Biological effects of perfluoroalkyl substances on running water ecosystems: A case study in Beiluo River, China.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are emerging contaminants that pose a threat to the biodiversity of the Beiluo River, a polluted watercourse on the Loess Plateau impacted by diverse human activities. However, the occurrence, spatial distribution, and substitution characteristics of PFASs in this region remain unclear. This study aimed to unravel PFAS distribution patterns and their impact on the aquatic ecosystems of the Beiluo River Basin. The total PFAS concentration in the area ranged from 16.64-35.70 ng/L, with predominantly perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs), collectively contributing 94%. The Mantel test revealed threats to aquatic communities from both legacy long-chain (perfluorooctanoic acid and sodium perfluorooctane sulfonic acid) and emerging (6:2 fluorotelomer sulfonic acid, 2-Perfluorohexyl ethanoic acid, and hexafluoropropylene oxide dimer acid (Gen-X)) PFSAs. The canonical correspondence analysis ordination indicated that trace quantities of emerging PFASs, specifically 2-Perfluorohexyl ethanoic acid and hexafluoropropylene oxide dimer acid (Gen-X), significantly influenced geographical variations in aquatic communities. In conclusion, this study underscores the importance of comprehensively exploring the ecological implications and potential risks associated with PFASs in the Beiluo River Basin.

Assessment of Fetal Exposure and Elimination of Perfluoroalkyl and Polyfluoroalkyl Substances: New Evidence from Paired Serum, Placenta, and Meconium Samples.

Multiple pieces of evidence have shown that prenatal exposure to perfluoroalkyl and polyfluoroalkyl substances (PFASs) is closely related to adverse birth outcomes for infants. However, difficult access to human samples limits our understanding of PFASs transport and metabolism across the human placental barrier, as well as the accurate assessment of fetal PFASs exposure. Herein, we assess fetal exposure to 28 PFASs based on paired serum, placenta, and meconium samples. Overall, 21 PFASs were identified first to be exposed to the fetus prenatally and to be metabolized and excreted by the fetus. In meconium samples, 25 PFASs were detected, with perfluorooctane sulfonate and perfluorohexane sulfonic acid being the dominant congeners, suggesting the metabolism and excretion of PFASs through meconium. Perfluoroalkyl sulfonic acids might be more easily eliminated through the meconium than perfluorinated carboxylic acids. Importantly, based on molecular docking, MRP1, OATP2B1, ASCT1, and P-gp were identified as crucial transporters in the dynamic placental transfer of PFASs between the mother and the fetus. ATSC5p and PubchemFP679 were recognized as critical structural features that affect the metabolism and secretion of PFASs through meconium. With increasing carbon chain length, both the transplacental transfer efficiency and meconium excretion efficiency of PFASs showed a structure-dependent manner. This study reports, for the first time, that meconium, which is a noninvasive and stable biological matrix, can be strong evidence of prenatal PFASs exposure.

Tracing the Bioaccessibility of Per- and Polyfluoroalkyl Substances in Fish during Cooking Treatment.

The effect of cooking on the contents of per- and polyfluoroalkyl substances (PFAS) in foods has been widely studied, but whether cooking-induced structural and chemical modifications in foods affect the oral bioaccessibility of PFAS remains largely unknown. In this study, three kinds of fishes with different fat contents were selected, and the bioaccessibility of PFAS during cooking treatment (steaming and frying) was evaluated using in vitro gastrointestinal simulation with gastric lipase addition. The results showed that related to their molecular structures, the bioaccessibility of an individual PFAS varied greatly, ranging from 26.0 to 108.1%. Cooking can reduce the bioaccessibility of PFAS, and steaming is more effective than oil-frying; one of the possible reasons for this result is that the PFAS is trapped in protein aggregates after heat treatment. Fish lipids and cooking oil ingested with meals exert different effects on the bioaccessibility of PFAS, which may be related to the state of the ingested lipid/oil and the degree of unsaturation of fatty acids. Gastric lipase boosted the release of long-chain PFAS during in vitro digestion, indicating that the degree of lipolysis considerably influences the bioaccessibility of hydrophobic PFAS. Estimated weekly PFAS intakes were recalibrated using bioaccessibility data, enabling more accurate and reliable dietary exposure assessments.

Novel Insights into the Adverse Health Effects of per- and Polyfluoroalkyl Substances on the Kidney via Human Urine Metabolomics.

