Heterogeneous Photodegradation Behavior of Liquid Crystal Monomers in Dust: Quantitative Structure-Activity Relationship and Product Identification.

The heterogeneous photodegradation behavior of liquid crystal monomers (LCMs) in standard dust (standard reference material, SRM 2583) and environmental dust was investigated. The measured photodegradation ratios for 23 LCMs in SRM and environmental dust in 12 h were 11.1 ± 1.8 to 23.2 ± 1.1% and 8.7 ± 0.5 to 24.0 ± 2.8%, respectively. The degradation behavior of different LCM compounds varied depending on their structural properties. A quantitative structure-activity relationship model for predicting the degradation ratio of LCMs in SRM dust was established, which revealed that the molecular descriptors related to molecular polarizability, electronegativity, and molecular mass were closely associated with LCMs' photodegradation. The photodegradation products of the LCM compound 4'-propoxy-4-biphenylcarbonitrile (PBIPHCN) in dust, including •OH oxidation, C-O bond cleavage, and ring-opening products, were identified by nontarget analysis, and the corresponding degradation pathways were suggested. Some of the identified products, such as 4'-hydroxyethoxy-4-biphenylcarbonitrile, showed predicted toxicity (with an oral rat lethal dose of 50%) comparable to that of PBIPHCN. The half-lives of the studied LCMs in SRM dust were estimated at 32.2-82.5 h by fitting an exponential decay curve to the observed photodegradation data. The photodegradation mechanisms of LCMs in dust were revealed for the first time, enhancing the understanding of LCMs' environmental behavior and risks.

Contamination Status of Novel Organophosphate Esters Derived from Organophosphite Antioxidants in Soil and the Effects on Soil Bacterial Communities.

The contamination status of novel organophosphate esters (NOPEs) and their precursors organophosphite antioxidants (OPAs) and hydroxylated/diester transformation products (OH-OPEs/di-OPEs) in soils across a large-scale area in China were investigated. The total concentrations of the three test NOPEs in soil were 82.4-716 ng g-1, which were considerably higher than those of traditional OPEs (4.50-430 ng g-1), OPAs (n.d.-30.8 ng g-1), OH-OPEs (n.d.-0.49 ng g-1), and di-OPEs (0.57-21.1 ng g-1). One NOPE compound, i.e., tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) contributed over 65% of the concentrations of the studied OPE-associated contaminants. A 30-day soil incubation experiment was performed to confirm the influence of AO168 = O on soil bacterial communities. Specific genera belonging to Proteobacteria, such as Lysobacter and Ensifer, were enriched in AO168 = O-contaminated soils. Moreover, the ecological function of methylotrophy was observed to be significantly enhanced (t-test, p < 0.01) in soil treated with AO168 = O, while nitrogen fixation was significantly inhibited (t-test, p < 0.01). These findings comprehensively revealed the contamination status of OPE-associated contaminants in the soil environment and provided the first evidence of the effects of NOPEs on soil microbial communities.

Algal Extracellular Organic Matter Induced Photochemical Oxidation of Mn(II) to Solid Mn Oxide: Role of Mn(III)-EOM Complex and Its Ability to Remove 17α-Ethinylestradiol.

Photosensitizer-mediated abiotic oxidation of Mn(II) can yield soluble reactive Mn(III) and solid Mn oxides. In eutrophic water systems, the ubiquitous algal extracellular organic matter (EOM) is a potential photosensitizer and may have a substantial impact on the oxidation of Mn(II). Herein, we focused on investigating the photochemical oxidation process from Mn(II) to solid Mn oxide driven by EOM. The results of irradiation experiments demonstrated that the generation of Mn(III) intermediate was crucial for the successful photo oxidization of Mn(II) to solid Mn oxide mediated by EOM. EOM can serve as both a photosensitizer and a ligand, facilitating the formation of the Mn(III)-EOM complex. The complex exhibited excellent efficiency in removing 17α-ethinylestradiol. Furthermore, the complex underwent decomposition as a result of reactions with reactive intermediates, forming a solid Mn oxide. The presence of nitrate can enhance the photochemical oxidation process, facilitating the conversion of Mn(II) to Mn(III) and then to solid Mn oxide. This study deepens our grasp of Mn(II) geochemical processes in eutrophic water and its impact on organic micropollutant fate.

