Spatio-temporal dynamics of per and polyfluoroalkyl substances (PFASs) and transfer to periphytic biofilm in an urban river: case-study on the River Seine

Assessment of PFDA toxicity on RTgill-W1 cell line via metabolomics and lipidomics approaches

Perfluorodecanoic acid (PFDA), a long-chain perfluoroalkyl substance (PFAS), is known for its environmental persistence and potential toxicity. This study evaluated PFDA toxicity in the RTgill-W1 cell line, a model for aquatic toxicology, using a combination of cell viability assays, reactive oxygen species (ROS) measurements, and high-throughput metabolomics and lipidomics. PFDA exposure resulted in significant, dose-dependent reductions in cell viability and increased ROS production, with an EC₅₀ value of 51.9 ± 1.7 mg/L, highlighting its cytotoxic potential. Metabolomic profiling revealed dose-dependent disruptions in 168 metabolites, impacting pathways related to amino acid metabolism, carbohydrate metabolism, lipid metabolism, vitamin and cofactor metabolism, and nucleotide metabolism. Furthermore, lipidomic analysis identified 102 significantly altered lipids, primary affecting glycerolipid metabolism, fatty acid biosynthesis, glycerophospholipid metabolism, sphingolipid metabolism - suggesting compromised membrane integrity, energy production, and signalling processes. These findings underscore PFDA's capacity to interfere with critical cellular processes and highlight the utility of integrated omics approaches in elucidating the molecular mechanisms of PFAS toxicity. Future studies should focus on validating fish cell assays through short-term in vivo tests to enhance their reliability and ecological relevance.

Metagenome-Assembled Genomes and Metatranscriptome Analysis of Perfluorooctane Sulfonate-Reducing Bacteria Enriched From Activated Sludge

Per- and polyfluoroalkyl substances (PFAS) exhibit a widespread distribution across diverse global ecosystems throughout their lifecycle, posing substantial risks to human health. The persistence of PFAS makes biodegradation a challenging yet environmentally friendly solution for their treatment. In the authors' previous study, a bacterial consortium capable of reducing perfluorooctane sulfonate (PFOS) was successfully enriched from activated sludge. This study aimed to investigate the array of genes associated with PFOS reduction via biosorption and biotransformation to elucidate the metabolic pathways. Two metagenome-assembled genomes (MAGs) based on 16S rRNA sequences that share 99.86% and 97.88% similarity with Hyphomicrobium denitrificans and Paracoccus yeei, respectively were obtained. They were found to contain several genes encoding enzymes that potentially regulate biofilm formation of biosorption and facilitate the desulfonation and defluorination processes of biotransformation. Transcriptomic analysis demonstrated the high expression levels of these genes, including alkanesulfonate monooxygenase, catechol dioxygenase, (S)-2-haloacid dehalogenase and putative cytochrome P450, suggesting their involvement in PFOS biotransformation. The expression of these genes supports the presence of candidate metabolites of PFOS biotransformation detected in the previous study. These findings emphasise the significant potential of bacterial consortia and the crucial role played by genes encoding enzymes in facilitating the remediation of PFOS contaminants.

Temporal and spatial distribution of inorganic fluoride, total adsorbable organofluorine, PFOA and PFOS concentrations in the Hungarian section of the Danube River

The existing technologies in municipal wastewater treatment plants are ineffective in eliminating persistent fluorine-containing contaminants. At the same time, there is an increasing demand for novel organofluorine compounds, particularly in the production of lithium-ion batteries, as well as in the agrochemical and pharmaceutical sectors for more efficient ingredients. This implies that we must account for ongoing changes in the fluorine levels within riverine environments. To determine the fluorine concentration in the water phase of rivers, it is essential to measure both inorganic fluoride and total organofluorine concentrations. These analytes were measured in water samples collected monthly from twelve locations along the Hungarian section of the Danube River during the period from July to December 2023, applying ion-chromatography and combustion ion-chromatography. The concentration of inorganic fluoride ranged from 28 to 76 µg/L, with a median of 45.3 µg/L. The total adsorbable organofluorine concentrations were between 0.22 and 12.5 µg/L, with a median of 2.43 µg/L. To assess the impact of restrictions on the use of PFOA and PFOS compounds, these substances were quantified using a UHPLC-Q-TOF-MS system. A comparison of our data with previously published concentrations in the Danube River reveals a decreasing tendency, justifying the restricted use of these chemicals.

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.

Combined toxicity of perfluoroalkyl substances and microplastics on the sentinel species Daphnia magna: Implications for freshwater ecosystems

Persistent chemicals from industrial processes, particularly perfluoroalkyl substances (PFAS), have become pervasive in the environment due to their persistence, long half-lives, and bioaccumulative properties. Used globally for their thermal resistance and repellence to water and oil, PFAS have led to widespread environmental contamination. These compounds pose significant health risks with exposure through food, water, and dermal contact. Aquatic wildlife is particularly vulnerable as water bodies act as major transport and transformation mediums for PFAS. Their co-occurrence with microplastics may intensify the impact on aquatic species by influencing PFAS sorption and transport. Despite progress in understanding the occurrence and fate of PFAS and microplastics in aquatic ecosystems, the toxicity of PFAS mixtures and their co-occurrence with other high-concern compounds remains poorly understood, especially over organisms' life cycles. Our study investigates the chronic toxicity of PFAS and microplastics on the sentinel species Daphnia, a species central to aquatic foodwebs and an ecotoxicology model. We examined the effects of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and polyethylene terephthalate microplastics (PET) both individually and in mixtures on Daphnia ecological endpoints. Unlike conventional studies, we used two Daphnia genotypes with distinct histories of chemical exposure. This approach revealed that PFAS and microplastics cause developmental failures, delayed sexual maturity and reduced somatic growth, with historical exposure to environmental pollution reducing tolerance to these persistent chemicals due to cumulative fitness costs. We also observed that the combined effect of the persistent chemicals analysed was 59% additive and 41% synergistic, whereas no antagonistic interactions were observed. The genotype-specific responses observed highlight the complex interplay between genetic background and pollutant exposure, emphasizing the importance of incorporating multiple genotypes in environmental risk assessments to more accurately predict the ecological impact of chemical pollutants.

