Atmospheric Environment最新文献

{"title":"Unveiling PM2.5 sources: Double and tracer conjugate PMF approaches for high-resolution organic, BC, and inorganic PM2.5 data","authors":"Mohd Faisal ,&nbsp;Umer Ali ,&nbsp;Ajit Kumar ,&nbsp;Mayank Kumar ,&nbsp;Vikram Singh","doi":"10.1016/j.atmosenv.2024.121011","DOIUrl":"10.1016/j.atmosenv.2024.121011","url":null,"abstract":"<div><div>A number of recent source apportionment studies have explored high-time resolution organic particulate matter, elemental particulate matter (PM), and Black Carbon (BC) datasets and attributed them independently to specific sources. However, proper unmixing of the actual sources operational on the ground most of the time cannot be achieved based on such an independent source apportionment approach, especially owing to the presence of secondary aerosol factors. Therefore, a combined analysis of all major PM_2.5 species is needed to better recognize the actual physical sources. Accordingly, in this study, using a combined dataset consisting of non-refractory PM_2.5 organic factors/major <em>m/z</em> signals from organics, elements, and BC, we evaluated two disparate factor analytic methodologies – namely, double-PMF (D-PMF) and Tracer-conjugate PMF (TC-PMF), to apportion PM_2.5 sources in Delhi winter (from December 15, 2020 to February 28, 2021) through real-time instrumentation (ACSM, Xact, and Aethalometer(AXA)). During the study period, the average PM_2.5 concentration was 182 μg/m³ (C-PM_2.5 = sum of NR-PM_2.5 (Organics, NO₃⁻, SO₄⁻², NH₄⁺), BC, and elements). For D-PMF, organic aerosols (OA) were initially deconvolved with positive matrix factorization (PMF) into hydrocarbon-like OA (HOA), biomass burning OA (BBOA), low volatile oxidized OA (LVOOA 1 and 2) and semi-volatile oxidized organic aerosols (SVOOA) before being coupled with elemental species and BC for a second PMF. The TC-PMF combined the major <em>m/z</em> signals from organics with the elemental species and BC. Both D-PMF and TC-PMF identified biomass burning, industrial, waste incineration, dust-related, traffic, secondary chloride, Pb-rich, power plant, and LVOOA dominated as the sources. Both solutions (D-PMF, TC-PMF) were found to be dominated by biomass burning (33.3% and 26.5%), followed by the power plant (27.4% and 18.4%) and the LVOOA dominant (14.2% and 18.6%) factors. The D-PMF and TC-PMF improved the interpretation of organic factor sources, such as apportioning considerable contributions of LVOOA2 (85%) to the power plant factor, which is often linked with regionally carried aged OA in the Organics PMF (O-PMF). Lastly, the D-PMF results significantly agreed with TC-PMF, indicating that either of the two techniques could be used to unmix the complex variety of PM_2.5 sources in the Delhi-NCR (National Capital Region) region and, arguably, the larger Indo-Gangetic Plains.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"343 ","pages":"Article 121011"},"PeriodicalIF":4.2,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143154326","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":"Mechanisms of synoptic circulation patterns influencing winter/spring PM2.5 concentrations in South Korea","authors":"Jung-Eun Esther Kim ,&nbsp;Changhyun Yoo","doi":"10.1016/j.atmosenv.2024.121016","DOIUrl":"10.1016/j.atmosenv.2024.121016","url":null,"abstract":"<div><div>This study comprehensively analyzes the spatiotemporal distribution of the meteorological variables and large-scale atmospheric patterns that produce high concentrations of particulate matter with aerodynamic diameters below 2.5 μm (PM_2.5) in South Korea. Through self-organizing map (SOM) analysis of upper-level geopotential height fields and aerosol optical depth (AOD), the recurring coupled patterns of the large-scale circulation and the AOD are classified into three clusters associated with high pollution episodes that frequently occur in spring and winter. In addition, the long-range transport is investigated for each SOM type using the Hybrid Single-Particle Lagrangian Integrated Trajectory model, which provides a comprehensive understanding of the factors influencing PM_2.5 levels. An analysis of frequency shows an increasing trend in one of the three spring patterns. Results from the Coupled Model Intercomparison Project Phase 6 indicate a continued increase in frequency for the aforementioned pattern with rising surface temperatures. Our findings underscore the importance of understanding synoptic-scale effects on PM_2.5 variability to inform mitigation strategies in the context of climate change.