Perfluorinated compounds in soil, surface water, and groundwater from rural areas in eastern China

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.

Prediction of the fluoride contents of different crop species via the random forest algorithm

Fluoride (F) is a trace element that is essential to the human body and occurs naturally in the environment. However, a deficiency or excess of F in the environment can potentially lead to human health issues. The pseudototal amount of F in soil often does not correlate directly with the F content in plants. Instead, the F content within plants tends to have a greater correlation with the bioavailable F in soils. In large-scale soil surveys, only the pseudototal elemental content of soils is typically measured, which may not be highly reliable for developing agricultural zoning plans. There are significant variations in the ability of different plants to accumulate F from soil. Additionally, due to variations in soil elemental absorption mechanisms among different plant species, when multiple crops are grown in an area, it is typically necessary to study the elemental absorption mechanisms of each crop. To address these issues, in this study, we examined the factors influencing F bioaccumulation coefficients in different crops based on 1:50,000 soil geochemical survey data. Using the random forest algorithm, four indicators-bioavailable P, bioavailable Zn, leachable Pb, and Sr-were selected from among 29 parameters to predict the F content within crops to replace bioavailable F in the soil. Compared with the multivariate linear regression (MLR) model, the random forest (RF) model provided more accurate and reliable predictions of the fluoride content in crops, with the RF model's prediction accuracy improving by approximately 95.23%. Additionally, while the partial least squares regression (PLSR) model also offered improved accuracy over MLR, the RF model still outperformed PLSR in terms of prediction accuracy and robustness. Additionally, it maximized the utilization of existing geochemical survey data, enabling cross-species studies for the first time and avoiding redundant evaluations of different types of agricultural products in the same region. In this investigation, we selected the Xining-Ledu region of Qinghai Province, China, as the study area and employed a random forest model to predict the crop F content in soils, providing a new methodological framework for crop production that effectively enhances agricultural quality and efficiency.

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

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

Constructed wetlands for the removal of organic micropollutants from wastewater: Current status, progress, and challenges

In this work, the practical utility of constructed wetlands (CWs) is described as a promising treatment option for micropollutants (MPs) in wastewater with the aid of their eco-friendly, low-energy, economically feasible, and ecologically sustainable nature. This paper offers a comprehensive review on CW technology with respect to the key strategies for MP removal such as phytoremediation, substrate adsorption, and microbial degradation. It explores the important factors controlling the performance of CWs (e.g., in terms of configurations, substrates, plant-microbe interactions, temperature, pH, oxygen levels, hydraulic loading rate, and retention time) along with the discussions on the pivotal role of microbial populations in CWs and plant-microbe cooperative remediation dynamics, particularly in relation to diverse organic MP patterns in CWs. As such, this review aims to provide valuable insights into the key strategies for optimizing MP treatment and for enhancing the efficacy of CW systems. In addition, the process-based models of constructed wetlands along with the numerical simulations based on the artificial neural network (ANN) method are also described in association with the data exploratory techniques. This work is thus expected to help open up new possibilities for the application of plant-microbe cooperative remediation approaches against diverse patterns of organic MPs present in CWs.

Crop Contamination and Human Exposure to Per- and Polyfluoroalkyl Substances around a Fluorochemical Industrial Park in China

Due to their significant environmental impact, there has been a gradual restriction of the production and utilization of legacy per- and polyfluoroalkyl substances (PFAS), leading to continuous development and adoption of novel alternatives. To effectively identify the potential environmental risks from crop consumption, the levels of 25 PFAS, including fourteen perfluoroalkyl acids (PFAAs), two precursor substances and nine novel alternatives, in agricultural soils and edible parts of various crops around a fluoride industrial park (FIP) in Changshu city, China, were measured. The concentration of ΣPFAS in the edible parts of all crops ranged from 11.64 to 299.5 ng/g, with perfluorobutanoic acid (PFBA) being the dominant compound, accounting for an average of 71% of ΣPFAS. The precursor substance, N-methylperfluoro-octanesulfonamidoacetic acid (N-MeFOSAA), was detected in all crop samples. Different types of crops showed distinguishing accumulation profiles for the PFAS. Solanaceae and leafy vegetables showed higher levels of PFAS contamination, with the highest ΣPFAS concentrations reaching 190.91 and 175.29 ng/g, respectively. The highest ΣAlternative was detected in leafy vegetables at 15.21 ng/g. The levels of human exposure to PFAS through crop consumption for various aged groups were also evaluated. The maximum exposure to PFOA for urban toddlers reached 109.8% of the standard value set by the European Food Safety Authority (EFSA). In addition, short-chained PFAAs and novel alternatives may pose potential risks to human health via crop consumption.

Occurrence, source apportionment, and ecological risk of legacy and emerging per- and poly-fluoroalkyl substances (PFASs) in the Dahei river basin of a typical arid region in China

Per- and poly-fluoroalkyl substances (PFASs) are artificial chemicals with broad commercial and industrial applications. Many studies about PFASs have been conducted in densely industrial and populated regions. However, fewer studies have focused on the PFASs' status in a typical arid region. Here, we investigated 30 legacy and emerging PFASs in surface water from the mainstream and tributaries of the Dahei River. Our results revealed that total PFASs concentrations (∑30PFASs) in water ranged from 3.13 to 289.1 ng/L (mean: 25.40 ng/L). Perfluorooctanoic acid (PFOA) had the highest mean concentration of 2.44 ng/L with a 100% detection frequency (DF), followed by perfluorohexanoic acid (PFHxA) (mean concentration: 1.34 ng/L, DF: 59.26%). Also, perfluorohexane sulfonate (DF: 44.44%), perfluorobutane sulfonate (DF: 88.89%), and perfluorooctane sulfonate (PFOS) (DF: 92.59%) had mean concentrations of 12.94, 2.00, and 1.05 ng/L, respectively. Source apportionment through ratio analysis and principal component analysis-multiple linear regression analysis showed that treated or untreated sewage, aqueous film-forming foam, degradation of precursors, and fluoropolymer production were the primary sources. The PFOS alternatives were more prevalent than those of PFOA. Conductivity, total phosphorus, and chlorophyll a positively correlated with Σ30PFASs and total perfluoroalkane sulfonates concentrations. Furthermore, ecological risk assessment showed that more attention should be paid to perfluorooctadecanoic acid, perfluorohexadecanoic acid, perfluorooctane sulfonate, perfluorohexane sulfonate, and (6:2 and 6:2/8:2) polyfluoroalkyl phosphate mono- and di-esters. The mass load of PFASs to the Yellow River was 1.28 kg/year due to the low annual runoff in the Dahei River in the arid region. This study provides baseline data for PFASs in the Dahei River that can aid in the development of effective management strategies for controlling PFASs pollution in typical arid regions in China.

Removal of perfluoroalkyl acids from aqueous media by surfactant-modified clinoptilolites

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are environmentally persistent, bioaccumulating, and toxic compounds that have attracted global attention. It is challenging to reduce the residual concentrations of these compounds to safe discharge limits. In this study, batch experiments were performed to evaluate natural clinoptilolite and clinoptilolites modified (MC) with cetylpyridinium chloride (CPC-MC), didodecyldimethylammonium bromide (DDAB-MC), hexadecyltrimethylammonium bromide (HDTMA-MC), and tetramethylammonium chloride (TMA-MC) as cost-effective aqueous PFAS adsorbents. The removal capacities of the adsorbents for the majority of the PFASs decreased in the following order: DDAB-MC > CPC-MC ≫ modified natural clinoptilolite with hexadecyltrimethyl ammonium bromide (HDTMA-MC) ≫ modified natural clinoptilolite with tetramethylammonium chloride (TMA-MC) ≈ natural clinoptilolite modified with NaCl (NC). In particular, CPC-MC and DDAB-MC reduced PFASs concentration in 50 μg/L by up to 98% for perfluorooctane sulphonate. Within 30 min, CPC-MC (30.5 μg/L) and DDAB-MC (32.1 μg/L) met the PFOS water quality criterion of 36 μg/L in inland surface waters. Both adsorbents met this criterion at the highest solution volume (40 mL) and 0.125 g/L (solid-to-liquid ratio of 1:8). PFASs with short hydrocarbon chains competed more for adsorption. PFASs with sulphonate functional groups were also adsorbed more than carboxyl groups in single- and multi-PFAS solutions. The modified surfaces of clinoptilolites controlled PFAS adsorption through hydrophobic and electrostatic interactions. PFAS removal with surfactant-modified clinoptilolites is cost-effective and protects aquatic environments by using surplus natural materials.

