环境科学与技术最新文献

Compound-specific isotope analysis (CSIA) is an established tool to track the in situ transformation of organic chemicals at contaminated sites. In this work, we evaluated the potential of multi-element CSIA to assess biodegradation of 2,3-dichloroaniline (2,3-DCA), which is a major industrial feedstock. Using controlled laboratory experiments, we determined, for the first time, negligible carbon (<0.5‰) and hydrogen (<10‰) isotope fractionation and a significant inverse nitrogen isotope fractionation (>10‰) during aerobic 2,3-DCA biodegradation by a mixed enrichment culture. The tentative identification of a glutamate conjugate of 2,3-DCA as a reaction intermediate indicates that the initial multistep enzymatic reaction may be rate-limiting. The formation of the glutamate adduct would increase the bond energy at the N atom, thus likely explaining the observed inverse N isotope fractionation. The corresponding nitrogen enrichment factor was +6.8 ± 0.6‰. This value was applied to investigate the in situ 2,3-DCA biodegradation at a contaminated site where the carbon and nitrogen isotope signatures from field samples suggested similar aerobic processes by native microorganisms. Under the assumption of the applicability of the Rayleigh model in a pilot wetland treating contaminated groundwater, the extent of biodegradation was estimated to be up to 80-90%. This study proposes multi-element CSIA as a novel application to study 2,3-DCA fate in groundwater and surface water and provides insights into biodegradation pathways.

The elevation of the low-temperature oxidation activity for Pt/CeO₂ catalysts is challenging to meet the increasingly stringent requirements for effectively eliminating carbon monoxide (CO) from automobile exhaust. Although reducing activation is a facile strategy for boosting reactivity, past research has mainly concentrated on applying H₂ as the reductant, ignoring the reduction capabilities of CO itself, a prevalent component of automobile exhaust. Herein, atomically dispersed Pt/CeO₂ was fabricated and activated by CO, which could lower the 90% conversion temperature (T₉₀) by 256 °C and achieve a 20-fold higher CO consumption rate at 200 °C. The activated Pt/CeO₂ catalysts showed exceptional catalytic oxidation activity and robust hydrothermal stability under the simulated working conditions for gasoline or diesel exhausts. Characterization results illustrated that the CO activation triggered the formation of a large portion of Pt⁰ terrace sites, acting as inherent active sites for CO oxidation. Besides, CO activation weakened the Pt-O-Ce bond strength to generate a surface oxygen vacancy (V_o). It served as the oxygen reservoir to store the dissociated oxygen and convert it into active dioxygen intermediates. Conversely, H₂ activation failed to stimulate V_o, but triggered a deactivating transformation of the Pt nanocluster into inactive Pt_xO_y in the presence of oxygen. The present work offers coherent insight into the upsurging effect of CO activation on Pt/CeO₂, aiming to set up a valuable avenue in elevating the efficiency of eliminating CO, C₃H₆, and NH₃ from automobile exhaust.

Landscape wildfires generate a substantial amount of dissolved black carbon (DBC) annually, yet the molecular nitrogen (N) structures in DBC are poorly understood. Here, we systematically compared the chemodiversity of N-containing molecules among three different DBC samples from rice straw biochar pyrolyzed at 300, 400, and 500 °C, one leached dissolved organic carbon (LDOC) sample from composted rice straw, and one fire-affected soil dissolved organic matter (SDOM_Fire) sample using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). N-Containing molecules contributed 20.0%, 36.1%, and 43.7% of total compounds in Combined DBC (pooling together the three DBC), LDOC, and SDOM_Fire, respectively, and molecules with fewer N atoms had higher proportions (i.e., N₁ > N₂ > N₃). The N-containing molecules in Combined DBC were dominated by polycyclic aromatic (62.2%) and aromatic (14.4%) components, while those in LDOC were dominated by lignin-like (50.4%) and aromatic (30.1%) components. The composition and structures of N-containing molecules in SDOM_Fire were more similar to those in DBC than in LDOC. As the temperature rose, the proportion of the nitrogenous polycyclic aromatic component in DBC significantly increased with concurrent enhanced oxidation and unsaturation of N. As indicated by density functional theory (DFT)-based thermodynamic calculations, the proportion of aliphatic amide N decreased from 23.2% to 7.9%, whereas that of nitroaromatic N increased from 10.0% to 39.5% as the temperature increased from 300 to 500 °C; alternatively, the proportion of aromatic N in the 5/6 membered ring remained relatively stable (∼31%) and that of aromatic amide N peaked at 400 °C (32.7%). Our work first provides a comprehensive and thorough description of molecular N structures of DBC, which helps to better understand and predict their fate and biogeochemical behavior.