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"343 ","pages":"Article 121016"},"PeriodicalIF":4.2,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143154282","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":"Evaluating air pollution and BTEX exposure effects on DNA damage: A human biomonitoring study in Zagreb, Croatia","authors":"Katarina Matković ,&nbsp;Andreja Jurič ,&nbsp;Ivana Jakovljević ,&nbsp;Luka Kazensky ,&nbsp;Mirta Milić ,&nbsp;Vilena Kašuba ,&nbsp;Silvije Davila ,&nbsp;Gordana Pehnec ,&nbsp;Irena Brčić Karačonji ,&nbsp;Ante Cvitković ,&nbsp;Pascal Wild ,&nbsp;Irina Guseva Canu ,&nbsp;Nancy B. Hopf ,&nbsp;Goran Gajski ,&nbsp;Marko Gerić","doi":"10.1016/j.atmosenv.2024.121004","DOIUrl":"10.1016/j.atmosenv.2024.121004","url":null,"abstract":"<div><div>Air pollution, a major global issue, comprises various solid and gaseous pollutants in urban environments, including particulate matter (PM) and volatile organic compounds (VOCs). Benzene, toluene, ethylbenzene, and isomeric xylenes (BTEX) constitute about 80% of VOC emissions, primarily from vehicle exhaust, tobacco smoke, petrol, paints, adhesives, and solvents, posing significant health risks including carcinogenic effects. Here we explore the impact of exposure to various measured air pollutants (NO₂, O₃, PM₁₀, PM_2.5, PAHs, and BTEX) on DNA damage among residents (N = 60) of Zagreb, Croatia during the colder part of the year due to anticipated higher pollutant levels. This was done by evaluating primary DNA damage using the comet assay and associating it to measured air pollutants and to blood values of BTEX as a biomarker of exposure. Measured DNA damage was also associated with additional lifestyle factors and sociodemographic data. Statistically significant positive correlations between % tail DNA and air pollutants were observed only for daily average for pyrene, measured one day prior to blood sampling. Passive smokers showed significantly higher DNA damage levels compared to non-smokers. The study emphasizes the importance of evaluating cumulative environmental exposures and their health effects, consistent with the exposome concept. Despite improvements in air quality across Europe, urban pollution levels remain hazardous, necessitating robust public health interventions to mitigate long-term health risks.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"343 ","pages":"Article 121004"},"PeriodicalIF":4.2,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153891","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":"Corrigendum to “Dry deposition of ammonia in a coastal dune area: Measurements and modeling” [Atmos. Environ. (298) (2023) 119596]","authors":"K.J.A. Vendel ,&nbsp;R.J. Wichink Kruit ,&nbsp;M. Blom ,&nbsp;P. van den Bulk ,&nbsp;B. van Egmond ,&nbsp;A. Frumau ,&nbsp;S. Rutledge-Jonker ,&nbsp;A. Hensen ,&nbsp;M.C. van Zanten","doi":"10.1016/j.atmosenv.2024.121009","DOIUrl":"10.1016/j.atmosenv.2024.121009","url":null,"abstract":"","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"343 ","pages":"Article 121009"},"PeriodicalIF":4.2,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153458","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":"COVID lockdowns significantly affect statewide atmospheric fine aerosols in India after excluding long-term pollution patterns and time-lag effect","authors":"Tunde O. Etchie ,&nbsp;Ayotunde T. Etchie ,&nbsp;Rachel T. Pinker ,&nbsp;Prashant Kumar ,&nbsp;Nedunchezhian Swaminathan","doi":"10.1016/j.atmosenv.2024.121013","DOIUrl":"10.1016/j.atmosenv.2024.121013","url":null,"abstract":"<div><div>Atmospheric fine particulate matter (PM_2.5, near-surface concentrations when size is ≤ 2.5 μm) affects global climate and human health. India alone accounts for a quarter of the global PM_2.5-related health burden. Studies in India, mostly in urban areas, have reported significant declines in PM_2.5 concentrations because of COVID-19 lockdown. These studies did not consider the long-term PM_2.5 patterns and time-lag effect (inter-yearly variations in PM_2.5 concentrations carried forward from one period to another due to interannual shifts in meteorological conditions). Since the studies focused primarily on urban areas, not covering rural/remote areas where pollution may rise during lockdown, it is still unclear what impact lockdown had on statewide pollution levels in India. Here, we examine whether significant changes