Persistent and semi-volatile organic contaminants remain important atmospheric tracers because of their environmental persistence, multiple emission pathways and capacity for regional transport. This study investigated the spatial and seasonal variability of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in northeastern France. Nitrogen-doped carbon-coated silicon carbide foam (NMC@SiC) passive air samplers were deployed at six urban, suburban and rural sites in the Strasbourg metropolitan area between 2018 and 2020. Twenty-one OCPs, sixteen PAHs, and twenty-two PCBs were quantified by gas chromatography-tandem mass spectrometry. PAHs exhibited the clearest spatial and seasonal variability, with higher concentrations at urban sites and cold-season or autumn enhancements depending on the location. Naphthalene dominated the PAH profile, while diagnostic ratios suggested dominant combustion inputs, including traffic, residential heating and biomass or solid-fuel burning. PCBs showed weaker spatial contrasts and more homogeneous distributions, with profiles dominated by penta-, hexa- and hepta-chlorinated congeners, indicating diffuse legacy contamination, possible PCB-containing materials, industrially influenced areas and regional redistribution. OCPs were dominated by dichlorodiphenyltrichloroethane-related compounds and hexachlorocyclohexane isomers, reflecting historical residues and secondary volatilization from contaminated environmental reservoirs. These findings highlight the combined influence of current urban emissions, persistent legacy reservoirs, secondary re-emissions and regional atmospheric transport on organic contaminant distributions in northeastern France.
Atmospheric ion escape driven by the solar wind is a key process controlling the long-term loss of the Martian atmosphere. Localized plasma clouds can carry substantial fluxes of planetary ions away from Mars, representing episodes of bulk escape. However, their origin has remained unclear due to the absence of simultaneous upstream measurements. Using joint observations from the MAVEN and Tianwen-1 missions, which provide real-time upstream monitoring, we present direct evidence that these plasma clouds are nonlinear wave packets generated by the Kelvin-Helmholtz instability (KHI). The spatial scale of KH waves is constrained for the first time via two-point measurements. Ion fluxes within plasma clouds are one to two orders of magnitude higher than those in typical steady-state escape channels. Our results indicate that KHI is an important process for solar wind coupling to planetary upper atmospheres and plays a crucial role in shaping atmospheric ion escape for unmagnetized planets.
Most discarded packaging in the environment originates from petroleum-derived plastics, which are environmental pollutants. Many proposals for new packaging employ biodegradable materials; however, these materials often require additives to impart specific properties to the final products. Therefore, research related to degradation processes is necessary to ensure their environmental safety of them. The aim of this study was to investigate the degradation of pure poly-(butylene adipate-co-terephthalate) (PBAT) films and films added with 5% (w/w) Rosemary essential oil (REO) (Rosmarinus officinalis L.) under two different natural atmospheric conditions in a semiarid climate from northeastern Brazil. To this end, 66 rectangular samples with an area of 6.8 cm2 were exposed for 120 days under two conditions: condition (I) sunlight, wind, dust, humidity, and the presence of rain and condition (II) sunlight, wind, dust, humidity, and absence of rain. The samples were evaluated in terms of mass, thickness, solubility, opacity, visual appearance, and spectroscopic profile in the mid-infrared region using the carbonyl index (CI) and hydroxyl index (HI). An increase in solubility proportional to the water exposure time was also observed for both films, corroborating the visual analysis, which revealed the formation of fissures throughout the entire set of samples and a higher opacity in the oil-added films, especially under condition I. In addition, films exposed to condition I exhibited a greater mass loss than those under condition II. Differences in degradation between pure and REO-added films also became more evident, with a greater reduction in CI observed for the added samples under both conditions, indicating chemical degradation due to ester bond cleavage in PBAT. Principal component analysis indicated that up to 45 days, the samples exhibited high spectral similarity; however, thereafter, increasing discrimination between samples from the two experimental conditions was observed. This indicates that although the samples showed a similar degradation pattern over time, those exposed to condition I (with rain) were more strongly affected by climatic conditions and exhibited stronger evidence of chemical degradation.
