Atmospheric Environment最新文献

{"title":"Sugars in clouds: Measurements and modelling investigation of their aqueous photodegradation","authors":"Angelica Bianco ,&nbsp;Lucas Pailler ,&nbsp;Muriel Joly ,&nbsp;Anne-Marie Delort ,&nbsp;Sophie Darfeuil ,&nbsp;Jean-Luc Jaffrezo ,&nbsp;Laurent Deguillaume","doi":"10.1016/j.atmosenv.2025.121167","DOIUrl":"10.1016/j.atmosenv.2025.121167","url":null,"abstract":"<div><div>Currently, studies show that only 10–30% at best of the organic matter dissolved in cloud water is characterized and sugars are among the compounds still unexplored. Numerous studies on the atmospheric particulate matter (PM) demonstrate their ubiquity, and their incorporation into cloud phase is therefore expected in light of their solubility.</div><div>In this work, a large array of sugars are measured at low concentration levels with an innovative LC-MSMS technique in 28 cloud water samples collected at the puy de Dôme and their environmental variability is analyzed. The total sugar concentration reaches 4.0 μmol L⁻¹, with an average value of 0.98 ± 0.94 μmol L⁻¹, with no clear seasonal trend. This represents on average 1.2% of dissolved organic carbon but reaches up to 3.7% for one sample. The most abundant sugars is levoglucosan (average 247.2 nmol L⁻¹) followed by glucose (168.2 nmol L⁻¹), mannitol (136.5 nmol L⁻¹) and 2-methyl-tetrols (130.6 nmol L⁻¹). Reactivity in the aqueous phase is simulated with the cloud chemistry model CLEPS to gain insights in the half-life time of four selected compounds in different meteorological and chemical scenarios. Results show a fast degradation of sugars in the aqueous phase, especially during summer, that could question the use of these tracers for long range transport in the free troposphere.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121167"},"PeriodicalIF":4.2,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vertical distribution and seasonal variations of dicarboxylic acids in urban PM2.5: Insights from multi-level observations on 600 m Canton tower in Guangzhou","authors":"Dian Ye ,&nbsp;Shengzhen Zhou ,&nbsp;Yuxuan Liang ,&nbsp;Chunlei Cheng ,&nbsp;Chenglei Pei ,&nbsp;Yao Li ,&nbsp;Min Gao ,&nbsp;Xijing Sun ,&nbsp;Siqi Chen ,&nbsp;Jian Hang ,&nbsp;Pingqing Fu ,&nbsp;Shaojia Fan","doi":"10.1016/j.atmosenv.2025.121166","DOIUrl":"10.1016/j.atmosenv.2025.121166","url":null,"abstract":"<div><div>Dicarboxylic acids are important constituents of organic aerosols, but the lack of their seasonal and vertical distribution hinders thorough knowledge of atmospheric physicochemical behavior. This study examines dicarboxylic acids at three heights (∼3, 118, and 488 m) on the 600 m high Canton Tower in urban Guangzhou, aiming to illustrate their primary sources and formation pathways across different seasons and heights. The concentration of dicarboxylic acids (678.7 ± 351.9 ng m⁻³) was lower or comparable to those in domestic cities but higher than in remote aeras. Oxalic acid had the highest concentration, with malonic, succinic, glyoxylic, and azelaic acids following. Most dicarboxylic acids peaked in autumn, following by winter, spring and summer. Higher dicarboxylic acids were observed at upper layers. The C₃/C₄ (1.5 ± 0.5) was relatively higher, and the proportion of C₂ in dicarboxylic acids increased with height. Our results showed that combustion and secondary conversion were primary sources of dicarboxylic acids in dry season, while biomass combustion and secondary formation processes dominated during wet season. Significant gas-phase oxidations were prevalent during summer, while aqueous-phase formations were prominent in spring. Aerosol aging process played an important role at higher atmospheric levels throughout the year, suggesting an enhanced atmospheric oxidation capacity in upper boundary layers. These vertical profiling measurements enable the identification of predominant origins and formation pathways of dicarboxylic acids across different seasons and boundary layer dynamics. The findings provide critical insights for understanding atmospheric chemical evolution processes, validating atmospheric models, and developing effective air pollution mitigation strategies.