Atmospheric Environment最新文献

{"title":"Seasonal characterization of primary and secondary sources of fine PM-bound water-soluble organic carbon in central Los Angeles","authors":"Yashar Aghaei ,&nbsp;Mohammad Mahdi Badami ,&nbsp;Mohammad Aldekheel ,&nbsp;Ramin Tohidi ,&nbsp;Constantinos Sioutas","doi":"10.1016/j.atmosenv.2025.121084","DOIUrl":"10.1016/j.atmosenv.2025.121084","url":null,"abstract":"<div><div>Understanding the sources and formation processes of fine particulate matter (PM_2.5) is crucial for improving urban air quality and public health. This study provides a real-time analysis of PM_2.5-bound water-soluble organic carbon (WSOC) and related carbonaceous species during winter, spring, and summer periods in 2023–2024, aiming to identify their major sources in central Los Angeles. Using advanced online monitoring equipment, including a Sunset Laboratory EC/OC analyzer and a custom-developed setup including a total organic carbon (TOC) analyzer coupled with a particle collection system, we obtained hourly measurements of organic carbon (OC), its fractions (OC₁-OC₄, based on volatility), elemental carbon (EC), and WSOC. Positive matrix factorization (PMF) identified three principal PM_2.5 sources: vehicular emissions, secondary organic carbon (SOC) formation influenced by nighttime aqueous-phase chemical processes, and SOC formation driven by daytime photochemical reactions. Vehicular emissions dominated EC levels, accounting for 86–95% across seasons. This factor also had high contributions from nitrogen oxides (NOₓ) (75–82%), vehicle counts (approximately 85%), and OC₁ (51–83%), reflecting the persistent influence of traffic emissions. Nighttime SOC formation was significant in winter, with WSOC and OC₄ contributing 58% and 40% to this factor. In contrast, daytime photochemical SOC formation was prominent in summer, with WSOC and OC₄ contributing 63% and 47%, and ozone loading up to 89%, reflecting increased photochemical activity. Spring exhibited a mix of aqueous and photochemical SOC formation, with similar contributions from WSOC (38-35%) and OC₄ (35-33%), reflecting the transitional season's mixed SOC formation mechanisms. Diurnal profiles revealed that primary emissions peaked during morning rush hours, while secondary formation processes elevated OC levels at night in winter and during afternoons in summer. The EC tracer method corroborated these findings by estimating primary and secondary organic carbon levels, highlighting significant seasonal and diurnal variations in carbonaceous aerosols. These results emphasize the need for targeted strategies addressing both primary emissions and the precursors of secondary aerosol formation, to improve air quality in Los Angeles.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121084"},"PeriodicalIF":4.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143317790","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 comprehensive gas-phase kinetics of α-methyl thiophene with Cl-atom and OH-radical: Experimental and theoretical studies","authors":"Prasanna Kumar Bej ,&nbsp;B. Rajakumar","doi":"10.1016/j.atmosenv.2025.121078","DOIUrl":"10.1016/j.atmosenv.2025.121078","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The rate coefficient for the reaction of methyl thiophene (MeTp) with Cl atom was measured to be (1.09 ± 0.24) × 10&lt;sup&gt;−10&lt;/sup&gt; cm&lt;sup&gt;3&lt;/sup&gt; molecule&lt;sup&gt;−1&lt;/sup&gt;s&lt;sup&gt;−1&lt;/sup&gt; at 298K and 760 Torr using the relative rate (RR) method. The experimental temperature-dependent rate coefficient was measured to be &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;258&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;358&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;K&lt;/mi&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow&gt;&lt;mn&gt;2.08&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mn&gt;0.10&lt;/mn&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;11&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;exp&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow&gt;&lt;mn&gt;484.5&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mn&gt;15.4&lt;/mn&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; cm&lt;sup&gt;3&lt;/sup&gt; molecule&lt;sup&gt;−1&lt;/sup&gt; s&lt;sup&gt;−1&lt;/sup&gt;. The theoretical rate coefficients for the reaction of MeTp with Cl-atom and OH radical were calculated at BD(T)/VDZ//BHandHLYP/6–31+g∗ and