Atmospheric Environment最新文献

{"title":"Establishing a national network for atmospheric mercury monitoring: preliminary spatial and temporal insights from Italy","authors":"Mariantonia Bencardino ,&nbsp;Antonella Tassone ,&nbsp;Maria Martino ,&nbsp;Francesco D’Amore ,&nbsp;Teresa Sprovieri ,&nbsp;Carmine Ungaro ,&nbsp;Virginia Andreoli ,&nbsp;Giulio Esposito ,&nbsp;Giorgio Siliprandi ,&nbsp;Guido Lanzani ,&nbsp;Lorenzo Angiuli ,&nbsp;Alessandra Nocioni ,&nbsp;Cristina Leonardi ,&nbsp;Francesca Sprovieri ,&nbsp;Nicola Pirrone","doi":"10.1016/j.atmosenv.2025.121477","DOIUrl":"10.1016/j.atmosenv.2025.121477","url":null,"abstract":"<div><div>In compliance with European air quality regulations and the Italian “Reti Speciali” agreement, a dedicated network of three strategically positioned monitoring stations was established in 2012. Designed to account for geographical variability, this network enabled the first coordinated sampling campaigns for atmospheric mercury (Hg) data in ambient air and deposition. The resulting representative nationwide data, collected from 2020 to 2023, enabled the detection of seasonal, temporal, and spatial variations, which are analyzed in this study. Throughout the observational period, atmospheric Hg levels varied among the stations, exhibiting annual mean values between 1.22 ± 0.25 and 2.01 <span><math><mrow><mo>±</mo><mspace></mspace><mn>0</mn><mo>.</mo><mn>42</mn><mspace></mspace><msup><mrow><mi>ng/m</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></math></span>. A notable decrease in concentrations was evident in the northern and central regions. Conversely, the southern station maintained relatively stable levels, likely attributable to the predominant influence of natural sources. Ambient air Hg concentrations were examined for the impact of potential sources, with analysis conducted at both synoptic and local scales. Long-range transport pathways were identified using Potential Source Contributing Function (PSCF) analysis, while local investigations incorporated meteorological parameters, ozone measurements, and nearby fire hot-spot data. Analysis of samples from Hg deposition monitoring campaigns (2021 - 2023) revealed total mercury deposition values below 20 <span><math><mrow><msup><mrow><mi>ng/m</mi></mrow><mrow><mn>2</mn></mrow></msup><mi>d</mi></mrow></math></span>. These efforts, which involved four sampling sessions per year at each station, showed that seasonal variations were primarily influenced by rainfall patterns.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121477"},"PeriodicalIF":3.7,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physicochemical characterization and risk assessment of indoor particulate matter in academic canteens: comparison with outdoor and insights from aerosol mass spectrometer","authors":"Debayan Mandal ,&nbsp;Abhishek Chakraborty ,&nbsp;Shruti Tripathi ,&nbsp;Sachchida Nand Tripathi","doi":"10.1016/j.atmosenv.2025.121490","DOIUrl":"10.1016/j.atmosenv.2025.121490","url":null,"abstract":"<div><div>This study investigates the physicochemical properties and potential health impacts of fine particulate matter (PM_2.5) in three canteens (C1, C2, and C3) within an academic cum residential campus. This study comprehensively evaluated PM_2.5 levels, chemical composition, and associated health risks. PM_2.5 concentrations were significantly elevated in the facilities, exceeding outdoor levels by 200–400 %. Aerosol mass and number size distributions exhibited lognormal patterns, with modes in the fine particle range (&lt;2.5 μm). Mean organic carbon (OC) concentrations were 45.44 (±14.29) μg/m³, 23.96 (±5.58) μg/m³,and 23.58(±3.98) μg/m³ in the C1,C2, and C3 respectively. Elemental carbon (EC) levels were 10.61 (±2.24) μg/m³, 9.88 (±1.30) μg/m³, and 8. 58(±0.77) μg/m³ in C1, C2, and C3 respectively. Secondary organic carbon (SOC) was found to be less prevalent than primary organic carbon (POC) in all the canteens. Overall, PM_2.5 compositions were dominated by organics (&gt;40 %) followed by elements and ions, though relative proportions varied significantly. Water-soluble organic carbon (WSOC) constituted over 60 % of OC in the canteens and 50 % in the outdoor location. Aerosol Mass Spectrometer (AMS) analysis showed 8–9 times higher N/C ratios in the canteens compared to outdoor environments. Organic aerosol evolution also showed stark differences between canteens and outdoor environments. Elemental analysis revealed significant concentrations of toxic and carcinogenic elements in canteens. The total respiratory deposited dose (TRDD) was found to be approximately 3 times higher in C1, 2 times higher in C2, and 1.5 times higher in C3 compared to the outdoor location. This comprehensive study of indoor particulate matter in canteens provides novel and crucial insights into air quality and potential health implications in these unique microenvironments.