coastal environments, monitoring efforts to identify PFAS in these regions are limited. Bivalves have been used as biomonitors for many pollutants, but their effectiveness in reflecting environmental PFAS contamination and the mechanisms of PFAS bioaccumulation is poorly understood. This study examined the impact of biological, chemical, and ecological variables on PFAS bioaccumulation in two bivalve species (i.e., Eastern oyster and Atlantic ribbed mussel) and developed a statistical model to predict the PFAS content in wild bivalves. Overall, the summed PFAS concentration in the bivalves closely mirrors that in water. We observed higher bioaccumulation factors for some perfluoroalkyl sulfonamides and branched PFAS isomers than for terminal PFAS of equivalent chain length. The isomer distribution and precursor-to-terminal compound ratios provide compelling evidence that the biotransformation of PFAS precursors likely drives these elevated factors. Additionally, the bioaccumulation factors of PFAS decrease with increasing organism size and age, suggesting that smaller and younger bivalves have greater bioaccumulation potential and are more susceptible to PFAS contamination. These findings provide critical information that guides the use of bivalves as biomonitors to evaluate PFAS contamination in aquatic environments.

Targeted screening, characterization and sources of per- and polyfluoroalkyl substances in plateau lake Yangzonghai, China

Per- and polyfluoroalkyl substances (PFAS) have been detected in lake ecosystems globally, even in remote areas at high altitudes. Compared to plain lakes with short water change cycles and significant human influence, plateau lakes are primarily tectonic closed or semi-closed lakes with steep terrain. Their long water change cycles lead to an obvious cumulative effect on pollutants. In this study, a targeted screening method for 74 PFAS in aquatic environment was established. The contamination characteristics of PFAS in surface water samples (0.5 m below the water surface) and bottom samples (0.5 m above the lake bottom) of plateau Lake Yangzonghai were studied and compared to a reference site in Dianchi Lake which has been severely affected by anthropogenic sources. Results showed that 32 PFAS were detected in Lake Yangzonghai with the total concentration (∑32PFAS) ranging from 14.95 to 26.42 ng L-1. Among the 27 PFAS with available standards for accurate quantification, 22 PFAS were detected, with the concentration of ∑22PFAS ranging from 13.27 to 20.17 ng L-1. Significant differences (p < 0.05) in PFAS concentrations were observed between surface water (22.12 ng L-1) and bottom water (18.18 ng L-1), demonstrating a stratification phenomenon. The spatial differences in PFAS concentrations in surface water were minimal, indicating that the surface water was uniformly mixed with limited local disturbance from human pollution. The main PFAS monomers were perfluorooctanoic acid (PFOA), 8-3 fluorotelomer carboxylic acid (8-3 FTCA), perfluoroheptanoic acid (PFHpA) and 2H-perfluoro-2-decenoic acid (8-2 FTUCA), while PFBA was not detected. This distribution remarkably differed from many other plain lakes and the reference lake. Source apportionment analysis showed that PFAS primarily originated from atmospheric transport and precursor degradation. The results provide a background pollution level of PFAS in the plateau lake near the city and will benefit for formulating control policies.

Fractionation and tidal characteristics of per- and polyfluoroalkyl substances in the estuarine maximum turbidity zone

Complex tidal processes and suspended particulate matter (SPM) behavior influence the land-sea transport of terrestrial contaminants in estuaries. Contaminants are generally trapped within the estuarine maximum turbidity zone (MTZ), where SPM concentrations peak, misleading flux estimation. Here, we conducted high-resolution continuous sampling over two tidal cycles within the MTZ of a semidiurnal estuary. Tidal variations of per- and polyfluoroalkyl substances (PFAS), a class of persistent organic pollutants, were analyzed in dissolved water and size-fractionated SPM. Results showed that variations in dissolved PFAS may related to the mixing of upstream and downstream. The predominant size range for SPM was found in 1-31 μm (75 %, mainly 10-31 μm), but the PFAS tended to be sorbed by 0.22-1 μm (60 %) and > 31 μm (37 %) fractions. Except during periods of sediment resuspension when particulate PFAS concentration decreased, the PFAS concentration in the 1-31 μm increased during flood tides and decreased during ebb tides, which may not be related to organic carbon/elemental carbon levels. The hourly dynamic flux of dissolved-phase and particulate-phase PFAS transport to the sea in the MTZ was calculated by combining it with a hydrodynamic model. This study first highlights the size-fractionated PFAS transport under tidal influences and provides hourly flux estimation with a hydrodynamic model.