Evanescent hormesis effect induced by environmentally relevant PFOS to marine Chlorella sp

Perfluorooctanesulfonic acid (PFOS) is widely detected in the aquatic environment. More attentions were paid to its acute biotoxicity at high-dose concentrations, whereas the actual long-term effect (hormesis or inhibition of growth) of PFOS with environmental concentrations on marine phytoplankton remains unclear. In this study, marine Chlorella sp. was exposed to PFOS at low concentrations (100 ng/L, 10 μg/L, and 1 mg/L) for 26 days. The hormesis effect disappeared at the population level on Day 18, but persisted at the molecular and cellular levels on Day 24, suggesting that the stimulatory hormetic effect induced by low-level PFOS (approximating environmental concentrations) does not persist throughout algal life cycle at population level. The 100 ng/L and 1 mg/L PFOS treatments caused algal cell to swell and shrink, respectively. The low-level PFOS treatments could accelerate cells apoptosis and induce cell necrosis at 100 ng/L. Specifically, the energy metabolism associated with carbohydrate metabolism and amino acid metabolism was significantly up-regulated as well as the reduced chlorophyll content (related to the down-regulation of porphyrin metabolism) to combat the 100 ng/L PFOS rather than be engaged in divide and growth. Additionally, the decreased biomass in the 100 ng/L treatment was also attributed to certain proteins associated with down-regulations of carotenoid biosynthesis, thiamine metabolism, non-homologous end-joining, and nitrogen metabolism along with the increased oxidative stress. Our findings provide a new insight into the long-term ecological effect of PFOS at environmental concentrations.

Interaction of microplastics with perfluoroalkyl and polyfluoroalkyl substances in water: A review of the fate, mechanisms and toxicity

It is well known that microplastics can act as vectors of pollutants in the environment and are widely spread in freshwater and marine environments. PFAS (perfluoroalkyl and polyfluoroalkyl substances) can remain in the aqueous environment for long periods due to their wide application and good stability. The coexistence of microplastics and PFAS in the aqueous environment creates conditions for their interaction and combined toxicity. Studies on adsorption experiments between them and combined toxicity have been documented in the literature but have not been critically summarized and reviewed. Therefore, in this review, we focused on the interaction mechanisms, influencing factors, and combined toxicity between microplastics and PFAS. It was found that surface complexation may be a new interaction mechanism between microplastics and PFAS. In addition, aged microplastics reduce the adsorption of PFAS due to the presence of oxygenated groups on the surface compared to virgin microplastics. Attached biofilms can increase the adsorption capacity and create conditions for biodegradation. And, the interaction of microplastics and PFAS affects their spatial and temporal distribution in the environment. This review can provide insights into the fate of microplastics and PFAS in the global aquatic environment, fill knowledge gaps on the interactions between microplastics and PFAS, and provide a basic reference for assessing their combined toxicity.

Anaerobic biodegradation of perfluorooctane sulfonate (PFOS) and microbial community composition in soil amended with a dechlorinating culture and chlorinated solvents

Perfluorooctane sulfonate (PFOS), one of the most frequently detected per- and polyfluoroalkyl substances (PFAS) occurring in soil, surface water, and groundwater near sites contaminated with aqueous film-forming foam (AFFF), has proven to be recalcitrant to many destructive remedies, including chemical oxidation. We investigated the potential to utilize microbially mediated reduction (bioreduction) to degrade PFOS and other PFAS through addition of a known dehalogenating culture, WBC-2, to soil obtained from an AFFF-contaminated site. A substantial decrease in total mass of PFOS (soil and water) was observed in microcosms amended with WBC-2 and chlorinated volatile organic compound (cVOC) co-contaminants - 46.4 ± 11.0 % removal of PFOS over the 45-day experiment. In contrast, perfluorooctanoate (PFOA) and 6:2 fluorotelomer sulfonate (6:2 FTS) concentrations did not decrease in the same microcosms. The low or non-detectable concentrations of potential metabolites in full PFAS analyses, including after application of the total oxidizable precursor assay, indicated that defluorination occurred to non-fluorinated compounds or ultrashort-chain PFAS. Nevertheless, additional research on the metabolites and degradation pathways is needed. Population abundances of known dehalorespirers did not change with PFOS removal during the experiment, making their association with PFOS removal unclear. An increased abundance of sulfate reducers in the genus Desulfosporosinus (Firmicutes) and Sulfurospirillum (Campilobacterota) was observed with PFOS removal, most likely linked to initiation of biodegradation by desulfonation. These results have important implications for development of in situ bioremediation methods for PFAS and advancing knowledge of natural attenuation processes.

The roles of typical emerging pollutants on N2O emissions during biological nitrogen removal from wastewater

N2O as a potent greenhouse gas often generates in the biological nitrogen removal (BNR) processes during wastewater treatment, which makes BNR become an important greenhouse gas emission source. The emerging pollutants (EPs) are ubiquitous in wastewater and they have shown to influence the BNR processes. However, the deep discussion on potential impacts of EPs on N2O emissions during BNR is rare. Moreover, the experimental parameters for EPs investigation in most of literatures are generally not in line with real-world BNR processes, which calls for deep elucidating the roles of EPs on N2O production and emission. In this work, a critical review summarizes the existing literature about influences of typical EPs on N2O emissions and associated mechanisms during BNR, and it discusses the impacts of some easily overlooked factors, such as real EPs environmental concentrations, EPs bioaccumulation, and multiple EPs coexistence on N2O emissions. This review will provide an insight into exploring and mitigating threats posed by typical EPs on N2O emissions.

