Concentration and distribution of per- and polyfluoroalkyl substances (PFAS) in the Asan Lake area of South Korea

Isomer-specific sediment-water partitioning and bioaccumulation of perfluoroalkyl sulfonyl fluorides

Perfluoroalkyl sulfonyl fluorides (PFASFs) have long been used as crucial synthetic intermediates in the production of various perfluoroalkyl substances. While, knowledge on the environmental occurrence and behaviors of PFASFs in the aquatic environment is still very limited, especially at the isomer-specific level. In this study, surface water, sediment, and fish samples were collected from the water environment near a wastewater treatment plant outlet, and analyzed them for five PFASFs. The highest mean water concentration was observed for linear perfluorobutyl sulfonyl fluoride (l-PFBSF; 122 ng/L, 10-457 ng/L). While, linear perfluorooctane sulfonyl fluoride (l-PFOSF) displayed the highest mean concentration in collected sediment (108 ng/g dw, 78-271 ng/g dw) and fish (113 ng/g ww, 48-244 ng/g ww). For detected PFASFs, their branched isomers accounted for mean 16-29 %, 8.2-11 %, and 16-25 % of total PFASFs (sum of linear and branched isomers) in water, sediment, and fish samples, respectively. Calculated log-transformed sediment-water partitioning coefficients (log Koc) of linear PFASFs linearly increased with the increasing carbon chain length, with the mean values ranging from 2.1 ± 0.36 (l-PFBSF) to 3.9 ± 0.18 (l-PFOSF). Calculated log-transformed bioaccumulation factors (log BAF) of linear PFASFs increased from 1.7 ± 0.34 (l-PFBSF) to 3.0 ± 0.27 (l-PFOSF) with the carbon chain length. Branched isomers of detected PFASFs displayed lower log Koc and log BAF values than their respective linear isomers. To our knowledge, this study provides the first evidence on isomer-specific environmental behaviors of PFASFs, which is crucial for assessing the ecological risks these compounds may pose.

Occurrence, bioaccumulation and trophodynamics of per- and polyfluoroalkyl substances (PFAS) in terrestrial and marine ecosystems of Svalbard, Arctic

Per- and polyfluoroalkyl substances (PFAS) enter the Arctic through long-range transport and local pollution. To date, little is known about their behavior in plant and benthic marine food webs in remote Arctic. In this study, we analyzed the environmental distribution and nutrient transfer of 20 PFAS in soil, sediment, plant and benthic biota samples collected between 2014 and 2016 in Svalbard, Arctic. Total concentrations of PFAS were in the ranges of 0.12-4.84 ng/g dry weight (dw) in soil, 0.15-0.93 ng/g dw in sediment, 0.11-16.6 ng/g dw in plant, and 0.049-26.2 ng/g dw in marine biota. Perfluorocarboxylic acids (PFCAs) dominated Σ20PFAS in all sample types except amphipods, in which perfluorooctane sulfonate (PFOS) made up 80 % of Σ20PFAS. The profile of PFAS components observed in the terrestrial and marine ecosystems suggests that atmospheric transport and oxidation of volatile precursors are important sources of PFCAs in the Arctic region. However, the impact of long-distance ocean transport and local emissions cannot be ignored. The biota-sediment or biota-soil bioaccumulation factors (BSAF) differed among plants and biota species, with mountain avens (BSAF of Σ20PFAS: 12.1) and amphipods (BSAF of Σ20PFAS: 44.9) having higher accumulation potential. PFOS, perfluorohexane sulfonamide (FHxSA) and Σ20PFAS have biomagnification potential in Arctic benthic biota, but short-chain PFCA exhibits trophic dilution. This is one of few studies to investigate the environmental behavior of PFAS in terrestrial and aquatic ecosystems in the remote Arctic, providing a basis for investigating the ecological risks of PFAS in polar regions.

Occurrence and distribution of brominated and fluorinated persistent organic pollutants in surface sediments focusing on industrially affected rivers

This study investigated legacy persistent organic pollutants, including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), and per- and polyfluoroalkyl substances (PFAS), as well as their alternatives, in sediments from five major rivers, to assess their contamination status and usage patterns. The concentration levels of ΣPBDEs (median 9.98 ng/g dry weight (dw), mean 190 ng/g dw), ΣHBCDs (median 9.35 ng/g dw, mean 39.8 ng/g dw), Σnovel brominated flame retardants (NBFRs) (median not detected, mean 821 ng/g dw), and ∑PFAS (median 1.14 ng/g dw, mean 13.9 ng/g dw) in river sediments affected by high industrial activity were statistically significantly higher than at other sites with less or no industrial activity (Kruskal-Wallis test, p < 0.05). The dominant compounds among legacy substances for brominated flame retardants (BFRs) and PFAS are decaBDE for PBDEs, γ-HBCD for HBCDs, and perfluorooctane sulfonate (PFOS) for PFAS. The detection frequencies of 1,2-Bis(2,4,6-tribromophenoxy)ethane (BTBPE) and 6:2 chlorinated perfluoroalkylether sulfonic acid (F53B), as alternative substances for PBDEs and PFOS, were 16% and 9%, respectively. Regarding substances used as alternatives for perfluorooctanoic acid (PFOA) were detected at only one site for hexafluoropropylene oxide dimer acid (Gen-X), while 4,8-dioxo-3H-perfluorononanoic acid (ADONA) was not detected. The hazard quotient (HQ) values from the ecological risk assessment were generally low (HQ < 1), except for ΣPBDEs and PFOS at several sites. The present study emphasizes the need for continuous monitoring and risk assessment of these pollutants in river sediments, particularly in industrial areas, and highlights the importance of addressing the ecological toxicity of these substances to safeguard aquatic ecosystems.

Presence and sources of per- and polyfluoroalkyl substances (PFASs) in the three major rivers on Hainan Island

Per- and polyfluoroalkyl substances (PFASs) have attracted considerable attention because of their toxicity, persistence and bioaccumulation potential. With the construction of the Hainan Free Trade Port and the rapid development of economy, environmental pollution on Hainan Island is becoming increasingly prominent. PFASs have been detected in the seawater and sediments of mangrove ecosystems on Hainan Island. As the receiving water of wastewater treatment plants (WWTPs) and industrial wastewater, rivers are inevitably contaminated by PFASs. However, few studies have focused on PFAS pollution in three large rivers (the Nandu, Changhua, and Wanquan rivers) on Hainan Island. In the present study, the pollution status, potential sources, and ecological risks of PFASs in these three major rivers were explored. Perfluorobutanonic acid (PFBA) (48.7%) was found to be the major PFASs in the surface waters, and perfluoroundecanoic acid (PFUnDA) (19.7%) was the major PFASs in the sediments of the three major rivers. The concentrations of ∑PFASs in the upper-midstream region were low due to minimal human influence and increased in the middle-lower reaches with increasing industrial activity and urbanization, whereas decreased at downstream sites near estuaries where river water was diluted with seawater. WWTP effluent, industrial wastewater discharge, the application and discharge of aqueous fire-fighting foam, storm runoff and landfill leachate were the major sources of PFASs in the three major rivers. In surface water, perfluorooctanoic acid (PFOA), perfluorooctane sulfonamide (PFOSA) and perfluorooctadecanoic acid (PFODA) posed low-moderate risks at 5.71-85.6% of the sampling sites. PFASs in the sediment posed no ecological risk. This study provides key data regarding the pollution status and potential sources of PFASs in large rivers on subtropical islands.

Occurrence levels of perfluoroalkyl carboxylic acids (PFCA) and perfluoroalkyl sulfonic acids (PFSA) in European perch (Perca fluviatilis) samples collected from inland waters in Latvia: Component profiles, spatial distribution and dietary exposure to consumers

This study was performed to evaluate the occurrence of perfluorinated substances (PFAS) in European perch (Perca fluviatilis) samples from Latvian freshwater bodies. Twenty-nine samples of perch tissue homogenates were analyzed on the content of PFAS representing different sampling sites to cover all territory of Latvia evenly. The total PFAS concentrations (∑PFAS) ranged from 0.27 to 3.50 ng g-1 (mean 1.03 ng g-1 and median 0.78 ng g-1, respectively), while total priority four PFAS (∑4PFAS) concentration was in the range from 0.20 to 3.09 ng g-1 (mean 0.72 ng g-1 and median 0.49 ng g-1, respectively). The most prominent PFAS representative was perfluoroctanesulfonic acid (PFOS), presented in all samples at concentrations from 0.18 to 3.04 ng g-1 and constituting ∼ 60% of the total selected PFAS fraction. Observed concentrations of ∑4PFAS were significantly lower than established maximum levels (MLs), reaching maximum contamination up to 7% of respective ML. Calculated dietary intake figures do not exceed the safety threshold constituting from 5 to 7.5% of EFSA tolerable weekly intake (TWI) of 4.4 ng kg-1 bw. wk-1, however, a significantly higher intake of up to 45% of TWI could be obtained if maximum ∑4PFAS concentrations are used in calculations. Analysis of the spatial distribution of PFAS concentrations across various sampling sites suggests multiple contamination sources impacting Latvian freshwater bodies. While observed concentrations generally appear lower compared to data from heavily industrialized regions, the possibility of localized areas within Latvia exhibiting elevated PFAS levels cannot be excluded.