Stability and Biotransformation of 6:2 Fluorotelomer Sulfonic Acid, Sulfonamide Amine Oxide, and Sulfonamide Alkylbetaine in Aerobic Sludge.

The 6:2 fluorotelomer sulfonamide (6:2 FTSAm)-based compounds signify a prominent group of per- and polyfluoroalkyl substances (PFAS) widely used in contemporary aqueous film-forming foam (AFFF) formulations. Despite their widespread presence, the biotransformation behavior of these compounds in wastewater treatment plants remains uncertain. This study investigated the biotransformation of 6:2 FTSAm-based amine oxide (6:2 FTNO), alkylbetaine (6:2 FTAB), and 6:2 fluorotelomer sulfonic acid (6:2 FTSA) in aerobic sludge over a 100-day incubation period. The biotransformation of 6:2 fluorotelomer sulfonamide alkylamine (6:2 FTAA), a primary intermediate product of 6:2 FTNO, was indirectly assessed. Their stability was ranked based on the estimated half-lives (t1/2): 6:2 FTAB (no obvious products were detected) ≫ 6:2 FTSA (t1/2 ≈28.8 days) > 6:2 FTAA (t1/2 ≈11.5 days) > 6:2 FTNO (t1/2 ≈1.2 days). Seven transformation products of 6:2 FTSA and 15 products of 6:2 FTNO were identified through nontarget and suspect screening using high-resolution mass spectrometry. The transformation pathways of 6:2 FTNO and 6:2 FTSA in aerobic sludge were proposed. Interestingly, 6:2 FTSAm was hardly hydrolyzed to 6:2 FTSA and further biotransformed to perfluoroalkyl carboxylic acids (PFCAs). Furthermore, the novel pathways for the generation of perfluoroheptanoic acid (PFHpA) from 6:2 FTSA were revealed.

Urinary Metabolites of Polycyclic Aromatic Hydrocarbons of Rural Population in Northwestern China: Oxidative Stress and Health Risk Assessment.

Polycyclic aromatic hydrocarbon (PAH) exposure is suspected to be linked to oxidative damage. Herein, ten PAH human exposure biomarkers [hydroxylated PAH metabolites (OH-PAHs)] and five oxidative stress biomarkers (OSBs) were detected in urine samples collected from participants living in a rural area (n = 181) in Northwestern China. The median molar concentration of ΣOH-PAHs in urine was 47.0 pmol mL-1. The 2-hydroxynaphthalene (2-OHNap; median: 2.21 ng mL-1) was the dominant OH-PAH. The risk assessment of PAH exposure found that hazard index (HI) values were <1, indicating that the PAH exposure of rural people in Jingyuan would not generate significant cumulative risks. Smokers (median: 0.033) obtained higher HI values than nonsmokers (median: 0.015, p < 0.01), suggesting that smokers face a higher health risk from PAH exposure than nonsmokers. Pearson correlation and multivariate linear regression analysis revealed that ΣOH-PAH concentrations were significant factors in increasing the oxidative damage to deoxyribonucleic acid (DNA) (8-hydroxy-2'-deoxyguanosine, 8-OHdG), ribonucleic acid (RNA) (8-oxo-7,8-dihydroguanine, 8-oxoGua), and protein (o, o'-dityrosine, diY) (p < 0.05). Among all PAH metabolites, only 1-hydroxypyrene (1-OHPyr) could positively affect the expression of all five OSBs (p < 0.05), suggesting that urinary 1-OHPyr might be a reliable biomarker for PAH exposure and a useful indicator for assessing the impacts of PAH exposure on oxidative stress. This study is focused on the relation between PAH exposure and oxidative damage and lays a foundation for the study of the health effect mechanism of PAHs.

Novel Defluorination Pathways of Perfluoroether Compounds (GenX): α-Fe2O3 Nanoparticle Layer Retains Higher Concentrations of Effective Hydrated Electrons.

The development of efficient defluorination technology is an important issue because the kind of emerging pollutant of hexafluoropropylene oxide dimer acid (GenX) as an alternative to perfluorooctanoic acid (PFOA) has the higher environmental risks. In the UV/bisulfite system, we first developed a hydrophobic confined α-Fe2O3 nanoparticle layer rich in oxygen vacancies, which accelerated the enrichment of HSO3- and GenX on the surface and pores through electrostatic attraction and hydrophobic interaction, retaining more hydrated electrons (eaq-) and rapidly destroying GenX under UV excitation. Especially, under anaerobic and aerobic conditions, the degradation percentage of GenX obtain nearly 100%, defluorination of GenX to 88 and 57% respectively. It was amazed to find that the three parallel H/F exchange pathways triggered by the rapid reactions of eaq- and GenX, which were unique to anaerobic conditions, improved the efficiency of fluoride removal and weaken the interference of dissolved oxygen and H+. Therefore, this study provided an available material and mechanism for sustainable fluoride removal from wastewater in aerobic and anaerobic conditions.