Interactions between biofilms and PFASs in aquatic ecosystems: Literature exploration

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been detected in most aquatic environments worldwide and are referred to as "forever chemicals" because of their extreme chemical and thermal stability. Biofilms, as basic aquatic bioresources, can colonize various substratum surfaces. Biofilms in the aquatic environment have to interact with the ubiquitous PFASs and have significant implications for both their behavior and destiny, which are still poorly understood. Here, we have a preliminary literature exploration of the interaction between PFASs and biofilms in the various aquatic environments and expect to provide some thoughts on further study. In this review, the biosorption properties of biofilms on PFASs and possible mechanisms are presented. The complex impact of PFASs on biofilm systems was further discussed in terms of the composition and electrical charges of extracellular polymeric substances, intracellular microbial communities, and overall contaminant purification functions. Correspondingly, the effects of biofilms on the redistribution of PFASs in the aqueous environment were analyzed. Finally, we propose that biofilm after adsorption of PFASs is a unique ecological niche that not only reflects the contamination level of PFASs in the aquatic environment but also offers a possible "microbial pool" for PFASs biodegradation. We outline existing knowledge gaps and potential future efforts for investigating how PFASs interact with biofilms in aquatic ecosystems.

Poly- and Perfluoroalkyl Substances (PFAS): Do They Matter to Aquatic Ecosystems?

Poly- and perfluoroalkyl substances (PFASs) are a group of anthropogenic chemicals with an aliphatic fluorinated carbon chain. Due to their durability, bioaccumulation potential, and negative impacts on living organisms, these compounds have drawn lots of attention across the world. The negative impacts of PFASs on aquatic ecosystems are becoming a major concern due to their widespread use in increasing concentrations and constant leakage into the aquatic environment. Furthermore, by acting as agonists or antagonists, PFASs may alter the bioaccumulation and toxicity of certain substances. In many species, particularly aquatic organisms, PFASs can stay in the body and induce a variety of negative consequences, such as reproductive toxicity, oxidative stress, metabolic disruption, immunological toxicity, developmental toxicity, cellular damage and necrosis. PFAS bioaccumulation plays a significant role and has an impact on the composition of the intestinal microbiota, which is influenced by the kind of diet and is directly related to the host's well-being. PFASs also act as endocrine disruptor chemicals (EDCs) which can change the endocrine system and result in dysbiosis of gut microbes and other health repercussions. In silico investigation and analysis also shows that PFASs are incorporated into the maturing oocytes during vitellogenesis and are bound to vitellogenin and other yolk proteins. The present review reveals that aquatic species, especially fishes, are negatively affected by exposure to emerging PFASs. Additionally, the effects of PFAS pollution on aquatic ecosystems were investigated by evaluating a number of characteristics, including extracellular polymeric substances (EPSs) and chlorophyll content as well as the diversity of the microorganisms in the biofilms. Therefore, this review will provide crucial information on the possible adverse effects of PFASs on fish growth, reproduction, gut microbial dysbiosis, and its potential endocrine disruption. This information aims to help the researchers and academicians work and come up with possible remedial measures to protect aquatic ecosystems as future works need to be focus on techno-economic assessment, life cycle assessment, and multi criteria decision analysis systems that screen PFAS-containing samples. New innovative methods requires further development to reach detection at the permissible regulatory limits.

Perfluoroalkyl acids (PFAAs) in urban surface water of Shijiazhuang, China: Occurrence, distribution, sources and ecological risks

It is extremely important to analyze the contaminative behaviors of Perfluoroalkyl acids (PFAAs) due to their serious threats to urban environments which are closely related to humans. Current study aimed to explore the distribution, source apportionment and ecological risk assessment of PFAAs in surface water from Shijiazhuang, China. The concentrations of ∑PFAAs ranged from 19.5 to 125.9 ng/L in the investigation area. Perfluorobutanesulfonic acid (PFBS) and perfluoropentanoic acid (PFPeA) were the predominant contaminants (mean value: 14.3 ng/L and 16.6 ng/L, respectively). The distribution of PFAAs according to geospatial analysis and hierarchical clustering analysis (HCA) showed that higher levels of ∑PFAAs were detected in the southern surface water of Shijiazhuang and there was a stepwise decrease from the wet season to the dry season. Furthermore, based on source apportionment, the dominant potential sources were found to be wastewater treatment plant (WWTP) effluents and industrial discharge. The risk quotients (RQs) revealed low ecological risks of all PFAAs for aquatic organisms in Shijiazhuang surface water. Collectively, this study provided basic data for regulatory strategies for controlling PFAA pollutions in urban surface water.

Effects of biofilms on the retention and transport of PFOA in saturated porous media

Understanding the fate and transport of perfluorooctanoic acid (PFOA) in soil and groundwater is essential to reliable assessments of its risks. This study investigated the impacts of Gram-positive Bacillus subtilis (BS), Gram-negative Pseudomonas aeruginosa (PA) and wild microbiota (WM) biofilm on the transport of PFOA in saturated sand columns at two ionic strengths (i.e., 1.0 and 20.0 mM NaCl). The retention of PFOA in biofilm-coated sand columns was higher than that in uncoated sand columns, due to biofilm-induced reinforced hydrophobic interactions and surface roughness, and decreased zeta potential. However, the retention effects varied among biofilm bacterial species with PFOA retardation factors in PA, WM and BS columns of 1.29-1.38, 1.21-1.29 and 1.11-1.15, respectively. Notably, PA biofilm had the most pronounced effect on PFOA retention. While increasing ionic strength promoted the retention of PFOA in BS biofilm-coated sand, it had no significant impact on PFOA transport in PA and WM biofilm-coated sand. This could be attributed to the differences in biofilm composition, deviating the ionic strengths effects on electrostatic double layer compression. The advection dispersion equation coupled with two-site kinetic retention model well described the transport of PFOA in all saturated columns. Our findings reveal that biofilm plays important roles in PFOA transport in porous media, instructive for risk assessment and remediation of PFOA contamination.