Bioaccumulation potentials of per-and polyfluoroalkyl substances (PFAS) in recreational fisheries: Occurrence, health risk assessment and oxidative stress biomarkers in coastal Biscayne Bay

Per-and polyfluoroalkyl substances (PFAS) are a group of synthetic, highly fluorinated, and emerging chemicals that are reported to be used for both industrial and domestic applications. Several PFAS have demonstrated persistent, bioaccumulative and toxic tendencies in marine organisms. Therefore, this research aims to characterize and quantify these compounds in both recreational fisheries and surface water samples, including estimating their bioaccumulation potentials. In addition, we assessed the potential contribution of biomonitoring tools such as oxidative stressors and morphological index on fish and ecological health. Finally, human health risk assessment was performed based on available toxicological data on limited PFAS. All PFAS were detected in at least one sample except for N-EtFOSAA in lobster which was below the method detection limit. ƩPFAS body burden ranged from 0.15 to 3.40 ng/g wet weight (ww) in blackfin tuna samples and 0.37-5.15 ng/g ww in lobster samples, respectively. Wilcoxon rank paired test (α = 0.05) shows that there is statistical significance (ρ < 0.05) of ƩPFAS between species. Bioaccumulation factors (BAF) suggest an increasing trend in PFAS classes (PFCAs < PFSAs < FTSs), with higher BAFs observed in tuna compared to lobster. Long-chain PFESAs and FASAA were reported at higher concentrations in lobster compared to Blackfin tuna due to their bioavailability through sediment-sorption interactions. Although Fulton's condition factor (FCF) indicates healthy fish conditions, oxidative stress biomarkers suggest that tuna and lobster might be under stress, which can weaken their immune system against exposure to emerging contaminants such as PFAS. Hazard risk (HR) suggests a low risk to human health based on the consumption of the studied species; however, the risk of contaminant exposure may be higher than estimated. This study is aimed at improving food safety by providing better understanding of how PFAS infiltrate into human diet and incorporating data on influence of contaminant exposure and environmental stressors on marine health.

Effect of physicochemical parameters on the occurrence of per- and polyfluoroalkyl substances (PFAS) in aquatic environment

Perfluoroalkyl substances (PFAS) and their distribution in aquatic environments have been studied extensively, but more information is needed to link these occurrences to their physicochemical characteristics. Understanding how these parameters influence PFAS can help predict their fate, mobility, and occurrences in water. This study reviewed the influence of physicochemical parameters on the occurrences of PFAS in aquatic environment using the relevant keywords to retrieve articles from databases spanning mostly between 2017 and 2024. The result suggests that high pH, turbidity, and dissolved oxygen, give high concentration of PFAS, while high electrical conductivity, temperature and salinity give low PFAS concentration in the water. Therefore, monitoring and safeguarding the aquatic bodies for human and environmental safety is imperative. Future studies should include the effects of the physicochemical properties on PFAS occurrences in the natural environment and focus on an organism's distinctive characteristics to comprehend the bioaccumulation and biomagnification of PFAS in them and environmental matrices.

Innovative non-targeted screening approach using High-resolution mass spectrometry for the screening of organic chemicals and identification of specific tracers of soil and dust exposure in children

Environmental contamination through direct contact, ingestion and inhalation are common routes of children's exposure to chemicals, in which through indoor and outdoor activities associated with common hand-to-mouth, touching objects, and behavioral tendencies, children can be susceptible and vulnerable to organic contaminants in the environment. The objectives of this study were the screening and identification of a wide range of organic contaminants in indoor dust, soil, food, drinking water, and urine matrices (N = 439), prioritizing chemicals to assess children's environmental exposure, and selection of unique tracers of soil and dust ingestion in young children by non-targeted analysis (NTA) using Q-Exactive Orbitrap followed data processing by the Compound Discoverer (v3.3, SP2). Chemical features were first prioritized based on their predominant abundance (peak area>500,000), detection frequency (in >50% of the samples), available information on their uses and potential toxicological effects. Specific tracers of soil and dust exposure in children were selected in this study including Tripropyl citrate and 4-Dodecylbenzenesulfonic acid. The criteria for selection of the tracers were based on their higher abundance, detection frequency, unique functional uses, measurable amounts in urine (suitable biomarker), and with information on gastrointestinal absorption, metabolism, and excretion, and were further confirmed by authentic standards. We are proposing for the first time suitable unique tracers for dust ingestion by children.