Environmental Science & Technology Letters Environ.最新文献

Fenton oxidation is widely used to degrade refractory organic compounds such as phenols. However, there is a dispute whether the hydrogen peroxide-induced regeneration of Fe(II) is the rate-limiting step in this process. This study systematically investigates the structure–activity relationship between organic substances and iron species in a Fenton-like system, with a focus on the degradation mechanism of phenolic pollutants. By integration of electrochemical characterization and quantum chemical calculation, three kinetic degradation modes are proposed, which are closely related to the molecular redox properties and coordination capability. The three phenolic–Fe(III) interaction modes include: (i) strong reductive electron transfer (zero-order kinetics), (ii) strong coordination forming ligand-stabilized Fe(III) complexes (autocatalysis), and (iii) synergistic electron transfer-coordination (mixed kinetics). Density functional theory calculations demonstrate that the intramolecular electron transfer pathway within the organo–Fe(III)–hydroperoxide complex exhibits a significantly lower activation energy (0.77 eV less) than traditional radical-mediated pathways, rationalizing the dominance of direct electron transfer over hydroxyl radical generation. This finding provides a unified theoretical framework that resolves long-standing ambiguity in the Fenton-like mechanism and offers new substrate-specific wastewater treatment design guidance.

Our understanding of transmission of influenza virus and other respiratory viruses is limited by the difficulty of detecting infectious viruses in aerosol particles. Most aerosol sampling methods are believed to contribute to virus inactivation, but the magnitude of this sampling artifact is unknown. To investigate this question, we aerosolized influenza A virus (IAV) and SARS-CoV-2 suspended in human saliva into a small chamber (3.7 L). Aerosols settled for 10 min onto either cells or a thin layer of liquid medium that was immediately transferred to cells for plaque assay. Aerosols that deposited directly onto cells led to the formation of 100× more plaque forming units (PFU) compared to aerosols that deposited first into liquid medium. Further experiments ruled out uneven aerosol distribution in the chamber or inefficient virus recovery as causes of this discrepancy. These findings indicate that aerosolized IAV and SARS-CoV-2 lost infectivity by approximately 2 log₁₀ PFU within ∼10 min unless they attached to cells quickly. As natural infection via inhalation occurs by direct deposition of the virus onto cells, we hypothesize that sampling directly onto cells more accurately reflects the potential for exposure to lead to infection.

Research on ultrashort-chain per- and polyfluoroalkyl substances (PFASs) in foods is quite scarce. This study comprehensively investigates the occurrence and dietary exposure of ultrashort-chain PFASs through a China Total Diet Study. Trifluoroacetic acid (TFA), perfluoropropanoic acid (PFPrA), and trifluoromethanesulfonic acid (TFMS) were detected in foods, exhibiting distinct differences in their dietary and regional distributions, particularly in plant-origin foods. Among them, TFA was the most prevalent and contributed the most in all food samples, with concentrations ranging from 1.45 to 39.0 ng/g (wet weight). These levels were 2-fold to 3-orders of magnitude higher than those of PFPrA and TFMS and other chain-length PFASs previously found in the same samples. Data on dietary exposure assessment indicated that the estimated dietary intake (EDI) of TFA ranged from 172.7 to 660.3 ng/kg body weight/day, accounting for an average of 96.9% of the total exposure to ∑17 PFASs for the general population. Furthermore, a preliminary assessment suggests that diet played a more significant role than drinking water in human exposure to ultrashort-chain PFASs, with plant-origin foods contributing over 90% of the total dietary exposure. These findings underscore the necessity for monitoring ultrashort-chain PFASs to assess their potential health risks from dietary exposure.

Geologic hydrogen production and underground storage are increasingly important for meeting rising energy demands while providing clean-combustion advantages. However, hydrogen’s high diffusivity and propensity for leakage through porous media necessitate direct evaluation of its transport behavior in subsurface materials. Whereas X-ray microcomputed tomography (μCT) studies often employ contrast agents or surrogate gases, this study leverages neutron transmission radiography/CT to observe hydrogen migration in situ. This work represents the first demonstration of real-time neutron radiography of hydrogen migration in reservoir and caprock lithologies. Cylindrical cores of Indiana limestone, Amherst Gray sandstone, and Tumey shale were subjected to constant-pressure hydrogen charging and scanned in real time using high-resolution neutron radiography. Results indicate immediate hydrogen infiltration in sandstone and limestone, with homogeneous distribution detected throughout their pore structure. In contrast, hydrogen remained largely absent from fine-grained shale under the same pressure, except in an apparently localized fracture zone, where neutron signatures confirmed the presence of hydrogen. Subsequent neutron CT of the sandstone sample, using image subtraction against an uncharged reference, corroborated hydrogen distribution patterns. Even under low-pressure, single-phase conditions, distinct neutron imaging signatures of hydrogen were achieved. These preliminary findings underscore the potential of neutron imaging for advancing subsurface hydrogen migration research.