BD(T)/AVDZ//M06-2X/6–311++g∗∗ level of theory respectively. The Arrhenius equation from the theoretically calculated rate coefficients for MeTp + Cl using the MESMER simulation was obtained to be &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mtext&gt;MeTp&lt;/mtext&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mtext&gt;Cl&lt;/mtext&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;200&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;400&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;K&lt;/mi&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow&gt;&lt;mn&gt;2.44&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mn&gt;0.12&lt;/mn&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;11&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;exp&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow&gt;&lt;mn&gt;438.2&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;14.9&lt;/mn&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; cm&lt;sup&gt;3&lt;/sup&gt; molecule&lt;sup&gt;−1&lt;/sup&gt; s&lt;sup&gt;−1&lt;/sup&gt;. The experimental and theoretical rate coefficients show a negative temperature dependence behaviour over the studied temperature range. The rate coefficient for MeTP + OH was calculated as &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;200&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;400&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;K&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mtext&gt;CVT&lt;/mtext&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mtext&gt;SCT&lt;/mtext&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow&gt;&lt;mn&gt;2.83&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.20&lt;/mn&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;13&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;exp&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow&gt;&lt;mn&gt;1641.7&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mn&gt;20.6&lt;/mn&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; cm&lt;sup&gt;3&lt;/sup&gt; molecule&lt;sup&gt;−1&lt;/sup&gt; s&lt;sup&gt;−1&lt;/sup&gt; from CVT/SCT methods. Following the MESMER simulation for MeTp + OH reaction, the Arrhenius expression was found to be &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msubsup&gt;&lt;mrow","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"347 ","pages":"Article 121078"},"PeriodicalIF":4.2,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402747","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":"Chemical composition of aerosols over the Arabian Sea based on global reanalyses data and on-board ship measurements","authors":"Garima Shukla ,&nbsp;N. Ojha ,&nbsp;Ashwini Kumar ,&nbsp;S. Harithasree ,&nbsp;I. Girach ,&nbsp;L.K. Sahu","doi":"10.1016/j.atmosenv.2025.121085","DOIUrl":"10.1016/j.atmosenv.2025.121085","url":null,"abstract":"<div><div>The knowledge of chemical composition of atmospheric aerosols is key to understand aerosol-cloud-climate interactions and surface water biogeochemistry in the oceanic regions. Despite of strong natural and anthropogenic sources in its upwind regions, the studies on aerosol composition have been very limited over the Arabian Sea. We have comprehensively analyzed the results from global models, ECMWF's CAMS and NASA's MERRA-2 reanalyses, in conjunction with our ship-based measurements. Both models captured the overall spatio-temporal variability in sulphate (SO₄²⁻) and sea salt (r = 0.76–0.86). However, there is large scatter in PM₁₀ and dust variability and the concentrations are typically overestimated by MERRA-2 except during winter, but underestimated by CAMS. Despite of difference in magnitudes, these models successfully reproduced the key seasonal features e.g., winter-time maxima in sulphate (9.0 ± 6.5 μg m⁻³ in MERRA-2, 11.9 ± 6.2 μg m⁻³ in measurements). While sulphate enhancement is most pronounced along India's west coast, the monsoon-time sea salt spike is strongest near east coast of the Middle-East (&gt;200 μg m⁻³) region. Trend analysis results from both models indicate a statistically significant increase in sulphate aerosols over the Arabian Sea during 2003–2022 period (0.4 μgm⁻³y⁻¹ in winter). However, long-term trends in sea salt and dust are not consistent between the two models and underscore a need for further investigations. Insights into aerosol distribution and model performances from this study would aid in planning future expeditions and refining chemistry-climate models, thereby enhancing our understanding of biogeochemical processes in the Indian Ocean.