Nontarget Identification of Novel Organophosphorus Flame Retardants and Plasticizers in Indoor Air and Dust from Multiple Microenvironments in China.

The indoor environment is a typical source for organophosphorus flame retardants and plasticizers (OPFRs), yet the source characteristics of OPFRs in different microenvironments remain less clear. This study collected 109 indoor air samples and 34 paired indoor dust samples from 4 typical microenvironments within a university in Tianjin, China, including the dormitory, office, library, and information center. 29 target OPFRs were analyzed, and novel organophosphorus compounds (NOPs) were identified by fragment-based nontarget analysis. Target OPFRs exhibited the highest air and dust concentrations of 46.2-234 ng/m3 and 20.4-76.0 µg/g, respectively, in the information center, where chlorinated OPFRs were dominant. Triphenyl phosphate (TPHP) was the primary OPFR in office air, while tris(2-chloroethyl) phosphate dominated in the dust. TPHP was predominant in the library. Triethyl phosphate (TEP) was ubiquitous in the dormitory, and tris(2-butoxyethyl) phosphate was particularly high in the dust. 9 of 25 NOPs were identified for the first time, mainly from the information center and office, such as bis(chloropropyl) 2,3-dichloropropyl phosphate. Diphenyl phosphinic acid, two hydroxylated and methylated metabolites of tris(2,4-ditert-butylphenyl) phosphite (AO168), and a dimer phosphate were newly reported in the indoor environment. NOPs were widely associated with target OPFRs, and their human exposure risk and environmental behaviors warrant further study.

Activation of persulfate for the degradation of ethyl-parathion in soil: Combined effects of microwave with biochar.

Sulfate radical (SO4•-), formed by persulfate (PS) activation during advanced oxidation process (AOPs), can be used for the remediation of organic contaminated soil. However, the role of biochar and microwave (MW) in the activation of PS is not fully understood, especially the corresponding mechanism. Herein, biochar combined with MW was used to activate PS for the remediation of ethyl-parathion (PTH)-polluted soil. The dynamic evolutions of PTH under different conditions, such as biochar content, particle size, reaction temperature, and the degradation mechanisms of PTH were also systematically investigated. Significant enhancement performance on PTH removal was observed after adding biochar, which was 88.78% within 80 min. Meanwhile, activating temperature exhibited remarkable abilities to activate PS for PTH removal. The higher content of adsorption sites in nano-biochar facilitated the removal of PTH. Furthermore, chemical probe tests coupled with quenching experiments confirmed that the decomposition of PS into active species, such as SO4•-, •OH, O2•- and 1O2, contributed to the removal of PTH in biochar combined with MW system, which could oxidize PTH into oxidative products, including paraoxon, 4-ethylphenol, and hydroquinone. The results of this study provide valuable insights into the synergistic effects of biochar and MW in the PS activation, which is helpful for the potential application of biochar materials combined with MW-activated PS in the remediation of pesticide-polluted soils.

Daily Exposure to Environmental Volatile Organic Compounds Triggers Oxidative Damage: Evidence from a Large-Scale Survey in China.

Volatile organic compounds (VOCs) are ubiquitous environmental pollutants and have been implicated in adverse health outcomes. In this study, concentrations of 11 VOC metabolites (mVOCs) and three oxidative stress biomarkers (8-oxo-7,8-dihydro-2'-deoxyguanosine, 8-oxo-7,8-dihydro-guanosine, and dityrosine) were determined in 205 urine samples collected from 12 cities across mainland China. Urinary ∑11mVOC concentrations ranged from 498 to 1660 ng/mL, with a geometric mean (GM) value of 1070 ng/mL. The factorial analysis revealed that cooking, solvents, and vehicle emissions were the three primary sources of VOC exposure. A significant regional variation was clearly found in ∑11mVOC concentrations across four regions in China, with high urine VOC concentrations found in North and South China (GM: 1450 and 1340 ng/mL). The multiple linear regression model revealed that most mVOCs were significantly positively correlated with three oxidative stress markers (ß range: 0.06-0.22). Mixture effect regression showed that isoprene, crotonaldehyde, acrolein, and benzene were the strongest contributors to oxidative stress. Approximately 80% of the participants have HQ values greater than 1.0 for 1,3-butadiene and benzene, suggesting that their exposure doses were close to potential adverse health effects. Our findings provide comprehensive information on human exposure and potential health risks of VOCs in China.