Current state of knowledge of environmental occurrence, toxic effects, and advanced treatment of PFOS and PFOA

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic synthetic compounds, with high chemical and thermal stability and a persistent, stable and bioaccumulative nature that renders them a potential hazard for the environment, its organisms, and humans alike. Perfluorooctane sulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) are the most well-known substances of this category and even though they are phased out from production they are still highly detectable in several environmental matrices. As a result, they have been spread globally in water sources, soil and biota exerting toxic and detrimental effects. Therefore, up and coming technologies, namely advanced oxidation processes (AOPs) and advanced reduction processes (ARPs) are being tested for their implementation in the degradation of these pollutants. Thus, the present review compiles the current knowledge on the occurrence of PFOS and PFOA in the environment, the various toxic effects they have induced in different organisms as well as the ability of AOPs and ARPs to diminish and/or eliminate them from the environment.

Toxicity assessment of perfluorooctanesulfonic acid (PFOS) on a spontaneous plant, velvetleaf (Abutilon theophrasti), via metabolomics

Spontaneous plants often play important ecological roles in terrestrial environments, but impacts of contaminants on spontaneous plants are seldom investigated. Per- and polyfluoroalkyl substances (PFAS), such as perfluorooctanesulfonic acid (PFOS) are ubiquitous in rural and urban soils. In this study, we assessed the effects of PFOS on a spontaneous plant, velvetleaf (Abutilon theophrasti), using endpoints such as plant growth, stress defense, PFOS uptake, and elemental and metabolite profile. We observed stunted growth in plants grown in PFOS-contaminated soils, with PFOS accumulating in their shoots by up to 3000 times more than the control plants. The other endpoints (decreased chlorophyll a synthesis, elevated oxidative stress, reduced shoot Mg concentration, and reduced biomass production) also explained the stunted growth of velvetleaf exposed to elevated PFOS concentrations. We found that 56 metabolites involved in 13 metabolic pathways were dysregulated. The synthesis of important antioxidants such as ascorbic acid, hydroxycinnamic acids (coumaric, caffeic, ferulic, and sinapic acids), and tocopherols decreased, resulting in loss of plant's defense to stress. PFOS also reduced the levels of growth-related and stress-coping metabolites including squalene, serotonin, noradrenalin, putrescine, and indole-3-propionic acid, which further corroborated the restricted growth of velvetleaf exposed to elevated PFOS. These findings provide insights on phytotoxicity of PFOS to velvetleaf, a resilient terrestrial spontaneous plant.

Reductive degradation mechanism of perfluorooctanoic acid (PFOA) during vacuum ultraviolet (VUV) reactions combining with sulfite and iodide

In this study, PFOA removal and defluorination were examined during vacuum ultraviolet (VUV) photolysis in the presence of sulfite and sulfite/iodide conditions. PFOA (24 μM) degradation rate constant (kobs) and defluorination amount in VUV photolysis, and VUV/sulfite, and VUV/sulfite/iodide reactions under nitrogen-purging condition were 5.50 × 10-3, 7.26 × 10-2, 1.60 × 10-1 min-1, and 34.6, 72.7, 73.9% in 6 h, respectively. When tert-butanol (t-BuOH), NO2-, and NO3- ions were added as radical scavengers, hydrated electrons (eaq-) was confirmed as the main species responsible for degrading PFOA and mediating defluorination in VUV-based reactions. While, during VUV photolysis, short-chain perfluoroalkyl carboxylic acids (PFCAs), such as PFHpA, PFHxA, PFPeA, and PFBA, were mainly produced as transformation products (TPs) by the chain-shortening mechanism, additional 14 and 15 TPs were identified in the VUV/sulfite and VUV/sulfite/iodide reactions by LC-QTOF/MS, respectively. The main degradation mechanisms in these reactions are H-F exchange (e.g., TP395 (m/z = 394.9739) and TP377 (m/z = 376.9838)), •SO3--F exchange (TP474, m/z = 474.9323), carbon double bond formation by defluorination (e.g., TP392 (m/z = 392.9455), TP410 (m/z = 410.9355), and TP436 (m/z = 436.9347)), and H-F exchange followed by hydration reaction (TP393, m/z = 392.9773), respectively. PFOA degradation pathways were proposed for these VUV-based reactions based on the identified TPs, their time profiles, and the density functional theory (DFT). Finally, the toxicity of PFOA and its TPs produced during three reactions were assessed using ECOSAR simulation.

Unveiling the hidden threat: spatiotemporal trends and source apportionments of per-and polyfluorinated alkyl substances in wastewater treatment plants in South Africa

At least 11 per-and polyfluorinated alkyl substances (PFASs) were more prevalent during the dry season, whereas only PFBA, L-PFBS, L-PFOS, and PFOA were prevalent during the wet season in 11 WWTPs. The ∑21 PFAS levels in the influent and the effluent ranged from 137 to 3327 ng/L and 265-7,699 ng/L in the dry season and 61-2,953 ng/L and 171-3,458 ng/L in the wet season, respectively. The highest mean concentrations were observed in the influent and effluent for PFOA (586 ng/L) and L-PFBS (552 ng/L); and FOET (1,399 ng/L) and PFNA (811 ng/L) during dry and wet seasons, respectively. During the wet season, 6:2 FTS was observed at the highest concentrations, exhibiting 4,900 ng/L (66%) and 2,351 ng/L (39%), 1,950 ng/L (53%) in SST and BNR, respectively. Principal component analysis (PCA), hierarchical clustering (HCA), and PFHpA/PFOA, PFBA/PFOA, and PFNA/PFOA ratios revealed mixtures of PFAS sources into WWTPs.

Risk assessment and partitioning behavior of PFASs in environmental matrices from an e-waste recycling area

OBJECTIVE

Perfluoroalkyl and polyfluoroalkyl substance (PFAS) contamination and their human exposure risks are a major concern. However, knowledge of PFAS contamination in environments near e-waste recycling sites and their health risk assessment are scarce.

METHODS

We measured the concentrations of PFASs in soil (n = 12), water (n = 12) and atmospheric samples (n = 26) by LCP-MS/MS, analyzed the source apportionment of PFASs by PCA, and investigated the child health risk assessment from an e-waste recycling area (Guiyu) and a reference area (Haojiang).

RESULTS

We found high concentrations of PFASs in the atmosphere and low concentrations of PFASs in soil. The average concentration of perfluoro-n-heptanoic acid (PFHpA) (9.43 ng/L) was highest among PFASs in water. The concentrations PFASs in the atmosphere and water were higher in the e-waste recycling area than in the reference area (p < 0.05). According to Multi-Linear regression model, we found that daily intake doses for PFASs in air of PFODA [β (95 % CI): -0.217 (-0.332, -0.048), p < 0.05] and PFBS [β (95 % CI): -0.064 (-0.106, -0.006), p < 0.05] were negatively associated with child BMI. PFBA [β (95 % CI: -1.039 (-2.454, -0.010), p < 0.05] was negatively correlated with child head circumference.

CONCLUSION

The concentrations of PFASs in the water and atmosphere are higher in the e-waste recycling site than in the reference area. We found that their intake affected growth and development in children. We need to reduce pollution from PFASs in the e-waste recycling area while maintaining a focus on their impact on child health.

The occurrence, spatial distribution, and well-depth dependence of PFASs in groundwater from a reclaimed water irrigation area

With the growing development of modern agriculture and industry, groundwater is facing more and more complex contaminants. One such contaminant is per- and polyfluoroalkyl substances (PFASs), which pose a potential risk to human health, particularly for those who rely on groundwater as their primary source of drinking water. In this study, we conducted a comprehensive investigation on the occurrence, spatial distribution, and source apportionment of PFASs in shallow (<60 m) and deep (>80 m) groundwater samples from a reclaimed water irrigation area in Beijing's suburbs. Our results showed that the average total PFAS concentration (∑10PFAS) for all samples was 10.55 ± 7.77 ng/L, ranging from 1.05 to 34.28 ng/L. The dominant congeners were PFBA, PFOA, and PFBS. No significant linear relationship was observed between PFAS concentrations and the well depth. However, the averaged ΣPFASs in groundwater were highest in the uppermost layer and declined sharply to a few ng/L in the deep aquifer below 80 m. PFASs showed elevated concentration in shallow aquifers in 9 out of 11 paired wells, indicating an overall descending trend of PFASs with increasing aquifer depth. The spatial distribution of PFASs was highly heterogeneous and showed different patterns in shallow and deep groundwater, which may be related to the complicated attenuation behavior of PFAS compounds when they transport and diffuse through overlapping aquifer layers. The influence of the landfill on groundwater PFASs was most pronounced within a 5 km radius. Source apportionment results indicated that reclaimed water irrigation is the main non-point source of PFASs in shallow groundwater. In contrast, deep groundwater is primarily subject to point sources and lateral recharge flow. This investigation of PFASs in shallow and deep wells provides a foundation for further exploration of PFASs transportation and risk prevention in regions where groundwater is a major water resource for domestic and industrial development.