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"347 ","pages":"Article 121085"},"PeriodicalIF":4.2,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402746","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":"Satellite-borne identification and quantification of wildfire smoke emissions in North America via a novel UV-based index","authors":"Ziyi Suo ,&nbsp;Qing Wang ,&nbsp;Yingcheng Lu ,&nbsp;Yixin Yao ,&nbsp;Qingjun Song ,&nbsp;Jing Ding ,&nbsp;Weiming Ju ,&nbsp;Zhengke Zhang","doi":"10.1016/j.atmosenv.2025.121069","DOIUrl":"10.1016/j.atmosenv.2025.121069","url":null,"abstract":"<div><div>Estimation of the smoke emissions released by wildfires has become a significant concern in the context of atmospheric environment and global climate change, in which satellite-borne optical remote sensing plays an important role. Previous studies have utilized the satellite-based aerosol optical depth (AOD) algorithm to estimate the wildfire-related total particulate matter emissions (TPM). However, this “top-down” approach is often impeded by false or missed detection due to extensive cloud cover and smokes with high concentrations, resulting in an underestimation of TPM. To address these limitations, this study proposes a new ultraviolet (UV)-based methodology for the identification and quantification of wildfire smokes from satellite platforms. The spectral characteristics of smoke plumes and different cloud types, including cirrus and cumulus clouds, are characterized by China's Haiyang-1C/D (HY-1C/D) satellites within both UV and visible wavelengths. Specifically, the 355 nm UV band displays a strong absorption pattern associated with smoke plumes. Based on this diagnostic spectral feature, an ultraviolet smoke index (UVSI) is developed, which can mitigate the impact of high background heterogeneity. Moreover, in comparison with the MODIS AOD algorithm, the UVSI index can not only improve the precision of smoke detection, especially for smokes with high concentrations, but also demonstrate a strong correlation with AOD at the numerical level. Accordingly, this study proposes the use of UVSI in place of AOD for TPM estimation. Combined with the fire radiative energy (FRE) measured by GOES-R satellite, the smoke emission coefficient (<em>C</em>_e) can be determined, which is 34.37 g MJ⁻¹ for the September 2020 burning season in North America. The above results would provide a new reference for operational monitoring and assessment of wildfire smokes.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121069"},"PeriodicalIF":4.2,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143317794","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":"Personal exposure to fine particles, inflammation and oxidative stress among commuters before, during and after COVID-19 outbreak in Taipei","authors":"Yueh-Lun Lee ,&nbsp;Kai-Jen Chuang ,&nbsp;Gui-Bing Hong ,&nbsp;Hua-Wei Chen ,&nbsp;Hsiao-Chi Chuang ,&nbsp;Wan Puteh Sharifa Ezat ,&nbsp;I-Jung Liu","doi":"10.1016/j.atmosenv.2025.121080","DOIUrl":"10.1016/j.atmosenv.2025.121080","url":null,"abstract":"<div><div>The association between fine particles exposure and adverse health effects during commuting has been reported in previous studies. However, knowledge about whether wearing masks has a protective effect on commuters’ air pollution exposure and related health effect is still limited. Therefore, the present study recruited 200 healthy participants in Taipei before, during and after the coronavirus disease 2019 (COVID-19) epidemic. All participants were required by law to wear masks when going out during the COVID-19 epidemic. Each participant was classified by his/her own commuting style, including subway, scooter, and walking. Three repeated measurements of inflammation marker, interleukin 6 (IL-6) and oxidative stress marker, 8-hydroxy-2-deoxyguanosine (8-OHdG) in sputum and urine, particulate matter with an aerodynamic diameter ≤2.5 μm (PM_2.5), temperature, and humidity were conducted for each participant during commuting. Mixed-effects models were used to investigate the association of PM_2.5 with IL-6 or 8-OHdG in sputum or urine before, during and after the COVID-19 epidemic. The study results showed that personal PM_2.5 exposure level (Mean ± standard deviation) was highest in the scooter group (52.1 ± 22.3 μg/m³) but lowest in the subway group (22.6 ± 9.7 μg/m³). Personal exposure to PM_2.5 was associated with increased IL-6 or 8-OHdG in sputum or urine before and after the COVID-19 epidemic among all groups. The effect of PM_2.5 on IL-6 or 8-OHdG in sputum or urine was not statistically significant in subway group or walking group during the COVID-19 epidemic. By naturally observing the phenomenon of commuters wearing masks before, during and after the COVID-19 epidemic, we suggest that wearing masks during commuting could be one of the preventive measures to reduce air pollution exposure.