Nontarget Identification of Novel Per- and Polyfluoroalkyl Substances (PFAS) in Soils from an Oil Refinery in Southwestern China: A Combined Approach with TOP Assay.

Oil refinery activity can be an emission source of perfluoroalkyl and polyfluoroalkyl substances (PFAS) to the environment, while the contamination profiles in soils remain unknown. This study investigated 44 target PFAS in soil samples collected from an oil refinery in Southeastern China, identified novel PFAS, and characterized their behaviors by assessing their changes before and after employing advanced oxidation using a combination of nontarget analysis and a total oxidizable precursor (TOP) assay. Thirty-four target PFAS were detected in soil samples. Trifluoroacetic acid (TFA) and hexafluoropropylene oxide dimer acid (HFPO-DA) were the dominant PFAS. Twenty-three novel PFAS of 14 classes were identified, including 8 precursors, 11 products, and 4 stable PFAS characterized by the TOP assay. Particularly, three per-/polyfluorinated alcohols were identified for the first time, and hexafluoroisopropanol (HFIP) quantified up to 657 ng/g dw is a novel precursor for TFA. Bistriflimide (NTf2) potentially associated with an oil refinery was also reported for the first time in the soil samples. This study highlighted the advantage of embedding the TOP assay in nontarget analysis to reveal not only the presence of unknown PFAS but also their roles in environmental processes. Overall, this approach provides an efficient way to uncover contamination profiles of PFAS especially in source-impacted areas.

Organophosphite Antioxidants and Novel Organophosphate Esters in Dust from China: Large-Scale Distribution and Heterogeneous Phototransformation.

A large-scale survey was conducted by measuring five organophosphite antioxidants (OPAs) and three novel organophosphate esters (NOPEs) in 139 dust samples across China. The median summed concentrations of OPAs and NOPEs in outdoor dust were 33.8 ng/g (range: 0.12-53,400 ng/g) and 7990 ng/g (2390-27,600 ng/g), respectively. The dust concentrations of OPAs associated with the increasing economic development and population density from western to eastern China, whereas the NOPE concentration in Northeast China (median, 11,900 ng/g; range, 4360-16,400 ng/g) was the highest. Geographically, the distribution of NOPEs was significantly associated with annual sunshine duration and precipitation at each sampling site. Results of laboratory experiments further revealed that the simulated sunlight irradiation promoted the heterogeneous phototransformation of OPAs in dust, and this process was accelerated with the existence of reactive oxygen species and enhanced relative humidity. Importantly, during this phototransformation, the hydroxylated, hydrolyzed, dealkylated, and methylated products, e.g., bis(2,4-di-tert-butylphenyl) methyl phosphate, were identified by nontargeted analysis, part of which were estimated to be more toxic than their parent compounds. The heterogeneous phototransformation pathway of OPAs was suggested accordingly. For the first time, the large-scale distribution of OPAs and NOPEs and the phototransformation of these "new chemicals" in dust were revealed.

Percutaneous Penetration of Liquid Crystal Monomers (LCMs) by In Vitro Three-Dimensional Human Skin Equivalents: Possible Mechanisms and Implications for Human Dermal Exposure Risks.

Liquid crystal monomers (LCMs) are indispensable materials in liquid crystal displays, which have been recognized as emerging persistent, bioaccumulative, and toxic organic pollutants. Occupational and nonoccupational exposure risk assessment suggested that dermal exposure is the primary exposure route for LCMs. However, the bioavailability and possible mechanisms of dermal exposure to LCMs via skin absorption and penetration remain unclear. Herein, we used EpiKutis 3D-Human Skin Equivalents (3D-HSE) to quantitatively assess the percutaneous penetration of nine LCMs, which were detected in e-waste dismantling workers' hand wipes with high detection frequencies. LCMs with higher log Kow and greater molecular weight (MW) were more difficult to penetrate through the skin. Molecular docking results showed that ABCG2 (an efflux transporter) may be responsible for percutaneous penetration of LCMs. These results suggest that passive diffusion and active efflux transport may be involved in the penetration of LCMs across the skin barrier. Furthermore, the occupational dermal exposure risks evaluated based on the dermal absorption factor suggested the underestimation of the continuous LCMs' health risks via dermal previously.