Diversity, composition, and assembly processes of bacterial communities within per- and polyfluoroalkyl substances (PFAS)-contained urban lake sediments

Per- and polyfluoroalkyl substances (PFAS) are widespread, highly persistent, and bio-accumulative compounds that are increasingly found in the sediments of aquatic systems. Given this accumulation and concerns regarding the environmental impacts of PFAS, their influence on sedimentary bacterial communities remains inadequately studied. Here, we investigated the concentrations of 17 PFAS in sediments from six urban lakes in Nanjing, China, and assessed their effects on the diversity, composition, potential interactions, and assembly mechanisms of sedimentary bacterial communities. Sediment concentrations of PFAS ranged from 4.70 to 5.28 ng·g-1 dry weight. The high concentrations of the short-chain perfluorobutanesulfonic acid (PFBS) suggested its substitution for the long-chain perfluorooctanesulfonic acid (PFOS). As alternatives to long-chain PFAS, short-chain PFAS had similar effects on bacterial communities. The short-chain perfluoropentanoic acid (PFPeA) and the long-chain perfluorotridecanoic acid (PFTrDA) were the most important PFAS related to the ecological patterns of the co-occurrence network and may alter the composition of the sedimentary bacterial communities in the urban lakes. The Anaerolineaceae family represented as keystone bacteria within the PFAS-affected bacterial co-occurrence network. Deterministic processes (65.9 %), particularly homogeneous selection (63.2 %), were the dominant process driving bacterial community assembly. PFAS promoted the phylogenetic clustering and influenced the community dispersal capabilities to shape bacterial community assembly. This study provides a comprehensive analysis of PFAS distribution in sediments across six urban lakes in Nanjing and provides novel insights into the effects of PFAS on sedimentary bacterial communities. Further research is required to elucidate the mechanisms underlying the impacts of PFAS on microbial communities and to evaluate their broader ecological consequences.

Decade-long historical shifts in legacy and emerging per- and polyfluoroalkyl substances (PFAS) in surface sediments of China's marginal seas: Ongoing production and ecological risks

Since the addition of perfluorooctane sulfonate (PFOS) to the Stockholm Convention in 2009, it became imperative to reassess the distribution and ecological risk of per- and polyfluoroalkyl substances (PFAS) in coastal sediments over the past decade as sediment records the history of pollutants from human activities. To achieve this, sediments were collected in 2009 and 2021 from China's coastal regions. Despite the consistent geographical pattern where the highest concentrations of ∑PFAS were found in the Yellow Sea, temporal changes have emerged. During the studied period, ∑PFAS levels experienced an increase in the East China Sea while concurrently witnessing a decrease in the South China Sea. Of significance, emerging PFAS compounds displayed not only rising concentrations but also a broader array, pointing towards their intensified production and utilization within China. Alarmingly, PFOS levels in sediments taken from the East China Sea maintained a consistently high ecological risk status over the last ten years. Significant correlations were found between long-chain PFAS and organic carbon content. Comparisons between datasets from 2009 to 2021 uncovered a shifting ecological risk landscape, with heightened concerns for PFOA in the East China Sea, while PFOS-associated risks appeared to diminish in the South China Sea-potentially reflecting the transition to alternative PFAS chemicals. The research reinforces the importance of continuous monitoring and emphasizes the urgent necessity for deeper exploration into the environmental implications and hazards posed by emerging PFAS.

Tissue-specific distribution and fatty acid content of PFAS in the northern Bohai Sea fish: Risk-benefit assessment of legacy PFAS and emerging alternatives

This study aimed to examine the distribution of poly- and perfluoroalkyl substances (PFAS) in 15 marine fish species from the northern Bohai Sea, investigate their sources of contamination, and evaluate the benefits-risks associated with the concurrent consumption of fish fatty acids and PFAS. The ∑PFAS concentrations in fish ranged from 9.38 to 262.92 ng·g-1 (dry weight). The highest PFAS levels were found in the viscera and gills, while the lowest levels were found in the muscles. Industrial effluents and sewage treatment plant discharges were the primary sources of PFAS contamination. The individual PFAS concentrations in fish were insignificantly correlated with their trophic levels (p > 0.05). However, the concentrations of hexafluoropropylene oxide dimer acid (HFPO-DA) or long-chain PFAS (C > 8) significantly increased with fish size (e.g., total length, weight) and lipid content (p < 0.001). The benefit-risk analysis suggests that HPFO-DA poses a higher health risk than perfluorooctanoic acid (PFOA) in fish (p < 0.05). Long-term consumption of contaminated fish may significantly increase human serum PFOA concentration and kidney cancer risk (p < 0.05). Daily consumption of 5 g (wet weight) muscle from Ditrema temmincki and Konosirus punctatus is recommended to meet the requirements for fatty acid supplementation without posing health risks.

Distinctive adsorption and transport behaviors of short-chain versus long-chain perfluoroalkyl acids in a river sediment

Perfluoroalkyl acids (PFAAs) embrace perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and other concerning chemicals of different chain length and terminal moieties. PFAAs can leach from municipal wastewater facilities as point sources discharging into rivers and receiving streams. In this study, we investigated the adsorption and transport behaviors of six select PFAAs in a Hudson River (USA) sediment in both batch and mesocosm studies. The adsorption capacities single and dual solute systems followed the order: PFBA < PFHxA ≈ PFBS < PFHxS < PFOA << PFOS. Mesocosm experiment that receives a continuous point source discharge of a mixture of these six PFAAs reached equilibrium after 4 weeks of operation. Total adsorbed PFAAs in the sediment was extracted and analyzed, following PFHxS (0.85 mg, 20.4%) ≈ PFBS (0.92 mg, 21.7%) < PFOA (1.02 mg, 27.3%) ≈ PFHxA (1.04 mg, 29.8%) < PFBA (1.12 mg, 30.1%) << PFOS (1.55 mg, 39.2%). PFOS showed highest adsorption, concentrating on the surface layer. Noticeably, two short-chain PFAAs, PFBA and PFHxA, were found with high vertical mobility, partitioning into deeper sediment. Two hotspots for PFAA sediment contamination were formed near the sediment surface downstream from the point source, providing new prospects to guide PFAA sediment cleanup and monitoring. Graphical abstract.

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.

Cytotoxicity and mechanisms of perfluorobutane sulfonate (PFBS) in umbilical cord fibroblast cells of Yangtze finless porpoise

Yangtze finless porpoises (YFP) accumulate high levels of per- and polyfluoroalkyl substances (PFASs). However, the health impacts of PFASs to YFP are still unknown because it is technically and ethically unfeasible to use the critically endangered YFP in toxicological exposures. To uncover the potential toxicities of PFASs to YFP, this study exposed a YFP umbilical cord fibroblast cell line to perfluorobutane sulfonate (PFBS), an emerging PFASs pollutant in the aquatic environments. After exposure, the cytotoxicity and mechanisms of PFBS were explored. Our preliminary experiments found that PFBS compromised the cell viability in a concentration and duration dependent manner. In an exposure of 48-h duration, the maximum no observed effect concentration (NOEC) of PFBS was determined to be 400 µM. High-throughput proteomics were then conducted to identify the differentially expressed proteins in YFP cells exposed to 400 µM PFBS for 48 h. The results found that PFBS exposure significantly perturbed the proteome fingerprints of YFP umbilical cord fibroblast cells. Functional annotation of differential proteins showed that PFBS had the potential to impair a variety of biological processes associated with the immunity, oxidative stress, metabolism, and proteolysis. Consistently, the intracellular levels of reactive oxygen species (ROS) and proinflammatory cytokine IL-1β were significantly increased by PFBS in YFP umbilical cord fibroblast cells. Overall, this study highlights the toxic effects of emerging PFASs on YFP and provides reference data to evaluate the health risks of aquatic pollution under the context of national YFP protection. To our knowledge, this is the first omics study using YFP umbilical cord fibroblast cells in ecotoxicology of PFASs, which is applicable to various cetacean species and pollutants.

Pilot Assessment of Impacts of Ozone and Ozone/Hydrogen Peroxide Treatment on the Fate of Per- and Polyfluoroalkyl Substances and Precursors

Per- and polyfluoroalkyl substances (PFAS) make up a large class of anthropogenic micropollutants prevalent in wastewater. Oxidative processes commonly used in wastewater potable reuse treatment may affect transformation of PFAS precursors, leading to elevated concentrations of perfluorinated alkyl acids (PFAAs) that are significant health concerns. This work conducted a pilot-scale investigation to assess the influence of ozonation (O3) and ozone/hydrogen peroxide (O3/H2O2) advanced oxidation process (AOP), respectively, on the fate of PFAS in a wastewater effluent subjected to reuse. The study evaluated 40 target PFAS and associated precursors [based on the total oxidizable precursor (TOP) assay] under various treatment conditions, including different ozone doses (1.0-4.0 mg·L-1), H2O2 doses (0-0.20 mg·L-1), and contact time (0-20 min). Results indicated that short-chain (C3-C7) PFAAs dominated in concentrations, while overall PFAA concentrations were elevated by both oxidative treatment processes, particularly after high-dose ozonation treatment. TOP assays revealed that there were considerable amounts of PFAA precursors in the reuse wastewater, and their concentrations were decreased after the oxidative treatment with an increase of some of the PFAAs. This pilot study demonstrated that ozone and ozone-based AOP treatments can have a moderate influence on the transformation of PFAS and increase in PFAA levels under practical conditions.

Efficient adsorption of short-chain perfluoroalkyl substances by pristine and Fe/Cu-loaded reed straw biochars

As the substitutes of legacy long-chain per-/polyfluoroalkyl substances (PFASs), short-chain PFASs have been widely detected in the environment. Compared to long-chain PFASs, short-chain PFASs have smaller molecules and are more hydrophilic. Therefore, they are more likely to experience long-distance transport and pose lasting environmental impacts. In this study, Fe-doped (R-Fe) and Cu-doped biochars (R-Cu) were prepared using reed straw biochar (R). The results showed that the PFBA and PFPeA sorption capacities of R-Fe were 25.81 and 43.59 mg g-1, 1.65 and 1.55 times higher than those of R, respectively. The PFBA and PFPeA sorption capacities of R-Cu were 19.34 and 33.69 mg g-1, 1.24 and 1.20 times higher than those of R, respectively. In addition, R, R-Fe, and R-Cu exhibited higher PFBA and PFPeA sorption capacities than the biochars previously reported. The excellent PFAS sorption performances of the biochars were attributed to the highly porous structure of R, which provided rich adsorption sites. Ion-pair sorption, pore filling, electrostatic interaction between the Fe/Cu and cationic groups on biochar and the anionic groups of PFASs, and hydrophobic interaction between the hydrophobic surface of biochar and the fluorinated tails of PFASs were the underlying sorption mechanisms. The biochars presented high removal rates (>86 %) of multiple PFASs (∑PFAS: 350 μg L-1) from synthetic wastewaters, including legacy and emerging PFASs of different chain lengths and with different functional groups. The biochars reported in this study are promising candidate adsorbents for treating waters contaminated with short-chain PFASs.