Per- and polyfluoroalkyl substances (PFAS) receive significant research attention due to their potential adverse effects on human health. Evidence shows that the kidney is one of the target organs of PFAS. In occupational exposure scenarios, high PFAS concentrations may adversely affect kidney metabolism, but whether this effect is reflected in the small metabolic molecules contained in urine remains unknown. In this study, 72 matched serum and urine samples from occupational workers of a fluorochemical manufactory as well as 153 urine samples from local residents were collected, and 23 PFAS levels were quantified. The concentrations of Σ23PFAS in the serum and urine samples of workers were 5.43 ± 1.02 µg/mL and 201 ± 46.9 ng/mL, respectively, while the Σ23PFAS concentration in the urine of the residents was 6.18 ± 0.76 ng/mL. For workers, high levels of urinary PFAS were strongly correlated with levels in serum (r = 0.57-0.93), indicating that urinary PFAS can be a good indicator for serum PFAS levels. Further, a urine nontargeted metabolomics study was conducted. The results of association models, including Bayesian kernel machine regression, demonstrated positive correlations between urinary PFAS levels and key small kidney molecules. A total of eight potential biomarkers associated with PFAS exposure were identified, and all of them showed significant positive correlations with markers of kidney function. These findings provide the first evidence that urine can serve as a matrix to indicate the adverse health effects of high levels of exposure to PFAS on the kidneys.

Molecular-Scale Investigation on the Formation of Brown Carbon Aerosol via Iron-Phenolic Compound Reactions in the Dark.

Brown carbon (BrC) is one of the most mysterious aerosol components responsible for global warming and air pollution. Iron (Fe)-induced catalytic oxidation of ubiquitous phenolic compounds has been considered as a potential pathway for BrC formation in the dark. However, the reaction mechanism and product composition are still poorly understood. Herein, 13 phenolic precursors were employed to react with Fe under environmentally relevant conditions. Using Fourier transform ion cyclotron resonance mass spectrometry, a total of 764 unique molecular formulas were identified, and over 85% of them can be found in atmospheric aerosols. In particular, products derived from precursors with catechol-, guaiacol-, and syringol-like-based structures can be distinguished by their optical and molecular characteristics, indicating the structure-dependent formation of BrC from phenolic precursors. Multiple pieces of evidence indicate that under acidic conditions, the contribution of either autoxidation or oxygen-induced free radical oxidation to BrC formation is extremely limited. Ligand-to-Fe charge transfer and subsequent phenoxy radical coupling reactions were the main mechanism for the formation of polymerization products with high molecular diversity, and the efficiency of BrC generation was linearly correlated with the ionization potential of phenolic precursors. The present study uncovered how chemically diverse BrC products were formed by the Fe-phenolic compound reactions at the molecular level and also provide a new paradigm for the study of the atmospheric aerosol formation mechanism.

Investigation with ESI FT-ICR MS on sorbent selectivity and comprehensive molecular composition of landfill leachate dissolved organic matter.

Molecular characterization of landfill leachate dissolved organic matter (LDOM) is essential for developing effective processing techniques. However, the molecular selectivity of extraction method and ionization modes often leads to the bias of molecular characterization of LDOM. Here, seven representative sorbents were selected and electrospray ionization negative ion mode (ESI (-)) and positive ion mode (ESI (+)) Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were used to investigate the molecular composition of different LDOM samples. Obvious sorbent selectivity during extraction procedure was observed, resulting in the underestimation of molecular diversity of LDOM from 32.7% to 69.3%. Totally, 14,000-18,000 unique molecules were obtained in a single sample, indicating the unprecedented molecular diversity of LDOM. Lignins, proteins and lipids are three major molecular groups in LDOM, and N or S containing molecules occupied 83%. Although much of total organic carbon was removed during biochemical treatment process, the molecular diversity of LDOM was not reduced because a considerable of bio-recalcitrant molecules was produced. The results uncover the sorbents selectivity and ionization modes selectivity in LDOM analysis and provided a comprehensive change of LDOM molecular composition during biochemical treatment, which benefits the development of accurate methods to remove organic carbon in landfill leachate.

Generation Mechanism of Perfluorohexanesulfonic Acid from Polyfluoroalkyl Sulfonamide Derivatives During Chloramination in Drinking Water.