Nontarget Identification of Novel Organophosphorus Flame Retardants and Plasticizers in Rainfall Runoffs and Agricultural Soils around a Plastic Recycling Industrial Park.

Plastic recycling and reprocessing activities may release organophosphate ester (OPE) flame retardants and plasticizers into the surrounding environment. However, the relevant contamination profiles and impacts remain not well studied. This study investigated the occurrence of 28 OPEs and their metabolites (mOPEs) in rainfall runoffs and agricultural soils around one of the largest plastic recycling industrial parks in North China and identified novel organophosphorus compounds (NOPs) using high-resolution mass spectrometry-based nontarget analysis. Twenty and twenty-seven OPEs were detected in runoff water and soil samples, with total concentrations of 86.0-2491 ng/L and 2.53-199 ng/g dw, respectively. Thirteen NOPs were identified, of which eight were reported in the environment for the first time, including a chlorine-containing OPE, an organophosphorus heterocycle, a phosphite, three novel OPE metabolites, and two oligomers. Triphenylphosphine oxide and diphenylphosphinic acid occurred ubiquitously in runoffs and soils, with concentrations up to 390 ng/L and 40.2 ng/g dw, respectively. The downwind areas of the industrial park showed elevated levels of OPEs and NOPs. The contribution of hydroxylated mOPEs was higher in soils than in runoffs. These findings suggest that plastic recycling and reprocessing activities are significant sources of OPEs and NOPs and that biotransformation may further increase the ecological and human exposure risk.

Infantile Internal and External Exposure to Neonicotinoid Insecticides: A Comparison of Levels across Various Sources.

Little is known about exposure of infants to neonicotinoid insecticides (NEOs). In this study, concentrations of six parent NEOs (p-NEOs) and N-desmethyl-acetamiprid (N-dm-ACE) were measured in urine and whole blood samples from infants, in addition to breast milk, infant formula, and tap water collected in South China. The p-NEO with the highest median concentration in urine (0.25 ng/mL) and blood (1.30) samples was dinotefuran (DIN), while imidacloprid (IMI) was abundant in breast milk (median: 0.27 ng/mL), infant formula (0.22), and tap water (0.028). The older infants (181-360 days) might face higher NEO and N-dm-ACE exposure than younger infants (0-180 days). Blood samples contained a significantly (p < 0.01) higher median concentration of ∑6p-NEOs (2.03 ng/mL) than that of urine samples (0.41), similar to acetamiprid (ACE), IMI, thiacloprid (THD), DIN, and N-dm-ACE, suggesting that NEOs readily partition into blood. Furthermore, breast-fed infants tend to have higher exposure levels than formula-fed infants. Infant formula prepared with tap water augmented the daily intake of ∑NEOs. The external sources contributed 80% of the total dose to IMI and clothianidin (CLO) exposure, while other unknown sources contributed to ACE, THD, and DIN exposure in infants. To the best of our knowledge, this is the first study to assess levels and sources of infantile exposure to NEOs through internal and external exposure assessment.

Nontarget Screening and Fate of Emerging Per- and Polyfluoroalkyl Substances in Wastewater Treatment Plants in Tianjin, China.

Wastewater treatment plants (WWTPs) are typical point sources of per- and polyfluoroalkyl substances (PFAS) released into the environment. The suspect and nontarget screening based on gas chromatography or liquid chromatography-high resolution mass spectrometry were performed on atmosphere, wastewater, and sludge samples collected from two WWTPs in Tianjin to discover emerging PFAS and their fate in this study. A total of 40 PFAS (14 neutral and 26 ionic) and 64 PFAS were identified in the atmosphere and wastewater/sludge, respectively, among which 5 short-chain perfluoroalkyl sulfonamide derivatives, 4 ionic PFAS, and 15 aqueous film-forming foam-related cationic or zwitterionic PFAS have rarely or never been reported in WWTPs in China. Active air sampling is more conducive to the enrichment of emerging PFAS, while passive sampling is inclined to leave out some ultrashort-chain PFAS or unstable transformation intermediates. Moreover, most precursors and intermediates could be enriched in the atmosphere at night, while the PFAS associated with aerosols with high water content or particles enter the atmosphere easily during the day. Although most emerging PFAS could not be eliminated efficiently in conventional treatment units, deep bed filtration and advanced oxidation processes could partly remove some emerging precursors.