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.

Advancement in utilization of bio-based materials including cellulose, lignin, chitosan for bio-inspired surface coatings with special wetting behavior: A review on fabrication and applications

Natural bio-material surface with hydrophobic behavior (aqueous droplet to roll off from its surface) has inspired researchers to design sustainable artificial coatings with hydrophobic or superhydrophobic behavior. The developed hydrophobic or superhydrophobic artificial coatings are highly useful in various applications such as water remediation, oil/water separation, self-cleaning, anti-fouling, anti-corrosion and also in medical fields including anti-viral, anti-bacterial efficacy. In recent years, among various coating materials, bio-based materials derived from plants and animals (cellulose, lignin, sugarcane bagasse, peanut shell, rice husk, egg cell etc.) are applied on various surfaces in order to develop fluorine free hydrophobic coatings with longer durability by lowering the surface energy and increasing the surface roughness. This review summarized recent developments in hydrophobic/superhydrophobic coating fabrication methods, properties and applications with the use of different bio-based materials and their combinations. In addition, basic mechanisms behind the coating fabrication process and their durability under different environmental conditions are also discussed. Moreover, prospects and limitations of bio-based coatings in practical applications have been highlighted.

Effect of dietary antioxidants on excretion of perfluorooctanoic acid (PFOA) via regulating uptake transporters expression and intestinal permeability in mice

Dietary antioxidants, including 2,6-di-tert-butyl-hydroxytoluene (BHT), α-tocopherol (αT) and tea polyphenol (TP), have been widely used in food. However, no data about the effect of food antioxidants on PFOA excretion were available. In this study, excretion of PFOA toward mice (four mice in each group) under the influence of co-ingested food antioxidants (i.e., BHT, αT, and TP) were investigated, and mechanism involved in excretion of PFOA, including RNA expression of uptake and efflux transporters in kidneys and liver involved in PFOA transport and intestinal permeability were also investigated. Chronic exposure to BHT (1.56 mg/kg) increased urinary PFOA excretion from 1795 ± 340 ng/mL (control) to 3340 ± 29.9 ng/mL (BHT treatment). TP treatment (12.5 mg/kg) decreased urinary excretion of PFOA, i.e., with a decrease percentage of 70% compared to the control. Organic anion transporting polypeptides (Oatps) act as uptake transporter mediate renal elimination or reabsorption of PFOA in the kidney. The decrease in urinary excretion of PFOA under TP treatment was associated with significantly (p < 0.05) enhanced expression of Oatp1a1 in the kidney (1.78 ± 0.58 vs 1.00 ± 0.18 in control), which facilitated renal reabsorption of PFOA and in turn decreased urinary excretion of PFOA. αT treatment (12.5 mg/kg) increased fecal PFOA excretion with a value of 228 ± 95.8 ng/g vs control (96.8 ± 22.7 ng/g). Mechanistic investigation revealed that αT treatment reduced intestinal permeability, resulting in increased fecal PFOA excretion.

Effect and mechanism of perfluorooctanoic acid (PFOA) on anaerobic digestion sludge dewaterability

Perfluorooctanoic acid (PFOA) as nonbiodegradable organic pollutant, its presence and risks in wastewater treatment system has aroused wide concern. This study investigated the effect and underlying mechanism of PFOA on anaerobic digestion sludge (ADS) dewaterability. Long-term exposure experiments were set up to investigate the effect with various concentration of PFOA dosed. Experimental results suggested that the existence of high concentration PFOA (over 1000 μg/L) could deteriorate ADS dewaterability. The long-term exposure to 100,000 μg/L PFOA of ADS increased specific resistance filtration (SRF) by 81.57%. It was found that PFOA promoted the release of extracellular polymeric substances (EPS), which was strongly associated with sludge dewaterability. The fluorescence analysis revealed that the high PFOA concentration could significantly improve the percentage of protein-like substances and soluble microbial by-product-like content, and then further deteriorated the dewaterability. The FTIR results showed that long-term exposure of PFOA caused loose protein structure in sludge EPS, which led to loose sludge floc structure. The loose sludge floc structure aggravated the deterioration of sludge dewaterability. The solids-water distribution coefficient (K_d) decreased with the increase of initial PFOA concentration. Moreover, PFOA significantly affected microbial community structure. Metabolic function prediction results showed significant decrease of fermentation function exposed to PFOA. This study revealed that the PFOA with high concentration could deteriorated sludge dewaterability, which should be highly concerned.

Groundwater Quality and Health: Making the Invisible Visible

Linking groundwater quality to health will make the invisible groundwater visible, but there are knowledge gaps to understand the linkage which requires cross-disciplinary convergent research. The substances in groundwater that are critical to health can be classified into five types according to the sources and characteristics: geogenic substances, biogenic elements, anthropogenic contaminants, emerging contaminants, and pathogens. The most intriguing questions are related to quantitative assessment of human health and ecological risks of exposure to the critical substances via natural or induced artificial groundwater discharge: What is the list of critical substances released from discharging groundwater, and what are the pathways of the receptors' exposure to the critical substances? How to quantify the flux of critical substances during groundwater discharge? What procedures can we follow to assess human health and ecological risks of groundwater discharge? Answering these questions is fundamental for humans to deal with the challenges of water security and health risks related to groundwater quality. This perspective provides recent progresses, knowledge gaps, and future trends in understanding the linkage between groundwater quality and health.

Perfluorononanoic Acid Induces Neurotoxicity via Synaptogenesis Signaling in Zebrafish

Perfluorononanoic acid (PFNA), commonly used as an alternative polyfluorinated compound (PFC) of perfluorooctanoic acid (PFOA), has been widely detected in the aquatic environment. Previous ecotoxicological and epidemiological results suggested that some neurobehavioral effects were associated with PFC exposure; however, the ecological impacts and underlying neurotoxicity mechanisms remain unclear, particularly in aquatic organisms during sensitive, early developmental stages. In this study, zebrafish embryos were exposed to environmentally relevant concentrations of PFNA for 120 h, and the neurological effects of PFNA were comprehensively assessed using transcriptional, biochemical, morphological, and behavioral assays. RNA sequencing and advanced bioinformatics analyses predicted and characterized the key biological processes and pathways affected by PFNA exposure, which included the synaptogenesis signaling pathway, neurotransmitter synapse, and CREB signaling in neurons. Neurotransmitter levels (acetylcholine, glutamate, 5-hydroxytryptamine, γ-aminobutyric acid, dopamine, and noradrenaline) were significantly decreased in zebrafish larvae, and the Tg(gad67:GFP) transgenic line revealed a decreased number of GABAergic neurons in PFNA-treated larvae. Moreover, the swimming distance, rotation frequency, and activity degree were also significantly affected by PFNA, linking molecular-level changes to behavioral consequences.

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.

Legacy and emerging poly- and perfluoroalkyl substances in wastewater treatment plant and receiving water: abundance, removal, and potential ecological risk

Poly- and perfluoroalkyl substances (PFASs) are toxic persistent organic pollutants and bioaccumulative chemicals, which affect the environment and ecology. PFASs in the wastewater treatment plant (WWTP) and receiving river downstream were investigated. Fourteen out of eighteen PFASs were detected, ranging from 197 to 0.14 ng L^-1. The main pollutants were 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoro-propoxy) propanoic acid (HFPO-DA), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA). The concentration of HFPO-DA (181 ng L^-1) was the highest in influent, which indicated the use and emission of PFASs in the sewage collection region of WWTP changed from legacy to emerging ones. However, PFOS from catering wastewater as the main source was dominant PFASs in the reclaimed water. Biological treatment could be effective in the removal of PFASs, especially for HFPO-DA. HFPO-DA could directly bind to cytochrome P450 and bring potential ecotoxicity to the surrounding environment, and the ecological risk of degradation products should be under consideration. Coagulation might result in PFASs release from sludge. More attention should be paid to sewage treatment process decision of WWTP for the control of PFASs.