The cosmogenic radionuclide 81Kr (half-life 229 ka) is widely used to date groundwater and ice on 104-106 year timescales. Anthropogenic nuclear activities can lead to an increase of 81Kr in the atmosphere, but this contribution has not been tightly constrained experimentally. We report a precise measurement of the anthropogenic contribution using Atom Trap Trace Analysis (ATTA). A pre-nuclear atmospheric krypton sample collected in the 1940s was measured alongside a present-day atmospheric sample, acquiring over one million 81Kr atom counts for each sample. Given the measured difference of δ = (0.09 ± 0.14)% and after correcting for the cross-sample contamination, we obtain an upper limit of 0.43% (90% confidence level) for the anthropogenic contribution, validating the stability of the atmospheric 81Kr baseline for high-precision dating applications.
This study presents direct in situ observational evidence of a cyclonic circulation cell east of Cape Santa María (CSM), in the northern Gulf of Cádiz (GoC). Three Lagrangian drifters deployed in October 2022 revealed a coherent cyclonic circulation cell with a characteristic diameter of approximately 40-45 km, consistently estimated from drifter trajectories and relative vorticity. Their trajectories showed alternating eastward and westward flows, modulated by wind variability, bathymetry, and mesoscale dynamics. Satellite observations showed a cooler, chlorophyll-a enriched core, consistent with upwelling and retention of enriched surface water masses within the circulation cell. High-resolution WRF atmospheric simulations indicated alternating easterly and westerly wind regimes that were associated with reversals in coastal circulation. Westerly winds between 18th and 24th October produced positive Ekman pumping east of CSM, creating conditions favourable to the intensification of cyclonic circulation. The IBI ocean model reproduced the main structure of the circulation cell structure, including flow accelerations near the shelf edge, and indicated upward vertical motions within the cyclonic circulation cell. A Lagrangian particle experiment suggested that the cyclonic cell favours both retention and offshore export of surface waters, with residence times of up to approximately 16 days. Overall, this study highlights the role of interactions between atmospheric forcing, bathymetry, and mesoscale dynamics in controlling small-scale surface circulation in the GoC, and underscores the value of integrating drifter observations, satellite data, and numerical models to characterize coastal dynamics.
Respiratory diseases remain a major public health challenge in tropical coastal cities, where persistent heat-humidity interactions and climate variability shape population vulnerability. This study quantified associations between atmospheric conditions and respiratory hospitalizations in Maceió, Brazil, using a 20-years time series (2000-2019). Weekly hospitalization rates stratified by age (children 0-4 years, adults 5-59 years, elderly ≥ 60 years), were modeled against meteorological variables-including temperature, relative humidity, precipitation, atmospheric pressure, and solar radiation-considering lag structure of 0, 1, and 2 weeks. Random Forest regression models were applied to capture nonlinear relationships and forecast hospitalization rates. Minimum temperature was the dominant predictor, exhibiting strong inverse associations across all age groups (ρ = - 0.65, p < 0.001), with effects persisting up to two weeks. Age-specific patterns were observed: children showed immediate sensitivity to thermal and precipitation variables, whereas elderly populations exhibited delayed responses to barometric pressure and evaporation. Model performance was high for children and adults (R2 = 0.83-0.90) and moderate for the elderly, with Symmetric Mean Absolute Percentage Error ranging from 13 to 25% across groups. Long-term trends revealed declining hospitalization rates among children and adults, contrasted by stabilization and subsequent increases in the elderly after 2010, consistent with demographic aging and increased climate sensitivity. These findings demonstrate the value of machine learning approaches for modeling complex climate-health relationships and provide a transferable framework for climate-informed respiratory risk assessment and early warning systems in tropical coastal environments.
Controlled burning of lead-acid battery plates can release lead-bearing particulate matter that disperses through the air, deposits on passive surfaces, and is transferred to edible crops. This study quantified the source-to-receptor pathway under field-calibrated conditions in Kushtia, Bangladesh, by monitoring PM2.5 and PM10 across a triangular sampling grid extending to 45 m, assessing passive Pb deposition on Whatman filter papers, and measuring Pb accumulation in red amaranth (Amaranthus tricolor L.). Three battery plates were burned per event, producing an approximate total mass loss of 149.7 ± 4.5 g. PM, deposition, and crop data all exhibited strong distance-dependent gradients, and two-way ANOVA represented significant effects of distance, time/week, and their interaction for all response variables (all p < 0.0001). PM2.5 showed the strongest distance-dependent association with both filter-paper Pb deposition and Pb accumulation in red amaranth within the sampled range, while PM10 showed significant but weaker associations within the sampled distance range. The background control plot remained below the instrumental detection limit, supporting atmospheric deposition as the dominant exposure pathway. The crop-response model showed an excellent fit (R2 = 0.948), since the Codex leafy-vegetable Pb benchmark is based on fresh weight while plant data were measured on a dry-weight basis, the threshold distance was evaluated across a plausible moisture range. Therefore, the 50 m setback is presented as a precautionary recommendation rather than a strict model-derived boundary. The findings provide a mechanistic basis for setback planning around informal battery-burning activities and highlight the food-safety risks of atmospheric Pb transfer to edible crops.