Increasing worldwide contamination with organic chemical compounds is a paramount environmental challenge facing humanity. Once they enter nature, pollutants undergo transformative processes that critically shape their environmental impacts and associated risks. This research unveils previously overlooked yet widespread pathways for the transformations of organic pollutants triggered by water vapor condensation, leading to spontaneous oxidation and hydrolysis of organic pollutants. These transformations exhibit variability through either sequential or parallel hydrolysis and oxidation, contingent upon the functional groups within the organic pollutants. For instance, acetylsalicylic acid on the goethite surface underwent sequential hydrolysis and oxidation that first hydrolyzed to salicylic acid followed by hydroxylation oxidation of the benzene moiety driven by the hydroxyl radical (^•OH). In contrast, chloramphenicol underwent parallel oxidation and hydrolysis, forming hydroxylated chloramphenicol and 2-amino-1-(4-nitrophenyl)-1,3-propanediol, respectively. The spontaneous oxidation and hydrolysis occurred consistently on three naturally abundant iron minerals with the key factors being ^•OH production capacity and surface binding strength. Given the widespread presence of iron minerals on Earth's surface, these spontaneous transformation paths could play a role in the fate and risks of organic pollutants of health concerns.

Environmentally benign cerium-based catalysts are promising alternatives to toxic vanadium-based catalysts for controlling NO_x emissions via selective catalytic reduction (SCR), but conventional cerium-based catalysts unavoidably suffer from SO₂ poisoning in low-temperature SCR. We develop a strongly sulfur-resistant Ce₁₊₁/TiO₂ catalyst by spatially confining Ce atom pairs to different anchoring sites of anatase TiO₂(001) surfaces. Experimental results combined with theoretical calculations demonstrate that strong electronic interactions between the paired Ce atoms upshift the lowest unoccupied states to an energy level higher than the highest occupied molecular orbital (HOMO) of SO₂ so as to be catalytically inert in SO₂ oxidation but slightly lower than HOMO of NH₃ so that Ce₁₊₁/TiO₂ has desired ability toward NH₃ activation required for SCR. Hence, Ce₁₊₁/TiO₂ shows higher SCR activity and excellent stability in the presence of SO₂ at low temperatures with respect to supported single Ce atoms. This work provides a general strategy to develop sulfur-resistant catalysts by tuning the electronic states of active sites for low-temperature SCR, which has implications for practical applications with energy-saving requirements.

Pertechnetate (⁹⁹TcO₄^-), a physiologically toxic radioactive anion, is of great concern due to its high mobility in environmental contamination remediation. Although the soluble oxyanion can be photoreduced to sparingly soluble TcO₂·nH₂O, its effective removal from a strongly acidic aqueous solution remains a challenge. Here, we found that low-crystalline nitrogen-doped titanium oxide (N-TiO₂, 0.6 g L^-1) could effectively uptake perrhenate (ReO₄^-, 10 mg L^-1, a nonradioactive surrogate for TcO₄^-) with 50.8% during 360 min under simulated sunlight irradiation at pH 1.0, but P25 and anatase could not. The nitrogen active center formed by trace nitrogen doping in N-TiO₂ can promote the separation and transfer of photogenerated carriers. The positive valence band value of N-TiO₂ is slightly higher than those of P25 and anatase, which means that the photogenerated holes have a stronger oxidizability. These holes are involved in the formation of strong reducing ^•CO₂^- radicals from formic acid oxidation. The active radicals convert ReO₄^- to Re(VI), which is subsequently disproportionated to Re(IV) and Re(VII). Effective photocatalytic reduction/removal of Re(VII)/Tc(VII) is performed on the material, which may be considered a potential and convenient strategy for technetium decontamination and extraction in a strongly acidic aqueous solution.