Target-triggered double fluorescent biosensors for rapid and sensitive detection of long-chain perfluorinated compounds using DNA probe and lysozyme fiber

Perfluorinated compounds (PFCs) are useful man-made chemicals and serve as new emerging organic pollutants due to their environmental and health concerns. Chromatography-mass detection methods often need complex procedure and are also too expensive, so there is a critical demand to develop rapid, inexpensive, easy-to-operate and sensitive methods for PFCs detection. In this work, double fluorescent biosensors ('DT sensor' and 'FT sensor') have been designed to quantitatively detect long-chain perfluorinated compounds (PFCs), due to their strong hydrophobic interaction with DNA probe or lysozyme fiber. The ratio and rapid fluorescence responses offered more obvious signal changes, and high sensitivity with a limit of detection (LOD) of 0.16 μM (98.2 ppb) for perfluorododecanoic acid (PFDoA). For three PFCs with longer perfluoroalkyl chain (CF₂), increased detection sensitivity was achieved due to a stronger hydrophobicity. The fluorescent biosensors showed a good selectivity for long-chain PFCs and served as cross-reactive sensors to differentiate three different long-chain PFCs. The biosensors also had robust signal response in tap water or serum samples, and the LOD can be further lowered to pM (ppt) level after sample preconcentration.

Identification and characterization of diverse isomers of per- and polyfluoroalkyl substances in Chinese municipal wastewater

Linear and branched isomers of per- and polyfluoroalkyl substances (PFASs) are simultaneously present in the environment. However, isomer profiles of PFASs in municipal wastewater treatment plants (WWTPs) are still unknown because of the limitations of standards. Here, influent and effluent samples from 148 municipal WWTPs in China were collected. Ion mobility spectrometry was introduced into high-resolution mass spectrometry-based suspect screening methods to identify the target and suspect PFAS isomers. A total of 38 branched isomers of 14 typical PFASs were identified in wastewater samples. Linear PFASs had higher detection rates (22.3%-100%) than branched isomers (2.0%-98%). Compared to the influents, proportions of branched isomers of most PFASs (except for perfluoropentanoic acid and perfluorohexanoic acid) increased in the effluents. The conventional biological treatment processes (such as anaerobic-anoxic-aerobic and oxidation ditch treatments) had poor removal efficiency for linear PFASs (<21.4%) and branched isomers (<13.4%). No difference on removal efficiency among treatment processes was found. Furthermore, isomer composition in the WWTPs showed obvious differences between East China region and other regions, and the usage of short-chain PFASs (perfluorobutanesulfonic acid and perfluorohexanesulfonic acid) may be a key factor for driving this difference. This study sheds lights on the identification and characterization of PFAS isomers in WWTPs, which would be useful for development of monitoring and control strategies of PFASs.

Distribution of legacy and novel per- and polyfluoroalkyl substances in surface and groundwater affected by irrigation in an arid region

Frequent exchange of surface water and groundwater occurs in arid/semi-arid areas due to high evaporation and intensive irrigation activities, affecting the migration and transformation of per- and polyfluoroalkyl substances (PFASs) and threatening drinking water safety. This study analyzed legacy PFASs and potential precursors in surface water, groundwater, soil, and aquifer solid samples collected from a typical arid area, the Hetao Irrigation District of Northern China, to explore PFASs distribution and transformation between surface and ground. Total PFASs (ΣPFASs) in surface water was 29-232 ng/L, higher than 2-77 ng/L in groundwater. ΣPFASs in soil were 0.29-0.59 ng/g, higher than 0.09-0.27 in the aquifer solids. Regarding horizontal distribution, the concentration of PFASs in groundwater increased in downtowns and the areas recharged with lake water. In terms of vertical distribution, ΣPFASs decreased with the increase of depth, and more PFASs adsorbed on clay particles in the aquifer. The total oxidable precursor analysis showed that 8:2 FT and 4:2 FT were the dominant precursors of PFASs, resulting in an increment of 0.1-4 ng/L PFASs. Hydrogen and oxygen stable isotope compositions suggest similar sources between surface water and groundwater in the study area, while principal component analysis and Bayesian inference also indicate that surface water is an important source of groundwater PFASs. The annual infiltration PFASs to groundwater from Ulansuhai was estimated by the water balance approach to be 9.39 kg. Results highlight the influence of agricultural irrigation activities and lake infiltration on groundwater PFASs in the arid region.

Perfluorooctanoic acid (PFOA) exposure in relation to the kidneys: A review of current available literature

Perfluorooctanoic acid is an artificial and non-degradable chemical. It is widely used due to its stable nature. It can enter the human body through food, drinking water, inhalation of household dust and contact with products containing perfluorooctanoic acid. It accumulates in the human body, causing potential harmful effects on human health. Based on the biodegradability and bioaccumulation of perfluorooctanoic acid in the human body, there are increasing concerns about the adverse effects of perfluorooctanoic acid exposure on kidneys. Research shows that kidney is the main accumulation organ of Perfluorooctanoic acid, and Perfluorooctanoic acid can cause nephrotoxicity and produce adverse effects on kidney function, but the exact mechanism is still unknown. In this review, we summarize the relationship between Perfluorooctanoic acid exposure and kidney health, evaluate risks more clearly, and provide a theoretical basis for subsequent research.

Identification of high-concern organic pollutants in tap waters from the Yangtze River in China based on combined screening strategies

Recently, numerous organic pollutants have been detected in water environment. The safety of our drinking water has attracted widespread attention. Effective methods to screen and identify high-concern substances are urgently needed. In this study, the combined workflow for the detection and identification of high-concern organic chemicals was established and applied to tap water samples from the Yangtze River Basin. The solid phase extraction (SPE) sorbents were compared and evaluated and finally the HLB cartridge was selected as the best one for most of the contaminants. Based on target, suspect and non-target analysis, 3023 chemicals/peaks were detected. Thirteen substances such as diundecyl phthalate (DUP), 2-hydroxyatrazine, dioxoaminopyrine and diethyl-2-phenylacetamide were detected in drinking water in the Yangtze River Basin for the very first time. Based on three kinds of prioritization principles, 49 ubiquitous, 103 characteristic chemicals and 13 inefficiently removed chemicals were selected as high-concern substances. Among them, 8, 31, 9, 3, 4 substances overlapped with the toxic, risky or high-concern chemicals lists in China, America, European Union, Japan, Korea, respectively. Specific management and removal strategies were further recommended. The workflow is efficient for identification of key pollutants.

Novel method in emerging environmental contaminants detection: Fiber optic sensors based on microfluidic chips

Recently, human industrial practices and certain activities have caused the widespread spread of emerging contaminants throughout the environmental matrix, even in trace amounts, which constitute a serious threat to human health and environmental ecology, and have therefore attracted the attention of research scholars. Different traditional techniques are used to monitor water pollutants, However, they still have some disadvantages such as high costs, ecological problems and treatment times, and require technicians and researchers to operate them effectively. There is therefore an urgent need to develop simple, inexpensive and highly sensitive methods to sense and detect these toxic environmental contaminants. Optical fiber microfluidic coupled sensors offer different advantages over other detection technologies, allowing manipulation of light through controlled microfluidics, precise detection results and good stability, and have therefore become a logical device for screening and identifying environmental contaminants. This paper reviews the application of fiber optic microfluidic sensors in emerging environmental contaminant detection, focusing on the characteristics of different emerging contaminant types, different types of fiber optic microfluidic sensors, methodological principles of detection, and specific emerging contaminant detection applications. The optical detection methods in fiber optic microfluidic chips and their respective advantages and disadvantages are analyzed in the discussion. The applications of fiber optic biochemical sensors in microfluidic chips, especially for the detection of emerging contaminants in the aqueous environment, such as personal care products, endocrine disruptors, and perfluorinated compounds, are reviewed. Finally, the prospects of fiber optic microfluidic coupled sensors in environmental detection and related fields are foreseen.

