环境科学与技术最新文献

Effective synthesis and application of single-atom catalysts on supports lacking enough defects remain a significant challenge in environmental catalysis. Herein, we present a universal defect-enrichment strategy to increase the surface defects of CeO₂-based supports through H₂ reduction pretreatment. The Pt catalysts supported by defective CeO₂-based supports, including CeO₂, CeZrO_x, and CeO₂/Al₂O₃ (CA), exhibit much higher Pt dispersion and CO oxidation activity upon reduction activation compared to their counterpart catalysts without defect enrichment. Specifically, Pt is present as embedded single atoms on the CA support with enriched surface defects (CA-HD) based on which the highly active catalyst showing embedded Pt clusters (Pt_C) with the bottom layer of Pt atoms substituting the Ce cations in the CeO₂ surface lattice can be obtained through reduction activation. Embedded Pt_C can better facilitate CO adsorption and promote O₂ activation at Pt_C-CeO₂ interfaces, thereby contributing to the superior low-temperature CO oxidation activity of the Pt/CA-HD catalyst after activation.

Monitoring of volatile organic compounds (VOCs) in air is crucial for understanding their atmospheric impacts and advancing their emission reduction plans. This study presents an innovative integrated methodology suitable for achieving semireal-time high spatiotemporal resolution three-dimensional measurements of VOCs from ground to hundreds of meters above ground. The methodology integrates an active AirCore sampler, custom-designed for deployment from unmanned aerial vehicles (UAV), a proton-transfer-reaction mass spectrometry (PTR-MS) for sample analysis, and a data deconvolution algorithm for improved time resolution for measurements of multiple VOCs in air. The application of the deconvolution technique significantly improves the signal strength of data from PTR-MS analysis of AirCore samples and enhances their temporal resolution by 4 to 8 times to 4-11 s. A case study demonstrates that the methodology can achieve sample collection and analysis of VOCs within 45 min, resulting in >120-360 spatially resolved data points for each VOC measured and achieving a horizontal resolution of 20-55 m at a UAV flight speed of 5 m/s and a vertical resolution of 5 m. This methodology presents new possibilities for acquiring 3-dimensional spatial distributions of VOC concentrations, effectively tackling the longstanding challenge of characterizing three-dimensional VOC distributions in the lowest portion of the atmospheric boundary layer.

Fabrication of robust isolated atom catalysts has been a research hotspot in the environment catalysis field for the removal of various contaminants, but there are still challenges in improving the reactivity and stability. Herein, through facile doping alkali metals in Pt catalyst on zirconia (Pt-Na/ZrO₂), the atomically dispersed Pt^δ+-O(OH)_x- associated with alkali metal via oxygen bridge was successfully fabricated. This novel catalyst presented remarkably higher CO and hydrocarbon (HCs: C₃H₈, C₇H₈, C₃H₆, and CH₄) oxidation activity than its counterpart (Pt/ZrO₂). Systematically direct and solid evidence from experiments and density functional theory calculations demonstrated that the fabricated electron-rich Pt^δ+-O(OH)_x- related to Na species rather than the original Pt^δ+-O(OH)_x-, serving as the catalytically active species, can readily react with CO adsorbed on Pt^δ+ to produce CO₂ with significantly decreasing energy barrier in the rate-determining step from 1.97 to 0.93 eV. Additionally, owing to the strongly adsorbed and activated water by Na species, those fabricated single-site Pt^δ+-O(OH)_x- linked by Na species could be easily regenerated during the oxidation reaction, thus considerably boosting its oxidation reactivity and durability. Such facile construction of the alkali ion-linked active hydroxyl group was also realized by Li and K modification which could guide to the design of efficient catalysts for the removal of CO and HCs from industrial exhaust.