Spatial heterogeneity of per- and polyfluoroalkyl substances caused by glacial melting in Tibetan Lake Nam Co due to global warming

Per- and polyfluoroalkyl substances (PFASs) in high-latitude polar regions and the Tibetan Plateau have received widespread international attention. Here, we measured 18 PFASs and 11 major isomers in the lake water, sediment, and surrounding runoff of Lake Nam Co in 2020. The concentrations of ultrashort-chain trifluoroacetic acid (TFA) and perfluoropropanoic acid (PFPrA) and major isomers of perfluoooctanoic acid (PFOA) and perfluoooctane sulfonate acid (PFOS) in water bodies in high-latitude polar regions and the Tibetan Plateau are reported for the first time. The results showed that the concentration of ∑PFASs in glacial runoff was approximately 139 % greater than that in nonglacial runoff. The concentrations of ∑PFASs in the lake water and sediment in the southern lake with multiple glacial runoff events were approximately 113 % and 108 % higher, respectively, than those in the northern lake. The concentrations of short-chain perfluorobutanoic acid (PFBA) and ultrashort-chain TFA and PFPrA, which may be indicators of ice and snow melt, exhibited significant spatial heterogeneity. Overall, the spatial heterogeneity of PFAS concentrations in the water, sediment and surrounding runoff of Lake Nam Co may be caused mainly by glacial melting.

Which pollutants and sources should be prioritized for control in multi-pollutants complex contaminated areas?

Risk assessment and source identification of multi-pollutants are essential for accurate control of soil contamination. However, complexity in pollutant properties and diversity in source types raise challenges to the target. Therefore, this study constructed a hierarchical ecological risk quantification method combined with risk ranking, risk of single pollutant using potential affected fraction (PAF), and joint risk of multi-pollutants employing msPAF. Taking regional contamination in South China as a case, the risk ranking was determined, while single and joint effects showed msPAF reaching 79.4 %, with risk as heavy metals (HMs) > per- and polyfluoroalkyl substances (PFASs) > polycyclic aromatic hydrocarbons (PAHs). Meanwhile, an integrated source apportionment method was established from three layers by principal component analysis to classify source types, multiple linear regression of distance to identify key sources, and positive matrix factorization to track omitted sources. Consequently, key sources were captured, with 80.8 %-93.2 % contribution of farmland and electroplating to three main HMs, 52.2 %-69.4 % contribution of roads to three main PAHs, and 71.1 %-73.2 % contribution of electroplating to two main PFASs. Further, omitted sources were tracked with contribution of 31.2 %-84.1 % to eight pollutants. The established methods can identify control targets, including high-risk pollutants and their key sources.

Distribution and ecological risk assessment of perfluoroalkyl carboxylic acids (PFCAs) in the coastal river, China

Perfluoroalkyl carboxylic acids (PFCAs) enter surface waters through wastewater discharge and atmospheric deposition, accumulating within aquatic ecosystems and organisms, causing dysfunction or mortality. This study investigates the migration, sources and ecological risks of six PFCAs in the coastal Wulong River basin and the estuary along the eastern coast of China. The six PFCAs detected in the Wulong River included, at concentrations ranging from 17.36 to 57.92 ng/L. The distribution of PFCAs concentrations throughout the estuary were as follows: Northeast China (414.07 ng/L) > North China (325.97 ng/L) > East China (249.53 ng/L) > South China (63.61 ng/L), with perfluorooctanoic acid (PFOA) being the dominant PFCA. Toxicity data was collected for all detected PFCAs and the species sensitivity distribution (SSD) method was used to derive the predicted no effect concentrations (PNECs) for all six PFCAs. The risk quotient (RQ) method showed that the risk posed to aquatic organisms in the river basin from all six PFCAs was relatively low (RQ < 1). However, joint probability curve (JPC) analysis revealed that the probability of perfluoropentanoic acid (PFPeA) causing harm to 5% of aquatic species reached 41.13%. Considering the frequency of occurrence and persistence of PFCAs in aquatic environments, these findings indicate they have the potential to induce serious toxic effects on aquatic organisms.

Distribution Control and Environmental Fate of PFAS in the Offshore Region Adjacent to the Yangtze River Estuary─A Study Combining Multiple Phases Analysis

The Yangtze River Estuary is the terminal sink of terrestrial per- and polyfluoroalkyl substances (PFAS) from the Yangtze River, while the environmental fate characteristics of legacy and emerging PFAS around this region have rarely been discussed. Here, 24 targeted PFAS in seawater, sediments, suspended particulate matter (SPM), and plankton in the offshore region adjacent to this estuary were investigated. The three dominant PFAS in all phases were perfluorooctanoic acid (PFOA, 23.8-61.9%), perfluorobutanoic acid (PFBA, 23.6-42.8%), and perfluoro(2-methyl-3-oxahexanoic) acid (HFPO-DA, 6.1-12.1%), and perfluoro-1-butane sulfonamide (FBSA, 0.1-7.3%) was first detected. The horizontal distributions of PFAS were dependent on salinity and disturbed by multiple water masses, while the vertical variations could be explained by their different partitioning characteristics in the water-SPM-sediment system (partition coefficients, Log Kd and Log Koc) and plankton (bioaccumulation factors, Log BAF). Although physical mixing was the major driver for PFAS settling (>83.7%), the absolute settling amount caused by the biological pump was still high (150.00-41994.65 ng m-2 day-1). More importantly, we found unexpected high Log Kd values of PFBA (2.24-4.55) and HFPO-DA (2.26-4.67), equal to PFOA (2.28-4.72), which brought concerns about their environmental persistence. Considering the increased detection of short-chain and emerging PFAS, more comprehensive environmental behaviors analysis is required urgently.

Occurrence and health risk assessment of PFAS and possible precursors: a case study in a drinking water treatment plant and bottled water (south Catalonia, Spain)

The presence of PFAS in drinking water may pose a serious threat to human health. This study aims to determine the levels of these compounds and their precursors in water samples from a drinking water treatment plant (DWTP) located in l'Ampolla (Spain) and to assess their fate. Additionally, ten Spanish bottled waters were analyzed to compare the occurrence of PFAS in the mentioned matrices and in drinking water. Off-line solid phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was applied to determine 26 PFAS and PFAS precursors after a total oxidizable precursor assay. The analytical method presents low quantification limits (0.25-5 ng/L). A total PFAS concentration of up to 16 ng/L in all the DWTP samples was obtained, and 6:2 FTS was the only precursor detected. Results are close to the quantification limits, resulting in a high degree of uncertainty, and for this, it is difficult to evaluate the DWTP PFAS removal efficiency. Regarding bottled water, total PFAS concentration found was up to 12 ng/L in one of ten samples, with no precursors detected. Exposure assessment revealed that there is no risk associated with the ingestion of the samples analyzed. Moreover, there were no differences in terms of risk between drinking water from l'Ampolla DWTP and bottled water.

The investigation of the enrichment behavior of identified PFAS and unknown PFAA-precursors in water and suspended particulate matter of the surface microlayer: A case study in Tianjin (China)

The surface microlayer (SML) is an important air water interface layer, known as the skin of the ocean, which has chemical enrichment properties. Chemical enrichment in the SML can affect the occurrence of pollutants in the underlying water and air samples. Although the enrichment of per- and polyfluorinated substances (PFAS), a class of persistent organic pollutants of high concern, has been reported in the SML, information on the behavior of unknown PFAA-precursors in SML is lacked, and it is not clear whether there is a similar PFAS enrichment in suspended particulate matter (SPM) in the SML. Therefore, to investigate these questions, we conducted a systematic survey of 24 PFAS in 11 paired water and SPM samples from the SML and underlying water (U50cm and U2m) from the Duliujian River, which flows to the Bohai sea in Tianjin, China. The ∑PFAS mean concentrations in the water and SPM samples were 38.2 ng/L and 64.6 ng/g dw, respectively. The PFAS concentrations of PFAS in the SML were higher than those in the underlying water, and the enrichment factors (EFs) were greater in the SPM than that in the water. The long-chain PFAS EFs were greater than those for short-chain PFAS, indicating that the EFs were positively correlated with the hydrophobicity. Moreover, by applying the total oxidizable precursor (TOP) assay, the unknown PFAA-precursors (C5-C12) in the water and SPM contributed 11.4∼86.4 mol% and 7.1∼88.0 mol% to total PFAS, respectively. The ecological risk of the targeted PFAS in the SML was relatively higher than that in the underlying water, indicating that PFAS in the SML require more attention. Preliminary estimates indicate that the PFAS-enriched SML is an important exposure route that poses a potential risk to wildlife in rivers and oceans.