Environmental pollution remains an urgent global challenge that threatens ecosystems and human health. Silicon carbide, with its exceptional chemical inertness, excellent thermal conductivity, and highly tunable electronic structure, has emerged as a powerful dual-phase platform for environmental remediation. This paper critically reviews how precise electronic structure engineering unlocks the catalytic potential of silicon carbide architectures across both aqueous and atmospheric environments. In wastewater treatment, strategies such as constructing heterojunctions and single-atom loading are highlighted for their ability to narrow bandgaps, strengthen internal electric fields, and induce hydrogen spillover effects. These modifications successfully overcome the high dissociation energy barriers of recalcitrant contaminants like per- and polyfluoroalkyl substances. In atmospheric remediation, silicon carbide inherently eliminates thermal runaway during volatile organic compound oxidation and strategically manages temperature-dependent synergistic mechanisms for treating multi-pollutant exhausts. This work meticulously evaluates how complex real-world variables, specifically dynamic pH fluctuations, competitive inorganic anions, and the dual role of moisture, dictate catalytic efficiencies alongside advanced microwave-assisted systems. Furthermore, Density Functional Theory (DFT) calculations are integrated to elucidate the atomic-level thermodynamic barriers and site-specific cleavage pathways driving these enhanced performances. Crucially, this review exposes significant gaps in current research, notably the over-reliance on idealized reaction conditions and static theoretical models without operando validation. By bridging these mechanistic insights with real-world complexities, this paper provides a systematic roadmap for transitioning silicon carbide-based catalysts from laboratory concepts to industrially viable environmental purification technologies.
Understanding the interplay between climate variability and human activities is essential for assessing long-term river flood hazards. Yet, the relative contributions of natural and anthropogenic drivers to flood magnitude remain poorly constrained due to limited multicentury records and insufficient integration of physical mechanisms with land-use histories. Here, we present the reconstruction of a 500-y history of Yangtze River flood variability using lake sediment archives, historical documents, and high-resolution climate reanalysis data. Our results reveal that flood frequency peaked during the Little Ice Age (~1500-1850 CE), driven by a weakened Western Pacific Subtropical High (WPSH), a southward-shifted Intertropical Convergence Zone (ITCZ), and enhanced southwesterly monsoonal moisture flux into the basin. These conditions were associated with El Niño-like tropical sea surface temperature (SST) anomalies and extratropical Rossby wave activity, highlighting the role of tropical-extratropical coupling in shaping flood-prone circulation regimes. Despite increased atmospheric temperature since 1850 CE, flood frequency declined, coinciding with a strengthened WPSH, a northward-shifted ITCZ, and the dominance of La Niña-like or neutral SST patterns. A nonstationary flood frequency model reveals that embankments and lake reclamation amplified the climate-driven 100-y flood magnitude by around 18% and 8%, respectively. These findings demonstrate that human interventions have intensified, rather than mitigated, the hydrological consequences of climatic forcing. Consistent with the recognition that flood risk is inherently nonstationary, our results provide empirical, multicentennial constraints on how atmospheric dynamics and landscape modification interact to shape flood hazards, highlighting the need for process-informed flood risk assessment in large river basins.