With the annual global electricity production exceeding 30,000 TWh, the safe transmission of electric power has been heavily relying on SF₆, the most potent industrial greenhouse gas. While promising SF₆ alternatives have been proposed, their compatibilities with materials used in gas-insulated equipment (GIE) must be thoroughly studied. This is particularly true as the emerging SF₆ alternatives generally leverage their relatively higher reactivity to achieve lower global warming potentials (GWPs). Here, a high-throughput compatibility screening of common GIE materials was conducted with a representative SF₆ alternative, namely, C₄F₇N (2,3,3,3-tetrafluoro-2-(trifluoromethyl)propanenitrile)/CO₂ gas mixtures. In this screening, the insulation performance of C₄F₇N/CO₂ gas mixtures, as an indicator of the C₄F₇N/materials compatibility level, was periodically monitored during the thermal aging with tens of materials from SF₆-insulated GIE, including desiccants/adsorbents, rubber, plastics, composites, ceramics, metals, etc. The identification of incompatible materials and the follow-up mechanism studies suggested that the acidity of materials represents the primary cause for C₄F₇N/materials incompatibility when C₄F₇N/CO₂ gas mixtures are used as a drop-in replacement solution for existing SF₆-insulated apparatuses. Mitigation strategies tackling the acidity of materials were then proposed and validated. Additionally, the amphoteric characteristics of C₄F₇N were briefly discussed. This work provides insight into the materials incompatibility of SF₆ alternatives, along with validated mitigation strategies, for the selection and design of materials used in future eco-friendly GIE.

As the number of coastal nuclear facilities rapidly increases and the wastewater from the Fukushima Nuclear Plant has been discharged into the Pacific Ocean, the nuclear environmental safety of China's marginal seas is gaining increased attention along with the heightened potential risk of nuclear accidents. However, insufficient work limits our understanding of the impact of human nuclear activities on the Yellow Sea (YS) and the assessment of their environmental process. This study first reports the ¹²⁹I and ¹²⁷I records of posthuman nuclear activities in the two YS sediments. Source identification of anthropogenic ¹²⁹I reveals that, in addition to the gaseous ¹²⁹I release and re-emission of oceanic ¹²⁹I discharged from the European Nuclear Fuel Reprocessing Plants (NFRPs), the Chinese nuclear weapons testing fallout along with the global fallout is an additional ¹²⁹I input for the continental shelf of the YS. The ¹²⁹I/¹²⁷I atomic ratios in the North YS (NYS) sediment are significantly higher than those in the other adjacent coastal areas, attributed to the significant riverine input of particulate ¹²⁹I by the Yellow River. Furthermore, we found a remarkable ¹²⁹I latitudinal disparity in the sediments than those in the seawaters in the various China seas, revealing that sediments in China's marginal seas already received a huge anthropogenic ¹²⁹I from terrigenous sources via rivers and thus became a significant sink of anthropogenic ¹²⁹I. This study broadens an insight into the potential impacts of terrigenous anthropogenic pollution on the Chinese coastal marine radioactive ecosystem.

Dissolved organic matter (DOM) in aquatic systems is a highly heterogeneous mixture of water-soluble organic compounds, acting as a major carbon reservoir driving biogeochemical cycles. Understanding DOM molecular composition is thus of vital interest for the health assessment of aquatic ecosystems, yet its characterization poses challenges due to its complex and dynamic chemical profile. Here, we performed a comprehensive chemical analysis of DOM from highly urbanized river and seawater sources and compared it to drinking water. Extensive analyses by nontargeted direct infusion (DI) and liquid chromatography (LC) high-resolution mass spectrometry (HRMS) through Orbitrap were integrated with novel computational workflows to allow molecular- and structural-level characterization of DOM. Across all water samples, over 7000 molecular formulas were calculated using both methods (∼4200 in DI and ∼3600 in LC). While the DI approach was limited to molecular formula calculation, the downstream data processing of MS2 spectral information combining library matching and in silico predictions enabled a comprehensive structural-level characterization of 16% of the molecular space detected by LC-HRMS across all water samples. Both analytical methods proved complementary, covering a broad chemical space that includes more highly polar compounds with DI and more less polar ones with LC. The innovative integration of diverse analytical techniques and computational workflow introduces a robust and largely available framework in the field, providing a widely applicable approach that significantly contributes to understanding the complex molecular composition of DOM.