Association Between Prenatal Exposure to Per- and Poly-Fluoroalkyl Substances From Electronic Waste Disassembly Areas and Steroid Hormones in Human Milk Samples

Per- and poly-fluoroalkyl substances (PFAS), which are long-lasting environmental contaminants that are released into the environment during the e-waste disassembly process, pose a threat to human health. Human milk is a complex and dynamic mixture of endogenous and exogenous substances, including steroid hormones and PFAS. Therefore, in this study, we aimed to investigate the association between PFAS and steroid hormones in human milk from women living close to an e-waste disassembly area. In 2021, we collected milk samples from 150 mothers within 4 weeks of delivery and analyzed them via liquid chromatography-tandem mass spectrometry to determine the levels of 21 perfluorinated compounds and five steroid hormones (estrone, estriol, testosterone, progesterone, and androstenedione [A-dione]). We also performed multiple linear regression analysis to clarify the association between maternal PFAS exposure and steroid hormone concentrations. Our results indicated that PFOA and PFOS were positively associated with estrone (β, 0.23; 95% CI, 0.08-0.39) and A-dione (β, 0.186; 95% CI, 0.016-0.357) concentrations in human milk, respectively. Further, the average estimated daily intake of PFOA and PFOS were 36.5 ng/kg bw/day (range, 0.52-291.7 ng/kg bw/day) and 5.21 ng/kg bw/day (range, 0.26-32.3 ng/kg bw/day), respectively. Of concern, the PFAS intake of breastfeeding infants in the study area was higher than the recommended threshold. These findings suggested that prenatal exposure to PFAS from the e-waste disassembly process can influence steroid hormones levels in human milk. Increased efforts to mitigate mother and infant exposure to environmental pollutants are also required.

PFOA-contaminated soil remediation: a comprehensive review

Soil and groundwater contamination has been raised as a concern due to the capability of posing a risk to human health and ecology, especially in facing highly toxic and emerging pollutants. Because of the prevalent usage of perfluorooctanoic acid (PFOA), in industrial and production processes, and subsequently the extent of sites contaminated with these pollutants, cleaning up PFOA polluted sites is paramount. This research provides a review of remediation approaches that have been used, and nine remediation techniques were reviewed under physical, chemical, and biological approaches categorization. As the pollutant specifications, environmental implications, and adverse ecological effects of remediation procedures should be considered in the analysis and evaluation of remediation approaches, unlike previous research that considered a couple of PFAS pollutants and generally dealt with technical issues, in this study, the benefits, drawbacks, and possible environmental and ecological adverse effects of PFOA-contaminated site remediation also were discussed. In the end, in addition to providing sufficient and applicable understanding by comprehensively considering all aspects and field-scale challenges and obstacles, knowledge gaps have been found and discussed.

Understanding the role of atmospheric deposition on the environmental load of per- and polyfluoroalkyl substances: A case study in Three Gorges Reservoir, China

Sixty-nine total suspended particle (TSP) samples, paired with forty-eight surface soil samples, covering four seasons from January 2021 to November 2021, were collected from the Three Gorges Reservoir Region (TGRR). Twenty per- and poly-fluoroalkyl substances (PFASs) were analyzed to evaluate their contamination characteristics and understand the role of atmospheric deposition on the environmental loads in TGRR. The annual average concentrations of PFASs in TSP and soil were 37.2 ± 1.22 pg·m-3 and 0.798 ± 0.134 ng·g-1, respectively. For TSP, concentrations were highest in spring and lowest in summer. For soil, it was in autumn and winter, respectively. The seasonality was more influenced by anthropogenic activities than by meteorological conditions or physicochemical parameters of the soil. Positive matrix fractionation (PMF) indicated that, based on annual averages, PFOA-based products (40.2 %) were the major sources of PFASs in TSP, followed by PFOS-based products (25.2 %) and precursor degradation (34.6 %). The highest source contributor for PFASs in spring was precursor degradation (40.9 %), while in other three seasons, it was PFOA-based products (39.9 %, 40.9 % and 52.0 %, respectively). The mean atmospheric dry and wet deposition fluxes of PFASs were estimated at 4.38 ng·m-2·day-1 and 23.5 ng·m-2·day-1, respectively. The contribution of atmospheric deposition to the inventory mass of PFASs in the surface soil was 22.3 %. These findings fill a gap in knowledge regarding the processes and mechanisms of the occurrence, sources and atmospheric deposition of PFASs in the TGRR.

Spatial distribution, source, and fate of per- and polyfluoroalkyl substances in the surrounding environment of closed and converted fluorochemical factories in Fujian, China

Following the closure of perfluorooctanesulfonic acid (PFOS) production to comply with the Stockholm Convention regulations or restrictions, manufacturers have shifted to developing short-chain alternatives like perfluorobutane sulfonic acid (PFBS). However, limited research has been conducted to evaluate the impact of this transition on the surrounding environment. This study focused on the spatial distribution, source, and fate of 18 per- and polyfluoroalkyl substances (PFAS) in the surrounding environment of the closure and transformation of two PFAS manufacturing plants in Fujian, China. The total concentrations of PFAS in surface water, sediment, and fish were within the range of 48.9-72,400 ng/L, 0.930-57.6 ng/g dw, and 3.33-1245 ng/g dw, respectively. The predominant compounds were PFBS, PFOS, and perfluorooctanoic acid (PFOA) among the three matrices. Principal component analysis highlighted significant differences in PFAS profiles across different regions of the Futun River, suggesting diverse sources of PFAS. Source apportionment indicated that despite being closed or converted for almost three years, the two factories still significantly impacted the surrounding environment. The shutdown factory mainly released PFAS characterized by perfluoroalkyl sulfonic acids. In contrast, the PFAS were released from conversion plant with the fingerprint being PFBS and perfluoroalkyl carboxylic acids. The conversion of the factories has resulted in the coexistence of long-chain and short-chain PFAS, which has complicated the composition of PFAS in the environment. As sewage treatment plant could not effectively remove PFBS and perfluorobutanoic acid (PFBA) in wastewater, and due to their strong migration ability, these chemicals had a wider impact range, increasing the difficulty of environmental restoration and management. Risk assessment showed that PFAS downstream of the two factories posed high or moderate ecological risks. Specifically, PFBS, PFOS, and PFOA displayed the highest risk quotients and should be paid further attention.

Trend of PFAS concentrations and prediction of potential risks in Taihu Lake of China by AQUATOX

Per- and polyfluoroalkyl substances (PFAS) are recognized as emerging environmental pollutants due to their high persistence and toxicities to humans and animals. Understanding the temporal trend of PFAS in the environment is important for their pollution control and making appropriate policies. Many studies have reported the PFAS concentrations in Taihu Lake, the third largest lake in China, while their temporal trend during the years was seldom investigated. This study summarizes the PFAS concentrations in the water, sediment and organisms in Taihu Lake from 2009 to 2020 to depict their temporal trends. Meanwhile, the ecological model of AQUATOX was applied to evaluate and predict the potential risks of PFAS from 2012 to 2030. The results showed that the total PFAS concentrations varied but without distinct increase or decrease in both water and sediment during the years, while PFAS concentrations in organisms significantly decreased. The yearly mean concentrations of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in the water were 21.7-25.4 ng/L and 9.7-26.5 ng/L respectively, lower than the Standards for Drinking Water Quality of China and the suggested water quality criteria to protect the aquatic organisms. In sediment, PFOA and PFOS concentrations were 0.16-0.69 ng/g and 0.15-0.82 ng/g respectively, much lower than the recommended sediment quality guideline values. Based on the AQUATOX prediction, there will be no major threats caused by PFAS to the growth of biota in Taihu Lake in the near future, while the biomass of some species (e.g. carp) will be affected under the perturbation of PFAS. Both field investigation and AQUATOX simulation showed that PFOS concentrations in invertebrates and fish descend steadily, while no remarkable decrease in PFOA concentrations was expected. This study suggests a decreasing ecological risk of PFAS in Taihu Lake, while highlights the necessity of continuous monitoring of PFAS contamination.

Occurrence, bioaccumulation, fate, and risk assessment of emerging pollutants in aquatic environments: A review

Significant concerns on a global scale have been raised in response to the potential adverse impacts of emerging pollutants (EPs) on aquatic creatures. We have carefully reviewed relevant research over the past 10 years. The study focuses on five typical EPs: pharmaceuticals and personal care products (PPCPs), per- and polyfluoroalkyl substances (PFASs), drinking water disinfection byproducts (DBPs), brominated flame retardants (BFRs), and microplastics (MPs). The presence of EPs in the global aquatic environment is source-dependent, with wastewater treatment plants being the main source of EPs. Multiple studies have consistently shown that the final destination of most EPs in the water environment is sludge and sediment. Simultaneously, a number of EPs, such as PFASs, MPs, and BFRs, have long-term environmental transport potential. Some EPs exhibit notable tendencies towards bioaccumulation and biomagnification, while others pose challenges in terms of their degradation within both biological and abiotic treatment processes. The results showed that, in most cases, the ecological risk of EPs in aquatic environments was low, possibly due to potential dilution and degradation. Future research topics should include adding EPs detection items for the aquatic environment, combining pollution, and updating prediction models.

Per- and polyfluoroalkyl substances induce lipid metabolic impairment in fish: Integration on field investigation and laboratory study

The biotoxicity of perfluoroalkyl and polyfluoroalkyl substances (PFASs) to aquatic organisms has been widely concerned. However, studies on toxic effects of PFASs are usually evaluated directly by using laboratory exposure rather than laboratory validation based on data obtained in the field. In this study, wild catfish (Silurus meridinalis) was explored on the relationship between PFASs bioaccumulation and lipid disorders. Nine and thirteen lipid metabolites were significantly associated with perfluorooctane sulfonate (PFOS) and 6:2/8:2Cl-PFESA (trade name F-53B) exposures, respectively; and the correlated lipid metabolites were the fatty acid (FA) and conjugates, FA esters, steroids, and glycerophosphate subclasses. The effects of PFASs on lipid metabolism of fish and its mechanism were further analyzed through exposure experiments. Zebrafish (Danio rerio) of different sexes underwent PFOS and F-53B exposures for 21 days at 100 ng/L and 100 μg/L. By determining gene expression levels, hepatic lipid contents, and histopathological change, the adverse effects order on lipid metabolism in male or female was 100 μg/L F-53B > 100 μg/L PFOS > 100 ng/L F-53B > 100 ng/L PFOS; the stress response in male was more intensive than that in female. PFOS and F-53B activated the peroxisome proliferator-activated receptor pathway, promoting the processes of FA and total cholesterol (T-CHO) transport, FA β-oxidation, FA synthesis, and finally induced FA and T-CHO transportation from blood into liver, then accelerated FA to FA ester transformation, and CHO into steroids. Laboratory experiments confirmed the field analysis. This study innovatively explored the adverse effects of PFOS and F-53B on lipid metabolism and their mechanisms at field and laboratory levels, highlighting concerns regarding PFASs health risks.