in fine-mode aerosol optical depth (AOD_f: columnar PM_2.5) occurred statewide across India because of lockdown after excluding the confounding variables. We found a substantial decrease in AOD_f in a few (28%) states/territories. The declines were significant (ANCOVA; α = 0.05) in some Northeastern states/territories: Sikkim (29%), Arunachal Pradesh (24%), Nagaland (5%), Mizoram (4%) and Uttarakhand (3%). However, in most states/territories, AOD_f increased significantly because of lockdown. The lockdown-associated hardship caused more people to rely on polluting cooking fuels, thereby increasing residential emissions, particularly in rural areas. At city-level, we found significant reductions in near-surface PM_2.5 concentrations due to lockdown. These declines were comparable or greater than previously reported. Also, there were significant reductions in AOD_f (PM_2.5 concentrations) at state (city) levels resulting from previous environmental intervention measures. If not accounted, previous environmental intervention measures can significantly bias lockdown effect estimates in India.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"343 ","pages":"Article 121013"},"PeriodicalIF":4.2,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153909","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":"A Bayesian technique for quantifying methane emissions using vehicle-mounted sensors with a Gaussian plume model","authors":"Daniel C. Blackmore ,&nbsp;Jean-Pierre Hickey ,&nbsp;Augustine Wigle ,&nbsp;Kirk Osadetz ,&nbsp;Kyle J. Daun","doi":"10.1016/j.atmosenv.2024.121002","DOIUrl":"10.1016/j.atmosenv.2024.121002","url":null,"abstract":"<div><div>Understanding the uncertainties associated with methane emission estimates is crucial for prioritizing leak repair interventions, enforcing environmental regulations, and modeling climate change. This paper presents a model-based Bayesian approach for describing the uncertainties associated with methane emissions estimates derived from vehicle-based concentration measurements, combined with the Gaussian plume dispersion model (GPM) and anemometry data. The approach begins by deriving a probability density function (pdf) that defines the likelihood of measuring a given release rate conditional on the true release rate. The width of the likelihood pdf is dominated by the GPM model error, which is explored using computational fluid dynamics simulations. The likelihood pdf is combined with a prior pdf that encodes what is known about the emission before the measurement to yield the posterior pdf, which comprehensively defines what is known about the release rate based on measurements and prior information. The technique is assessed by comparing releases inferred from single plume transects with ground truth emission rates, and it is found that the 90% creditability interval contains the true release rate approximately 90% of the time. The Bayesian approach can also be used to optimize measurement paths and/or consider the limitations of these technologies with respect to atmospheric conditions.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"344 ","pages":"Article 121002"},"PeriodicalIF":4.2,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143308530","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":"Characterization and sources of volatile organic compounds in a provincial capital city of northern China in 2019–2024: Impact of public events","authors":"Haoxin Sui ,&nbsp;Houyong Zhang ,&nbsp;Yisheng Zhang ,&nbsp;Wenxin Tao ,&nbsp;Xing Peng ,&nbsp;Xuan Ge ,&nbsp;Sufan Zhang ,&nbsp;Ming Wang ,&nbsp;Xiaofei Qin ,&nbsp;Mingyue Du ,&nbsp;Jinhua Du ,&nbsp;Dasa Gu","doi":"10.1016/j.atmosenv.2024.121000","DOIUrl":"10.1016/j.atmosenv.2024.121000","url":null,"abstract":"<div><div>The COVID-19 outbreak and the Beijing Winter Olympics provided an opportunity to study the impact of human activities on volatile organic compounds (VOCs) in the atmosphere. Continuous measurements of 117 VOC species were conducted in urban Ji'nan, the capital city of Shandong Province, North China Plain, from 2019 to 2024. The total volatile organic compound concentrations ranged from 30.7 ppbv to 41.7 ppbv, and the seasonal characteristics of VOCs were generally high in autumn and winter and low in spring and summer, with alkanes as the component with the highest percentage. The average VOC volume fraction increased by 24.8% after the COVID-19 outbreak compared to that before the outbreak, among which the