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121080"},"PeriodicalIF":4.2,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143317795","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":"Trends of PM1 aerosol chemical composition, carbonaceous aerosol, and source over the last 10 years at Melpitz (Germany)","authors":"Samira Atabakhsh ,&nbsp;Laurent Poulain ,&nbsp;Alessandro Bigi ,&nbsp;Martine Collaud Coen ,&nbsp;Mira Pöhlker ,&nbsp;Hartmut Herrmann","doi":"10.1016/j.atmosenv.2025.121075","DOIUrl":"10.1016/j.atmosenv.2025.121075","url":null,"abstract":"<div><div>Submicron particles (PM₁) play a critical role in air quality, climate, and human health. Long-term monitoring is essential to identify changes in atmospheric composition driven by natural or anthropogenic emissions and processes. This study presents ten years of continuous measurements (Sept. 2012–Aug. 2022) at the TROPOS Melpitz research station in Germany, a Central European rural background site influenced by its location between Eastern and Western Europe. Using an aerosol chemical speciation monitor (ACSM) and a multi-angle absorption photometer (MAAP), alongside a rolling positive matrix factorization (PMF) model for organic aerosol (OA) source apportionment, we analyzed PM₁ trends, chemical composition, and source contributions over a decade. The results reveal a significant negative PM₁ trend of −4.59% y⁻¹, with pronounced decreases occurring in fall and winter. Eastern air masses showed marked improvements (−28% y⁻¹), likely reflecting regional mitigation policies. OA, contributing 44% of total PM₁, showed a negative trend of −2.05% y⁻¹ and comprised three primary OA (POA) sources—hydrocarbon-like OA (HOA), biomass burning OA (BBOA), and coal combustion OA (CCOA)—and two oxygenated OA (OOA) factors (less-oxidized and more-oxidized OA, LO-OOA and MO-OOA). HOA (7% of total OA) remained relatively stable, with a minor decline (−0.25% y⁻¹) under Eastern air masses. In contrast, BBOA (10% of OA) and CCOA (12% of OA) displayed strong seasonality, driven by residential heating and energy production. Notably, BBOA increased by +0.48 % y⁻¹ during summer, likely due to the rise in wood pellet heating, recreative, and/or wildfires, while CCOA showed a modest increase (+0.27% y⁻¹) in Western air masses. The OOA factors, LO-OOA and MO-OOA (31% and 40% of OA, respectively), reflected distinct seasonal patterns tied to atmospheric formation pathways. Both showed declining trends in Eastern air masses (−1.52% y⁻¹ and −1.09% y⁻¹), indicating changes in biogenic emissions and/or anthropogenic precursors. Finally, eBC(PM₁) decreased by −1.3 % y⁻¹ with strong source dependency. Compared to urban areas, the overall decrease of PM mass concentration and anthropogenic OA looks limited, emphasizing a potentially lower effect of political mitigation outside cities. Overall, the findings underscore the importance of monitoring long-term changes in PM₁ composition and sources, which are crucial for understanding aerosol physical properties, refining climate models and public health, and evaluating the impacts of mitigation efforts on air quality and climate in different environments. Further studies on a similar approach are strongly needed to better understand the geographical variation of the aerosol chemical composition and evaluate their potential effect.