Trace Analysis Method Based on UPLC-MS/MS for the Determination of (C2-C18) Per-and Polyfluoroalkyl Substances and Its Application to Tap Water and Bottled Water

As the usage of long-chain perfluoroalkyl and polyfluoroalkyl substances (PFASs) may be gradually restricted, short-chain and even ultra-short-chain PFASs have been widely produced and used, which has put forward new requirements for the simultaneous analysis of the above substances. Using solid phase extraction two-fraction elution and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), an experimental method was established for the simultaneous analysis of ultrashort-chain, short-chain, and long-chain PFASs and the precursor perfluorohexanesulfonamide (FHxSA) in low-concentration water, such as tap water and bottled water. By optimizing the volume of methanol in the first-fraction elution, the concentration of ammonia in the second-fraction elution, and the concentration of ammonium acetate in the mobile phase, the high recovery and low detection limit (0.01-3 ng/L) were obtained. In addition, this method was used to measure nine tap water samples and six bottled water samples for validation, and the results showed that the concentration of PFASs in bottled water was lower than that in tap water. This study first reported the trifluoroacetic acid concentration in bottled water (6.61 ± 9.60 ng/L), which was lower than that in tap water (1712 ± 174 ng/L). The main substances in tap water and bottled water are both ultrashort-chain PFASs (C2-C3), accounting for more than 50%. There are few reports on the simultaneous analysis of ultrashort-chain, short-chain, and long-chain PFASs (C2-C18) and the precursor FHxSA in low-concentration water samples, and the new method can be further developed for different environmental media.

Spatial distribution, compositional profile, sources, ecological and human health risks of legacy and emerging per- and polyfluoroalkyl substances (PFASs) in freshwater reservoirs of Punjab, Pakistan

Per- and polyfluoroalkyl substances (PFASs) are a large group of chemicals reported in global environment and are responsible for various adverse impacts on humans and environment. We report a comprehensive study on occurrence of PFASs, including legacy, substitute and emerging ones, from Pakistan. Surface water samples were collected from five ecologically important freshwater reservoirs in Pakistan, namely, Head Panjnad (HP), Head Trimmu (HT), Chashma Barrage (CB), Head Blloki (HB), and Head Qadirabad (HQ). The detection frequencies of PFASs ranged between 37 %-100 %. The highest concentration of ∑₁₅PFASs was detected at HP (114.1 ng L^-1), whereas the lowest at HQ (19.9 ng L^-1). Among the analyzed PFASs, 6:2 fluorotelomer sulfonic acid (6:2 FTS) and perfluorooctanoic acid (PFOA) showed maximum mean concentrations of 9.1 ng L^-1 and 7 ng L^-1 at HP, followed by Perfluorooctane sulfonic acid (PFOS) with level of 0.99 ng L^-1 at HT. The ecological risk assessment for selected species i.e., daphnid, mysid, fish and green algae showed that PFOS, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) exhibited moderate risk i.e., Hazard Quotients (HQs) < 1 to the modeled organisms, whereas perfluorobutane sulfonic acid (PFBS) showed the high risk to green algae (HQs = 8.6) and PFOA presented a high risk to all the organisms (HQs ranged between 1.04 and 7.38). The level of ∑PFASs at HP (114.1 ng L^-1) exceed the EU guideline value of ∑PFASs in water (100 ng L^-1), however the risk quotient (RQ_mix) values of all age groups were < 1 implying that the detected PFASs in water do not pose risk to human health. Source apportionment through Positive Matrix Factorization (PMF) showed that industrial effluent is the main source of PFASs in freshwater reservoirs. Comparable concentrations of legacy and substitute PFASs in this study indicate that legacy PFASs are still in use adjacent to ecologically important water reservoirs.

Exposure and Health Risk Assessment of Per- and Polyfluoroalkyl Substances in Crayfish from the Middle and Lower Reaches of the Yangtze River

Per- and polyfluoroalkyl substances (PFASs) are a novel class of emerging persistent organic pollutants (POPs) owing to their environmental persistence and bioaccumulation. Red swamp crayfish is a major source of exposure to PFASs, while the dietary intake of PFASs from crayfish is still unclear. We investigated the concentrations of PFASs in 130 batches of crayfish and 100 environmental samples from Middle and Lower Reaches of the Yangtze River Delta. Seven Perfluoroalkyl carboxylic acids (PFCAs), 3 Perfluoroalkyl sulfonates (PFSAs), and 6:2 Cl-PFESA were analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Meanwhile, PFASs exposure levels were examined concretely in four tissues of crayfish and different circulation links. The average daily intake (ADI) risk model was used to evaluate the human health risk of consuming crayfish and suggested that the risk of PFASs exposure is at a low level.

Effects of perfluorinated compounds homologues on chemical property, microbial composition, richness and diversity of urban forest soil

Perfluorinated compounds (PFCs), as an important class of new persistent organic pollutants, are widely distributed in the environment. Yet the effects of different types and concentrations of PFCs on soil microbial community in urban forest ecosystems are remain uncertain. Here, two typical PFCs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), were selected to carry out a pot experiment in greenhouse with singly and joint treatment at different concentrations, to examine their effects on composition and diversity of soil microorganisms and availability of soil macronutrients by using high-throughput Illumina sequencing approach. The results showed both PFOA and PFOS application significantly increased soil NO3--N and NH4+-N content, but did not alter total phosphorus content, compared to the control check (CK) treatments. Total potassium content was reduced in PFOA treatments but increased in PFOS and PFOA×PFOS treatments. The most dominant bacterial phylum was Chloroflexi in low and medium PFCs concentrations and the CK treatments, but it was switched to Acidobacteria in high concentrations. No obvious change was detected for the composition of the dominant fungi community in PFCs treatments compared to the CK treatments. With the increase of PFCs concentrations, soil bacterial richness decreased but its diversity increased, whereas the richness and diversity of fungal community usually decreased. Redundancy analyses revealed that soil fungal community was more sensitive to PFCs pollutants than soil bacterial communities. Further data analysis revealed by structural equation model (SEM) that the PFCs exposed for 60 days indirectly affects the diversity and richness of soil bacteria and fungi by directly affecting NO3--N and NH4+-N content. The results suggested the concentration of PFCs pollutants played a primary role in determining the composition, richness and diversity of forest soil microbial communities.

Sources, occurrence, and treatment techniques of per- and polyfluoroalkyl substances in aqueous matrices: A comprehensive review

Per- and polyfluoroalkyl substances (PFAS), a class of synthetic organic pollutants, have prompted concerns about their global prevalence and possible health effects. This review consolidates the most recent data on different aspects of PFAS, such as their occurrence, and prominent sources. The current literature analysis of PFAS occurrence suggests significant variation in their concentration ranging from 0.025 to 1.2 × 10⁸ ng/L in wastewater, 0.01 to 8.9 × 10⁵ ng/L in surface water, and <0.01 to 1.3 × 10⁴ ng/L in groundwater globally. Since conventional treatment techniques are inadequate in remediating PFAS, innovative treatment approaches based on their removal or mineralization mechanism have been comprehensively reviewed. Advanced treatment technologies have shown degradation or removal of PFAS to be around 6 and > 99.9% in different aqueous matrices. However, due to significant drawbacks in their applicability in wastewater treatment plants (WWTPs), a novel treatment train approach has emerged as an effective alternative. This approach synergistically integrates multiple remediation techniques while addressing the impediments of individual treatments. Furthermore, nanofiltration (NF270) combined with electrochemical degradation has been demonstrated to be the most efficient (>98%) treatment train approach in PFAS remediation. If implemented in WWTPs, nanofiltration followed by adsorption using activated carbon is also a viable method for PFAS removal.

Global distributions, source-type dependencies, and concentration ranges of per- and polyfluoroalkyl substances in groundwater

A meta-analysis was conducted of published literature reporting concentrations of per- and polyfluoroalkyl substances (PFAS) in groundwater for sites distributed in 20 countries across the globe. Data for >35 PFAS were aggregated from 96 reports published from 1999 to 2021. The final data set comprises approximately 21,000 data points after removal of time-series and duplicate samples as well as non-detects. The reported concentrations range over many orders of magnitude, from ng/L to mg/L levels. Distinct differences in concentration ranges are observed between sites located within or near sources versus those that are not. Perfluorooctanoic acid (PFOA), ranging from <0.03 ng/L to ~7 mg/L, and perfluorooctanesulfonic acid (PFOS), ranging from 0.01 ng/L to ~5 mg/L, were the two most reported PFAS. The highest PFAS concentration in groundwater is ~15 mg/L reported for the replacement-PFAS 6:2 fluorotelomer sulfonate (6:2 FTS). Maximum reported groundwater concentrations for PFOA and PFOS were compared to concentrations reported for soils, surface waters, marine waters, and precipitation. Soil concentrations are generally significantly higher than those reported for the other media. This accrues to soil being the primary entry point for PFAS release into the environment for many sites, as well as the generally significantly greater retention capacity of soil compared to the other media. The presence of PFAS has been reported for all media in all regions tested, including areas that are far removed from specific PFAS sources. This gives rise to the existence of a "background" concentration of PFAS that must be accounted for in both regional and site-specific risk assessments. The presence of this background is a reflection of the large-scale use of PFAS, their general recalcitrance, and the action of long-range transport processes that distribute PFAS across regional and global scales. This ubiquitous distribution has the potential to significantly impact the quality and availability of water resources in many regions. In addition, the pervasive presence of PFAS in the environment engenders concerns for impacts to ecosystem and human health.