 The nasal mucosa is the primary defense mechanism of the upper respiratory tract. Its functionality relies heavily on the intricate balance of mucociliary clearance (MCC), mucosal hydration, epithelial tight junction integrity, and local immunological responses. While the detrimental physiological effects of low humidity and cold temperatures on nasal function are extensively documented in the literature, the physiological and pathological impacts of chronic exposure to high relative humidity (RH) and high temperatures-the defining characteristics of tropical and equatorial climates-remain significantly underrepresented and poorly synthesised. Given that approximately 40% of the global population lives in these climate zones, understanding these mechanisms is of paramount importance to global health. This evidence gap is particularly critical for sub-Saharan Africa, where sinonasal disorders constitute a significant and underappreciated component of the otolaryngological disease burden, yet region-specific clinical guidelines remain largely absent. Compounding this, rapid urbanisation across African and Asian tropical cities is accelerating the adoption of air-conditioning, creating novel patterns of indoor-outdoor micro-climatic exposure that may be fundamentally altering the epidemiology of chronic rhinitis. This systematic review aims to comprehensively evaluate the correlation between high ambient humidity in tropical climates and nasal mucosal function. The primary endpoints include mucociliary clearance times, ciliary beat frequency (CBF), mucus rheology (viscoelasticity), epithelial barrier integrity, and the epidemiological prevalence of specific sinonasal disorders such as tropical allergic rhinitis and non-allergic vasomotor rhinitis. A rigorous systematic literature search was conducted in strict adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search spanned PubMed, Scopus, Web of Science, and the Cochrane Library for peer-reviewed articles published between January 1, 2000, and January 1, 2025. Inclusion criteria mandated studies evaluating human nasal mucosal physiology, MCC time, CBF, and humidity levels exceeding 70%. Risk of bias was assessed using the Newcastle-Ottawa Scale for observational studies and the Cochrane Risk of Bias tool for randomised trials. Out of 1,420 initially identified records, 45 studies met the stringent inclusion criteria for qualitative synthesis. The aggregated data indicate a complex, non-linear, U-shaped relationship between ambient RH and MCC efficiency: optimal MCC occurs between 40% and 60% RH, while chronic exposure to tropical humidity (>70% RH) combined with high ambient temperatures (>28°C) is associated with mucosal engorgement, altered mucus rheology characterised by decreased viscosity and elasticity, and a paradoxical slowing of ciliary beat frequency (CBF). Furthermore, the modern tropical lifestyle involves frequent, abrupt transitions between highly humid outdoor environments and cold, desiccating air-conditioned indoor spaces. This 'micro-climatic shock' may contribute to reactive turbinate hypertrophy, disrupted osmotic gradients, and increased susceptibility to perennial aeroallergens such as house dust mites and fungal spores. High ambient humidity in tropical climates is associated with altered nasal mucosal function, including impaired MCC and changes in mucus rheology. These findings highlight the need for climate-specific approaches to the management of sinonasal disorders. Keywords: Nasal mucosa; humidity; tropical climate; mucociliary clearance; rhinitis; air-conditioning.
Aerosol particles, profoundly influenced by human activities, play pivotal roles in air quality and climate. The formation and growth of new atmospheric particles is a leading source of high-concentration aerosol particles in urban environments and also the largest source of uncertainties in global climate predictions. Recent advances in experimental and theoretical research have dramatically improved our understanding of urban new particle formation (NPF), showing that the abundant anthropogenic pollutants in complex urban atmospheres enable the fast formation of new particles that are highly selective toward the gaseous precursors and chemical processes. The uniqueness of urban atmospheres causes the underrepresentation of urban NPF in regional and global models, while the evolving urban environments complicate the prediction of future environmental and climate effects of NPF. In this review, we link the latest molecular-level chemical mechanisms and implications on climate predictions and air pollution control by assessing the methodology to investigate urban NPF, sorting out the latest mechanistic findings, and discussing their implementation in three-dimensional models.
Rapid and accurate characterization of antimicrobial resistance is essential for effective patient treatment and outcomes. Infection-causing microorganisms often harbour multi-drug resistance, requiring multiple tests for identification. Here, we present a multiplex functional assay using liquid atmospheric pressure (LAP) matrix-assisted laser desorption/ionization (MALDI) as next-generation MALDI biotyping technology, which can accurately determine antibiotic resistance/susceptibility within three hours from <5 µL of bacterial culture, employing a beta-lactam antibiotic panel. Strains with common resistance genes, including OXA-48, KPC-3, and VIM-1, as well as susceptible isolates, are easily and reliably classified. Concurrent with multi-drug testing, the same bacterial sample provides species-identifying lipid and protein profiles (up to 100% classification accuracy) and characterization through tandem mass spectrometry (MS/MS) protein sequencing, facilitated by LAP-MALDI's ability to generate multiply charged protein ions. Detection of multiple antibiotics, their degradation products and lipids/proteins with high mass accuracy, along with the possibility of protein sequencing, offers new diagnostic possibilities for clinical microbiology and antimicrobial stewardship that are less probability-based than conventional MALDI biotyping.