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121166"},"PeriodicalIF":4.2,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620007","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":"Environmental benefit assessment of vehicle electrification in the fuel cycle: A case study of Chengdu","authors":"Zhaoyang Fan ,&nbsp;Hui Tong ,&nbsp;Naixiu Sun ,&nbsp;Yangxin Xiong ,&nbsp;Xuan Qu ,&nbsp;Hongjun Mao ,&nbsp;Jianfei Peng","doi":"10.1016/j.atmosenv.2025.121148","DOIUrl":"10.1016/j.atmosenv.2025.121148","url":null,"abstract":"<div><div>In recent years, vehicle emissions have emerged as one of the most significant sources of air pollutants and CO₂ in Chinese cities. Promoting electric vehicles (EVs) has become a critical strategy for mitigating vehicle-related pollution. While replacing conventional internal combustion engine vehicles (ICEVs) with EVs reduces on-road emissions, the associated increase in electricity consumption and power plant emissions may introduce negative environmental impacts. Overlooking emissions from the upstream fuel production stage can lead to overestimating the benefits of vehicle electrification policies. Therefore, it is essential to comprehensively quantify the environmental effects of electric vehicle promotion policies during the whole fuel cycle. Given that generation emissions are closely tied to the electricity mix, Chengdu (a city with over 85% hydropower) was selected as a pilot city for this study. The research follows a structured approach of ‘emission inventory establishment - air quality simulation - environmental benefit assessment - policy scenario analysis'. We systematically account for fleet emissions in Chengdu over the fuel cycle, simulate pollutant concentrations using the SMOKE-WRF-CMAQ model, estimate premature deaths through the GEMM model with Chinese population distribution data, and evaluate energy-saving and carbon-reduction potentials under various scenarios. The findings reveal that the Electricity Vehicles (EV) scenario reduces annual GHG-100 emissions by nearly 80% compared to the Business As Usual (BAU) scenario, while the Electricity Vehicles with Low-Carbon power grid (EVLC) scenario brings an additional 2.3% reduction. The EV policy significantly reduces PM_2.5, NO_X, and SO₂ concentrations in Chengdu's central urban area but leads to a notable increase in O₃ levels. These differences are further amplified when considering population-weighted concentrations, reflecting fluctuations in population prevalence. Finally, we monetise the impacts of pollutant and greenhouse gas emissions using the Value of a Statistical Life (VSL) and Social Cost of Carbon (SCC), estimating that the promotion of EVs avoids approximately 3913 million yuan in economic losses. These results provide a theoretical foundation and data support for the scientific promotion of vehicle electrification policies and the formulation of low-carbon green development strategies for urban transport in Chengdu.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121148"},"PeriodicalIF":4.2,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592958","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":"Deciphering aerosol carbon fractions in PM2.5 & PM10 and their possible sources in Eastern Himalaya region","authors":"Sweta Kumari ,&nbsp;Anirban Middey","doi":"10.1016/j.atmosenv.2025.121165","DOIUrl":"10.1016/j.atmosenv.2025.121165","url":null,"abstract":"<div><div>This study provides a comprehensive assessment of particulate matter (PM10 and PM2.5) and their carbonaceous fractions-organic carbon (OC) and elemental carbon (EC), across the Sikkim Himalaya region during the summer and winter of 2022. Sampling was conducted at four strategically selected locations: Gangtok (1151m), Pelling (1962m), Mangan (1353m), and Lachen (2740m). Due to harsh winter condition, Lachen was inaccessible, limiting winter sampling to the remaining three sites. Quartz filter-based low volume air sampling was employed to ensure high precision data collection. Annual average concentrations of PM2.5 exceeded the National Ambient Air Quality Standards (NAAQs) of 