Perfluoroalkyl acids in the aquatic environment of a fluorine industry-impacted region: Spatiotemporal distribution, partition behavior, source, and risk assessment

The present study investigated the temporal and spatial distributions, partition behaviors, sources, and risks of 14 perfluoroalkyl acids (PFAAs) in the aquatic environment of a fluorine industry-impacted region. The total concentrations of 14 PFAAs (ΣPFAAs) were 118.10-2235.4 ng/L, 40.00-2316.1 ng/g dw, and 6.90-180.5 ng/g dw in dissolved, suspended particle matter (SPM), and sedimentary phases, respectively. The predominant pollutants in the dissolved and SPM phases were perfluoroalkyl carboxylic acids (PFCAs) with carbon chain lengths <9, whereas C13 and C14 PFCAs accounted for a large proportion in the sedimentary phase. The dry season exhibited the highest concentration of ΣPFAAs in the dissolved phase (500.9 ± 350.2 ng/L), while the wet season showed the highest concentrations of ΣPFAAs in the SPM and sedimentary phases (591.6 ± 469.1 ng/g dw and 59.7 ± 35.5 ng/g dw, respectively). Significantly higher concentrations of PFAAs have been found in sewage plant and industrial areas. The concentration of PFAAs in the Xupu water source area (XPS) was slightly higher than that in other water source areas of the Yangtze River, which were either not affected or were less affected by the fluorine industry. The log K_D-SPM (distribution coefficient between SPM and water), log K_D-SED (distribution coefficient between sediment and water), and log K_OC-SED (the organic carbon normalized distribution coefficient) of PFAAs showed significant differences between the wet season and dry season, which may also be affected by carbon chain length. Source identification results showed that industries, wastewater discharge, and nonpoint sources were the main sources of PFAAs in this region. The ecological risk posed by long-chain PFAAs in aquatic organisms cannot be ignored, especially in areas with intensive industrial and agricultural activities. Health risks may exist for local toddlers with long-term exposure to perfluorooctanoic acid (PFOA) through drinking water intake and dermal contact.

Occurrence and distribution of per-and polyfluoroalkyl substances (PFAS) in surface and groundwaters in an urbanized and agricultural area, Southern Brazil

Per- and polyfluoroalkyl substances, known as PFAS, are emerging contaminants detected in surface water, groundwater, drinking water, air, and food. Due to its chemical stability and high hydrophobicity, these compounds are used as surfactants, surface protectors, flame retardants, textile impregnation, fire-fighting foam, and pesticides and may be a risk for human health in the long-term exposure. Currently, a little research has been carried out for these compounds in Brazil. In this study, the concentration and distribution of 23 PFAS were analyzed in groundwater samples collected from water wells in urbanized areas and in surface water samples from Porto Alegre, one of the biggest cities in Brazil. The total concentrations of PFAS (ΣPFAS) in a groundwater sample varied between 22 and 718 ng L^-1. Eleven PFAS species were detected in groundwater, including PFOA, PFHxA, PFPeA, PFBA, PFDA, PFNA, and PFOS. Most of PFAS were quantified in samples located in the aquifer formed by medium to coarse sands intercalated with silty-sandy lenses and low organic matter content that could facilitate the percolation of these compounds. The total concentrations of PFAS (ΣPFAS) in a surface water sample varied between 11 and 17 ng L^-1. Ten species were founded in surface water being PFOA, PFOS, and PFHpA the most dominant. Considering all the samples, PFOA was the predominant species in the study. In addition, tributary water bodies had higher concentrations of PFAS than the main water body (Guaiba Lake) probably due dilution process.

Per- and polyfluoroalkyl substances (PFAS) in river discharge: Modeling loads upstream and downstream of a PFAS manufacturing plant in the Cape Fear watershed, North Carolina

The Cape Fear River is an important source of drinking water in North Carolina, and many drinking water intakes in the watershed are affected by per- and polyfluoroalkyl substances (PFAS). We quantified PFAS concentrations and loads in river water upstream and downstream of a PFAS manufacturing plant that has been producing PFAS since 1980. River samples collected from September 2018 to February 2021 were analyzed for 13 PFAS at the upstream station and 43-57 PFAS downstream near Wilmington. Frequent PFAS sampling (daily to weekly) was conducted close to gauging stations (critical to load estimation), and near major drinking water intakes (relevant to human exposure). Perfluoroalkyl acids dominated upstream while fluoroethers associated with the plant made up about 47% on average of the detected PFAS downstream. Near Wilmington, Σ₄₃PFAS concentration averaged 143 ng/L (range 40-377) and Σ₄₃PFAS load averaged 3440 g/day (range 459-17,300), with 17-88% originating from the PFAS plant. LOADEST was a useful tool in quantifying individual and total quantified PFAS loads downstream, however, its use was limited at the upstream station where PFAS levels in the river were affected by variable inputs from a wastewater treatment plant. Long-term monitoring of PFAS concentrations is warranted, especially at the downstream station. Results suggest a slight downward trend in PFAS levels downstream, as indicated by a decrease in flow-weighted mean concentrations and the best-fitting LOADEST model. However, despite the cessation of PFAS process wastewater discharge from the plant in November 2017, and the phase-out of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in North America, both fluoroethers and legacy PFAS continue to reach the river in significant quantities, reflecting groundwater discharge to the river and other continuing inputs. Persistence of PFAS in surface water and drinking water supplies suggests that up to 1.5 million people in the Cape Fear watershed might be exposed.

Bioaccumulation of per- and polyfluoroalkyl substance in fish from an urban river: Occurrence, patterns and investigation of potential ecological drivers

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in aquatic environments and a recent shift toward emerging PFAS is calling for new data on their occurrence and fate. In particular, understanding the determinants of their bioaccumulation is fundamental for risk assessment purposes. However, very few studies have addressed the combined influence of potential ecological drivers of PFAS bioaccumulation in fish such as age, sex or trophic ecology. Thus, this work aimed to fill these knowledge gaps by performing a field study in the Seine River basin (France). Composite sediment and fish (European chub, Squalius Cephalus) samples were collected from four sites along a longitudinal transect to investigate the occurrence of 36 PFAS. Sediment molecular patterns were dominated by fluorotelomer sulfonamidoalkyl betaines (i.e. 6:2 and 8:2 FTAB, 46% of ∑PFAS on average), highlighting the non-negligible contribution of PFAS of emerging concern. C₉-C₁₄ perfluoroalkyl carboxylic acids, perfluorooctane sulfonic acid (PFOS), perfluorooctane sulfonamide (FOSA) and 10:2 fluorotelomer sulfonate (10:2 FTSA) were detected in all fish samples. Conversely, 8:2 FTAB was detected in a few fish from the furthest downstream station only, suggesting the low bioaccessibility or the biotransformation of FTABs. ∑PFAS in fish was in the range 0.22-3.8 ng g^-1 wet weight (ww) and 11-140 ng g^-1 ww for muscle and liver, respectively. Fish collected upstream of Paris were significantly less contaminated than those collected downstream, pointing to urban and industrial inputs. The influence of trophic ecology and biometry on the interindividual variability of PFAS burden in fish was examined through analyses of covariance (ANCOVAs), with sampling site considered as a categorical variable. While the latter was highly significant, diet was also influential; carbon sources and trophic level (i.e. estimated using C and N stable isotope ratios, respectively) equally explained the variability of PFAS levels in fish.