Perfluorononanoate and Perfluorobutane Sulfonate Induce Cardiotoxic Effects in Zebrafish

Globally, per- and polyfluoroalkyl substances are common artificial ingredients in industrial and consumer products. Recently, they have been shown to be an emerging human health risk. Perfluorononanoic acid (PFNA)/perfluorononanoate and perfluorobutane sulfonic acid (PFBS)/perfluorobutane sulfonate cause reproductive toxicity and hepatotoxicity, disrupt thyroid functions, and damage embryonic development in zebrafish. However, the cardiotoxic effects of PFNA and PFBS have not been fully established. We found that PFNA and PFBS exposures repress hatchability while increasing malformation and mortality in zebrafish embryos. Hematoxylin and eosin staining as well as assessment of the transgenic zebrafish line Tg(myl7:nDsRed) revealed that exposure of embryos to PFNA increases the occurrence of severe cardiac malformations relative to exposure to PFBS. Moreover, we evaluated the differential expressions of cardiac development-associated genes in response to PFNA and PFBS, which validated the potential cardiotoxic effects, consistent with cardiac dysfunctions. Overall, our findings reveal novel cardiotoxic effects of PFNA and PFBS in zebrafish, implying that they may exert some cardiotoxic effect in humans. To the best of our knowledge, ours is the first study to show that PFNA exerts more severe cardiotoxic effects in zebrafish when compared with PFBS. Based on these findings, studies should evaluate the mechanisms of their cardiotoxic effects. Environ Toxicol Chem 2022;41:2527-2536. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Per- and polyfluoroalkyl substances (PFASs) in groundwater from a contaminated site in the North China Plain: Occurrence, source apportionment, and health risk assessment

Per-and polyfluoroalkyl substances (PFASs) are manmade chemicals that have wide industrial and commercial application. However, little research has been carried out on PFASs pollution in groundwater from a previously contaminated site. Here, we investigated 43 PFASs in a monitoring campaign from two different aquifers in the North China Plain. Our results revealed that total PFASs concentrations (∑₄₃PFASs) ranged from 0.22 to 3,776.76 ng/L, with no spatial or compositional differences. Moreover, perfluorooctanoic acid (PFOA) and perfluoroheptane sulfonate (PFHpS) were the dominant pollutants with mean concentrations of 177.33 ng/L and 51 ng/L, respectively. ∑₄₃PFAS decreased with well depth due to the adsorption of PFASs to the aquifer materials. Water temperature, total organic carbon, dissolved oxygen, and total phosphorus concentrations were correlated to the PFAS concentrations. Principal component analysis indicated that the main sources of PFASs in groundwater were untreated industrial discharge, untreated domestic wastewater, food packaging, aqueous film forming foams and metal plating, and surface runoff, which overlapped with the industries that previously existed in a nearby city. Human health risks from drinking contaminated groundwater were low to the local residents, with children aged 1-2 years being the most sensitive group. One specific site with a high PFOA concentration was of concern, as it was several orders higher than the 70 ng/L recommended by US Environmental Protection Agency health advisory. This study provided baseline data for PFASs in a previously-contaminated site, which will help in the development of effective strategies for controlling PFASs pollution in the North China Plain.

Distributions and sources of traditional and emerging per- and polyfluoroalkyl substances among multiple environmental media in the Qiantang River watershed, China

The presence of per- and polyfluoroalkyl substances (PFASs) in the food chain poses a threat to human health. Water and the atmosphere are the major transport pathways for PFASs in the environment, while water, soil and sediment are sinks. Herein, the concentrations and distributions of traditional and emerging PFASs in multi-environmental media samples in the Qiantang River watershed were comprehensively investigated. Twenty-five PFASs, including seven emerging PFASs, were identified. The concentrations in water, soil, sediment and PM2.5 ranged from 3.58 to 786 ng L-1, 0.72 to 12.3 ng g-1, 0.73 to 6.60 ng g-1, and 93.9 to 255 pg m-3, respectively, with mean concentrations of 149 ng L-1, 4.70 ng g-1, 4.31 ng g-1, and 156 pg m-3. Perfluorooctanoic acid (PFOA) was the dominant contaminant in water, soil, and sediment, and perfluoropentanoic acid (PFPeA) was the dominant contaminant in PM2.5. Hexafluoropropylene oxide-dimer acid (HFPO-DA) and 6 : 2 chlorinated polyfluorinated ether sulfonate (6 : 2 Cl-PFESA), as substitutes for PFOA and perfluorooctane sulfonate (PFOS), were detected, indicating the gradual replacement of traditional PFOA and PFOS in this area. Perfluoro-3,6-dioxaheptanoic acid (NFDHA), as a component of the aqueous film-forming foam FN-3, was first detected in this area. Short-chain PFASs were mainly distributed in water and PM2.5, while long-chain PFASs were distributed in the solid phase, such as soil, sediment, and PM2.5. Based on principal component analysis (PCA), the major PFAS sources were emulsifiers from fluorine polymerization and surface-active agents from the textile, papermaking, leather, and other industries. In addition, correlation analysis showed that water was the main source and transport pathway of short-chain perfluoroalkyl carboxylic acid (PFCA), HFPO-DA, and NFDHA in this area, while the atmosphere combined with PM2.5 was the main transport pathway for both short- and long-chain PFCAs, PFOS, and 6 : 2 Cl-PFESA.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) in groundwater: current understandings and challenges to overcome

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been frequently detected in groundwater globally. With the phase-out of perfluorooctane sulfonate (PFOS) and perfluorooctanate (PFOA) due to their risk to the ecosystem and human population, various novel PFASs have been used as replacements and detected in groundwater. In order to summarize the current understanding and knowledge gaps on PFASs in groundwater, we reviewed the studies about environmental occurrence, transport, and risk of legacy and novel PFASs in groundwater published from 1999 to 2021. Our review suggests that PFOS and PFOA could still be detected in groundwater due to the long residence time and the retention in the soil-groundwater system. Firefighting training sites, industrial parks, and landfills were commonly hotspots of PFASs in groundwater. More novel PFASs have been detected via nontarget analysis using high-resolution mass spectrometry. Some novel PFASs had concentrations comparable to that of PFOS and PFOA. Both legacy and novel PFASs can pose a risk to human population who rely on contaminated groundwater as drinking water. Transport of PFASs to groundwater is influenced by various factors, i.e., the compound structure, the hydrochemical condition, and terrain. The exchange of PFASs between groundwater and surface water needs to be better characterized. Field monitoring, isotope tracing, nontarget screening, and modeling are useful approaches and should be integrated to get a comprehensive understanding of PFASs sources and behaviors in groundwater.