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121490"},"PeriodicalIF":3.7,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-resolution anthropogenic emission inventory for China (2015–2024): Spatiotemporal changes and environmental application","authors":"Dongpu Li ,&nbsp;Hongli Liu ,&nbsp;Guo Duan","doi":"10.1016/j.atmosenv.2025.121495","DOIUrl":"10.1016/j.atmosenv.2025.121495","url":null,"abstract":"<div><div>Anthropogenic emission inventories serve not only as key inputs for chemical transport models but also as essential tools for evaluating the effectiveness of emission control measures. Here, this study employed the emission inventory from Chinese Unified Atmospheric Chemistry Environment model (CCES) to analyze the spatiotemporal characteristics of China's anthropogenic emissions from 2015 to 2024, and to evaluate its performance in simulating aerosols and their gaseous precursors. Furthermore, this study compared CCES with the Multi-resolution Emission Inventory for China (MEIC) and the Emissions Database for Global Atmospheric Research (EDGAR) to explore the emission discrepancies. National total anthropogenic emissions declined markedly over the decade: sulfur dioxide (SO₂) dropped by 60.8 %, while emissions of nitrogen oxides (NO_x), particulate matter with an aerodynamic diameter ≤10 μm (PM₁₀) and ≤2.5 μm (PM_2.5), carbon monoxide (CO) and ammonia (NH₃) decreased by 19.9–42.6 %. The three inventories exhibited decreases during 2015–2020, but the reduction rates for SO₂, PM_2.5 and PM₁₀ slowed after 2018. Although the inventories diverged substantially in absolute magnitude, they displayed nearly identical seasonal patterns. Relative to MEIC, EDGAR reported higher industrial SO₂ emissions, whereas CCES yielded higher traffic-related NO_x emissions. CCES-driven simulations reproduced spatiotemporal variability of SO₂, nitrogen dioxide (NO₂) and PM_2.5 concentrations, albeit with negative biases for SO₂ and PM_2.5 and a positive bias for NO₂ at most monitoring sites. Despite these remaining uncertainties, CCES can capture the dominant spatiotemporal patterns of China's emissions and thus provide valuable insights into their variability.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121495"},"PeriodicalIF":3.7,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insight into the characteristics and source apportionment of PM2.5 oxidative potential over Xi'an, China","authors":"Gezi Bai ,&nbsp;Zhenxing Shen ,&nbsp;Jie Liu ,&nbsp;Shasha Huang ,&nbsp;Jian Sun ,&nbsp;Diwei Wang ,&nbsp;Hongai Zhang ,&nbsp;Liu Yang ,&nbsp;Hongmei Xu","doi":"10.1016/j.atmosenv.2025.121489","DOIUrl":"10.1016/j.atmosenv.2025.121489","url":null,"abstract":"<div><div>The oxidation potential (OP) of PM_2.5 increased the prevalence of respiratory and pulmonary diseases of human health. In this study, high-time-resolution sampling was conducted in summer and winter in Xi'an, and the dithiothreitol (DTT) assay was employed to quantify PM_2.5 OP. The results showed that winter PM_2.5 OP was more twice than summer, and nighttime OP was higher than daytime both in summer and winter. In summer, the mass-normalized DTT consumption rate (DTT_m) exhibited two peaks at 4:00–8:00 and 12:00–16:00. In winter, high DTT_m appeared during the nighttime periods (20:00–4:00). Functional group revealed that peak areas of R-ONO₂, aromatic C=C, and C=O from ketones, quinones and amides had consistent trends with DTT values in summer, confirmed that nitrogenous organic aerosols enhanced the oxidative activity. While on winter night, the high peak areas of O-H, aliphatic C-H, polysaccharide C-O, and deformation of aromatic C-H coincided with DTT_m variation, inferred these function groups had an important effect on OP. The Multi-Layer Perceptron (MLP) model results revealed that vehicle emission was the largest contributor to DTT activity both in summer (33 %) and winter (34 %). In summer, vehicle emission contributed the most between 16:00–20:00 and 0:00–4:00. Secondary formation contributed significantly during daytime (31 %–34 %). Vehicle emission contributed the most between 12:00–16:00 and 0:00–4:00 in winter. Combustion emissions contributed significantly during night-time (29 %–36 %). This study links OP with chemical components and source contributions, offering critical insights into health risks associated with PM_2.5 exposure.