Per- and polyfluoroalkyl substances (PFASs), including perfluorohexanesulfonic acid (PFHxS), as emerging persistent organic pollutants widely detected in drinking water, have drawn increasing concern. The PFHxS contamination of drinking water always results from direct and indirect sources, especially the secondary generations through environmental transformations of precursors. However, the mechanism of the transformation of precursors to PFHXS during the drinking water treatment processes remains unclear. Herein, the potential precursors and formation mechanisms of PFHxS were explored during drinking water disinfection. Simultaneously, the factors affecting PFHxS generation were also examined. This study found PFHxS could be generated from polyfluoroalkyl sulfonamide derivatives during chlorination and chloramination. The fate and yield of PFHxS varied from different precursors and disinfection processes. In particular, monochloramine more favorably formed PFHxS. Several perfluoroalkyl oxidation products and decarboxylation intermediates were detected and identified in the chloraminated samples using Fourier-transform ion cyclotron resonance mass spectrometry. Combined with density functional theory calculations, the results indicated that the indirect oxidation via the attack of the nitrogen atom in sulfonamide groups might be the dominant pathway for generating PFHxS during chloramination, and the process could be highly affected by the monochloramine dose, pH, and temperature. This study provides important evidence of the secondary formation of PFHxS during drinking water disinfection and scientific support for chemical management of PFHxS and PFHxS-related compounds.

Isomer-specific perfluoroalkyl acids accumulation, excretion and maternal transfer to eggs in chickens around a fluorochemical manufactory in China.

The co-existing of multiple Per- and polyfluoroalkyl substances (PFASs) might pose more complicated situation for the exposure risk of environment and biota, especially for the surrounding area of the contaminated communities. In this study, tissues and organs of free-ranged chickens, paired eggs, corresponding feces, water, soil/dust, and feed samples around a fluorochemical manufactory were collected to investigate the tissue-isomer-specific accumulation, elimination and maternal transfer to eggs of PFASs. Free-ranged chickens had much higher ∑PFASs concentrations than farm chickens, and PFBA and PFOS were the predominant PFASs in tissues and organs, which is consistence with the electrochemical fluorination (ECF) production pattern of this manufactory. This result implied that PFASs released from manufactory production is a direct exposure source to the chickens. ∑PFASs concentrations in yolk samples were higher than other tissues and organs, while the concentrations in albumen were lowest. Isomer profiles analysis indicated that n-PFOS proportions in tissues, organs, yolk, and albumen ranged from 85.3 %-98.1 %, whereas in the feces with the percentage of 72.9 %, indicating that the branched PFOS isomers showed faster excretion rate than n-PFOS for chickens. Resident's estimated daily intakes (EDIs) of ∑PFASs via chicken were in the range of 6.41 to 107.18 ng/kg·bw/d. Notably, the EDIs of the sum of four PFASs were higher than the TDI of EFSA in 2020, indicating potential health risks.

Vital Environmental Sources for Multitudinous Fluorinated Chemicals: New Evidence from Industrial Byproducts in Multienvironmental Matrices in a Fluorochemical Manufactory.

Direct emissions from fluorochemical manufactory are an important source of per- and polyfluoroalkyl substances (PFASs) to the environment. In this study, a wide range of PFASs, including 8 legacy PFASs, 8 long-chain perfluoroalkyl carboxylic acids (PFCAs), and 40 emerging PFASs, were investigated through a target screening in multienvironmental matrices from a fluorochemical manufactory in China. Indoor dust was the most polluted matrix, wherein 52 PFASs were detected, and the median concentration of long-chain PFCA was 276 ng/g. A high level of short-chain PFAS in total suspended particles (median concentration = 416 ng/m3) and the effluent in the manufactory (Σ48PFAS = 212 µg/L) will undoubtedly increase the burden on the surrounding environment. Twenty-four industrial byproducts were ascertained to be generated during the electrochemical fluorination (ECF) process, and eight fluorinated alternatives were considered to be produced during product development. Twelve PFASs were quantified for the first time in the working environments. Perfluoropropane sulfonic acid, perfluoro (2-ethoxyethane) sulfonic acid (PFEESA), and 2-perfluorohexyl ethanoic acid are abundant fluorinated alternatives, with median levels of 1187-17204 ng/g in the dust. Significant positive correlations between ECF-related PFAS products and byproducts indicate that the detected values are strongly connected with the industrial source. Hierarchical cluster analysis further manifests their affiliation. Our findings raise the need for further investigations of emerging PFAS (including the first report of PFAS, such as PFEESA, in the environment) which may be released during the production process in the fluorochemical manufactories.