Exploring the source, migration and environmental risk of perfluoroalkyl acids and novel alternatives in groundwater beneath fluorochemical industries along the Yangtze River, China

The widely used legacy perfluoroalkyl acids (PFAAs) with serious environmental hazards are gradually restricted and being replaced by novel alternatives. Here, for an efficient control of emerging environmental risks in groundwater, we systematically studied the source apportionment, spatial attenuation, composition change and risk zoning of 12 PFAAs and five novel alternatives within a region of ~200 km² around a mega fluorochemical industrial park (FIP) along the Yangtze River, and in-depth explored potential association between groundwater and soil pollution as well as influencing factors on contaminant migration and risk distribution in the aquifer. Short-chain PFAAs and novel alternatives together accounted for over 70% in groundwater, revealing their prevalence in replacing legacy perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Novel alternatives for PFOA were mainly hexafluoropropylene oxide dimer acid (GenX) and hexafluoropropylene oxide trimer acid (HFPO-TA), while those for PFOS were 6:2 chlorinated polyfluorinated ether sulfonic acid (6:2 Cl-PFESA) and 6:2 fluorotelomer sulfonic acid (6:2 FTS). PFAAs (maximum total: 1339 ng/L) and novel alternatives (maximum total: 208 ng/L) in groundwater were mostly derived from the FIP, and exhibited an exponentially decreasing trend with increasing distance. Compared with those in groundwater, more diverse sources of PFAAs and novel alternatives in surface soil were identified. The transport of these chemicals may be retarded by clayed surface soils with high organic matter contents. High aquifer permeability could generally promote the dilution and migration of PFAAs and novel alternatives in groundwater, as well as reduce the differences in their spatial distribution. Shorter-chain components with smaller molecules and higher hydrophilicity exhibited greater migration capacities in the aquifer. In addition, different levels of health risk from PFOS and PFOA were zoned based on drinking groundwater, and high risks tended to be distributed in areas with relatively poor aquifer water yield due to higher pollutant accumulation.

Occurrence and Risk Assessment of Perfluorooctanoate (PFOA) and Perfluorooctane Sulfonate (PFOS) in Surface Water, Groundwater and Sediments of the Jin River Basin, Southeastern China

Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) levels were determined in surface water, groundwater and sediments of the Jin River Basin, southeastern China. PFOA was detected in most of the samples, and its concentrations ranged from 0.53 to 8.77 ng/L, 0.26 to 15.1 ng/L and not detected (ND) to 23.9 ng/g in surface water, groundwater and sediments, respectively. Unlike PFOA, the detection frequency of PFOS was lower than 32%, and its concentrations ranged from ND to 2.56 ng/L, ND to 7.01 ng/L, ND to 11.1 ng/g in surface water, groundwater and sediments, respectively. The environmental risk assessment showed that PFOA could pose a high risk to surface water and groundwater, and both PFOA and PFOS posed a high risk to sediments. Moreover, the adults living in the Jin River Basin were at insignificant health risk to exposure to PFOA and PFOS through water consumption.

Perfluoroalkyl Substances (PFASs) in Rivers and Drinking Waters from Qingdao, China

Perfluoroalkyl substances (PFASs) in rivers; drinking water sources (reservoirs and groundwater); and various types of drinking waters (tap waters, barreled pure waters, and bottled mineral waters) in Qingdao, Eastern China were quantified by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The total concentrations of PFASs (ΣPFASs) in the river waters ranged from 28.3 to 292.2 ng/L, averaging 108 ± 70.7 ng/L. PFBS was the most abundant compound, with a maximum concentration of 256.8 ng/L, followed by PFOA (maximum concentration: 72.4 ng/L) and PFBA (maximum concentration: 41.6 ng/L). High levels of PFASs were found in rivers in the suburban and rural areas. The estimated annual mass loading of the total PFASs to Jiaozhou Bay (JZB) was 5.9 tons. The PFASs in the drinking water reservoirs were relatively low. The ΣPFASs in the tap water ranged from 20.5 ng/L to 29.9 ng/L. Differences in the PFAS levels and composition profiles were found among barreled water at different market sites and for different brands of mineral water products. The sequence of the contamination levels of the waters related to drinking water was reservoir water > tap water > barrel water > groundwater > bottled mineral water. The PFASs in drinking water may not pose a serious risk to the drinking water consumers of Qingdao City.

Per- and polyfluoroalkyl substances (PFAS) in the Three-North Shelter Forest in northern China: First survey on the effects of forests on the behavior of PFAS

Per- and polyfluoroalkyl substances (PFAS) are a family of anthropogenic chemicals, that have attracted increasing attention since the early 2000 s. Although forests have been shown to act as a filter and important sink for nonpolar persistent organic pollutants (POPs), relevant reports on PFAS are lacking. Air, soil, and leaf samples were collected inside and outside the forest from two regions of the Three-North Shelter Forest in northern China between 2017 and 2018. Twenty-seven PFAS were analyzed to study the effect of forest on the transport and fate of PFAS. The average ratios of PFAS in the air outside to inside the forest (Q_air) ranged from 2.83 ± 0.78-10.6 ± 3.1. A significant positive correlation was found between Q_air and the n-octanol-air partition coefficient of individual PFAS (p = 0.041). Higher Q_air values for most ionic PFAS were found in broad-leaved forests than in coniferous forests. Soil samples outside the forests showed higher PFAS levels than those inside. The measured concentrations of 8:2 fluorotelomer alcohol, a volatile neutral PFAS, in leaf samples were two orders of magnitude higher than those estimated using the equilibrium leaf-air partition of nonpolar POPs, indicating that it may not fit the case of PFAS with surface activity.

Distribution, source identification and health risk assessment of PFASs in groundwater from Jiangxi Province, China

There is an urgent need to investigate on the distribution and fate of short-chain analogues and emerging per- and polyfluoroalkyl substances (PFASs) in groundwater, and little research on their source apportionment and health risks through the drinking water exposure pathway has been carried out. In present study, the concentration and source of 22 PFASs, including five alternatives: 6:2 fluorotelomer sulfonate (6:2 FTS), potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (F-53B), hexafluoropropylene oxide trimer acid (HFPO-TA), hexafluoropropylene oxide dimer acid (HFPO-DA) and ammonium 4, 8-dioxa-3H-perfluorononanoate (ADONA), were analyzed in 88 groundwater samples from wells in Jiangxi Province, southeastern China. The total PFASs concentration (Σ₁₈PFASs) in groundwater varied from 1.27 to 381.00 ng/L (mean 47.60 ng/L). Short-chain perfluorobutanoic acid (PFBA) and perfluoropentanoic acid (PFPeA) were the most abundant perfluorinated carboxylic acids (PFCAs), and short-chain perfluorobutanesulfonate (PFBS) was the most abundant perfluorinated sulfonic acids (PFSAs) in groundwater samples. The quantitative source apportionment by nonnegative matrix/tensor factorization coupled with k-means clustering (NMFk) model suggested that short-chain homologues and emerging alternatives have been used as substitutes for legacy PFOS and PFOA. Furthermore, the human risk assessment results showed that the estimated daily intakes (EDIs) for short-chain PFCAs were higher than that of PFOA, whereas the EDIs of PFBS, 6:2 FTS and F-53B were comparable to that of PFOS.

Distribution, sources, and dietetic-related health risk assessment of perfluoroalkyl acids (PFAAs) in the agricultural environment of an industrial-agricultural interaction region (IAIR), Changshu, East China

The exploration of the distribution and dietetic-related health risks of perfluoroalkyl acids (PFAAs) in industrial-agricultural interaction regions (IAIRs) is of significant importance, due to the transfer of many PFAA-related factories to developing countries with intensive agricultural activities. In the present study, based on the local diet, edible parts of rice, vegetables, fish, and their corresponding soils and irrigation/aquaculture water were investigated in a typical Chinese city (Changshu). The concentrations of total perfluoroalkyl acids (ΣPFAAs) in the edible parts of rice /vegetables and fish tissues ranged from 26.69 to 37.09 ng/g dw, 12.93 to 40.77 ng/g dw, and 13.27 to 29.82 ng/g ww, with perfluorohexanoic acid (PFPeA) and perfluorooctane sulfonic acid (PFOS) as the most dominant compounds. The PFAA concentrations in the corresponding rice soils, vegetable soils, irrigation water, and aquaculture water ranged from 11.99 to 26.33 ng/g dw, 14.06 to 36.19 ng/g dw, 141.36 to 297.00 ng/L, and 179.23 to 235.82 ng/L, respectively. Biota-sediment accumulation factor (BSAF) values for the plant-soil system were far greater than those for bioaccumulation factor (BAF) values for the plant-irrigation water system. PFAAs were more inclined to accumulate in the gills of fish as determined by their highest BAF values. Correlation analysis showed that PFAAs in root vegetables had a stronger correlation with those in soil compared with those in irrigation water. Source analysis showed that emissions from fluoride industries, textiles, and food industries may be the dominant sources of PFAAs in agricultural environments. The estimated dietary intake (EDI) for the selected diet was lower than that for rice/vegetables but was higher than that found in fish. Toddlers (2-5 years) had the highest exposure risk, and rural residents were more exposed to PFAAs than urban residents under the selected diet.