40 μg/m³, with the values of 66.48 ± 10.81 μg/m³ (Gangtok), 42.05 ± 17.48 μg/m³ (Pelling), and 61.39 ± 13.24 μg/m³ (Mangan). PM10 levels followed a similar trend: 89.99 ± 12.04 μg/m³ (Gangtok), 58.64 ± 20.17 μg/m³ (Pelling), 82.71 ± 14.94 μg/m³ (Mangan). Winter exhibited significantly higher OC and EC concentrations, especially in Gangtok, attributed to intensified vehicular emissions and biomass burning. The OC/EC ratio exceeding 2 in winter suggests enhanced secondary organic carbon formation, predominately from biomass and coal combustion. Gangtok exhibits the highest SOC/OC ratio, indicating enhanced secondary organic aerosol formation, likely due to higher anthropogenic emissions or favourable atmospheric conditions. In contrast, lower SOC/OC ratios in Pelling and Mangan suggest weaker atmospheric processing or lower VOC emissions. Correlation analysis indicates primary emissions as the dominant source of OC and EC, with transboundary pollution playing a critical role. Air mass Trajectory analysis highlights substantial pollution transport from Afghanistan, and the Indo-Gangetic plain, emphasizing the regional impact on Himalayan air quality. This study underscores, the urgent need for integrated air quality management strategies to mitigate both local and cross-border pollution, safeguarding the fragile Himalayan ecosystem and public health. A combination of emission control policies, real-time monitoring, and predictive modelling is essential to address the escalating air pollution crisis in this ecologically sensitive region.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121165"},"PeriodicalIF":4.2,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636633","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":"Spatial and seasonal variations and trends in carbon monoxide over China during 2013–2022","authors":"Yanlun Xie ,&nbsp;Han Han ,&nbsp;Jane Liu","doi":"10.1016/j.atmosenv.2025.121163","DOIUrl":"10.1016/j.atmosenv.2025.121163","url":null,"abstract":"<div><div>Carbon monoxide (CO) pollution is one of the unsolved atmospheric environmental issues over countries worldwide. Here, we comprehensively assess the spatial-seasonal variations and trends in CO over China during 2013–2022, by site categorization and cause analysis, which have not been reported in previous studies. Our analysis is based on surface observations, statistical classification techniques, and sensitivity simulations from a global chemical transport model, GEOS-Chem. The results show that CO concentrations and their seasonal variation are higher over the North China Plain than other areas of China during 2013–2022. CO concentrations have decreased at −38.2 ± 31.4 ppbv yr⁻¹ (−3.7% ± 1.8% yr⁻¹) over China during 2013–2022. The declining trends in CO concentrations vary with space, stronger over larger, more polluted, and more industralized cities. GEOS-Chem simulations suggest that the decrease in CO anthropgenic emissions in China would be the main driver for the decreasing trends of CO over China, with a contribution of 80% to the trend. Meteorology, CO anthropgenic emissions over foreign regions, and emissions from biomass burning are the remaining drivers. Our results suggest remarkable benefits of emission reductions in China in abating CO pollution and enhance our understanding on trends of long-term CO pollution over China during 2013–2022.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121163"},"PeriodicalIF":4.2,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143576868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-range transport influence on wintertime submicron aerosol chemical composition from simultaneous measurements in Lithuania and Southern Sweden","authors":"Agnė Minderytė ,&nbsp;Julija Pauraite ,&nbsp;Erik Ahlberg ,&nbsp;Adam Kristensson ,&nbsp;Steigvilė Byčenkienė ,&nbsp;Axel C. Eriksson","doi":"10.1016/j.atmosenv.2025.121162","DOIUrl":"10.1016/j.atmosenv.2025.121162","url":null,"abstract":"<div><div>Due to the large extent of seawater surface over the globe, aerosol particles spend significant time being transported over this type of surface. Therefore, global aerosol circulation is