Exposure pathways and bioaccumulation of per- and polyfluoroalkyl substances in freshwater aquatic ecosystems: Key considerations

Due to the bioaccumulative behavior, toxicity, and recalcitrance to degradation, per- and polyfluoroalkyl substances (PFAS) are a focus for many researchers investigating freshwater aquatic ecosystems. PFAS are a diverse set of chemicals that accumulate and transport quite differently in the environment depending on the length of their fluoroalkyl chains and their functional groups. This diversity in PFAS chemical characteristics combined with varying environmental factors also impact the bioaccumulation of these compounds in different organisms. In this review, we evaluate environmental factors (such as organic carbon, proteins, lipids, and dissolved cations) as well as PFAS characteristics (head group, chain-length, and concentration) that contribute to the significant variation seen in the literature of bioaccumulation metrics reported for organisms in aquatic ecosystems. Of the factors evaluated, it was found that PFAS concentration, dissolved organic matter, sediment organic matter, and biotransformation of precursor PFAS tended to significantly impact reported bioaccumulation metrics the most. Based on this review, it is highly suggested that future studies provide sufficient details of important environmental factors, specific organism traits/ behavior, and PFAS concentrations/compounds when reporting on bioaccumulation metrics to further fill data gaps and improve our understanding of PFAS in aquatic ecosystems.

Natural biofilm as a potential integrative sample for evaluating the contamination and impacts of PFAS on aquatic ecosystems

Natural biofilm can be a suitable medium for the monitoring of pollutants. Limited information is currently available regarding the occurrence of per- and polyfluoroalkyl substances (PFAS) in periphytic biofilm and low-trophic level organisms of freshwater ecosystems. In this study, surface water, biofilm, phytoplankton, and freshwater snails were collected from Taihu Lake, China, and characterized for 16 PFAS, including legacy compounds (PFSAs/PFCAs) and PFAS of emerging concern (fluorotelomer sulfonates and F-53B). The colonized biofilms effectively bioaccumulated PFAS from water, with the total concentration (∑PFAS) in the range of 1.96-20.1 ng/g wet weight, and the bioaccumulation factor increased with the PFAS log K_ow values. As compared with phytoplankton, the ∑PFAS in biofilms displayed a stronger correlation with those in water. PFAS distinctly biomagnified from the biofilm to freshwater snail, with the biomagnification factor in the range of 3.09 ± 2.03 - 17.8 ± 10.2, implying the important role of biofilm in PFAS transfer in aquatic environment. Extracellular proteins production in biofilm increased with the water PFAS concentrations. The total extracellular polymeric substances (EPS) content increased with the water PFAS concentration firstly and then declined to a steady level, while the algal chlorophyll level exhibited a similar relationship with the PFAS in biofilm. High PFAS levels were also associated with depressed alpha diversity of fungal community in biofilms. Biofilm appears as a relevant indicator to characterize the occurrence of PFAS in aquatic ecosystems.

Phytotoxic effects of microcystins, anatoxin-a and cylindrospermopsin to aquatic plants: A meta-analysis

Global warming and eutrophication may lead to increased incidence of harmful algal blooms and related production of cyanotoxins that can be toxic to aquatic plants. Previous studies have evaluated the phytotoxic effects of cyanotoxins on aquatic plants. However, most studies have evaluated only a limited number of plant species and cyanotoxins; there is also considerable variability between studies, which obscures general patterns and hinders understanding of the phytotoxic effects of cyanotoxins. Here, we conducted a comprehensive meta-analysis by compiling 41 published papers to estimate the phytotoxic effects of anatoxin-a, cylindrospermopsin, and microcystins in 34 species of aquatic plants, with the aim of 1) investigating the phytotoxicity of different cyanotoxins to aquatic plants; 2) determining the aquatic plant species most sensitive to the phytotoxic effects of cyanotoxins; and 3) evaluating the bioaccumulation potential of cyanotoxins in aquatic plants. Most aquatic plants were negatively affected by cyanotoxin exposure and their response was dose-dependent; however, morphological indicators and photosynthesis of certain aquatic plants were marginally stimulated under low concentrations of anatoxin-a and cylindrospermopsin. Anatoxin-a showed the greatest bioaccumulation capacity in aquatic plants compared to cylindrospermopsin and microcystin variants. Bioaccumulation factors of cyanotoxins in aquatic plants generally decreased with increasing water exposure concentrations. Our study supports the One Health goal to manage the risk of public exposure to toxic substances, and indicates that cyanotoxins warrant further investigations in aquatic plants. Environmental managers and public health authorities need to be alert to the long-term exposure and chronic toxicity of cyanotoxins, and the potential trophic transfer of cyanotoxins from aquatic plants to higher-order organisms.

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

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

Levels and trends of perfluoroalkyl acids (PFAAs) in water (2013-2020) and fish from selected riverine basins in Spain

The aim of the present study was to assess the presence of perfluoroalkyl acids (PFAAs), namely perfluoroalkane sulfonates and perfluoroalkyl carboxylic acids, in Spanish river basins in order to: identify potential spatiotemporal variations; evaluate the effectiveness of the measures implemented for the reduction/elimination of these pollutants; verify the fulfillment of the Environmental Quality Standards (EQSs) in the European Union. PFOS and PFOA were determined in 116 water samples from four sites in the Duero basin, the largest in the Iberian Peninsula, collected seasonally from 2013 to 2020. In addition, 30 fish sample composites from the sample banks of Duero, Tagus, Ebro, Eastern Cantabrian and Catalonian basins were analyzed for 15 PFAAs. Median PFOS and PFOA concentrations were 0.72 and 0.42 ng/L, ranging from values below the limit of quantification (LOQ) to 81 and 22 ng/L, respectively. During the studied period, 51% of water samples were above the EQS of 0.65 ng/L for PFOS. In the case of fish, the PFOS range was <LOQ-59 with 33% of the samples above the EQS of 9.1 ng/g wet weight. Moreover, fish from the Tagus and Catalonian basins showed median concentrations above the EQS. Particularly, fish collected around highly populated areas such as Madrid and Barcelona showed the greatest PFAA concentrations. Overall, PFAA concentrations in water and fish increased significantly with population density suggesting urban areas as their main source. Although our results suggested decreasing tendencies for PFOS and PFOA in water, significant trends only could be confirmed at two sampling sites.