Contamination status, partitioning behavior, ecological risks assessment of legacy and emerging per- and polyfluoroalkyl substances in a typical heavily polluted semi-enclosed bay, China

The contaminant status, spatial distribution, partitioning behavior, and ecological risks of 26 legacy and emerging perfluoroalkyl and polyfluoroalkyl substances (PFASs) in Laizhou Bay, China were investigated. The concentrations of ∑PFASs in surface and bottom seawater ranged from 37.2 to 222 ng/L and from 34.2 to 305 ng/L with an average of 116 ± 62.7 and 138 ± 93.8 ng/L, respectively. There were no significant differences in the average concentrations between the surface and bottom seawater (P > 0.05). Perfluorooctanoic acid (PFOA) and short-chain PFASs dominated the composition of PFASs in seawater. The concentrations of ∑PFASs in sediments ranged from 0.997 to 7.21 ng/g dry weight (dw), dominated by perfluorobutane sulfonate (PFBS), perfluorobutanoic acid (PFBA), and long-chain PFASs. The emerging alternatives of perfluoro-1-butane-sulfonamide (FBSA) and 6:2 fluorotelomer sulfonic acid (6:2 FTSA) were detected for the first time in Laizhou Bay. The ∑PFASs in seawater in the southwest of the bay were higher than those in the northeast of the bay. The ∑PFASs in sediments in the northeast sea area were higher than those in the inner area of the bay. Log Kd and log Koc values increased with increasing carbon chain length for PFASs compounds. Ecological risk assessments indicated a low ecological risk associated with HFPO-DA but a moderate risk associated with PFOA contamination in Laizhou Bay. Positive matrix factorization (PMF) analysis revealed that fluoropolymer manufacturing, metal plating plants, and textile treatments were identified as major sources contributing to PFASs contamination.

Multi-media distribution and risk assessment of per- and polyfluoroalkyl substances in the Huai River Basin, China

The widespread existence, environmental persistence, and risks of per- and polyfluoroalkyl substances (PFASs) have attracted widespread attention. Herein, the distribution and risk assessment of PFASs were investigated from the Huai River Basin. The ranges in different media were 29.83-217.96 (average of 75.82 ± 35.64 ng/L) in water, 0.17-9.55 ng/g (2.56 ± 2.83 ng/g) in sediments, and 0.21-9.76 ng/g (3.43 ± 3.07 ng/g) in biota. Perfluoropentanoic acid (PFPeA) was the most prevalent PFAS in surface water, followed by perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA), accounted for 42.62 %, 22.23 % and 17.72 % of the total concentrations of the PFASs analyzed, respectively. PFBA was dominant in sediments, accounting for 60.37 % of the total concentrations of the PFASs analyzed. Perfluorooctane sulfonate (PFOS) was the main pollutant in biota, and the highest concentration (5.09 ng/g) was found in Channa argus. Considering the measured concentrations in water, sediments and biota, the sediment-water partition coefficients (log Kd) and bioaccumulation factors (BAF) of PFASs were determined. The log Kd of the PFASs differed among those with a different carbon chain length, C7-C11 PFASs were more likely to be adsorbed onto sediments as the carbon chain length increases, and PFUnDA and PFDA showed the higher BAF value in Channa argus. PFASs in the Huai River Basin posed an acceptable ecological risk, and long-chain PFAS contamination provided green algae with a higher potential ecological risk. Compared to drinking water, aquatic products constituted a higher PFASs threat to human health, especially for children. The highest HQ was found in PFOS, with an HQmax of 0.97-4.32. Residents in the Huai River Basin should reduce their intake of Channa argus, Coilia nasus, and Carassius auratus, children aged 2 to 4 are limited to consuming no more than 6.9 g/d, 9.7 g/d, and 16.6 g/d, respectively.

Fluoro-functionalized plant biomass adsorbent: Preparation and application in extraction of trace perfluorinated compounds from environmental water samples

Perfluorinated compounds (PFCs) are toxic and widely present in the environment, and therefore effective adsorbents are required to remove PFCs from environmental water. In the present study, a new type of fluorinated biomass materials was synthesized via an ingenious fluorosilanization reaction. These adsorbents were applied for the adsorption of 13 typical PFCs, including perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs). By comparing their adsorption performance, Fluorinated cedar slag (FCS) was discovered to have the best absorption efficiency and enabled highly efficient enrichment of PFCs. The adsorption recovery of FCS with the investigated PFCs is greater than 90% under the optimal adsorption condition. Ascribed to the high affinity of F-F sorbent-sorbate interaction, FCS had good adsorption capacities of PFCs from aqueous solution, with the maximum adsorption capacity of 15.80 mg/g for PFOS and 10.71 mg/g for PFOA, respectively. Moreover, the adsorption time could be achieved in a short time (8 min). Using the FCS absorbent, an innovative FCS-solid phase extraction assisted with high performance liquid chromatography-electrospray-tandem mass spectrometry (FCS-SPE-HPLC-ESI-MS/MS) method was first developed to sensitively detect PFCs in the environmental water samples. The intra-day and inter-day recovery rates of the 13 compounds ranged from 90.7%-104.3%, with the RSD of 2.1%-4.7% (intra-day) and 2.5%-8.5% (inter-day), respectively. This research demonstrates the potential of the newly fluoro-functionalized plant biomass to adsorb PFCs from environmental water, with the advantages of high adsorption efficiencies, high anti-interference, easy operation and low economic cost.

An Integrated Metabolomics-Based Model, and Identification of Potential Biomarkers, of Perfluorooctane Sulfonic Acid Toxicity in Zebrafish Embryos

Known for their high stability and surfactant properties, per- and polyfluoroalkyl substances (PFAS) have been widely used in a range of manufactured products. Despite being largely phased out due to concerns regarding their persistence, bioaccumulation, and toxicity, legacy PFAS such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid continue to persist at high levels in the environment, posing risks to aquatic organisms. We used high-resolution magic angle spinning nuclear magnetic resonance spectroscopy in intact zebrafish (Danio rerio) embryos to investigate the metabolic pathways altered by PFOS both before and after hatching (i.e., 24 and 72 h post fertilization [hpf], respectively). Assessment of embryotoxicity found embryo lethality in the parts-per-million range with no significant difference in mortality between the 24- and 72-hpf exposure groups. Metabolic profiling revealed mostly consistent changes between the two exposure groups, with altered metabolites generally associated with oxidative stress, lipid metabolism, energy production, and mitochondrial function, as well as specific targeting of the liver and central nervous system as key systems. These metabolic changes were further supported by analyses of tissue-specific production of reactive oxygen species, as well as nontargeted mass spectrometric lipid profiling. Our findings suggest that PFOS-induced metabolic changes in zebrafish embryos may be mediated through previously described interactions with regulatory and transcription factors leading to disruption of mitochondrial function and energy metabolism. The present study proposes a systems-level model of PFOS toxicity in early life stages of zebrafish, and also identifies potential biomarkers of effect and exposure for improved environmental biomonitoring. Environ Toxicol Chem 2024;00:1-19. © 2024 SETAC.

Legacy and alternative per-and polyfluoroalkyl substances (PFASs) in the Bohai Bay Rim: Occurrence, partitioning behavior, risk assessment, and emission scenario analysis

The use of alternative per- and polyfluoroalkyl substances (PFASs) has been practiced because of the restrictions on legacy PFASs. However, knowledge gaps exist on the ecological risks of alternatives and relationships between restrictions and emissions. This study systematically analyzed the occurrence characteristics, water-sediment partitioning behaviors, ecological risks, and emissions of legacy and alternative PFASs in the Bohai Bay Rim (BBR). The mean concentration of total PFASs was 46.105 ng/L in surface water and 6.125 ng/g dry weight (dw) in sediments. As an alternative for perfluorooctanoic acid (PFOA), hexafluoropropylene oxide dimer acid (GenX) had a concentration second only to PFOA in surface water. In sediments, perfluorobutyric acid (PFBA) and GenX were the two predominant contaminants. In the water-sediment partitioning system, GenX, 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (F-53B), and 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (8:2 Cl-PFESA) tended to be enriched towards sediments. The species sensitivity distribution (SSD) models revealed the low ecological risks of PFASs and their alternatives in the BBR. Moreover, predicted no-effected concentrations (PNECs) indicated that short-chain alternatives like PFBA and perfluorobutane sulfonate (PFBS) were safer for aquatic ecosystems, while caution should be exercised when using GenX and F-53B. Due to the incremental replacement of PFOA by GenX, cumulative emissions of 1317.96 kg PFOA and 667.22 kg GenX were estimated during 2004-2022, in which PFOA emissions were reduced by 59.2 % due to restrictions implemented since 2016. If more stringent restrictions are implemented from 2023 to 2030, PFOA emissions will further decrease by 85.0 %, but GenX emissions will increase by an additional 21.3 %. Simultaneously, GenX concentrations in surface water are forecasted to surge by 2.02 to 2.45 times in 2023. This study deepens the understanding of PFAS alternatives and assists authorities in developing policies to administer PFAS alternatives.