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121075"},"PeriodicalIF":4.2,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348988","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":"Influence of ambient particulate matter and environmental factors on the seasonal bioaerosol load in the middle Indo-Gangetic Plain","authors":"Aman Deep Gupta ,&nbsp;Vivek Srivastava ,&nbsp;Neha Yadav ,&nbsp;Santosh K. Misra ,&nbsp;Tarun Gupta","doi":"10.1016/j.atmosenv.2025.121081","DOIUrl":"10.1016/j.atmosenv.2025.121081","url":null,"abstract":"<div><div>The study investigated the bioaerosol load and associated possible health risks at diverse macro-environments in the middle Indo-Gangetic Plain (IGP) region. The seasonal bioaerosol load investigations showed summer and monsoon seasons having higher concentrations than winter and post-monsoon seasons in outdoor environments. Besides meteorological factors (temperature and RH), the cytotoxic effect of PM_2.5 was seen on ambient bioaerosol concentrations (R = −0.97, p &lt; 0.05). This adverse effect of PM_2.5 on bioaerosols was also validated in lab studies on model organism <em>Escherichia coli</em>. The results demonstrated bacteriostatic effects in used range of concentrations. Although lethal concentration (LC₅₀) was not reached even at PM_2.5 treatment of 80 μg/ml, a concentration-dependent inhibition of bacterial cell viability was observed.</div><div>Furthermore, the health risk associated with bioaerosol exposure in the region was very high. The calculated hazard ratio was greater than one at all IGP locations, with very high potential of infection in polluted city center compared to pristine city outskirts. Higher hospital visits related to pulmonary infections by the people was reported in the city center compared to the city outskirts. The Gram-negative bacteria was found to be more closely associated with respiratory problems in the exposed population. The detailed investigations found pathogenic bacteria, particularly those associated with the genera <em>Streptococcus, Staphylococcus, Enterococcus, Pseudomonas,</em> and <em>Enterobacteriaceae</em>, to be prominent in the ambient air. Simultaneously, seven fungal genera were identified, with <em>Aspergillus</em> and <em>Penicillium</em> being most prevalent in the region.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121081"},"PeriodicalIF":4.2,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143317796","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":"Data fusion of modelled and-measured deposition in the U.S. and Canada, part I: Description of methodology and validation of wet deposition of sulfur and nitrogen","authors":"Alain Robichaud ,&nbsp;Amanda Cole ,&nbsp;Irene Cheng ,&nbsp;Hazel Cathcart ,&nbsp;Jian Feng ,&nbsp;Amy Hou","doi":"10.1016/j.atmosenv.2025.121074","DOIUrl":"10.1016/j.atmosenv.2025.121074","url":null,"abstract":"<div><div>This study constitutes Part I of the ADAGIO project (Atmospheric Deposition Analysis Generated by Integrating Observations into model), initiated by Environment and Climate Change Canada (ECCC) to improve the accuracy of sulfur (S), nitrogen (N), and ozone deposition estimates across Canada and the United States. Using deterministic data fusion, it combines numerical models and ground-level observations to generate seasonal objective analyses (OAs) for twelve chemical species, including gases, particulates, and precipitation species, over multiple years (2010, 2013, 2014, 2015, 2016, 2019). OAs are computed seasonally to enable high-resolution estimates of annual total deposition, validate air quality models, assess model errors, and evaluate ecosystem impacts, such as acidification and eutrophication. ADAGIO employs Optimal Interpolation, optimized through sensitivity tests, to integrate measurements with archived outputs from ECCC’s GEM-MACH regional air quality model. The ADAGIO project spans three papers, addressing wet deposition (pollutants in precipitation), dry deposition (gas and particles deposited onto surfaces), and total annual deposition (wet and dry combined). Objectives of ADAGIO include deriving total annual N and S deposition over North America and comparing seasonal OAs with model outputs to identify biases and errors. Part I, presented here, focuses on wet deposition and represents the first application of optimal interpolation for fusing wet deposition estimates with observational data over a continental scale. This innovative approach using OI marks a significant advancement in deposition data fusion methodologies over North America</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"347 ","pages":"Article 121074"},"PeriodicalIF":4.2,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427700","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":"Atmospheric aerosols in the South Pacific: A regional baseline and characterization of aerosol fractions","authors":"Alejandra Isaza ,&nbsp;Jimmy Hilly ,&nbsp;Merlinde Kay ,&nbsp;Abhnil Prasad ,&nbsp;Andrew