Degradation of Perfluorooctanoic Acid by Chlorine Radical Triggered Electrochemical Oxidation System.

Electrochemical oxidation (EO) has been shown to have the unique ability to degrade perfluorooctanoic acid (PFOA), although the radical chemistry involved in this degradation is unclear, particularly in the presence of chloride ions (Cl-). In this study, reaction kinetics, free radical quenching, electron spin resonance, and radical probes were used to examine the roles of ·OH and reactive chlorine species (RCS, including Cl·, Cl2•-, and ClO·) in the EO of PFOA. Using EO in the presence of NaCl, PFOA degradation rates of 89.4%-94.9% and defluorination rates of 38.7%-44.1% were achieved after 480 min with PFOA concentrations ranging from 2.4 to 240 µM. The degradation occurred via the synergistic effect of ·OH and Cl· rather than through direct anodic oxidation. The degradation products and density functional theory (DFT) calculations revealed that Cl· triggered the first step of the reaction, thus the initial direct electron transfer was not the rate-limiting step of PFOA degradation. The change in Gibbs free energy of the reaction caused by Cl· was 65.57 kJ mol-1, which was more than two times lower than that triggered by ·OH. However, ·OH was involved in the subsequent degradation of PFOA. The synergistic effect of Cl· and ·OH in PFOA degradation is demonstrated for the first time in this study, which is promising for the development of electrochemical technology to remove perfluorinated alkyl substances from the environment.

Microplastics affect soybean rhizosphere microbial composition and function during vegetative and reproductive stages.

Microplastics (MPs) are emerging contaminants in agricultural soil, whereas their effects on the rhizosphere microbial ecosystems and biogeochemical nitrogen cycles during plant growth remain unknown. Here, a 70-day greenhouse experiment was carried out with black and fluvo-aquic soil to evaluate the influence of polyamide (PA), polyethylene (PE), polyester (PES), and polyvinyl chloride (PVC) MPs on the bacterial communities and functions in the soybean rhizosphere. The PA treatment consistently affected the rhizobacterial alpha diversity in the fluvo-aquic soil at soybean vegetative and reproductive growth stages, whereas the PE, PES, and PVC treatments had a short-term effect on the bacterial alpha diversity. At two growth stages, 6 and 23 biomarkers were consistently abundant in the PA treatment in the black soil and fluvo-aquic soil, respectively, and order Rhizobiales was found to be a biomarker for PA MPs contamination in both soils. Additionally, PA treatment decreased bacterial network complexity and tightness, whereas the effects of the PE, PES, and PVC on bacterial co-occurrence patterns varied depending on the soil types. Furthermore, PES and PVC treatments inhibited ammonification processes in the soybean rhizosphere, and PE could temporarily inhibit ammonia oxidation and denitrification processes according to the variations of N-cycling gene abundances. These effects on soil N-cycling also varied with soil types and soybean growth stages. This study provides profound information for understanding of MPs residues on the assembly of the soybean rhizosphere communities and function during plant development.

Comparative stress response assessment of PFOS and its alternatives, F-53B and OBS, in wheat: An insight of toxic mechanisms and relative magnitudes.

Emerging alternatives to perfluorooctane sulfonate (PFOS), including 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) and p-perfluorous nonenoxybenzene sulfonate (OBS), have been widely detected in the real environment as PFOS restriction. However, the toxicity in plants and the underlying mechanism of F-53B and OBS remain scarce, especially compared to PFOS. PFOS and their emerging alternatives pose significant potential risks to food, especially for crops, safety and human health with the great convenience of high chemical stability. Germination toxicity, oxidative stress biomarkers, and metabolomics were used to compare the relative magnitudes of toxicity of PFOS and its alternatives in wheat (Triticum aestivum L.). PFOS, F-53B, and OBS inhibited wheat germination compared to the control group, with germination inhibition rates of 45.6%, 53.5%, and 64.3% at 400 µM PFOS, F-53B, and OBS exposure, respectively. Moreover, oxidative stress biomarker changes were observed in PFOS, F-53B, and OBS, with OBS being more pronounced. The chlorophyll concentrations in wheat shoots increased, and the anthocyanin concentration decreased along with the increased exposure concentration. Superoxide dismutase (SOD) activity increased in wheat root but decreased in the shoot. Peroxidase (POD) activity and malondialdehyde (MDA) concentration increased, whereas catalase (CAT) activity decreased. Regarding metabolomics, PFOS, F-53B, and OBS exposure (10 µM) significantly altered 85, 133, and 134 metabolites, respectively. According to KEGG enrichment analysis, F-53B specifically affects lipid metabolism, whereas OBS causes an imbalance in amino acid and carbohydrate metabolism. These findings suggested that PFOS, F-53B, and OBS have distinct toxic mechanisms. Thus, our results indicated that the relative size of the toxicity in wheat is as follows: OBS > F-53B > PFOS, and this finding provides a new reference basis for the phytotoxicity assessment of F-53B and OBS.