Exploring the origin of efficient adsorption of poly- and perfluoroalkyl substances in household point-of-use water purifiers: Deep insights from a joint experimental and computational study.

Poly- and perfluoroalkyl substances (PFAS) are harmful chemicals to humans and widely detected in water bodies including tap water. PFAS cannot be efficiently removed from water through conventional treatment processes used in full-scale drinking water treatment plants, posing a latent risk to human health via drinking tap water. Here in-field investigations show that the household point-of-use (POU) water purifiers constituted with coconut shell activated carbon can achieve 21%-99% removal for 14 legacy and emerging PFAS in tap water based on the ratio of influent and effluent. Extensive characterizations combine with chemical analyses demonstrate that physical adsorption based on Van der Waals force can remove 23 PFAS from tap water, wherein the hydrophobicity of PFAS is the crucial factor. Density functional theory calculations together with the quantitative structure-activity relationship model confirm that both topological structures as well as hydrophobicity of PFAS and electrostatic interactions between the strong electronegative F atoms and the adsorbent surface are the most critical factors controlling the PFAS adsorption to activated carbon. Overall, our results offer insights into the molecular mechanisms that enable the adsorption of PFAS in POU filters.

Efficient photodegradation of PFOA using spherical BiOBr modified TiO2 via hole-remained oxidation mechanism.

Photo-induced holes (h+) oxidation is an efficient approach for perfluorooctanoic acid (PFOA; C7F15COOH) removal. To maintain a high amount of h+ on the surface of photocatalysts participating in the PFOA photodegradation could be a critical issue. Herein, a highly efficient spherical BiOBr-modified nano-TiO2 (P25) was synthesised and used for PFOA photodegradation through direct oxidation with h+. A high number of h+ could be generated and remain on the surface of P25/BiOBr due to the appropriate position of the conduction band (CB) and valence band (VB) levels between P25 and BiOBr. Meanwhile, PFOA molecules were coordinated to the P25/BiOBr's surface via unidentate binding, being directly activated and oxidised by h+, resulting in a decomposition yield of 99.5% (100 mg/L) under simulated solar light irradiation within 100 min, at the initial pH condition (3.5). A stepwise photodegradation pathway was proposed due to the significant intermediates detected as the short-chain perfluorinated carboxylic acids (C2-C7). Reactive oxygen species (ROS) generation, scavenging and trapping analysis indicated that the direct oxidation on h+ followed PFOA degradation. In a real aqueous environment of Tangxun lake (adjusted pH 3.5), stable common anions and natural organic matter (NOM) would restrain the PFOA photodegradation. However, adding 10 mg/L of NO3- or HA could reduce the inhibition effect of PFOA photodegradation. These findings gave an alternative strategy to drive an h+ directly oxidation to treat PFOA contaminated water bodies.

The effect of anthropogenic activities on the environmental fate of chlorinated paraffins in surface soil in an urbanized zone of northern China.

Chlorinated paraffins (CPs) have been widely used as halogenated flame retardants and plasticizers since the mid-20th century. The prevalence of CPs in soil has been widely reported, but the distribution pattern of CPs in urbanized zones and their association with multiple socioeconomic variables have not been adequately explored. Herein, short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) were investigated in surface soil samples from Tianjin, China, a typical urbanized area. The concentration distributions of SCCPs and MCCPs showed similar trends in different administrative divisions and land use types: urban areas > suburbs > outer suburbs (p < 0.001) and residential areas > greenbelts > agricultural areas (p < 0.001). The CP congeners in residential surface soils mainly included those with longer carbon chains and high degree of chlorination, while the CP congeners in agricultural surface soils mainly consisted of those with shorter carbon chains and fewer chlorine substituents. Multiple statistical approaches were used to explore the association between socioeconomic factors and CP distribution. CP concentration was significantly correlated to population density and gross domestic product (GDP) (p < 0.001), and structural equation models incorporating administrative regional planning showed an indirect impact on the distribution of MCCP concentration due to the influence of regional planning on population density. These results highlight the association between CP contamination and the degree of urbanization, and this paper provides useful information toward mitigating the exposure risk of CPs for urban inhabitants.

