环境科学与技术最新文献

Per- and polyfluoroalkyl substances (PFAS) have been detected in plant fiber-based food packaging and most such packaging is disposed in landfills. The objective of this research was to evaluate the release of volatile PFAS to the gas-phase from PFAS-containing, single-use food packaging materials and from municipal solid waste (MSW) during anaerobic decomposition under simulated landfill conditions. After screening 46 materials for total F and 6:2 fluorotelomer alcohol (FTOH), packaging materials were classified as high or low F. High F materials included microwavable popcorn bags, natural plates, compostable bowls, biodegradable boxes, bagasse containers and eco-friendly plates, while the low F materials tested were paper plates, eco-friendly food trays and poly coated freezer paper. Summed PFAS release from the high F materials was 62–800 ng PFAS/g sample and 6:2 FTOH comprised 96.8–99.9% of the summed PFAS. The low F materials and MSW released 0.1–0.4 ng summed PFAS/g sample and 7:2-secondary (s) FTOH was the dominant volatile PFAS. PFAS were generally released early in the 123–285-day decomposition cycle, suggesting that some PFAS will be released prior to the installation of landfill gas collection systems. Nonetheless, PFAS have been reported in collected landfill gas, indicating that release occurs over many years.

This study demonstrates the release of volatile PFAS to the gas phase from PFAS-contaminated plant fiber-based food packaging under simulated landfill conditions.

Methanogenic archaea are known to play a crucial role in the biogeochemical cycling of arsenic (As); however, the molecular basis of As transformation mediated by methanogenic archaea remains poorly understood. Herein, the characterization of the redox transformation and methylation of As by Methanosarcina acetivorans, a model methanogenic archaeon, is reported. M. acetivorans was demonstrated to mediate As(V) reduction via a cytoplasmic As reductase (ArsC) in the exponential phase of methanogenic growth and to methylate As(III) via a cytoplasmic As(III) methyltransferase (ArsM) in the stationary phase. Characterization of the ArsC-catalyzed As(V) reduction and the ArsM-catalyzed As(III) methylation showed that a thioredoxin (Trx) encoded by MA4683 was preferentially utilized as a physiological electron donor for ArsC and ArsM, providing a redox link between methanogenesis and As transformation. The structures of ArsC and ArsM complexed with Trx were modeled using AlphaFold-Multimer. Site-directed mutagenesis of key cysteine residues at the interaction sites of the complexes indicated that the archaeal ArsC and ArsM employ evolutionarily distinct disulfide bonds for interacting with Trx compared to those used by bacterial ArsC or eukaryotic ArsM. The findings of this study present a major advance in our current understanding of the physiological roles and underlying mechanism of As transformation in methanogenic archaea.

Bio-nano hybrids (BNH), combining semiconductors and microorganisms, have shown great promise for effective solar-to-fuel energy conversion. However, the high-energy ultraviolet (UV) photons in the solar spectrum can cause severe photocorrosion of semiconductors and irreversible photodamage to microorganisms within BNH. Here, we developed an encapsulation strategy using natural luminogens with aggregation-induced emission characteristics (AIEgens) to construct a protective layer for BNH, effectively shielding them against high-energy UV photons. We incorporated natural berberine (BBR) into the BNH composed of Methanosarcina barkeri and polymeric carbon nitrides (CN_x). The self-assembled BNH-BBR system displayed a 2.75-fold higher CH₄ yield than BNH under simulated solar irradiation. Mechanism analysis revealed that BBR acted as a UV sunscreen for BNH by converting high-energy short wavelengths into low-energy long wavelengths, thereby reducing the accumulation of reactive oxygen species and alleviating the photocorrosion of CN_x. Furthermore, BBR functioned as a photosynergist for BNH by regulating photoelectron production and utilization, enhancing the intracellular energy formation in M. barkeri for growth and metabolism. This work provides important insights into the effective and scalable conversion of CO₂ into valuable biofuels with BNH under light illumination containing high-energy photons.

The unpredictable biodegradation of fluorotelomer (FT)-based per- and polyfluoroalkyl substances (PFAS) causes complicated risk management of PFAS-impacted sites. Here, we have successfully used redundancy analysis to link FT-based precursor biodegradation to key microbes and genes of soil microbiomes shaped by different classes of carbon sources: alcohols (C2-C4), alkanes (C6 and C8), an aromatic compound (phenol), or a hydrocarbon surfactant (cocamidopropyl betaine [CPB]). All the enrichments defluorinated fluorotelomer alcohols (n:2 FtOH; n = 4, 6, 8) effectively and grew on 6:2 fluorotelomer sulfonate (6:2 FtS) as a sulfur source. The butanol-enriched culture showed the highest defluorination extent for FtOHs and 6:2 FtS due to the high microbial diversity and the abundance of desulfonating and defluorinating genes. The CPB-enriched culture accumulated more 5:3 fluorotelomer carboxylic acid, suggesting unique roles of Variovorax and Pseudomonas. Enhanced 6:2 FtOH defluorination was observed due to a synergism between two enrichments with different carbon source classes except for those with phenol- and CPB-enriched cultures. While the 6:2 fluorotelomer sulfonamidoalkyl betaine was not degraded, trace levels of 6:2 fluorotelomer sulfonamidoalkyl amines were detected. The identified species and genes involved in desulfonation, defluorination, and carbon source metabolism are promising biomarkers for assessing precursor degradation at the sites.