In situ self-sacrificial synthesis of polypyrrole/biochar composites for efficiently removing short- and long-chain perfluoroalkyl acid from contaminated water.

Efficient removal of perfluoroalkyl acids (PFAAs), especially short-chain ones, from contaminated water is of great challenge and is urgently called for so as to safeguard the ecosystem and human health. Herein, polypyrrole (PPy) functionalized biochar (BC) composites were innovatively synthesized by an in situ self-sacrificial approach to allow efficient capture of PFAAs with different chain lengths. Compared with conventional PPy-based composites synthesized by direct polymerization using FeCl3 as an oxidizing agent, PPy/BC composites were fabricated utilizing freshly generated Fe3+ as an oxidizing agent from self-sacrificial Fe3O4 for pyrrole monomers in situ polymerizing on BC. As a result, with the support of BC and gradual release of Fe3+, PPy overcame its tendency to aggregate and became uniformly dispersed on BC, and meanwhile, PPy could well tailor the surface chemistry of BC to endow its positively charged surface. Consequently, the composites exhibited strong sorption capacities of 3.89 and 1.53 mmol/g for short-chain perfluorobutanoic acid (PFBA) and perfluorobutane sulfonic acid (PFBS), 2.55 and 1.22 mmol/g for long-chain perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), respectively, which were superior to those of pristine BC, commercial activated carbon, and anion exchange resins reported. Additionally, they could effectively remove 17 different classes of per- and polyfluoroalkyl substances (PFAS) (removal >95%) from actual PFAS-contaminated water, and the spent sorbent could be well regenerated and reused at least 5 times. An integrated analysis indicated that such an outstanding PFAA sorption performance on PPy/BC composites could be mainly attributed to surface adsorption enhanced by electrostatic attractions (anion exchange interaction) with the traditional hydrophobic interaction and pore filling of less contribution, particularly for short-chain analogues. These results are expected to inform the design of BC with greater ability to remove PFAS from water and the new sorbent could help water facilities comply with PFAS regulations.

Spatial distribution and risk assessment of polycyclic aromatic hydrocarbons in soils from contaminated sites in Eastern China.

A total of 16 polycyclic aromatic hydrocarbons (PAHs) were measured in 28 soil column samples from two contaminated industrial sites in Eastern China. The total concentration of 16 PAHs (∑PAHs) in the surface soil (0-20 cm) was measured up to 52,600 ng/g (dry weight basis) with a remarkable spatial difference in the studied contaminated sites. The concentrations of the ∑PAHs in soils decreased with the increase in soil depth (0-10 m). The surface and subsurface soil presented a tenfold higher concentration than the soil with depth greater than 4 m. Additionally, the vertical migration tendency of the PAHs was found to be correlated significantly with their hydrophobicity (R2 = 0.79, P < 0.01). Naphthalene (with lowest octanol-water partition coefficient among the studied PAHs) showed the greatest average soil depth at which its peak concentration occurred. Furthermore, risk quotient analysis by using benzo[a]pyrene as reference compound showed that 71.4% of the samples exhibited high ecological risk for soil. Moreover, the total carcinogenic risk of the PAHs in the surface soil samples was assessed at 5.61 × 10-5-1.28 × 10-4 and 4.41 × 10-6-9.43 × 10-5 for male and female workers, respectively, in which 67.9%-71.4% of the samples showed potential risk. Generally, these results suggest a further consideration of ecological and health risks associated with PAHs in contaminated sites in Eastern China.