largely impacted by the processes particles undergo during long-range transport overseas. In this study, we investigated submicron aerosol (PM₁) chemical composition changes during long-range transport events over the southern Baltic Sea across two sites in Sweden (Hyltemossa) and Lithuania (Preila). The chemical composition was determined simultaneously using mass spectroscopy (time-of-flight aerosol chemical speciation monitor (ToF-ACSM)) in Hyltemossa and quadrupole ACSM (Q-ACSM) in Preila and filter-based optical (AE33 in Hyltemossa and AE31in Preila) methods. The aim of the study was to investigate the effect of long-range air mass transport over the sea on PM₁ chemical composition at the two remote background sites in the southern Baltic Sea region. The campaign average PM₁ concentration in Preila (11.2 μg/m³) was higher than in Hyltemossa (6.3 μg/m³). Yet, during long-range transport events, PM₁ concentration in Preila, downwind, was 40% lower (2.5 μg/m³) than in Hyltemossa (4.3 μg/m³), upwind, suggesting aerosol removal and dilution processes over the sea. We used the meteorological and spatial parameters from backward trajectory analysis to categorise the long-range air mass transport events across the two sites. Then the combinations of dilution, wet and dry deposition, emissions over land and other processes were labelled as the sea transport effect, wet deposition processes and land-atmosphere interaction. The results showed that during the events when air mass trajectories stretched from west to east from over Hyltemossa to Preila without precipitation along the path, the PM₁ concentration decreased on average by 50%. The addition of precipitation resulted in a larger decrease (70%) of PM₁ concentration. However, during the events with precipitation when air mass trajectories passed over a continental area before arriving at the downwind site, the net decrease was the lowest (27%). The lowest relative change in PM₁ concentration during those events suggests the potential uptake of pollutants into the air mass over land with more significant anthropogenic pollution sources. Our approach allows us to quantitively assess the mitigating effects of sea transport, wet deposition processes and the opposite effect when air mass is advected over land on PM₁ concentration using the proposed classification based on meteorological and spatial parameters of HYSPLIT backward trajectories.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121162"},"PeriodicalIF":4.2,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143611514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"East Asian dust storm in March 2021: Perspective views from ground observation, satellite measurement and numerical simulation","authors":"Yi-Bo Xue ,&nbsp;Xiao-Xiao Zhang ,&nbsp;Jia-Qiang Lei ,&nbsp;Sheng-Yu Li ,&nbsp;Lian-You Liu ,&nbsp;Zi-Fa Wang ,&nbsp;Wen-Jun Tian ,&nbsp;Xiao Tang ,&nbsp;Xue-Shun Chen","doi":"10.1016/j.atmosenv.2025.121152","DOIUrl":"10.1016/j.atmosenv.2025.121152","url":null,"abstract":"<div><div>During March 13–18, 2021, East Asia experienced the strongest dust storm in the last decade. This windblown dust event caused large-scale dispersion of aerosol pollution, and attracted widespread attention due to its severe impacts on land-atmosphere-marine ecosystems. Here we investigated the dust sources, transport, and deposition of this dust storm and its effects on the Asia-Pacific region by using ground observations, satellite remote sensing products, and numerical simulation. The results showed that the potential aeolian dust source was mainly located in the Gobi Desert in southern Mongolia and central Inner Mongolia. This dust storm generated rapid increases in ambient particle concentrations over northern and eastern China, the Korean peninsula, and southwestern Japan. Air quality in 82% of the studied East Asian cities deteriorated noticeably as a result of mineral dust intensification. The ground-based Mie-scattering lidar detected the long-distance dispersion of dust aerosols in the 3–5 km high altitudes over Seoul, Osaka, Tokyo, and Niigata. Approximately 16.1 Tg of floating dust was deposited in the