The rising in situ chemical oxidation (ISCO) technologies based on polymerization reactions have advanced the removal of emerging contaminants in the aquatic environment. However, despite their promise, uncertainties persist regarding their effectiveness in eliminating structurally complex contaminants, such as sulfonamide antibiotics (SAs). This study elucidated that oligomerization, rather than mineralization, predominantly governs the removal of SAs in the carbon materials/periodate system. The amine groups in SAs played a crucial role in forming organic radicals and subsequent coupling reactions due to their high f^- index and low bond orders. Moreover, the study highlighted the robust adhesion of oligomers to the catalyst surface, facilitated by enhanced van der Waals forces and hydrophobic interactions. Importantly, plant and animal toxicity assessments confirmed the nontoxic nature of oligomers deposited on the carbon material surface, affirming the efficacy of carbon material-based ISCO in treating contaminated surface water and groundwater. Additionally, a novel classification approach, Δlog k, was proposed to differentiate SAs based on their kinetic control steps, providing deeper insights into the quantitative structure-activity relationship (QSAR) and facilitating the selection of optimal descriptors during the oligomerization processes. Overall, these insights significantly enhance our understanding of SAs removal via oligomerization and demonstrate the superiority of C-ISCO based on polymerization in water decontamination.

Cosmetics make up one of the consumer product categories most widely known to contain perfluoroalkyl and polyfluoroalkyl substances (PFASs), including precursors to perfluorooctanoic acid (PFOA) and other perfluoroalkyl acids (PFAAs). Because of the way cosmetics are used, most of the PFASs present in these products are likely to reach wastewater treatment plants (WWTPs), which suggests that cosmetics may contribute significantly to the load of PFOA and other PFASs at WWTPs. However, the majority of PFASs present as intentional ingredients in cosmetics cannot be quantified with the available analytical methods. To address this issue, we developed a methodology to estimate the total PFAS mass in cosmetics as well as the corresponding mass of total organic fluorine and of fluorinated side chains associated with PFAA precursors, using various ingredient databases and ingredient concentrations reported by manufacturers. Our results indicate that the cosmetics sold in California during a one-year period cumulatively contain 650-56 000 kg of total PFASs, 370-37 000 kg of organic fluorine, and 330-20 000 kg of fluorinated side chains associated with PFAA precursors. Among the 16 product subcategories considered, >90% of the PFAS mass came from shaving creams and gels, hair care products, facial cleansers, sun care products, and lotions and moisturizers, while the sum of all nine makeup subcategories accounted for <3%. Comparing our estimates to available WWTP influent data from the San Francisco Bay Area suggests that cosmetics may account for at least 4% of the precursor-derived PFAAs measured in wastewater. As the first study ever to estimate the total mass of PFASs contained in cosmetics sold in California, our results shed light on the significance of certain cosmetics as a source of PFASs to WWTPs and can inform effective source reduction efforts.

Waterborne pathogens invariably present considerable threats to public health. The quorum sensing (QS) system is instrumental in coordinating bacterial growth and metabolisms. However, the responses and regulatory mechanisms of bacteria to various disinfection technologies through quorum sensing are still unclear. This study examines the inactivation effect of chlorination and ozonation on biofilms and planktonic cells of QS signaling-deficient mutants of Pseudomonas aeruginosa. Cell counting and viability assessment revealed that the combined disinfection of chlorine and ozone was the most effective for inactivating planktonic P. aeruginosa within 10 min of exposure. Additionally, microfluidic chip culture demonstrated that the secretion of quinolone signals escalated biofilms' disinfection resistance. Disinfection exposure significantly altered the gene expression of wild-type strains and QS signaling-deficient mutants. Moreover, the QS system triggered multilayered gene expression programs as a responsive protection to disinfectant exposure, including oxidative stress, ribosome synthesis, and the nutrient absorption of bacteria. These insights broaden our understanding of bacterial QS in response to disinfection, promising potential strategies toward efficient disinfection processes.