concentrations of aromatics increased most markedly (334.7%), and those of alkanes increased by 95.2%. Alkenes, alkynes, halocarbons, and oxygenated VOCs showed decreasing trends. The volume fraction of each VOC species showed a decreasing trend during the Beijing Winter Olympics air quality guarantee period compared with the pre-Beijing Winter Olympics period, with a 16.7%–36.3% reduction rate. The positive matrix factorization model identified six sources: vehicle emission, industrial mixing sources, solvent use, oil and gas volatilization, biogenic and secondary sources, and combustion sources. Influenced by the resumption of work and production by enterprises after the COVID-19 pandemic, solvent use increased by 26.7% after the pandemic, and the contribution of diesel vehicle emissions was significant. After the pandemic, the contribution of industrial mixing sources decreased by 28.6%, whereas coal combustion sources increased by 5.3% compared to the pre-COVID-19 period. During the Beijing Winter Olympics air quality guarantee period, coal combustion sources and vehicle emission sources decreased by 11.6% and 6.5%, respectively, and contributions from industrial sources and biogenic and secondary sources increased by 13.2% and 6.4%, respectively, compared with those during the pre-Beijing Winter Olympics period. During the Beijing Winter Olympics air quality guarantee period, the results of the backward airflow trajectory, and potential source area analysis, showed a strong influence of air mass transmission in the southwest direction, and VOCs emissions from industrial sources had higher values in the southwest region. Before the COVID-19 outbreak, there were obvious ship sources from the long-range transmission of the near-coastal region in the Yellow Sea. However, in post-COVID-19, long-range transport contributions from ship sources vanished due to the upgrading of marine oils after implementing the DECA 2.0.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"343 ","pages":"Article 121000"},"PeriodicalIF":4.2,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153427","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":"Mobile measurements of atmospheric decamethylcyclopentasiloxane (D5) in Eastern China","authors":"Haifeng Yu ,&nbsp;Yunhua Chang ,&nbsp;Lin Cheng ,&nbsp;Wen Tan ,&nbsp;Liang Zhu ,&nbsp;Jianlin Hu","doi":"10.1016/j.atmosenv.2024.121001","DOIUrl":"10.1016/j.atmosenv.2024.121001","url":null,"abstract":"<div><div>Decamethylcyclopentasiloxane (D5) is prevalent in European and North American urban air due to the use of personal care products. China accounts for 55% of global siloxane production, yet the atmospheric concentration and sources of D5 in China remain largely unexplored. Using the Vocus mobile laboratory, here we performed high time-resolved measurements of D5 along a north-south transect (∼700 km) in eastern China. Prior to reaching the destination, Nanjing Chemical Industry Park (NCIP), D5 concentration had a low variability of minute-mean concentration (2.6 ± 1.3 pptv). Population density didn't exhibit a correlation with D5 concentration (1-min average concentration) (<em>R</em>² = 0.06), whereas a significant correlation was observed between the city-scale population and D5 concentration (<em>R</em>² = 0.74). Concentrated spikes in D5 concentrations (peaking at 384.8 pptv per second) were observed around NCIP, home to nearly 400 energy and chemical companies. These D5 concentrations were highly correlated with agrochemical-related dichlorobenzenes (<em>R</em>² = 0.99) rather than other petrochemical-related tracers. Unlike developed countries, D5 in China's air may primarily originate from emissions released during production processes.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"344 ","pages":"Article 121001"},"PeriodicalIF":4.2,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143355247","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":"Impact of Land Use Land Cover (LULC) on the physical processes of a dense fog episode: A case study using WRF model from the National Capital Region, India","authors":"Anie K Lal,&nbsp;Ravi Kumar Kunchala,&nbsp;Manju Mohan","doi":"10.1016/j.atmosenv.2024.121014","DOIUrl":"10.1016/j.atmosenv.2024.121014","url":null,"abstract":"<div><div>The rapid growth in population and urban development has attracted considerable scientific attention due to its impact on the local and regional atmospheric environment. Given its scientific significance, in