Northwest Pacific Ocean. The intensity of dust deposition in the East China Sea was almost twice that in the Yellow Sea and the Sea of Japan. Satellite data revealed that dust particles transported remotely from the East Asian desert were deposited in the North Pacific, resulting in an evident increase (55%–86%) in regional chlorophyll-a concentrations within a week after this dust storm event. Marine algal blooms developed quickly in response to the joint effects of atmospheric dry or wet deposition and surface-ocean currents. This study quantitatively assessed the potential influences of this strong East Asian dust storm on the atmospheric and marine environment, providing a multi-angle perspective for investigating the dynamic long-range transport of aerosols and its implications for global dust cycles.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121152"},"PeriodicalIF":4.2,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical and toxicological characteristics of fine particles from festive fireworks in urban residential communities","authors":"Shreya Dubey ,&nbsp;Vinayak Sahota ,&nbsp;Akshay Kumar ,&nbsp;Nidhi Prajapati ,&nbsp;Vijaya Laxmi ,&nbsp;Balram Dangi ,&nbsp;Harish C. Phuleria","doi":"10.1016/j.atmosenv.2025.121160","DOIUrl":"10.1016/j.atmosenv.2025.121160","url":null,"abstract":"<div><div>In urban areas of low-and middle-income countries, short-term anthropogenic activities, such as festive fireworks, escalate air pollution. Diwali, one of the major Indian festivals, leads to severe air quality conditions due to massive emissions from fireworks. While the mass concentrations in ambient fixed locations are well explored, the chemical characterization and the redox-active components during such events, as well as potential exposures in residential outdoor locations, are poorly studied. This study focuses on examining the diurnal variation of fine particulate matter (PM_2.5) and its chemical and toxicological properties in residential areas during festive fireworks. A 5-day continuous diurnal monitoring was conducted across different residential sites in Mumbai, India, using real-time PM sensors collocated with the gravimetric measurements. The collected particles were subjected to multiple optical (b_abs_{_,}₃₇₀ and b_abs_{_,}₈₈₀), chemical (ionic, water-soluble organic carbon, elemental), and oxidative potential (OP^DTT and OP^AA) analyses. The study shows that the average increase in residential outdoor PM_2.5 concentration on Diwali night was ∼2.6 times higher than on non-Diwali night (206 ± 167 μg/m³). Similarly, optical parameters (b_abs_{_,}₃₇₀ and b_abs_{_,}₈₈₀) are elevated by 1.5 times, ions such as K⁺, NH₄⁺, NO₃⁻, and SO₄²⁻ by 5 times while Zn, Pb, Mn, and Cu spiked by ∼ 3 times during Diwali night. Toxicity of the particles as estimated by OP^DTTv and OP^AAv, increased by ∼1.5-fold during Diwali night, and was significantly correlated with NO₃⁻, SO₄²⁻, Mn, Ni, and As (p &lt; 0.05). Chemical speciation data reveal that toxic pollutants from Diwali fireworks increase particle toxicity. This study highlights the need for strict regulation of fireworks and policies addressing acute emission events. To protect public health, long-term air quality management strategies are essential in urban areas of India, rather than just short-term bans on fireworks or other episodic events.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121160"},"PeriodicalIF":4.2,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601284","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":"Method for planning subarea emission reduction strategies to improve ozone over a large area: A case of Taiwan","authors":"Tu-Fu Chen,&nbsp;Xin-Li Gong,&nbsp;Chang-You Tsai,&nbsp;Ken-Hui Chang","doi":"10.1016/j.atmosenv.2025.121149","DOIUrl":"10.1016/j.atmosenv.2025.121149","url":null,"abstract":"<div><div>Inappropriate reduction strategies can exacerbate ozone pollution. While previous research has primarily focused on developing emission reduction strategies for large areas, this study aimed to create a method for quickly planning emission reductions in subareas within a larger area. Using Taiwan (large area) as