Perfluoroalkyl Substances in the Western Tropical Atlantic Ocean

The dispersion of perfluoroalkyl substances (PFAS) in surface and deep-water profiles (down to 5845 m deep) was evaluated through the Western Tropical Atlantic Ocean (TAO) between 15°N and 23°S. The sum concentrations for eight quantifiable PFAS (∑₈PFAS) in surface waters ranged from 11 to 69 pg/L, which is lower than previously reported in the same area as well as in higher latitudes. Perfluoroalkyl carboxylic acids (PFCAs) were the predominant PFASs present in the Western TAO. The 16 surface samples showed variable PFAS distributions, with the predominance of perfluorooctanoic acid (PFOA) along the transect (67%; 11 ± 8 pg/L) and detection of perfluoroalkyl sulfonic acids (PFSAs) only in the Southern TAO. Perfluoroheptanoic acid (PFHpA) was often detected in the vertical profiles. PFAS distribution patterns (i.e., profiles and concentrations) varied with depth throughout the TAO latitudinal sectors (North, Equator, South Atlantic, and in the Brazilian coastal zone). Vertical profiles in coastal samples displayed decreasing PFAS concentrations with increasing depth, whereas offshore samples displayed higher PFAS detection frequencies in the intermediate water masses. Together with the surface currents and coastal upwelling, the origin of the water masses was an important factor in explaining PFAS concentrations and profiles in the TAO.

Biofilms Enhance the Adsorption of Toxic Contaminants on Plastic Microfibers under Environmentally Relevant Conditions

Microplastics (MPs) exposed to the natural environment provide an ideal surface for biofilm formation, which potentially acts as a reactive phase facilitating the sorption of hazardous contaminants. Until now, changes in the contaminant sorption capacity of MPs due to biofilm formation have not been quantified. This is the first study that compared the capacity of naturally aged, biofilm-covered microplastic fibers (BMFs) to adsorb perfluorooctane sulfonate (PFOS) and lead (Pb) at environmentally relevant concentrations. Changes in the surface properties and morphology of aged microplastic fibers (MF) were studied by surface area analysis, infrared spectroscopy, and scanning electron microscopy. Results revealed that aged MFs exhibited higher surface areas because of biomass accumulation compared to virgin samples and followed the order polypropylene>polyethylene>nylon>polyester. The concentrations of adsorbed Pb and PFOS were 4-25% and 20-85% higher in aged MFs and varied among the polymer types. The increased contaminant adsorption was linked with the altered surface area and the hydrophobic/hydrophilic characteristics of the samples. Overall, the present study demonstrates that biofilms play a decisive role in contaminant-plastic interactions and significantly enhance the vector potential of MFs for toxic environmental contaminants. We anticipate that knowledge generated from this study will help refine the planetary risk assessment of MPs.

Fingerprinting Plastic-Associated Inorganic and Organic Matter on Plastic Aged in the Marine Environment for a Decade

The long-term aging of plastic leads to weathering and biofouling that can influence the behavior and fate of plastic in the marine environment. This is the first study to fingerprint the contaminant profiles and bacterial communities present in plastic-associated inorganic and organic matter (PIOM) isolated from 10 year-aged plastic. Plastic sleeves were sampled from an oyster aquaculture farm and the PIOM was isolated from the intertidal, subtidal, and sediment-buried segments to investigate the levels of metal(loid)s, polyaromatic hydrocarbons (PAHs), per-fluoroalkyl substances (PFAS) and explore the microbial community composition. Results indicated that the PIOM present on long-term aged high-density polyethylene plastic harbored high concentrations of metal(loid)s, PAHs, and PFAS. Metagenomic analysis revealed that the bacterial composition in the PIOM differed by habitat type, which consisted of potentially pathogenic taxa including Vibrio, Shewanella, and Psychrobacter. This study provides new insights into PIOM as a potential sink for hazardous environmental contaminants and its role in enhancing the vector potential of plastic. Therefore, we recommend the inclusion of PIOM analysis in current biomonitoring regimes and that plastics be used with caution in aquaculture settings to safeguard valuable food resources, particularly in areas of point-source contamination.

Bioaccumulation of Per- and polyfluoroalkyl substances (PFASs) in a tropical estuarine food web

The biomagnification of per- and polyfluoroalkyl substances (PFASs) was investigated in a tropical mangrove food web from an estuary in Bahia, Brazil. Samples of 44 organisms (21 taxa), along with biofilm, leaves, sediment and suspended particulate matter were analyzed. Sum (∑) PFAS concentrations in biota samples were dominated by perfluorooctane sulfonate (PFOS, 93% detection frequency in tissues; 0.05 to 1.97 ng g^-1 ww whole-body (wb)), followed by perfluorotridecanoate (PFTrDA, 57%; 0.01 to 0.28 ng g^-1 ww wb). PFOS precursors such as perfluorooctane sulfonamide (FOSA, 54%; 0.01 to 0.32 ng g^-1 ww wb) and N-ethyl perfluorooctane sulfonamide (EtFOSA; 30%; 0.01 to 0.21 ng g^-1 ww wb) were also detected. PFAS accumulation profiles revealed different routes of exposure among bivalve, crustacean and fish groups. Statistics for left-censored data were used in order to minimize bias on trophic magnification factors (TMFs) calculations. TMFs >1 were observed for PFOS (linear + branched isomers), EtFOSA (linear + branched isomers), and perfluorononanoate (PFNA), and in all cases, dissimilar accumulation patterns were observed among different trophic positions. The apparent biodilution of some long-chain PFCAs through the food chain (TMF < 1) may be due to exposure from multiple PFAS sources. This is the first study investigating bioaccumulation of PFASs in a tropical food web and provides new insight on the behavior of this ubiquitous class of contaminants.