Dansie","doi":"10.1016/j.atmosenv.2025.121048","DOIUrl":"10.1016/j.atmosenv.2025.121048","url":null,"abstract":"<div><div>Atmospheric aerosols are a major component of the earth's climate system and modulate air quality at local and regional scales. One region that has seen little attention is the South Pacific, despite air quality being of increasing concern for human health in Pacific Island Countries and Territories (PICTs). A review of literature on sources of pollution emissions in the Pacific region reveals that while most of the studies have focused on specific emission events, the annual cycle and long-term variability of the different aerosol types is rarely considered. Hence, this study provides a regional overview of aerosols over the Pacific using two global reanalyses (NASA/MERRA-2 and ECMWF/CAMS) and one satellite-based product (VIIRS). The uncertainties of the different data sources are discussed. The spatio-temporal variability of total Aerosol Optical Depth (AOD) and different aerosol species is shown and discussed in relation to the pollution sources previously investigated. In general, CAMS exhibits a higher total AOD (0.11) compared to MERRA-2 (0.09), both lower than VIIRS (0.12). Both reanalyses show that sea salt is the predominant aerosol source in the region, whereas sulphates and organic matter aerosols are also significant pollution sources, particularly over the islands in Melanesia. Both reanalyses capture the annual variation of AOD similarly, with higher total AOD levels occurring from September to February (SON and DJF), and lower levels from March to May (MAM). Besides capturing the aerosols seasonal variability, both reanalyses also capture extreme aerosol peaks, which evidence the long-range transport of dust from the Australian outback, black carbon and organic matter from major Australian bushfires, and sulphates from volcanic eruptions. This study serves as a baseline for further air quality assessment in the PICTs, considering that the seasonal variation presented here has not been thoroughly analyzed before but can be expected to play an important role in regional atmospheric and ocean biochemistry as well as potential impacts on human health in the Pacific.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121048"},"PeriodicalIF":4.2,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348590","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":"Atmospheric degradation of biofuel cyclic esters initiated by chlorine atom: Product yields and ring-retaining oxidation vs. ring opening mechanisms","authors":"Andrea Baptista ,&nbsp;Rodrigo G. Gibilisco ,&nbsp;María B. Blanco ,&nbsp;Mariano A. Teruel","doi":"10.1016/j.atmosenv.2025.121073","DOIUrl":"10.1016/j.atmosenv.2025.121073","url":null,"abstract":"<div><div>A product study was carried out for the reaction of γ-caprolactone and γ-heptalactone with Cl atoms at (298 ± 2) K and atmospheric pressure. The experiments were performed in a 480L glass multipass reactor with <em>in situ</em> FT-IR detection. The main products identified and quantified includes (in molar yield %): succinic anhydride (68 ± 2), propanoic acid (25 ± 1), acetaldehyde (59 ± 1), formaldehyde (10 ± 1) and acetic anhydride (26 ± 2) in the Cl atoms with γ-caprolactone reaction. Meanwhile, butanoic acid (26 ± 1), succinic anhydride (70 ± 2), propanaldehyde (63 ± 1) and propanoic acid (11 ± 1) were identified and quantified for Cl atoms with γ-heptalactone reaction. In addition, a chemical mechanism has been proposed taking into account the identified and quantified products. The mechanistic provided by the identified products, reveals that the degradation mechanisms can proceed either through ring opening or oxidation pathways. In these sense, the opening path leads to the carboxylic acids formation and the oxidation forms succinic anhydride. The succinic anhydride quantification, as the major product in both reactions, suggests that the oxidation ring is the most relevant channel in the reactions studied. Considering that the identified acids and anhydrides are of atmospheric importance, due to their potential for acidification of the troposphere and the atmospheric implications have been discussed.</div></div>","PeriodicalId":250,"journal":{"name":"Atmospheric Environment","volume":"346 ","pages":"Article 121073"},"PeriodicalIF":4.2,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143317787","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}