Microbial inorganic mercury (iHg(II)) methylation, mediated by hgcAB genes, is a key process controlling the formation of neurotoxic methylmercury (CH₃Hg) in the environment. In this study, the arsRhgcAB gene cluster from Pseudodesulfovibrio hydrargyri BerOc1, a well-known Hg-methylating bacterium, was heterologously expressed in the non-methylating sulfate reducer Oleidesulfovibrio alaskensis G20. The heterologous expression of the arsRhgcAB gene cluster conferred the ability to methylate mercury to O. alaskensis G20, supporting its sufficiency to induce CH₃Hg production in a non-methylating sulfate-reducing host. Although CH₃Hg production rates in the engineered O. alaskensis G20 strain were lower than those in P. hydrargyri BerOc1, both strains followed a saturation reaction trend. Additionally, the engineered O. alaskensis G20 strain exhibited lower demethylation rates than the wild-type one, with a saturable kinetic profile similar to that of P. hydrargyri BerOc1, indicating that a regulatory mechanism, likely mediated by ArsR, limits demethylation. The expression of arsRhgcAB not only enables iHg(II) methylation but also influences CH₃Hg demethylation, unveiling regulated dynamics more complex than previously recognized. Understanding these pathways is essential to better predict cellular Hg pools, elucidating the fate of mercury in anoxic ecosystems and ultimately developing microbially based strategies to mitigate CH₃Hg production.

The ongoing polysubstance use crisis in the United States has recently been intensified by an increase in the use of nitazenes and nitazene-laced fentanyl. Despite the increasing trend in nitazene identifications reported by the National Forensic Laboratory Information System since 2019, reliance on conventional epidemiological approaches and logistical challenges often delay timely forensic reporting. We developed and validated an analytical method capable of nearly real-time quantification of several nitazenes in wastewater samples. Of a total of nine nitazene analogues, metonitazene was quantified most frequently (1.92–4.19 ng/L), followed by N-pyrrolidino etonitazene, isotonitazene, butonitazene, and etonitazene, during Super Bowl and Mardi Gras celebrations in New Orleans, Louisiana. Metonitazene and N-pyrrolidino etonitazene were discharged at average rates of 4.07 ± 1.99 and 0.48 ± 0.20 mg day^–1 (1000 people)⁻¹, respectively, during Super Bowl and Mardi Gras weeks in New Orleans. Interestingly, protonitazene and N-pyrrolidino protonitazene were discharged only after Mardi Gras at average rates of 8.90 ± 5.70 and 0.92 ± 0.08 mg day^–1 (1000 people)⁻¹, respectively. This is the first report of comprehensive quantification of nitazenes, including butonitazene, metonitazene, etonitazene, and isotonitazene, in municipal wastewater, highlighting their usage in the United States.

Fluorinated polymers are essential for lithographic patterning during electronics fabrication, and a variety of per- and polyfluoroalkyl substances (PFASs) of unknown sources are frequently measured in wastewater from electronics fabrication facilities (fabs). We tested the hypothesis that the fluorinated polymers contained in top antireflective coatings (TARCs) can be transformed under oxidizing or reducing conditions to form PFASs measured in fab wastewater. Three TARCs were characterized using combustion ion chromatography and ¹⁹F and ¹³C nuclear magnetic resonance (NMR) spectroscopy to quantify total fluorine and characterize structural features of the fluorinated components. Transformation experiments were conducted under oxidizing and reducing conditions, and products were identified by means of ¹⁹F NMR, high-resolution mass spectrometry, and ion chromatography. Under oxidizing conditions, fluorinated components transformed to primarily produce perfluoroalkylcarboxylic acids (PFCAs) when the structure contained nonfluorinated carbon atoms. Under reducing conditions, more highly fluorinated polymers exhibited near-complete defluorination, whereas ultrashort side-chain fluorotelomer-based polymers were more resistant to transformation. Fluorine mass balances demonstrated that most fluorine was recovered as discovered transformation products or as unreacted fluorinated polymer under oxidizing and reducing conditions. These findings help explain the presence of PFCAs in fab wastewater and provide insights on structure-transformation relationships.