an example, this study illustrates how to determine the emission reductions required in each county (subarea) to achieve a 50% reduction in the number of DM8O3 (daily maximum 8-h average ozone) pollution station-days across the entire region (the preset goal). The methodology began with observational data to calculate the expected DM8O3 concentration improvements needed to meet the preset goal. CMAQ-DDM simulations were then conducted to evaluate cross-county O₃ transport, revealing the reciprocal impact of emissions between counties on air quality. The results indicated that NO_X emission reductions caused O₃ deterioration, leading to a focus exclusively on NMHC reductions. A system of simultaneous linear equations was constructed to link emission reductions, the cross-county O₃ transport, and the expected improvements. Linear programming was applied to calculate the required NMHC reductions for each county. The findings showed that most counties needed to reduce NMHC emissions by 30%–40%, while some required only 20%. CMAQ simulations of the improvements resulting from these emission reductions (referred to as validated improvements) confirmed that they met the expected improvements in most counties and across Taiwan as a whole. Finally, a nonlinear correction factor, defined as the ratio of validated to linear improvements, was introduced to refine the system of linear equations. This refinement effectively addressed the biases associated with using a system of linear equations to represent the nonlinear processes of ozone formation and ensured that all counties achieved their expected improvements.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121149"},"PeriodicalIF":4.2,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143576871","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":"Particulate matter (PM) and ozone air quality in Urumqi of Northwest China: Seasonality, trends, and sources","authors":"Xiali Liu ,&nbsp;Shixian Zhai ,&nbsp;Ke Li ,&nbsp;Lei Zhu ,&nbsp;Song Liu ,&nbsp;Viral Shah ,&nbsp;Amos P.K. Tai ,&nbsp;Guannan Geng ,&nbsp;Xuewei Hou ,&nbsp;Ali Mamtimin ,&nbsp;Xia Li ,&nbsp;Tianliang Zhao","doi":"10.1016/j.atmosenv.2025.121150","DOIUrl":"10.1016/j.atmosenv.2025.121150","url":null,"abstract":"<div><div>The city of Urumqi experiences severe air pollution, for which the variations and causes remain unclear. Here, we comprehensively investigate the seasonality, trends, and drivers of fine and coarse particulate matter (PM_2.5 and PM_2.5-10) and ozone (O₃) in Urumqi in the Chinese national context by statistical analysis of surface and satellite observations during 2015–2023. Wintertime PM_2.5 in Urumqi is twice as high as that averaged over Eastern China due to intensive emissions and unfavourable topography and meteorology, monthly PM_2.5-10 in Urumqi of above 40 μg m⁻³ year-round is driven by spring and autumn natural dust episodes and ubiquitous anthropogenic fugitive dust. During 2015–2023, PM_2.5 and PM_2.5-10 decreased by 34–38% credited to emissions control. However, the maximum daily 8h average (MDA8) O₃ in Urumqi increases rapidly at a rate of 2.5 ppbv yr⁻¹ due to increased volatile organic compounds (VOCs), decreased nitrogen oxides (NO_x) in earlier years of 2015–2016, and decreased PM_2.5. Impacts from VOCs and NO_x emission changes are supported by summertime O₃ formation regime transits from VOCs-limited to NO_x and VOCs co-limited during 2015–2023 as depicted by surface O₃-nitrogen dioxide (NO₂) correlations and satellite formaldehyde (HCHO)/NO₂ ratios. Responses of PM_2.5, PM_2.5-10, O₃, and related gases during the 2020 winter and summer epidemic lockdowns conform to our findings for their 2015–2023 trends. This study concludes that joint NO_x and VOCs emissions control would be particularly effective in reducing PM_2.5 and O₃ in Urumqi. This study also provides references for studying air quality in other places with limited observations.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"350 ","pages":"Article 121150"},"PeriodicalIF":4.2,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601287","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}