Lethal and sublethal toxicity of perfluorooctanoic acid (PFOA) in chronic tests with Hyalella azteca (amphipod) and early-life stage tests with Pimephales promelas (fathead minnow)

Perfluoroalkyl substances (PFAS), including perfluorooctanoic acid (PFOA), are industrial chemicals that are of concern due to their environmental presence, persistence, bioaccumulative potential, toxicity, and capacity for long-range transport. Despite a large body of research on environmental exposure, insufficient chronic aquatic toxicity data exist to develop water quality targets for clean-up of federal contaminated sites in Canada. Thus, our objective was to assess the aqueous toxicity of PFOA in chronic tests with Hyalella azteca (amphipod) and early-life stage tests with Pimephales promelas (fathead minnow). Toxicity data were analyzed based on measured PFOA concentrations. Amphipod exposures were 42 d (0.84-97 mg/L) and examined survival, growth, and reproduction. Fathead minnow exposures were 21 d (0.010-76 mg/L), which encompassed hatching (5 d) and larval stages until 16 d post-hatch; endpoints included hatching success, deformities at hatch, and larval survival and growth. Amphipod survival was significantly reduced at 97 mg/L (42-d LC50 = 51 mg/L), but growth and reproduction were more sensitive endpoints (42-d EC50 for both endpoints = 2.3 mg/L). Fathead minnows were less sensitive than amphipods, exhibiting no significant effects in all endpoints with the exception of uninflated swim bladder, which was significantly higher at 76 mg/L (15%) than controls (0%). Maximum concentrations of PFOA are generally in the ng/L range in global surface waters, but can reach the μg/L range in close proximity to major source inputs; therefore, environmental concentrations are well below those that caused toxicity in the current study. Our data will provide valuable information with which to assess the risk of PFOA at contaminated sites, and to set a target for site remediation.

Role of Biofilms in Contaminant Bioaccumulation and Trophic Transfer in Aquatic Ecosystems: Current State of Knowledge and Future Challenges

In freshwater environments, microbial assemblages attached to submerged substrates play an essential role in ecosystem processes such as primary production, supported by periphyton, or organic matter decomposition, supported by microbial communities attached to leaf litter or sediments. These microbial assemblages, also called biofilms, are not only involved in nutrients fluxes but also in contaminants dynamics. Biofilms can accumulate metals and organic contaminants transported by the water flow and/or adsorbed onto substrates. Furthermore, due to their high metabolic activity and their role in aquatic food webs, microbial biofilms are also likely to influence contaminant fate in aquatic ecosystems. In this review, we provide (1) a critical overview of the analytical methods currently in use for detecting and quantifying metals and organic micropollutants in microbial biofilms attached to benthic substrata (rocks, sediments, leaf litter); (2) a review of the distribution of those contaminants within aquatic biofilms and the role of these benthic microbial communities in contaminant fate; (3) a set of future challenges concerning the role of biofilms in contaminant accumulation and trophic transfers in the aquatic food web. This literature review highlighted that most knowledge on the interaction between biofilm and contaminants is focused on contaminants dynamics in periphyton while technical limitations are still preventing a thorough estimation of contaminants accumulation in biofilms attached to leaf litter or sediments. In addition, microbial biofilms represent an important food resource in freshwater ecosystems, yet their role in dietary contaminant exposure has been neglected for a long time, and the importance of biofilms in trophic transfer of contaminants is still understudied.

Sediment Microbial Diversity in Urban Piedmont North Carolina Watersheds Receiving Wastewater Input

Urban streams are heavily influenced by human activity. One way that this occurs is through the reintroduction of treated effluent from wastewater treatment plants. We measured the microbial community composition of water, sediment, and soil at sites upstream and downstream from two Charlotte treatment facilities. We performed 16S rRNA gene sequencing to assay the microbial community composition at each site at four time points between the late winter and mid-summer of 2016. Despite the location of these streams in an urban area with many influences and disruptions, the streams maintain distinct water, sediment, and soil microbial profiles. While there is an overlap of microbial species in upstream and downstream sites, there are several taxa that differentiate these sites. Some taxa characteristics of human-associated microbial communities appear elevated in the downstream sediment communities. In the wastewater treatment plant and to a lesser extent in the downstream community, there are high abundance amplicon sequence variants (ASVs) which are less than 97% similar to any sequence in reference databases, suggesting that these environments contain an unexplored biological novelty. Taken together, these results suggest a need to more fully characterize the microbial communities associated with urban streams, and to integrate information about microbial community composition with mechanistic models.

Contaminants of Emerging Concern in the Seine River Basin: Overview of Recent Research

For over 30 years, the sources and the transfer dynamics of micropollutants have been investigated in the PIREN-Seine programme. Recent works included a wide range of chemicals and biological contaminants of emerging concern (i.e. contaminants whose occurrence, fate and impact are scarcely documented). This chapter presents a brief overview of research recently conducted on contaminants as diverse as macro- and microplastics, poly- and perfluoroalkyl substances (PFASs), pathogenic protozoa, antibiotics and the associated antibiotic resistance. The multiscalar study of plastics and PFASs at a large spatial scale is rare; the results produced in recent years on the Seine River catchment have provided an original contribution to the investigation of the dynamics of these contaminants in urban environments. The results also highlighted that pathogenic protozoa are ubiquitous in the Seine River basin and that the contamination of bivalves such as Dreissena polymorpha could reflect the ambient biological contamination of watercourses. The widespread occurrence of antibiotics in the Seine River was demonstrated, and it was shown that the resistome of biofilms in highly urbanised rivers constitutes a microenvironment where genetic support for antibiotic resistance (clinical integrons) and resistance genes for trace metals are concentrated.