The untold story of PFAS alternatives: Insights into the occurrence, ecotoxicological impacts, and removal strategies in the aquatic environment

Due to increasing regulations on the production and consumption of legacy per- and polyfluoroalkyl substances (PFAS), the global use of PFAS substitutes increased tremendously, posing serious environmental risks owing to their bioaccumulation, toxicity, and lack of removal strategies. This review summarized the spatial distribution of alternative PFAS and their ecological risks in global freshwater and marine ecosystems. Further, toxicological effects of novel PFAS in various freshwater and marine species were highlighted. Moreover, degradation mechanisms for alternative PFAS removal from aquatic environments were compared and discussed. The spatial distribution showed that 6:2 chlorinated polyfluorinated ether sulfonate (6:2 CI-PFAES, also known as F-53B) was the most dominant emerging PFAS found in freshwater. Additionally, the highest levels of PFBS and PFBA were observed in marine waters (West Pacific Ocean). Moreover, short-chain PFAS exhibited higher concentrations than long-chain congeners. The ecological risk quotients (RQs) for phytoplankton were relatively higher >1 than invertebrates, indicating a higher risk for freshwater phytoplankton species. Similarly, in marine water, the majority of PFAS substitutes exhibited negligible risk for invertebrates and fish, and posed elevated risks for phytoplanktons. Reviewed studies showed that alternative PFAS undergo bioaccumulation and cause deleterious effects such as oxidative stress, hepatoxicity, neurotoxicity, histopathological alterations, behavioral and growth abnormalities, reproductive toxicity and metabolism defects in freshwater and marine species. Regarding PFAS treatment methods, photodegradation, photocatalysis, and adsorption showed promising degradation approaches with efficiencies as high as 90%. Finally, research gaps and future perspectives for alternative PFAS toxicological implications and their removal were offered.

First insights into per-and polyfluoroalkyl substance contamination in edible fish species of the Indus water system of Pakistan

Per- and polyfluoroalkyl substances (PFASs) are a group of emerging contaminants, that have a wide range of applications in industrial and commercial products. The direct discharge of untreated industrial and domestic wastewater into freshwater bodies is a common practice in developing countries, which are the main contributors to PFASs in the aquatic environment. The situation is further worsened due to poor wastewater treatment facilities and weak enforcement of environmental regulations in countries like Pakistan. The current study was designed to assess PFASs contamination in muscle tissues of edible fish species from major tributaries of the Indus System, including Head Panjnad (HP), Head Trimmu (HT), Chashma Barrage (CB), Head Blloki (HB) and Head Qadirabad (HQ). The analysis of target PFAS was performed using ultrahigh-performance liquid chromatography coupled with a quadrupole Orbitrap high-resolution mass spectrometry. The highest levels of ∑17PFASs were observed in S. seenghala, C. mirigala from HB, and C. mirigala from HQ with a mean value of 45.4 ng g-1, 43.7 ng g-1, and 40.8 ng g-1, respectively. Overall, the compositional profile of fish samples was predominated by long-chain PFASs such as PFOA, PFOS, PFHpS, and PFDS. The accumulation of PFASs in fish species is dependent on the physiochemical properties of PFASs, characteristics of the aquatic environment, and fish species. Significant associations of PFASs with isotopic composition (p < 0.05), feeding habits (p < 0.05), and zones (p < 0.05) indicate that dietary proxies could be an important predictor of PFASs distribution among species. The C7-C10 PFASs exhibited bio-accumulative tendency with an accumulation factor ranging from 0.5 to 3.4. However, none of the fish samples had sufficiently high levels of PFOS to cause human health risk (HR < 1). For future studies, it is s recommended to conduct seasonal monitoring and the bioaccumulation pattern along trophic levels of both legacy and emerging PFASs.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in water and edible fish species of Karun River, Ahvaz, Iran: spatial distribution, human health, and ecological risk assessment

Per- and polyfluoroalkyl substances (PFASs) such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are environmental contaminants with unfavorable impacts on human health and nature. This study aimed to determine the PFOA and PFOS concentration in water and fish samples from Karun, the largest river in Iran. According to the results, the PFOA and PFOS in water samples were 5.81-69.26 ng/L and not detected (n.d.)-35.12 ng/L, respectively. The dry season displayed higher concentrations in water samples than in the wet season. The maximum PFOS concentration measured was related to Barbus barbules sp. (27.89 ng/g). The human health risk assessment indicated minor risks (hazard ratio, HR < 1) from PFOA and PFOS through consuming contaminated drinking water and fish. Only HR value of PFOS in downstream area exceeded slightly 1.0, indicating potential health risk due to consumption of the river fish. Considering the average PFASs concentration, the risk quotients (RQs) showed low ecological risk.

Proposal for priority emerging pollutants in the Nakdong river, Korea: Application of EU watch list mechanisms

The Nakdong River, the longest in Korea, has received numerous pollutants from heavily industrialized and densely populated areas while being used as a drinking water source. A number of research have reported occurrences of emerging pollutants (EPs) in the river. The results requested efficient monitoring and systematic management strategies such as EU watch list under Water Framework Directive. The aim of this study is to propose a watch list through preliminary monitoring of the river and risk-based prioritization approach. As candidates for monitoring target, 632 substances were selected based on literature and database searches. Among them, 175 substances were subjected to target screening method whereas 457 were evaluated via suspect screening. A risk-based prioritization was applied to substances quantified through target screening based on concentrations, and a scoring-based prioritization was applied to substances tentatively identified through suspect screening. Sampling campaigns (n = 12) were conducted from October 2020 to September 2021, at 8 sampling sites along the river. As a result, 130 target substances were quantified above the LOQ. Among the 21 substances whose priority score was assigned through risk-based prioritization, telmisartan and iprobenfos were identified with very high environmental risk while candesartan, TBEP, imidacloprid, azithromycin and clotrimazole were classified with high or intermediate risk. As result of the scoring system for 39 tentatively identified substances, 6 substances (benzophenone, caprolactam, metolachlor oxanilic acid, heptaethylene glycol, octaethylene glycol and pentaethylene glycol), which were then confirmed with reference standards, showed a potential environmental risk. Those substances prioritized through target and suspect screening followed by scoring systems can be a subset for the watch list and potential targets for nationwide water quality monitoring program in the future.

Biomagnification and health risks of perflfluoroalkyl acids (PFAAs) in seafood from the Yangtze river estuary of China

Bioaccumulation and human health risk assessment of Perfluoroalkyl acids (PFAAs) is important for pollutant hazard assessment. In this study, 26 aquatic organisms were collected from the Yangtze River estuary, the PFAAs concentrations in organisms were detected by liquid chromatography-mass spectrometry, and the trophic levels of organisms were constructed using nitrogen isotope analysis. The results showed that Perfluorobutane sulfonate (PFBS) was predominant in organisms with the mean concentration of 6.43 ± 8.21 ng/g ww. The biomagnification of organisms along the food chain was widespread, and the biomagnification factor (BMF) of perfluorooctane sulfonic (PFOS) was the most prominent. Trophic magnifcation factors (TMFs) of PFAAs were estimated in the marine food web, and TMFs >1 were observed in Perfluorodecanoic acid (PFDA), Perfluoroundecanoic acid (PFUnDA), Perfluorododecanoic acid (PFDoDA), and PFOS, indicating the biomagnifcation effects of these 4 individual PFAAs in organisms at Yangtze River estuary. The estimated daily intake (EDI) of PFBS was highest in adolescents aged 6-18 years, with EDIs of 18.9 ng/kg·bw/day for males and 14.0 ng/kg·bw/day for females. The hazard ratio (HR) of PFAAs reported in different age and gender groups were lower than 1.

Dietary exposure to per- and polyfluoroalkyl substances: Potential health impacts on human liver

Per- and polyfluoroalkyl substances (PFAS), dubbed "forever chemicals", are widely present in the environment. Environmental contamination and food contact substances are the main sources of PFAS in food, increasing the risk of human dietary exposure. Numerous epidemiological studies have established the link between dietary exposure to PFAS and liver disease. Correspondingly, PFAS induced-hepatotoxicity (e.g., hepatomegaly, cell viability, inflammation, oxidative stress, bile acid metabolism dysregulation and glycolipid metabolism disorder) observed from in vitro models and in vivo rodent studies have been extensively reported. In this review, the pertinent literature of the last 5 years from the Web of Science database was researched. This study summarized the source and fate of PFAS, and reviewed the occurrence of PFAS in food system (natural and processed food). Subsequently, the characteristics of human dietary exposure PFAS (population characteristics, distribution trend, absorption and distribution) were mentioned. Additionally, epidemiologic evidence linking PFAS exposure and liver disease was alluded, and the PFAS-induced hepatotoxicity observed from in vitro models and in vivo rodent studies was comprehensively reviewed. Lastly, we highlighted several critical knowledge gaps and proposed future research directions. This review aims to raise public awareness about food PFAS contamination and its potential risks to human liver health.

Combustion of high-calorific industrial waste in conventional brick kilns: An emerging source of PFAS emissions to agricultural soils

The brick kilns in the South Asian region are widely documented to partially combust high-calorific waste components of synthetic-industrial origin, which contain hazardous constituents, including per- and polyfluoroalkyl substances (PFAS). Correspondingly, these establishments are necessarily built on agricultural land to easily acquire clay by excavating soil horizons, thus making cultivation soils vulnerable to PFAS contaminations. In this pioneering study, the occurrence, distribution profile, traceability and human health risk exposure to forty-four legacy and novel PFAS homologues, including two ultrashort-chain (C2-C3) PFAS, were investigated in agricultural soils around thirty-two conventional brick kilns across three districts of Pakistan. ⅀44PFAS concentrations ranged from 14.3 to 465 ng/g (median: 28.2 ng/g), which were 2 to 70 folds higher than those in background soils, and slightly higher than those reported in agricultural soils in the global literature. The highest occurrence was observed for PFAS alternatives, i.e., 6:2 fluorotelomer sulfonate (6:2 FTSA) (40 %) and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) (4.5 %). A significant positive correlation (p < 0.01) was observed among the concentrations of short-chain perfluoroalkyl acids (C4-C7) and novel PFOS substitutes, implying their origin from common sources. Furthermore, ultrashort-chain and short-chain perfluorocarboxylic acids (PFCA) (89 %) and perfluorosulfonic acids (PFSA) (63 %) dominated over long-chain's PFCA (11 %) and PFSA (37 %), respectively. The estimated daily intake to children exposed in surrounding inhabited communities, at 95th percentile concentrations was found to be approaching the European tolerable daily intake limit of 0.63 ng/kg bw/day. Therefore, the brick manufacturing industry is identified as a novel source of PFAS in the adjacent environment and for residents. This suggests the need for further investigations to elucidate the origin of emerging contaminants in the waste streams of the region to safeguard ecological integrity.