The integrity and morphology of the selective layer of RO membranes significantly influence transport phenomena and membrane performance, motivating its cross-sectional imaging. Focused ion beam scanning electron microscopy (FIB-SEM) is a less complex technique for cross-sectional imaging that offers a broader field of view and a greater depth of focus, albeit with less resolution than transmission electron microscopy (TEM). In this study, we introduce and demonstrate a new surface-milling approach to improve the FIB-SEM imaging of RO membranes. We develop a bilayer conductive Pt coating topped with a protective carbon deposit; this approach avoids the need to cryo-fracture the membranes, which overcomes drawbacks associated with TEM and conventional FIB-SEM cross-sectional milling (e.g., curtaining and polymer melting). Applied to a commercial RO membrane, the method enabled robust quantification of key structural features and clear visualization of void spaces within the ridge-and-valley structure of the selective layer and pores in the uppermost portion of the support layer. The bilayer platinum coating enhances the delineation of the upper boundary of the selective layer, enabling rapid and accurate identification. With a field of view more than 20 times larger than TEM, FIB-SEM imaging captures a substantially greater cross-sectional area, yielding more representative measurements.

Trifluoroacetic acid (TFA) is a mobile and persistent compound that is widespread in the environment. While TFA forms in the atmosphere and deposition is its primary loss process, the relative contributions of wet and dry deposition require observational constraints. Here, we present a record of TFA in total, wet, and dry deposition in Toronto, Canada, between 2018 and 2024. Samples were collected using custom-built total and automated wet deposition samplers. All total (n = 103) and wet (n = 98) deposition samples contained TFA, with concentrations ranging from 0.07–4.55 μg L^–1 and 0.09–3.19 μg L^–1, respectively. Seasonal variation showed fluxes peaking in summer months, consistent with atmospheric oxidation of precursors as a major source. Fluxes in 2020 were statistically lower than other years by a factor of 2–5, coinciding with reduced anthropogenic activity during COVID-19 lockdowns. This suggests that TFA sources in Toronto are mainly driven by short-lived precursors. The median dry deposition flux (106 μg m^–2 a^–1) accounted for 0–94% (median 37%) of the total TFA deposition, higher and more variable than model estimates. These results provide the first field-based quantification of TFA in dry deposition, demonstrating that it is a significant and previously underrepresented removal pathway.

This study examined the effects of PFOS on adipocyte differentiation and lipid metabolism in mouse 3T3-L1 preadipocytes. At 10 and 100 μM, PFOS enhanced adipogenesis, promoting intracellular oil droplet accumulation and upregulating key markers, including PPARγ, perilipin, fatty acid-binding protein 4 (FABP4), lipoprotein lipase (LPL), CD36, fatty acid synthase (FASN), and glucose transporter 4 (GLUT4). It also increased adipokines (adiponectin and resistin). Compared to troglitazone (TGZ), a PPARγ agonist, PFOS induced milder differentiation effects. Cotreatment with PFOS and TGZ diminished TGZ’s pro-adipogenic potency, indicating potential interference. PFOS further influenced N6-methyladenosine (m6A) RNA modifications by altering the expression of m6A writers (METTL3 and VIR) and eraser (FTO), suggesting post-transcriptional regulation of adipogenic genes. Functional evaluations showed that PFOS preserved forskolin-stimulated lipolysis without impairing it. However, it upregulated metabolic markers, including carnitine palmitoyltransferase-1a (CPT1a), pyruvate dehydrogenase kinase (PDHK), and fibroblast growth factor-21 (FGF21), alongside elevated ATP levels in the 100 μM PFOS-treated group. These molecular changes suggest enhanced energy expenditure or energy stress, despite the cells’ morphological resemblance to white adipocytes. This duality likely arises from PFOS’s modulation of PPARγ signaling and m6A RNA modifications. By elucidating these mechanisms, the study highlights potential metabolic risks associated with PFOS exposure.