Southern Hemisphere humpback whales accumulate persistent and toxic chemicals, which are transported to Antarctica through distant sources and in situ usage. The extreme seasonal migration-associated fast of humpback whales results in the remobilization of persistent and lipophilic environmental contaminants from liberated fat stores. Mitochondria play a key role in lipid metabolism, and any disruption to mitochondrial function is expected to influence whole-organism bioenergetics. It is therefore of interest to advance understanding of the impact of known contaminants of the Antarctic sea-ice ecosystem upon humpback whale cellular bioenergetics. Using cell line-based in vitro testing, this study employed the Seahorse Extracellular Flux Analyzer to study cellular metabolic activity in live humpback whale fibroblast cells. The assay, based on oxygen consumption rate, provides insights into the cause of cellular bioenergetic disruption. Immortalized skin fibroblasts were exposed to four priority environmental chemicals found in the Antarctic sea-ice ecosystem. Our findings reveal chemical-dependent functional alterations and varying bioenergetic profile responses. Chlorpyrifos was observed to decrease mitochondrial basal oxygen consumption; dieldrin increased basal oxygen consumption; trifluralin's impact was dose-specific, and endosulfan displayed no effect. Our results provide unique insights into environmental chemical mechanisms of action on cellular bioenergetics, generating much-needed taxa-specific chemical effect data in support of evidence-based conservation policy and management.

Reactive oxygen species (ROS) produced from the oxygenation of reactive Fe(II) species significantly affect the transformation of metalloids such as Sb at anoxic-oxic redox interfaces. However, the main ROS involved in Sb(III) oxidation and Fe (oxyhydr)oxides formation during co-oxidation of Sb(III) and Fe(II) are still poorly understood. Herein, this study comprehensively investigated the Sb(III) oxidation and immobilization process and mechanism during Fe(II) oxygenation. The results indicated that Sb(III) was oxidized to Sb(V) by the ROS produced in the aqueous and solid phases and then immobilized by formed Fe (oxyhydr)oxides via adsorption and coprecipitation. In addition, chemical analysis and extended X-ray absorption fine structure (EXAFS) characterization demonstrated that Sb(V) could be incorporated into the lattice structure of Fe (oxyhydr)oxides via isomorphous substitution, which greatly inhibited the formation of lepidocrocite (γ-FeOOH) and decreased its crystallinity. Notably, goethite (α-FeOOH) formation was favored at pH 6 due to the greater amount of incorporated Sb(V). Moreover, singlet oxygen (¹O₂) was identified as the dominant ROS responsible for Sb(III) oxidation, followed by surface-adsorbed ·OH_ads, ·OH, and Fe(IV). Our findings highlight the overlooked roles of ¹O₂ and Fe (oxyhydr)oxide formation in Sb(III) oxidation and immobilization during Fe(II) oxygenation and shed light on understanding the geochemical cycling of Sb coupled with Fe in redox-fluctuating environments.

The effect of aqueous solution chemistry on the ionic hydration structure and its corresponding nanofiltration (NF) selectivity is a research gap concerning ion-selective transport. In this study, the hydration distribution of two typical monovalent anions (Cl^- and NO₃^-) under different aqueous solution chemical conditions and the corresponding transmembrane selectivity during NF were investigated by using in situ liquid time-of-flight secondary ion mass spectrometry in combination with molecular dynamics simulations. We demonstrate the inextricable link between the ion hydration structure and the pore steric effect and further find that ionic transmembrane transport can be regulated by breaking the balance between the hydrogen bond network (i.e., water-water) and ion hydration (i.e., ion-water) interactions of hydrated ion. For strongly hydrated (H₂O)_nCl^- with more intense ion-water interactions, a higher salt concentration and coexisting ion competition led to a larger hydrated size and, thus, a higher ion rejection by the NF membrane, whereas weakly hydrated (H₂O)_nNO₃^- takes the reverse under the same conditions. Stronger OH^--anion hydration competition resulted in a smaller hydrated size of (H₂O)_nCl^- and (H₂O)_nNO₃^-, showing a lower observed average hydration number at pH 10.5. This study deepens the long-overlooked understanding of NF separation mechanisms, concerning the hydration structure.