Occurrence and Distribution of Disinfection Byproducts in Domestic Wastewater Effluent, Tap Water, and Surface Water during the SARS-CoV-2 Pandemic in China.

Intensified efforts to curb transmission of the Severe Acute Respiratory Syndrome Coronavirus-2 might lead to an elevated concentration of disinfectants in domestic wastewater and drinking water in China, possibly resulting in the generation of numerous toxic disinfection byproducts (DBPs). In this study, the occurrence and distribution of five categories of DBPs, including six trihalomethanes (THMs), nine haloacetic acids (HAAs), two haloketones, nine nitrosamines, and nine aromatic halogenated DBPs, in domestic wastewater effluent, tap water, and surface water were investigated. The results showed that the total concentration level of measured DBPs in wastewater effluents (78.3 µg/L) was higher than that in tap water (56.0 µg/L, p = 0.05), followed by surface water (8.0 µg/L, p < 0.01). Moreover, HAAs and THMs were the two most dominant categories of DBPs in wastewater effluents, tap water, and surface water, accounting for >90%, respectively. Out of the regulated DBPs, none of the wastewater effluents and tap water samples exceeded the corresponding maximum guideline values of chloroform (300 µg/L), THM4 (80 µg/L), NDMA (100 ng/L), and only 2 of 35 tap water samples (67.6 and 63.3 µg/L) exceeded the HAA5 (60 µg/L) safe limit. HAAs in wastewater effluents showed higher values of risk quotient for green algae. This study illustrates that the elevated use of disinfectants within the guidance ranges during water disinfection did not result in a significant increase in the concentration of DBPs.

PM2.5-bound potentially toxic elements (PTEs) fractions, bioavailability and health risks before and after coal limiting.

Fractions, bioavailability, health risks of fine particulate maters (PM2.5)-bound potentially toxic elements (PTEs) (Pb, Cd, Cr, Cu and Zn) were investigated before and after coal limiting in Baoding city. The winter PM2.5 samples were collected at different functional areas such as residential area (RA), industrial area (IA), suburb (SB), street (ST) and Botanical Garden Park (BG) in 2016 (coal dominated year) and 2017 (gas dominated year). The fractions and bioavailability of PTEs were determined and evaluated based on BCR sequential extraction. Health risks through inhalation exposure were evaluated by US EPA health risk assessment model. The results from different years and functional areas were compared and discussed. The fractions and bioavailability of PM2.5-bound PTEs varied with functional areas. The percentages of cadmium (Cd) and zinc (Zn) in acid-soluble fraction (F1-Cd and F1-Zn) to the total amount of Cd and Zn were low in BG samples (p < 0.05). Bioavailability of Cd were high in SB samples (p < 0.05). Total contents of PM-bound PTEs in 2017 generally decreased compared with 2016. The differences of fraction and bioavailability between 2016 and 2017 depended on the elements and areas. Higher proportions of copper (Cu) in acid-soluble fraction (F1-Cu) and bioavailability of Cu (p < 0.05) were found in 2017 samples. Significant differences were found just at IA and RA for Pb, Cd and Zn. Our results indicated that the health risks from inhalation exposure for PTEs in PM2.5 declined about 11%-52% after the coal limiting in this city.

Elemental mercury removal from flue gas by CoFe2O4 catalyzed peroxymonosulfate.

A magnetic cobalt ferrite (CoFe2O4) catalyst was prepared by sol-gel method, and characterized by a X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Brunauer-Emmett-Teller (BET) and hysteresis loop method. The chemical states on surface of the fresh and spent catalysts were analyzed by a X-ray photoelectron spectroscopy (XPS). The experiments of elemental mercury (Hg0) removal from flue gas were conducted in a laboratory scale using activated peroxymonosulfate (PMS) catalyzed by CoFe2O4, and the effects of the dosage of catalyst, the concentration of PMS, initial solution pH and reaction temperature on mercury removal efficiency were investigated. The average removal efficiency of Hg0 could maintain steady at 85% in 45min when the concentrations of CoFe2O4 and PMS were 0.288g/L and 3.5mmol/l respectively, solution pH was 7 and reaction temperature was 55°C. In order to speculate the reaction mechanism, ethyl alcohol and isopropyl alcohol were used as the quenching agents to indirectly prove the existence of SO4- and OH.