According to the mass spectrometry (MS) design principles, the ions generated in an atmospheric pressure ion source must pass through a narrow-bore capillary in order to maintain the needed system vacuum pressure. The ion transmission efficiency through the inlet capillary is one of the key factors directly influencing the analytical performance of MS. Its design and operating parameters, including inner diameter, length, temperature, and those related to the ion source operation, can alter ion diffusion losses, gas flow dynamics, and space-charge effects both around and inside the inlet capillary, thereby influencing ion sampling efficiency and transmission efficiency to the mass analyzer. A comprehensive simulation of ion transmission efficiency through an MS inlet capillary has been performed in this study by adjusting the important design and operating parameters. The simulation results show that the ion transmission efficiency through the inlet capillary is positively correlated with the inner diameter of the capillary and negatively correlated with the length of the capillary. Specifically, under the conditions of a capillary diameter of 0.8 mm and a temperature of 573.15 K, the ion transmission efficiency through a 10-cm-long capillary can reach 90%. The efficiency decreases with a reduction in the inner diameter or an increase in the length. When the temperature exceeds 573.15 K, the flow field inside the capillary transits from laminar to turbulent flow, leading to a sharp decline in ion transmission efficiency. For every 100-K increase in temperature beyond this point, the ion transmission efficiency decreases by 10%-20%. The main results from this study have provided crucial design guidelines, emphasizing the use of larger diameters, moderate lengths, and strict temperature control below the turbulent transition threshold to maximize ion transmission and overall instrument sensitivity for MS instruments.
Soil salinization seriously threatens global food security with continuously expanding affected areas. Bacillus megaterium-based bioinoculant serves as an eco-friendly strategy for saline-alkali land remediation, whereas wild-type (WT) strains generally exhibit poor salt-alkali tolerance. To address this limitation, atmospheric and room temperature plasma (ARTP) mutagenesis combined with a microbial microdroplet culture (MMC) high-throughput screening system was adopted to screen high salt-tolerant B. megaterium mutant followed by multi-omics characterization. Using WT B. megaterium LD (CGMCC No.21828) as the original strain, a mutant library was constructed via optimized ARTP treatment, and the elite mutant SLD48 was isolated under dynamically increasing salt gradients. Compared with the wild type, SLD48 possesses a larger genome of 6,252,538 bp and acquires 28 extra functional genes including spoIVCA and pJ_gene0003. Intracellular osmoprotectants (proline, glycine betaine) and antioxidant α-tocopherol were markedly accumulated in SLD48. moreover, exogenous supplementation of these substances in the culture medium can effectively alleviate the damage caused by salt stress to the cells. In pot trials with saline-alkali soil, the rhizosphere colonization of SLD48 reached 3.52 × 10⁵ CFU/g (2.46-fold of LD), and maize shoot fresh weight increased by 40.5% after inoculation. Collectively, this work confirms that mutant SLD48 is a promising microbial resource for saline-alkali soil improvement and crop yield promotion.
Rising atmospheric CO2 is expected to have limited direct effects on C4 photosynthesis because the carbon-concentrating mechanism maintains near-saturating CO2 at Rubisco. Consequently, growth responses of C4 plants to elevated CO2 (eCO2) are generally attributed to indirect improvements in plant water relations. However, it remains unclear whether sustained exposure to eCO2 also induces changes in photosynthetic capacity that contribute directly to carbon gain. We examined the interactive effects of CO2 concentration and soil water availability on photosynthesis, biochemical capacity, and growth in three African C4 grasses grown under ambient (400 ppm) and elevated (550 ppm) CO2. Elevated CO2 increased net photosynthesis across species, with stronger responses under drought. Intrinsic water-use efficiency increased primarily through enhanced assimilation, while stomatal responses were contingent on water availability rather than driven directly by elevated CO2. Importantly, eCO2 induced species- and context-dependent increases in apparent photosynthetic capacity after prolonged treatment exposure. Megathyrsus maximus showed strong Vcmax increases under both water treatments and Jmax upregulation under well-watered conditions, Heteropogon contortus exhibited biochemical upregulation primarily under drought, and Themeda triandra showed little evidence of acclimation. Growth responses closely mirrored these physiological patterns, occurring only in species exhibiting coordinated biochemical adjustment. These results indicate that C4 responses to eCO2 cannot be explained solely by stomatal water saving and provide evidence that species-specific changes in apparent photosynthetic capacity may contribute to sustained carbon gain, particularly under water limitation.