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121489"},"PeriodicalIF":3.7,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144842372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rethinking environmental boundaries for contaminants of emerging concern","authors":"Ivan Kourtchev ,&nbsp;Max R. McGillen ,&nbsp;John Wenger ,&nbsp;Neil M. Donahue","doi":"10.1016/j.atmosenv.2025.121492","DOIUrl":"10.1016/j.atmosenv.2025.121492","url":null,"abstract":"<div><div>The global proliferation of synthetic chemicals has led to the widespread and continuous release of Contaminants of Emerging Concern (CECs) into the environment. CECs include pharmaceuticals, pesticides, personal care products and other industrial chemicals that pose a significant risk to both ecosystems and human health. Regulatory frameworks have predominantly targeted aquatic systems; however, mounting evidence reveals the capacity of many CECs to volatilise, aerosolise and undergo atmospheric transport. This perspective highlights the overlooked atmospheric dimension of CECs and analyses the key physicochemical parameters governing their transfer to the atmospheric domain. The results indicate that many CECs can mobilise from water or soil and undergo atmospheric transport in both the gas- and particle-phase, crossing between several environmental continua as a result. While intrinsic properties such as vapour pressure and partitioning coefficients are central to this analysis, environmental factors such as temperature, humidity, solar radiation, and transformation reactions further modulate the environmental fate and impact of CECs. We emphasise the need for environmental monitoring and regulatory frameworks to incorporate air as a critical vector for CEC dispersion and exposure. Key research priorities identified measurements of CECs in the atmosphere, further development of predictive models, and toxicity evaluation of airborne CECs to better inform policy for protecting public and environmental health.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121492"},"PeriodicalIF":3.7,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of the net mitigation effect of vegetative environmental buffer (VEB) to reduce ammonia and particulate matter (PM) emissions","authors":"Zijiang Yang ,&nbsp;Qi Yao ,&nbsp;Cathleen J. Hapeman ,&nbsp;Hong Li ,&nbsp;Joseph G. Alfieri ,&nbsp;Michael D. Buser ,&nbsp;Laura L. McConnell ,&nbsp;Peter M. Downey ,&nbsp;Alba Torrents","doi":"10.1016/j.atmosenv.2025.121488","DOIUrl":"10.1016/j.atmosenv.2025.121488","url":null,"abstract":"<div><div>Concentrated animal feeding operations (CAFOs), such as poultry farms, contribute significantly to air pollution, particularly ammonia (NH₃) and particulate matter (PM) emissions. Vegetative environmental buffers (VEBs) offer a sustainable, cost-effective, and low-maintenance solution for mitigating NH₃ and PM emissions from CAFOs, and some previous studies showed that pollutant concentrations behind the VEBs were substantially reduced compared with concentration directly from the source. However, due to the lack of a controlled dataset for non-VEB situations, the net effect of VEBs could hardly be assessed. Thus, the dataset from the previous study was used to develop a methodology for quantitatively evaluating the efficacy of VEBs in reducing NH₃ and PM emissions from a poultry house, and to distinguish the net pollutant reduction achieved by VEBs from those resulting merely from atmospheric dilution and dispersion. The results showed that VEB can effectively mitigate air pollutants emissions and attributes enhanced ground-level reductions of NH₃ (72.7 % ± 9.1 %), total suspended particle (TSP) (61.9 % ± 10.0 %), PM₁₀ (62.5 % ± 9.9 %) and PM_2.5 (94.6 % ± 6.5 %). In addition, VEB demonstrated better mitigation performance during daytime. Meteorological conditions showed no correlation with pollutant concentrations or enhanced reduction ratios while significant positive correlations between reductions of NH₃ and PM were also observed. These results demonstrated that VEBs are effective in reducing NH₃ and PM emissions from poultry houses. The results from this study will inform conservation practice guidelines and assist land managers in employing VEBs for poultry house emitted air pollution reductions.