Source apportionment and crop bioaccumulation of perfluoroalkyl acids and novel alternatives in an industrial-intensive region with fluorochemical production, China: Health implications for human exposure

Due to their great environmental hazards, the widely used legacy perfluoroalkyl acids (PFAAs) are gradually restricted, and novel alternatives are being developed and applied. For efficient control of emerging environmental risks in agricultural production, we systematically studied the source apportionment in field soils and bioaccumulation characteristics in multiple crops of 12 PFAAs and five novel alternatives in an industrial-intensive region of China, followed by human exposure estimation and health risk assessment. Compared with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), shorter-chained PFAAs and novel alternatives have become the dominant components in local soils and crops, indicating their wide application. A positive matrix factorization (PMF) model coupled with multivariate analysis identified fluoropolymer manufacturing and textile treatment as the principal sources. The bioaccumulation factors (BAFs) of individual PFAAs and alternatives in crops decreased with increasing carbon chain lengths. As a novel alternative of PFOA, hexafluoropropylene oxide dimer acid (GenX) exhibited much higher BAFs; for the alternative of PFOS, 6:2 chlorinated polyfluorinated ether sulfonic acid (6:2 Cl-PFESA) showed lower BAFs. The bioaccumulation capacities of PFAAs and alternatives were also associated with soil organic matter and crop species. Through crop consumption, short-chained PFAAs and novel alternatives might pose emerging human health threats.

PFAS Molecules: A Major Concern for the Human Health and the Environment

Per- and polyfluoroalkyl substances (PFAS) are a group of over 4700 heterogeneous compounds with amphipathic properties and exceptional stability to chemical and thermal degradation. The unique properties of PFAS compounds has been exploited for almost 60 years and has largely contributed to their wide applicability over a vast range of industrial, professional and non-professional uses. However, increasing evidence indicate that these compounds represent also a serious concern for both wildlife and human health as a result of their ubiquitous distribution, their extreme persistence and their bioaccumulative potential. In light of the adverse effects that have been already documented in biota and human populations or that might occur in absence of prompt interventions, the competent authorities in matter of health and environment protection, the industries as well as scientists are cooperating to identify the most appropriate regulatory measures, substitution plans and remediation technologies to mitigate PFAS impacts. In this review, starting from PFAS chemistry, uses and environmental fate, we summarize the current knowledge on PFAS occurrence in different environmental media and their effects on living organisms, with a particular emphasis on humans. Also, we describe present and provisional legislative measures in the European Union framework strategy to regulate PFAS manufacture, import and use as well as some of the most promising treatment technologies designed to remediate PFAS contamination in different environmental compartments.

Sorption of Perfluorooctane sulfonate (PFOS) including its isomers on hydrargillite as a function of pH, humic substances and Na2SO4

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant (POP) and emergent contaminant that are widespread in the environment. Understanding the mechanisms controlling the distribution of PFOS and its isomers between hydrargillite and the water phase is important in order to study their redistribution and mobility in the environment. This study investigated the effects of pH, humic acid, fulvic acid and Na₂SO₄ on sorption of PFOS isomers to hydrargillite. A mixture of PFOS isomers was spiked into water and hydrargillite was added to the system and shaken for one day; the system was tested with different aqueous composition. Concentrations of PFOS isomers in the aqueous phase were quantified using an ultra-performance liquid chromatograph coupled to a triple quadrupole mass spectrometer. Our results showed that the distribution coefficients of PFOS isomers were found to be 0.76, 0.71, 0.93 and 0.90 at pH 6.5, for 3-/4-/5- PFOS, 6-/2-PFOS, L-PFOS and total PFOS respectively. The distribution coefficients increased at lower pH and decreased at alkaline conditions. The presence of humic substances (HS) increased the sorption slightly at the environmental pH of 6.5, although a competition effect was observed during acidic conditions. A tendency of PFOS distribution to hydrargillite in the presence of Na₂SO₄ was like its behavior in the presence of HS although the mechanisms behind the sorption were interpreted differently. This study revealed that L-PFOS was readily sorbed when no other chemicals were added or in 20 mg/L FA or 100 mg/L Na₂SO₄. We suggest that an increase in PFOS sorption in the presence of HS may be due to hydrophobic mechanisms while Na₂SO₄ contributed to increased sorption through ionic strength effects.

Occurrence and removal of poly/perfluoroalkyl substances (PFAS) in municipal and industrial wastewater treatment plants

The presence of poly- and perfluoroalkyl substances (PFAS) has caused serious problems for drinking water supplies especially at intake locations close to PFAS manufacturing facilities, wastewater treatment plants (WWTPs), and sites where PFAS-containing firefighting foam was regularly used. Although monitoring is increasing, knowledge on PFAS occurrences particularly in municipal and industrial effluents is still relatively low. Even though the production of C8-based PFAS has been phased out, they are still being detected at many WWTPs. Emerging PFAS such as GenX and F-53B are also beginning to be reported in aquatic environments. This paper presents a broad review and discussion on the occurrence of PFAS in municipal and industrial wastewater which appear to be their main sources. Carbon adsorption and ion exchange are currently used treatment technologies for PFAS removal. However, these methods have been reported to be ineffective for the removal of short-chain PFAS. Several pioneering treatment technologies, such as electrooxidation, ultrasound, and plasma have been reported for PFAS degradation. Nevertheless, in-depth research should be performed for the applicability of emerging technologies for real-world applications. This paper examines different technologies and helps to understand the research needs to improve the development of treatment processes for PFAS in wastewater streams.

A Review on Emerging Pollutants in the Water Environment: Existences, Health Effects and Treatment Processes

Emerging pollutants (EPs), also known as micropollutants, have been a major issue for the global population in recent years as a result of the potential threats they bring to the environment and human health. Pharmaceuticals and personal care products (PPCPs), antibiotics, and hormones that are used in great demand for health and cosmetic purposes have rapidly culminated in the emergence of environmental pollutants. EPs impact the environment in a variety of ways. EPs originate from animal or human sources, either directly discharged into waterbodies or slowly leached via soils. As a result, water quality will deteriorate, drinking water sources will be contaminated, and health issues will arise. Since drinking water treatment plants rely on water resources, the prevalence of this contamination in aquatic environments, particularly surface water, is a severe problem. The review looks into several related issues on EPs in water environment, including methods in removing EPs. Despite its benefits and downsides, the EPs treatment processes comprise several approaches such as physico-chemical, biological, and advanced oxidation processes. Nonetheless, one of the membrane-based filtration methods, ultrafiltration, is considered as one of the technologies that promises the best micropollutant removal in water. With interesting properties including a moderate operating manner and great selectivity, this treatment approach is more popular than conventional ones. This study presents a comprehensive summary of EP’s existence in the environment, its toxicological consequences on health, and potential removal and treatment strategies.

Comprehensive adsorption behavior and mechanism of PFOA and PFCs in various subsurface systems in China

The adsorption-desorption performance of perfluorooctanoic acid (PFOA), one of the environmentally persistent pollutants which is refractory to degrade in soil, was investigated and reported. The adsorption-desorption process of PFOA was firstly conducted using different fractions (sand, coarse silt and fine silt) of soil collected from Shanghai, China. More than 50% of PFOA (2.0 mg/L) could be adsorbed by soils while only less than 10% of which could be desorbed once contamination occurs. The kinetics and particle diffusion rates of PFOA in different fractions of soil were calculated and analyzed in detail. Apart from this, the retention of short-chained PFCs, which can be generated as degradation products of PFOA, were also measured. In single solute systems, the adsorption of pollutants in soils dramatically increased as the chain length of PFCs grew longer. Similarly, in mixed solutions, preferential adsorption of longer-chained PFCs over shorter chains in soils were sited, attributable to the stronger hydrophobicity of the pollutants. However, the desorption of them performed in reverse, where the desorption rates of longer-chained PFCs were far lower than those of shorter ones. Furthermore, influencing factors including pH, temperature and co-existing matters were studied during the adsorption process. After comprehending the adsorption behavior of PFOA in soil fractions, the situation of the adsorption of PFOA in various soils chosen from nine provinces in China was investigated and compared. There was an obvious discrepancy, whether it be from the rate or the amount of adsorption of PFOA (approximately 10%), in the nine different soils. Finally, a multiple linear regressive equation was employed to sort influencing parameters which are prone to affect the adsorption of PFOA in soils, the contribution of these are provided in order of relevance. These results demonstrate the adsorption performance and behavior of PFOA and PFCs in different soils, which can be utilized as a scientific reference for maximizing remediation of PFOA polluted sites in the future.