Enhanced removal of short- and long-chain per- and poly-fluoroalkyl substances from aqueous phase using crushed grafted chitosan beads: Performance and mechanisms

The widespread use of per- and poly-fluoroalkyl substances (PFASs), environmentally persistent halogenated hydrocarbons, in various industrial and commercial applications has caused significant concerns owing to their contamination of soil and groundwater. Chitosan is a biopolymer substance with abundant amine and hydroxyl functional groups, making it a good candidate for adsorption of PFASs. This study aimed to increase chitosan's adsorption capacity by grafting additional amine functional groups on its surface for the removal of long- and short-chain PFASs from an aqueous phase. Two types of chitosan-based sorbents were developed: crushed chitosan beads (CBs) and polyethyleneimine-grafted CBs (GCBs). Batch adsorption tests assessed the adsorption capacities of the sorbents in terms of the sorption kinetics, isotherms, selectivity, and reusability. Based on the results, the GCBs had significant potential for adsorbing PFASs. These capacities were significantly higher than those demonstrated by the CBs. The sorption kinetics data revealed that the GCBs had a fast sorption rate. Furthermore, the GCBs demonstrated a high adsorption affinity, with log Kd values ranging from 1.5 to 2.5 for PFASs at environmentally relevant concentrations (1000 ng L-1). They also demonstrated excellent selectivity sorption for these compounds, even in the presence of other organic and inorganic pollutants.

An integrated assessment of ecological and human health risks of per- and polyfluoroalkyl substances through toxicity prediction approaches

Per- and polyfluoroalkyl substances (PFAS) are also known as "forever chemicals" due to their persistence and ubiquitous environmental distribution. This review aims to summarize the global PFAS distribution in surface water and identify its ecological and human risks through integrated assessment. Moreover, it provides a holistic insight into the studies highlighting the human biomonitoring and toxicological screening of PFAS in freshwater and marine species using quantitative structure-activity relationship (QSAR) based models. Literature showed that PFOA and PFOS were the most prevalent chemicals found in surface water. The highest PFAS levels were reported in the US, China, and Australia. The TEST model showed relatively low LC50 of PFDA and PFOS for Pimephales promelas (0.36 and 0.91 mg/L) and high bioaccumulation factors (518 and 921), revealing an elevated associated toxicity. The risk quotients (RQs) values for P. promelas and Daphnia magna were found to be 269 and 23.7 for PFOS. Studies confirmed that long-chain PFAS such as PFOS and PFOA undergo bioaccumulation in aquatic organisms and induce toxicological effects such as oxidative stress, transgenerational epigenetic effects, disturbed genetic and enzymatic responses, perturbed immune system, hepatotoxicity, neurobehavioral toxicity, altered genetic and enzymatic responses, and metabolism abnormalities. Human biomonitoring studies found the highest PFOS, PFOA, and PFHxS levels in urine, cerebrospinal fluid, and serum samples. Further, long-chain PFOA and PFOS exposure create severe health implications such as hyperuricemia, reduced birth weight, and immunotoxicity in humans. Molecular docking analysis revealed that short-chain PFBS (-11.84 Kcal/mol) and long-chain PFUnDA (-10.53 Kcal/mol) displayed the strongest binding interactions with human serum albumin protein. Lastly, research challenges and future perspectives for PFAS toxicological implications were also discussed, which helps to mitigate associated pollution and ecological risks.

The sources and bioaccumulation of per- and polyfluoroalkyl substances in animal-derived foods and the potential risk of dietary intake

Per- and polyfluoroalkyl substances (PFAS) have attracted increasing attention due to their environmental persistence and potential toxicity. Diet is one of the main routes of human exposure to PFAS, particularly through the consumption of animal-derived foods (e.g., aquatic products, livestock and poultry, and products derived from them). This review summarizes the source, bioaccumulation, and distribution of PFAS in animal-derived foods and key influential factors. In most environmental media, perfluorooctanoic acid and perfluorooctane sulfonate are the dominant PFAS, with the levels of short-chain PFAS such as perfluorobutyric acid and perfluorohexane sulfonate surpassing them in some watersheds and coastal areas. The presence of PFAS in environmental media is mainly influenced by suspended particulate matter, microbial communities as well as temporal and spatial factors, such as season and location. Linear PFAS with long carbon chains (C ≥ 7) and sulfonic groups tend to accumulate in organisms and contribute significantly to the contamination of animal-derived foods. Furthermore, PFAS, due to their protein affinity, are prone to accumulate in the blood and protein-rich tissues such as the liver and kidney. Species differences in PFAS bioaccumulation are determined by diet, variances in protein content in the blood and tissues and species-specific activity of transport proteins. Carnivorous fish usually show higher PFAS accumulation than omnivorous fish. Poultry typically metabolize PFAS more rapidly than mammals. PFAS exposures in the processing of animal-derived foods are also attributable to the migration of PFAS from food contact materials, especially those in higher-fat content foods. The human health risk assessment of PFAS exposure from animal-derived foods suggests that frequent consumption of aquatic products potentially engender greater risks to women and minors than to adult males. The information and perspectives from this review would help to further identify the toxicity and migration mechanism of PFAS in animal-derived foods and provide information for food safety management.

Comparative developmental toxicities of zebrafish towards structurally diverse per- and polyfluoroalkyl substances

Structurally diverse per- and polyfluoroalkyl substances (PFASs) are increasingly detected in ecosystems and humans. Therefore, the clarification of their ecological and health risks is urgently required. In the present study, the toxicity of a series of PFASs, including PFOS, PFBS, Nafion BP1, Nafion BP2, F53B, OBS, PFOA, PFUnDA, PFO5DoDA, HFPO-TA was investigated. Similarities and differences in the developmental toxicity potentials were revealed. Our results demonstrated that PFUnDA exhibited the highest toxicity with the lowest EC50 value of 4.36 mg/L (for morphological abnormality); this was followed by F53B (5.58 mg/L), PFOS (6.15 mg/L), and OBS (10.65 mg/L). Positive correlations with volatility/solubility and chemotypes related to specific biological activity, including the bioconcentration factor (LogBCF), and negative correlations with lipid solubility and carbon chain component-related chemotypes, including the number of carbon and fluorine atoms, provided a reasonable explanation in the view of molecular structures. Furthermore, comparative transcriptome analysis provided molecular evidence for the relationship between PFASs exposure and malformations. Common differentially expressed genes (DEGs) involved in spine curve development, pericardial edema, and cell/organism growth-related pathways presented common targets, leading to toxic effects. Therefore, the present results provide novel insights into the potential environmental risks of structurally diverse PFASs and contribute to the selection of safer PFAS replacements.

Accumulation and dietary risks of perfluoroalkyl substances in fish and shellfish: A market-based study in Barcelona

Since the 1940s, per- and polyfluoroalkyl substances (PFAS) have been widely produced and used in various applications due to their unique properties. Consequently, the principal exposure routes of PFAS have been broadly studied, leading to the conclusion that dietary exposure (more specifically, the consumption of fish and seafood) was one of their main contributors. Thus, developing an analytical method that determines the level of PFAS in fish and seafood has become a relevant subject. In this work, a previous analytical method has been optimized to determine 12 PFAS in fish muscle from salmon, tuna, cod, hake, sardine, anchovy, and sole, as well as in seven different seafood species (i.e., cuttlefish, octopus, squid, shrimp, Norway lobster, prawn, and mussel) by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Subsequently, the PFAS profile of the different species was studied to determine if it was consistent with that previously reviewed in the literature and to know the most relevant contribution of PFAS for each species. Finally, human exposure to PFAS through their consumption was estimated by the daily intake for seven different age/gender groups. PFAS were obtained from 0.014 to 0.818 ng g-1 wet weight in fish samples. Sardines, anchovies, and soles presented the highest PFAS levels. However, cod samples also showed some PFAS traces. Regarding seafood, PFAS levels range from 0.03 to 36.7 ng g-1 dry weight for the studied species. A higher concentration of PFAS has been found in the cephalopods' spleens and the crustaceans' heads. PFOS and PFBS were the predominant compounds in each seafood species, respectively. On the other hand, in the case of mussels, which are the less polluted species of the study, contamination by longer-chained PFAS was also observed. Finally, the total intake of PFAS due to fish and shellfish consumption for the Spanish adult population was estimated at 17.82 ng day-1. Nevertheless, none of the analyzed samples exceeded the European Food Safety Authority (EFSA) risk value for the supervised PFAS in any age/gender group reviewed.

Effects of combined exposure of PVC and PFOA on the physiology and biochemistry of Microcystis aeruginosa

Microplastics (MPs) and per- and polyfluoroalkyl substances (PFASs) have drawn significant attention as emerging threats to aquatic ecosystems. There are currently just a few investigations on the combined toxicity of PFAS and MP on freshwater microalgae. In this research, the combined toxicity of polyvinyl chloride (PVC) and perfluorooctanoic acid (PFOA) to Microcystis aeruginosa was investigated. The results indicated that the combination of these pollutants inhibited the growth of M. aeruginosa and promoted the synthesis and release of Microcystin-LR (MC-LR). Individual and combined exposure caused different responses to cellular oxidative stress. Under the Individual exposure of PFOA, when the concentration was greater than 20.0 mg/L, the catalase (CAT) activity increased significantly, and when it was greater than 100.0 mg/L, the malondialdehyde (MDA) content increased significantly, but there is no significant change under combined exposure. PVC and PFOA exposure also caused physical damage to the algal cells and reduced the content of extracellular polymer substances (EPS) based on analysis of cell morphology. Metabolic analysis revealed that carbohydrate metabolism and amino acid metabolism of the algae were affected. The current study offers a fresh theoretical framework for MPs and PFASs environmental risk evaluations.