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121488"},"PeriodicalIF":3.7,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparing alder, birch and grass pollen concentrations derived from spatiotemporal statistical and dispersion models across Switzerland","authors":"Behzad Valipour Shokouhi ,&nbsp;Kees de Hoogh ,&nbsp;Danielle Vienneau ,&nbsp;Regula Gehrig ,&nbsp;Andreas Pauling ,&nbsp;Marloes Eeftens","doi":"10.1016/j.atmosenv.2025.121486","DOIUrl":"10.1016/j.atmosenv.2025.121486","url":null,"abstract":"<div><div>While several studies have compared the performance of statistical and dispersion modelling methods for air pollution, none have done so for pollen.</div><div>We developed a statistical machine learning model for daily pollen concentrations of five highly allergenic pollen types (hazel, alder, birch, ash, and grasses) across Switzerland (2000–2023). Daily average predictions for grass, alder and birch pollen were available for 2017–2023 from the COSMO-ART dispersion model, the operational forecast model at the Swiss Federal Office of Meteorology and Climatology. In this study, we have compared estimated concentrations for overlapping pollen types and years at three levels: (1) pollen measurement stations, (2) a 1 × 1 km national grid, and (3) residential addresses of the Swiss National Cohort.</div><div>At the grid and cohort address levels, statistical and dispersion models showed a strong correlation for grass (0.75) and birch (0.70) pollen and a moderate correlation for alder pollen (0.41). Cross-validated Pearson's correlations between statistically modelled and measured pollen concentrations ranged from 0.80 (alder), 0.85 (birch) to 0.86 (grass), with root-mean-squared logarithmic error (RMSLE) values of 0.33, 0.31 and 0.35, respectively. Pearson correlations between COSMO-ART predictions and measured concentrations were 0.41 (alder), 0.75 (birch) and 0.63 (grass), with the highest RMSLE of 0.88 for alder pollen, while RMSLEs of grass and birch models were 0.63 and 0.67, respectively.</div><div>Statistical models showed higher agreement with measured pollen concentrations at stations than COSMO-ART for all pollen types. Correlations between the two models were high for grass and birch pollen predictions, but notably lower for alder pollen.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121486"},"PeriodicalIF":3.7,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ice core evidence of rapid climate and environmental changes on the Tibetan plateau","authors":"Yulan Zhang ,&nbsp;Shichang Kang","doi":"10.1016/j.atmosenv.2025.121483","DOIUrl":"10.1016/j.atmosenv.2025.121483","url":null,"abstract":"<div><div>Ice core records from the Tibetan Plateau (TP) provide regional indicators of climatic and environmental changes and permit reconstruction of variations in human-made atmospheric pollutants during past hundreds of years. To comprehensively understand the TP's climate and environment history, we addressed the past climate and environmental changes reconstructed by ice core evidences, focusing on the variations of anthropogenic pollutants (e.g., mercury, black carbon). Since the 1980s, more than 40 ice cores across the TP have been drilled and some of them are investigated. Key benchmarker layers within the TP ice cores, such as peak values of <em>ß</em>-activity and tritium in 1963 AD, provide effective means for precise dating. The TP ice core reconstructions revealed the recent warming from the 1900s with different warming rate on the southern or northern TP, which were also affected by the large-scale atmospheric circulations. Emissions of human-related pollutants have seriously affected and altered Earth's environment and shown an increasing trend in the TP ice cores, especially since the 1950s. These existed variability of the reconstructions among ice cores in different TP regions was mainly controlled by interactions between the South Asian monsoon and westerly intensity. We also discussed the uncertainties of TP ice core dating currently, highlighting the recent rapid climate warming is threatening ice core archives. In the future, new techniques for dating and chemical analysis should be explored and more ice core archives should be obtained for the next generation.