Small insects utilize atmospheric flows to facilitate appetitive and migratory behaviors. In the convective and nocturnal boundary layers, these insects may experience high-speed updrafts which can present significant aerodynamics challenges. While it is known from field observations that small insects resist these updrafts, how they do so while maintaining flight stability is unknown. Here we investigate the flight behavior of two insect species, the 3-mm fruit fly (Drosophila melanogaster) and the 2-mm fungus gnat (Lycoriella ingenua), while exposed to quiescent air and to a steady 0.433 m s-1 upwards flow within a vertical wind tunnel. We used high-speed 3D photogrammetry to capture flight trajectories and wing and body kinematics. Both species maintained a constant vertical flight velocity in quiescent conditions and in the updraft by maintaining a consistent beat frequency while significantly reducing their stroke amplitude (and thus saving energy), though with some size-specific differences. The smaller fungus gnats kept the dorsal portion of their stroke more so than the larger fruit flies, thereby maintaining the lift-generating clap-and-fling mechanism which is generally required at the lower Reynolds numbers at which they operate. Both species also maintained a similar relative flow velocity, which combines wing tangential velocity and animal velocity with respect to the free stream. Finally, the updraft somewhat affected flight stability in the fungus gnat (as seen in its more sinuous flight trajectories) but not in the fruit fly, which did not change the sinuosity of its trajectories in the updraft. These findings provide a bridge between large- and small-scale studies of small insects in the atmosphere.
The adsorption and photocatalytic conversion of CO2 molecules to mitigate atmospheric greenhouse gas concentrations and manufacture value-added chemicals require efficient CO2 reduction reaction catalysts. In this study, a surface bond competition approach was developed to obtain high-performance CO2 adsorbents and syngas production photocatalysts via the sulfurization-driven enhancement of surface basicity and interfacial interaction. The heat treatment of Mg-Al-layered double hydroxide nanosheets under a flow of CS2 yielded sulfur-doped MgO/MgAl2O4Sx nanosheets. The sulfur-doping-induced enhancement of surface basicity originated from the increased electron density on oxygen through competition with covalent metal-sulfur bonds, substantially enhancing the CO2 adsorptivity. The sulfur-doped MgO/MgAl2O4Sx nanosheets acted as effective hybridization matrices for ZnIn2S4 nanoplates, boosting their activity for photocatalytic syngas production (i.e., ≈3.3 mmol g-1 h-1 with the ratio of CO/H2 = 2.2). Density functional theory calculations revealed that hybridization with MgO/MgAl2O4Sx nanosheets was effective in lowering both the adsorption energy of CO2 and the energy barrier for the conversion of *COOH to *CO. Systematic in situ spectroscopic investigations highlighted that the hybridization with MgO/MgAl2O4Sx enhanced Lewis acid-base interaction between ZnIn2S4 and absorbed CO2, and the contribution of associative pathways, which were attributed to sulfur-doping-assisted reinforcement in interfacial electronic coupling between hybridized components.