Occurrence and partitioning behavior of per- and polyfluoroalkyl substances (PFASs) in water and sediment from the Jiulong Estuary-Xiamen Bay, China

Twenty-four per- and polyfluoroalkyl substances (PFASs) were analyzed in water and sediment from the Jiulong Estuary-Xiamen Bay to study their seasonal variations, transport, partitioning behavior and ecological risks. The total concentration of PFASs in water ranged from 11 to 98 ng L^-1 (average 45 ng L^-1) during the dry season, 0.19-5.7 ng L^-1 (average 1.5 ng L^-1) during the wet season, and 3.0-5.4 ng g^-1 dw (average 3.9 ng g^-1 dw) in sediment. In water samples, short-chain PFASs were dominated by perfluorooctanoic acid (PFBA) in the dry season and perfluorobutane sulfonate (PFBS) in the wet season, while long chain PFASs, such as perfluorooctane sulfonate (PFOS), dominated in the sediment. The highest concentration of PFASs in water were found in the estuary; in contrast, the highest level of PFASs in sediment were found in Xiamen Bay. These spatial distributions of PFASs indicate that river discharge is the main source of PFASs in estuarine water, while the harbor, airport and wastewater treatment plant near Xiamen Bay may be responsible for the high PFBS and PFOS concentrations in water and sediment. The partition coefficients (log K_d) of PFASs between sediment and water (range from 1.64 to 4.14) increased with carbon chain length (R² = 0.99) and also showed a positive relationship with salinity. A preliminary environmental risk assessment indicated that PFOS and perfluorooctanoic acid (PFOA) in water and sediment pose no significant ecological risk to organisms.

Occurrence of perfluoroalkyl substances in selected Victorian rivers and estuaries: An historical snapshot

This reconnaissance study was undertaken in 2012 to examine the occurrence of common perfluoroalkyl substances (PFAS), including perfluoroalkyl sulphonic acids and perfluoroalkyl carboxylic acids in rivers and estuaries in Port Philip Bay, Victoria, Australia. In total, 19 PFAS were screened in grab samples of water using a combination of solid phase extraction and liquid chromatography - mass spectrometry measurement techniques. Eighteen of the PFAS screened were observed in samples. The highest level of PFOS observed at a freshwater site was 0.045 μg/L; this concentration is approximately half the draft Australian 95% species protection level for total PFOS. The highest level of PFOA in the study (0.014 μg/L) was some four orders of magnitude lower than the draft Australian trigger value for PFOA (220 μg/L). However, none of the PFAS observed at the freshwater sites had research quotient (RQ) or toxicity unit (TU) values above 1 or -3, respectively. The highest concentration of PFOS observed at an estuarine site was 0.075 μg/L; the highest level of PFOA, 0.09 μg/L). There are no Australian marine water quality trigger values for PFAS, so potential risk was assessed using the European environment quality standards (EQS) adopted in EU Directive 2013/39/EU, RQ and TU methods. In that context, none of the PFAS observed at estuary sites had concentrations higher than the EU standards, or RQ above 1 or Log 10 TU above -3. Together these assessments suggest none of the PFAS screened would have posed an acute risk to organisms in the fresh or estuary waters studied at the time of sampling on an individual or collective basis. However, the detection of these PFAS in Victorian estuaries highlights that the issue is not just an issue for more densely populated countries in the northern hemisphere, but also potentially of concern in Australia. And, in that context, more sampling campaigns in Port Philip Bay are of paramount importance to assess the potential risk pose by these compounds to aquatic ecosystems.

Assessing exposure to legacy and emerging per- and polyfluoroalkyl substances via hair - The first nationwide survey in India

In recent years, environmental issues emerging from per- and polyfluoroalkyl substances (PFAS) have raised high concern worldwide. Levels of human exposure to PFAS remain unknown in India. Biomonitoring data obtained from hair analysis have been evidenced to provide insight into retrospective human exposure to PFAS. In this study, 25 PFAS, including perfluoroalkyl acids and their precursors, were measured in 39 human hair samples collected from 14 cities in India. The inuflence of gender on the PFAS levels was also examined. To our knowledge, this is the first attempt to provide preliminary indicative data (due to the limited sample size and variability in hair-length sampling) on the levels of PFAS in Indian hair. The concentrations of total PFAS in hair varied from below matrix-specific limit of quantification (<0.02 ng/g) to 3.78 ng/g. Among 9 PFAS quantified, perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid (PFOS), and perfluorooctanoic acid (PFOA) were the predominant compounds. Categorized into 4 regions, PFAS contamination exhibited certain regional difference where South India may show higher levels than the other regions. Highly significant positive correlation was observed between PFHxS and PFOS (p ≪ 0.001; r = 0.644), suggesting similar pathways of exposure to the two compounds. Higher PFAS occurrence was generally observed in the hair of females. Our results highlighted the urgent need to investigate the deposition mechanism of PFAS in hair.

Evidence for the Trophic Transfer of Perfluoroalkylated Substances in a Temperate Macrotidal Estuary

The present survey examines the trophodynamics of a suite of 19 perfluoroalkyl substances (PFASs) in a temperate macrotidal estuary (Gironde, SW France). Across the 147 biota samples (18 taxa) collected, perfluorooctane sulfonate (PFOS), perfluorooctane sulfonamide (FOSA), and C₈-C₁₄ perfluoroalkyl carboxylates (PFCAs) were the most-recurrent analytes. ΣPFASs ranged between 0.66-45 ng per g of wet weight of the whole body. Benthic organisms had relatively high ΣPFASs compared to demersal organisms and displayed specific composition profiles with higher relative abundances of C₈ and C₉ PFCAs. Trophic magnification factors (TMFs) were determined through the use of linear mixed effect models including censored data, thereby considering data below detection limits as well as the interspecific variability of δ¹⁵N and PFAS levels (random effects). TMFs were almost consistently >1 in the benthic food web as well as when considering all data pooled together, providing evidence for the biomagnification of several PFASs in estuarine environments. In addition, in contrast with previous observations, TMFs determined in the estuarine benthic web were found to significantly decrease with increasing chain length for C₈-C₁₄ PFCAs and C₆-C₈ perfluoroalkyl sulfonates. This suggests that PFAS chemical structure might not be necessarily predictive of TMFs, which are also influenced by the trophic web characteristics.