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121483"},"PeriodicalIF":3.7,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144828297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the causal relationship between air pollution and aortic disease risk: a multivariable Mendelian randomization analysis","authors":"Yilin Pan ,&nbsp;Zhaobin Sun ,&nbsp;Junwen Chen ,&nbsp;Long Feng ,&nbsp;Tai Huang ,&nbsp;Xiaonan He","doi":"10.1016/j.atmosenv.2025.121485","DOIUrl":"10.1016/j.atmosenv.2025.121485","url":null,"abstract":"<div><div>Understanding the impact of air pollution on aortic diseases such as aortic dissection (AD) and aortic aneurysm (AA) is crucial given their high morbidity and mortality rates. This study leverages Mendelian randomization (MR) to explore the causal relationships between various air pollutants and the risk of developing AD and AA. Utilizing genetic variants as instrumental variables from comprehensive genome-wide association studies (GWAS), we conducted both univariate and multivariable MR analyses. Our findings indicate a significant positive association between increased exposure to PM_2.5 and an elevated risk of AD. Conversely, other investigated relationships did not show significant causal effects. These results underscore the critical need for public health interventions and policies aimed at reducing exposure to air pollutants to prevent serious aortic conditions. The insights provided by this study have important implications for air quality management and public health strategies.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121485"},"PeriodicalIF":3.7,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144842371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impacts of aerosol acidity and liquid water content on secondary inorganic aerosol pollution in East Asian megacities: Beijing and Seoul","authors":"Junrui Wang ,&nbsp;Zhijun Wu ,&nbsp;Tao Qiu ,&nbsp;Ruiqi Man ,&nbsp;Taomou Zong ,&nbsp;Yanting Qiu ,&nbsp;Wenxu Fang ,&nbsp;Shiyi Chen ,&nbsp;Dapeng Liang ,&nbsp;Mijung Song ,&nbsp;Junyoung Ahn ,&nbsp;Jiyi Lee ,&nbsp;Min Hu","doi":"10.1016/j.atmosenv.2025.121479","DOIUrl":"10.1016/j.atmosenv.2025.121479","url":null,"abstract":"<div><div>Despite considerable progress in air quality improvement, fine particulate matter (PM_2.5) pollution remains prevalent during the autumn and winter seasons in eastern Asian megacities: Beijing and Seoul. Here, we conducted synchronous field observations of PM_2.5 chemical composition in Beijing and Seoul as part of the FRIEND Project, spanning the period from November 10th to December 10th, 2022 and we aimed to understand sulfate, nitrate, and ammonium (SNA) formation mechanism. The observations revealed that SNA, especially nitrate, were the primary contributor to particle matter pollution, accounting for 66 % and 76 % of PM_2.5 in Beijing and Seoul, respectively, during pollution period (PM_2.5&gt;60 μg/m³). This indicated secondary inorganic aerosol formation was a key driver to force the urban fine particulate matter pollution in eastern Asian megacities. We found that the enhanced aerosol liquid water content (ALWC) during pollution episode facilitated SNA formation, then, contributing to the PM_2.5 pollution. Such phenomenon was found in both cities. Aerosol acidity in Seoul was higher than that of in Beijing, leading to the different sulfate formation pathways. During observed pollution episode, liquid-phase sulfate was primarily formed through oxidation by transition metal ions (TMI) and hydrogen peroxide (H₂O₂) in Beijing, while in Seoul, sulfate was mainly formed through TMI-catalyzed oxidation. Nitrate primarily existed in the particulate phase during pollution period with ambient relative humidity larger than 60 % in Beijing. In contrast, around 20 % of nitrate was still in the gas phase in Seoul due to low aerosol pH. The sensitivity analysis of particulate matter to precursors in both cities highlighted the needs for differentiated management strategies to reduce NOx and NH₃ emissions under varying ALWC and pH conditions.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"361 ","pages":"Article 121479"},"PeriodicalIF":3.7,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144828298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}