Environmental exposure and ecological risk of perfluorinated substances (PFASs) in the Shaying River Basin, China

There have been concerns raised about the environmental effects of perfluoroalkyl substances (PFASs) because of their toxicity, widespread distribution, and persistence. Understanding the occurrences and ecological risk posed by PFASs is essential, especially for the short-chain replacements perfluorobutanoic acid (PFBA) and perfluorobutane sulfonic acid (PFBS), which are now becoming predominant PFASs. The lack of aquatic life criteria (ALC), however, prevents an accurate assessment of the ecological risks of PFBA and PFBS. This study thus investigated the occurrence of 15 PFASs at 29 sampling sites in Shaying River Basin (in China) systematically, conducted the toxicity tests of PFBA and PFBS on eight resident aquatic organisms in China, and derived the predicted non-effect concentration (PNEC) values for PFBA and PFBS for two environmental media in China. The results showed that the total PFASs concentrations (ΣPFASs) ranged from 5.07 to 20.32 ng/L (average of 10.95 ng/L) in surface water, whereas in sediment, ΣPFASs ranged from 6.46 to 20.05 ng/g (dw) (average of 11.51 ng/g). The presence of PFBS was the most prominent PFASs in both water (0.372-8.194 ng/L) and sediment (4.54-15.72 ng/g), demonstrating that short-chain substitution effects can be observed in watersheds. The PNEC values for freshwater and sediment were 6.60 mg/L and 8.30 mg/kg (ww), respectively, for PFBA, and 14.04 mg/L, 37.08 mg/kg (ww), respectively, for PFBS. Ecological risk assessment of two long-chain PFASs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), and two short-chain PFASs, PFBA and PFBS, using the hazard quotient method revealed that Shaying River and other major River Basins in China were at risk of PFOS contamination. This study contributes to a better understanding of the presence and risk of PFASs in the Shaying River and first proposes the ALCs for PFBA and PFBS in China, which could provide important reference information for water quality standards.

Revealing the factors resulting in incomplete recovery of perfluoroalkyl acids (PFAAs) when implementing the adsorbable and extractable organic fluorine methods

Per- and polyfluoroalkyl substances (PFASs) are environmental contaminants of concern. Techniques that quantify total organic fluorine (TOF) such as the adsorbable organic fluorine (AOF) and extractable organic fluorine (EOF) methods are important for PFAS risk assessments. The objective of this study was to systematically evaluate each step of the AOF (loading, washing, combustion) and EOF (loading, washing, elution, combustion) methods for the recovery of ten ultrashort-, short-, and long-chain unsubstituted perfluoroalkyl acids (PFAAs). We measured the overall recovery of fluoride for each method for each PFAA, and the recovery of each PFAA around the loading, washing, and elution steps. We also measured the combustion efficiency of each PFAA by direct combustion. The overall AOF and EOF recovery ranged from 9.3%-103.3% to 21.0%-108.1%, respectively, with higher recoveries measured for PFAAs with increasing chain length in both methods. The three ultrashort-chain PFAAs (trifluoroacetic acid, perfluoropropionic acid, and perfluoropropanesulfonic acid) exhibited the lowest overall recoveries from 9.3-25.2% for AOF and 21.0-51.5% for EOF. We found that decreases in the overall recovery are the result of losses of ultrashort- and short-chain PFAAs during the washing step and the incomplete mineralization of perfluoroalkyl sulfonic acids during combustion for AOF and incomplete elution of short- and long-chain PFAAs and the loss of ultrashort-chain PFAAs during the washing step for EOF. Our data suggest that the EOF method is more appropriate than the AOF method for measuring TOF in samples containing ultrashort- and short-chain PFAAs and that methodological improvements are possible with a focus on the washing, elution, and combustion steps.

Source, transport, and fate of perfluoroalkyl acids (PFAAs) in turbid bay environments: Significant roles of suspended sediment and water column stratification

The coastal area was the major region receiving pollution from land-based sources into the sea. Perfluoroalkyl acids (PFAAs) in famous bays had aroused wide concern, but the importance of underdeveloped or small bays with notable levels of PFAAs were often neglected. Moreover, the roles of suspended sediment (SPS) and water column stratification on PFAA behaviors were unclear. In this study, PFAAs distribution in multiphase-multilayer in four underdeveloped bays (two urban bays and two island bays) were investigated. The urban bays not only had higher PFAA contamination but also posed a greater threat of short-chain PFAAs in water-SPS-sediment system than the island bays. The major source of PFAAs in water and SPS was domestic sewage in urban bays and was rainfall-runoff in island bays. Water column stratification with higher PFAA partition in water-SPS system in the surface layer than in the bottom layer was only found in the urban bays due to the higher human activity intensity. These provided new perspectives for managing emerging contaminants and establishing water quality criteria in the turbid coastal environment. The key role of SPS as a carrier offered possibilities to accurately differentiate the effects of dissolved and particulate PFAAs on bioavailability.

Per- and polyfluoroalkyl substances (PFASs) in consumable species and food products

Per- and polyfluoroalkyl substances (PFASs) are a group of thousands of manmade chemicals widely used in consumer products and industrial processes. Toxicological studies have suggested that exposure to PFASs may lead to several adverse effects, including infertility and cancer development. In light of their widespread use, the contamination of food products has created health concerns in sites directly influenced by industrial and anthropogenic activity. In the present contribution, the current knowledge of PFAS contamination was systematically reviewed in order to provide with the knowledge gaps and main sources of contamination, as well as critically evaluate estimated dietary intake and relative risk values of the consulted studies. Legacy PFASs remain the most abundant despite their production restrictions. Edible species from freshwater bodies exhibit higher PFAS concentrations than marine species, probably due to low hydrodynamics and dilution in lentic ecosystems. Studies in food products from multiple sources, including aquatic, livestock, and agricultural, agree that the proximity to factories and fluorochemical industries rendered significantly higher and potentially hazardous PFAS contamination. Short-chain PFAS are suggested as chemicals of emerging concern to food security. However, the environmental and toxicological implications of short-chain congeners are not fully understood and, thus, much research is needed in this sense.

Degradation and Defluorination of Per- and Polyfluoroalkyl Substances by Direct Photolysis at 222 nm

The susceptibility of 19 representative per- and polyfluoroalkyl substances (PFAS) to direct photolysis and defluorination under far-UVC 222 nm irradiation was investigated. Enhanced photolysis occurred for perfluorocarboxylic acids (PFCAs), fluorotelomer unsaturated carboxylic acids (FTUCAs), and GenX, compared to that at conventional 254 nm irradiation on a similar fluence basis, while other PFAS showed minimal decay. For degradable PFAS, up to 81% of parent compound decay (photolysis rate constant (k222 nm) = 8.19-34.76 L·Einstein-1; quantum yield (Φ222 nm) = 0.031-0.158) and up to 31% of defluorination were achieved within 4 h, and the major transformation products were shorter-chain PFCAs. Solution pH, dissolved oxygen, carbonate, phosphate, chloride, and humic acids had mild impacts, while nitrate significantly affected PFAS photolysis/defluorination at 222 nm. Decarboxylation is a crucial step of photolytic decay. The slower degradation of short-chain PFCAs than long-chain ones is related to molar absorptivity and may also be influenced by chain-length dependent structural factors, such as differences in pKa, conformation, and perfluoroalkyl radical stability. Meanwhile, theoretical calculations indicated that the widely proposed HF elimination from the alcohol intermediate (CnF2n+1OH) of PFCA is an unlikely degradation pathway due to high activation barriers. These new findings are useful for further development of far-UVC technology for PFAS in water treatment.

Spatial and temporal variability of per- and polyfluoroalkyl substances (PFAS) in environmental media of a small pond: Toward an improved understanding of PFAS bioaccumulation in fish

Per- and polyfluoroalkyl substances (PFAS) are highly fluorinated compounds with many industrial applications, for instance as ingredients in fire-suppressing aqueous film-forming foams (AFFF). Several PFAS have been demonstrated to be persistent, bioaccumulative and toxic. This study better characterizes the bioaccumulation of PFAS in freshwater fish through a spatial and temporal analysis of surface water and sediment from a stormwater pond in a former Naval air station (NAS) with historic AFFF use. We sampled environmental media from four locations twice per week for five weeks and sampled fish at the end of the sampling effort. The primary PFAS identified in surface water, sediment, and biota were perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) followed by perfluorooctanoic acid (PFOA) in environmental media and perfluoroheptane sulfonate (PFHpS) in biota. We observed significant temporal variability in surface water concentrations at the pond headwaters following stochastic events such as heavy rainfall for many compounds, particularly PFHxS. Sediment concentrations varied most across sampling locations. In fish, liver tissue presented the highest concentrations for all compounds except PFHxS, which was highest in muscle tissue, suggesting the influence of fine-scale aqueous PFAS fluctuations on tissue distribution. Calculated log bioaccumulation factors (BAFs) ranged from 0.13 to 2.30 for perfluoroalkyl carboxylates (PFCA) and 0.29-4.05 for perfluoroalkane sulfonates (PFSA) and fluctuated greatly with aqueous concentrations. The variability of PFAS concentrations in environmental media necessitates more frequent sampling efforts in field-based studies to better characterize PFAS contamination in aquatic ecosystems as well as exercising caution when considering single time-point BAFs due to uncertainty of system dynamics.