this study, we employ the Weather Research and Forecasting (WRF) model to investigate the physical mechanisms underlying the impact of Land Use Land Cover (LULC) changes on the fog life cycle of a recent dense fog episode in January 2021. The model domain covers the Delhi National Capital Region (NCR) at a resolution of 2 km. We conducted two sensitivity experiments: The control run (CNTL), representing the current LULC, and the Experimental run (EXP), by integrating the land use conditions from 2004. Results from these experiments suggest that the model reasonably reproduces the near-surface meteorological conditions and vertical profiles during the severe fog episode. Over the past two decades, urban and built-up areas and dryland croplands increased by 119.73% and 118.97%, most of which were converted from irrigated croplands and other vegetated areas. We noticed that the increase in urban areas has led to an advancement in fog dissipation by about 1–2 h. The early dissipation also results in modifying the Liquid Water Path (LWP), consequently forming fog holes. Moreover, this phenomenon is likely to escalate if urban areas continue to develop in the future. We further attribute the near-surface soil moisture as a primary factor influencing the early lifting and dissipation of the fog layer by affecting surface fluxes (quantified by Bowen Ratio (BR)) and Turbulent Kinetic Energy (TKE), and expediting the heating (0.5°C–2°C) and drying (5%–20%) of the near-surface boundary layer (&lt;500m from the land surface).</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"343 ","pages":"Article 121014"},"PeriodicalIF":4.2,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143154280","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":"Insights into aerosol vertical distribution, subtype, and secondary particle formation in central Himalayas: A COVID-19 lockdown perspective","authors":"Vikas Rawat ,&nbsp;Narendra Singh ,&nbsp;Surendra K. Dhaka ,&nbsp;Prabir K. Patra ,&nbsp;Yutaka Matsumi ,&nbsp;Tomoki Nakayama ,&nbsp;Sachiko Hayashida ,&nbsp;Mizuo Kajino ,&nbsp;Sanjeev Kimothi","doi":"10.1016/j.atmosenv.2024.121015","DOIUrl":"10.1016/j.atmosenv.2024.121015","url":null,"abstract":"<div><div>Pristine Himalayan environment is being increasingly affected by the exogenous pollutants which are often observed over mountains. This study, for the first time, elucidates upon the impact of COVID-19 lockdown on the concentrations of primary and secondary aerosols along with associated dynamics, across the boundaries of two regions with very different geographical features. PM_2.5 measurements from northern Indian atmosphere during three distinct phases (P-I, P-II, P-III) of 2020, were investigated against previous three year's mean (2017–2019) over Delhi/NCR (DN) in the Indo-Gangetic Plain (IGP) and Nainital (NT) in the Central Himalaya (CH) using integrated ground based, spaceborne and reanalysis datasets. Strict lockdown measures led to a substantial reduction in PM_2.5 levels in north India, with ∼62% decrease in DN and a minor ∼8% in NT region, for a couple of weeks, along with decrease in other primary absorbing aerosols (BC, OC and dust), conversely, an enhancement was observed in the scattering aerosol (SO₄²⁻). Vertical profiles of Extinction Coefficient from CALIPSO satellite revealed substantial reductions (∼60%) in aerosol content across 0–6 km, over study region with a larger decline in the foothills. Particulate depolarization ratio (PDR) and Particulate color ratio (PCR) declined with altitude by 44% and 31% respectively due to prevalence of fine particles over CH and irregular shapes near the surface (DN). In P-II, aerosol subtype occurrences changed significantly above boundary layer (2–4 km) and reduction in primary aerosols did not contribute to reducing PM_2.5 concentrations. P-III exhibited enhanced secondary particle formation exacerbated by Stratosphere-Troposphere Exchange (STE) events of O₃ that increased the oxidizing capacity in atmosphere. Overall, an upsurge in SO₄²⁻ and HNO₃, was observed in CH and DN region respectively. These findings highlight the significance of secondary aerosols in reduced primary emissions and need of comprehensive case study employing box and regional chemistry models.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"343 ","pages":"Article 121015"},"PeriodicalIF":4.2,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143154284","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}