Wildfires are widely known to deteriorate air quality by increasing particulate matter concentrations both locally and in downwind regions. However, wildfire-induced decreases in particulate matter remain poorly understood. In this study, we investigated a reduction in sulfate (SO42-) concentrations observed over Northeast Asia during the Siberian wildfire event in July 2014. The Community Multiscale Air Quality (CMAQ) model was applied in conjunction with the high-resolution Fire INventory from the National Center for Atmospheric Research (FINN) to simulate wildfire emissions and their impacts. Large amounts of pollutants emitted from the Siberian wildfires were transported over long distances, generally leading to increases in particulate matter concentrations across Northeast Asia. However, during 26-29 July 2014, an unusual decrease in SO42- concentrations of up to -1.56 μg m-3 was identified over Northeast China, the Shandong Peninsula, and the Yellow Sea. This decrease was attributed to the scavenging of hydroxyl radicals (OH) by wildfire-emitted gaseous species such as CO and volatile organic compounds (VOCs), which suppressed the oxidation of anthropogenic SO2 and consequently reduced sulfate formation. Source apportionment analysis revealed that the reduced sulfate originated predominantly from inland anthropogenic SO2 emissions (92.30%), with a smaller contribution from oceanic sources (7.70%). These findings demonstrate that wildfire emissions can reduce secondary inorganic aerosol formation in downwind regions through complex chemical interactions with anthropogenic pollutants. This mechanism has important implications for PM2.5 composition and air quality management in Northeast Asia, where inorganic aerosols constitute a substantial fraction of fine particulate matter.
The inherent resistance of low-density polyethylene (LDPE) to degradation leads to its continued accumulation in the natural environment. The present study evaluates an integrated approach coupling cold atmospheric plasma (CAP) pretreatment with hydrocarbon-driven biostimulation to accelerate microbial degradation of LDPE. The degradation of untreated and pretreated LDPE was analyzed in Winogradsky columns with diesel as a co-substrate. After 45 days, the system containing both pretreated LDPE and diesel (W4) showed the highest LDPE weight loss (4.22 ± 0.73%), outperforming systems with only CAP-pretreated LDPE (3.06 ± 0.99%) and untreated LDPE with diesel (1.14 ± 0.39%). The LDPE sheet in the W4 system also exhibited an increase in hydrophilicity, indicated by a reduction in the water contact angle (52.43 ± 7.15°) as compared to the unaided system (70.03 ± 3.80°). The appearance of carbonyl functional groups, together with ester formation detected by GC-MS, further confirmed advanced LDPE oxidation in the W4 system. The synergistic LDPE treatment resulted in a decrease in crystallinity from 0.50 ± 0.06 (untreated LDPE) to 0.39 ± 0.01. Moreover, the enzymes involved in LDPE depolymerization, including laccase, manganese peroxidase, alkane monooxygenase, and cutinase, showed elevated activity under biostimulated conditions. The LDPE-degrading microbes were dominated by Gammaproteobacteria, Bacilli, Alphaproteobacteria, and Actinobacteria. Further, the amplification of cAMP signaling, secondary metabolite biosynthesis, and the ether lipid metabolism pathway in the W4 system supported enhanced microbial adaptation to LDPE. The synergy of plasma pretreatment with biostimulation for LDPE degradation offers a low-energy, environmentally sustainable approach that surpasses the performance of each method used independently.
Biological nitrogen fixation (BNF) by diazotrophs contributes to increasing nitrogen (N) availability in nutrient-poor deadwood during the decomposition process. However, chronically elevated atmospheric N deposition may increase N availability, thereby reshaping diazotrophic community and suppressing BNF. We simulated high N deposition by repeatedly applying ammonium-nitrate solution to deadwood of 13 tree species over 9 years (N addition) and compared diazotrophic community composition and BNF rates with untreated controls. Deadwood N concentrations increased over time in both control and N addition, with N addition resulting in higher N concentrations at the final sampling, although significant treatment effects were detected only in Tilia and Pinus. Chronic high-N addition was associated with reduced BNF activity, with significant suppression primarily observed in coniferous deadwood, while responses among broadleaved species were weak, variable, or absent. The N addition altered diazotroph richness and community composition by increasing the abundance of Bradyrhizobium and by reducing Methylocapsa across all tree species. Under N addition, BNF correlated positively with nifH gene copy numbers in broadleaved deadwood but negatively in coniferous deadwood. Co-occurrence networks were more interconnected and modular under N addition, with diazotrophs (e.g., Azospirillum) central in broadleaved deadwood and fungi (e.g., Meliniomyces, Athelia) central in coniferous deadwood. Tree clade (coniferous vs. broadleaved) strongly shaped richness and community response, with broadleaved and coniferous species showing distinct patterns.Overall, the largely robust diversity and community composition of diazotrophs and BNF activity under high N addition suggest that moderately increasing N deposition has little influence on fungal deadwood decomposition and the function of deadwood as a carbon pool in forest ecosystems.