Permafrost is a crucial part of the Earth's cryosphere. These millennia-old frozen soils not only are significant carbon reservoirs but also store a variety of chemicals. Accelerated permafrost thaw due to global warming leads to profound consequences such as infrastructure damage, hydrological changes, and, notably, environmental concerns from the release of various chemicals. In this perspective, we metaphorically term long-preserved substances as "dormant chemicals" that experience an "awakening" during permafrost thaw. We begin by providing a comprehensive overview and categorization of these chemicals and their potential transformations, utilizing a combination of field observations, laboratory studies, and modeling approaches to assess their environmental impacts. Following this, we put forward several perspectives on how to enhance the scientific understanding of their ensuing environmental impacts in the context of climate change. Ultimately, we advocate for broader research engagement in permafrost exploration and emphasize the need for extensive environmental chemical studies. This will significantly enhance our understanding of the consequences of permafrost thaw and its broader impact on other ecosystems under rapid climate warming.

Investing in nonpotable water reuse (NPWR) is essential for circular urban water management. Existing research lacks methods to determine the number and capacities of NPWR plants (i.e., degree of decentralization) for large-scale applications in existing cities. We developed a spatial optimization framework in which the degree of decentralization emerges from the collective decisions of urban districts regarding where to send wastewater for reclamation and where to source water for nonpotable uses. We modified the genetic algorithm to optimize collective decisions with objectives including minimizing freshwater withdrawal, electricity consumption, and the cost of NPWR plants. Optimization results suggest an optimal number from one to eight among Pareto optimal solutions, with two to three being most common in Hong Kong. The cost-effective solutions suggest locations of NPWR plants in Kowloon and Hong Kong Island where NPWR demand is significant, while the electricity use for freshwater and seawater is high. The city could save about 6% freshwater and 29.4% seawater while consuming 20.7% more electricity. Overall, our spatial optimization framework provides a holistic evaluation of the optimal degree of decentralization for NPWR at the water-energy-cost nexus on an urban scale. Our findings serve as a benchmark to explore more energy-conscious planning strategies in Hong Kong.

Accelerated vehicle retirement is recognized as crucial for managing fleet emissions effectively. However, the emergence of new energy vehicles introduces complexities in assessing their environmental impacts. This study developed a dynamic fleet-based life cycle assessment model to analyze the effects of four distinct scrappage strategies in China from 2021 to 2060. The results underscore the importance of a meticulously chosen retirement strategy that harmonizes fleet characteristics with advancements in vehicle technology to promote sustainable mobility. Accelerated retirement strategies are demonstrated to enhance vehicle sales and expedite the incorporation of new energy vehicles into the fleet. Although these policies reduce greenhouse gas and carbon monoxide emissions, they may exacerbate other air pollutants, necessitating vigilant management. Additionally, the temporal distribution of environmental impacts reveals the critical need for long-term assessments. By evaluating six negative externalities of emissions, the research indicates that targeted scrappage policies, which advocate for the retirement of older vehicles, could potentially generate economic benefits of 6.81 to 7.29 billion dollars in reduced losses. However, an overly aggressive scrappage policy could increase negative externalities, leading to additional costs ranging from 0.84 to 3.31 billion dollars. This study reveals the intricate long-term environmental consequences of scrappage strategies accompanying the rise of new energy vehicles and lays a methodological groundwork for ongoing research into the most effective retirement scheme.

A collaborative COS conversion of Hg⁰ in natural gas on the nitrogen-doped and copper oxide-supported carbon aerogel (0.9PPD-Cu/CA), which is synthesized by the p-phenylenediamine sources and carbon source of sodium alginate, was proposed to overcome the easy deactivation of the catalyst, high reaction temperature, and limited lifespan. At 40 °C, the 0.9PPD-Cu/CA presented a 100% COS conversion efficiency in the presence of H₂O; meanwhile, the N doping realized the enhancement of basic density, leading to an improved COS conversion, and the intermediates H₂S in the reaction were wholly adsorbed, implying that 0.9PPD-Cu/CA was a bifunctional carbon material. Furthermore, the Hg⁰ addition achieved a synergistic performance as well as higher COS yield and a significant lifetime period, in which the sulfur immediate could have a high reactive activity for Hg⁰ and the sulfate proportion would be alleviated as well. Subsequently, the catalyst poisoning would be alleviated after the protection of the collaborative process by strengthening the electron transfer, consuming the sulfur-based products, and accelerating the cleavage of the H-S bond. Finally, the synergetic mechanism on COS and Hg⁰ on 0.9PPD-Cu/CA was concluded according to the experimental results and sample analysis. Additionally, the effects of space velocity and the regeneration performance were explored.