Environmental science: atmospheres最新文献

{"title":"Quantifying the dominant sources influencing the 2016 particulate matter pollution episode over northern India†","authors":"Prerita Agarwal, David S. Stevenson and Mathew R. Heal","doi":"10.1039/D3EA00174A","DOIUrl":"https://doi.org/10.1039/D3EA00174A","url":null,"abstract":"<p >Intense episodes of fine particulate matter (PM<small>_2.5</small>) pollution often overwhelm large areas of the Indo-Gangetic Plain (IGP) in northern India during the post-monsoon season, a time when crop residue burning is at its peak. We conduct idealised emission sensitivity experiments using the WRF-Chem model to investigate the leading causes and spatiotemporal extent of one such extreme episode from 31 Oct to 8 Nov 2016, when hourly PM<small>_2.5</small> levels exceeded 500 μg m<small>⁻³</small> across much of the IGP on several days. We utilise the anthropogenic emissions from EDGARv5.0 and the latest FINNv2.5 for fire emissions and evaluate modelled and observed ambient PM<small>_2.5</small> and black carbon (BC) concentrations across the IGP. The model captured the PM<small>_2.5</small> and BC peaks during the latter half of the episode and underestimated on other days. We find that biomass burning (BB) emissions during this episode have the strongest effect across the source regions in the upper (NW) IGP, followed by Delhi (middle IGP), where it contributes 50–80% to 24 h mean PM<small>_2.5</small>. Complete elimination of BB emissions decreases PM<small>_2.5</small> concentrations by 400 μg m<small>⁻³</small> (80–90%) in the upper IGP and by 280 μg m<small>⁻³</small> (40–80%) across the middle IGP during this episode. Contributions from the BB source to daily varying BC concentrations are 80–90%, 40–85% and 10–60% across upper, middle and lower IGP, respectively. BB emissions dominantly contribute to daily mean secondary organic aerosols (80%), primary organic aerosols (90%), dust (60%), and nitrate (50%) components of PM<small>_2.5</small> across the upper and middle IGP. In comparison, the anthropogenic share of these compounds was nearly one-third everywhere except across the lower IGP. The buildup of the episode across the middle IGP was facilitated by prolonged atmospheric stratification and stagnation, causing BB-derived BC and PM<small>_2.5</small> to be trapped in the lowest 1 km. Our work emphasises the need for rigorous policy interventions during post-monsoon to reduce agricultural crop burning, together with targeted anthropogenic emissions control across the IGP, to minimise such extreme episodes in the future.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 6","pages":" 655-669"},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d3ea00174a?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The formation and transport of HNO3 over the Yellow Sea and its impact on the January 2018 PM2.5 episode in Seoul†","authors":"Hyeon-Yeong Park, Joon-Young Ahn, Sung-Chul Hong, Jae-Bum Lee and Seog-Yeon Cho","doi":"10.1039/D4EA00034J","DOIUrl":"https://doi.org/10.1039/D4EA00034J","url":null,"abstract":"<p >The formation of HNO<small>₃</small> gas over the Yellow Sea and its impact on particulate nitrate concentrations in Seoul during the PM<small>_2.5</small> episode in Seoul in January 2018 were studied by analyzing monitoring data and running WRF-CMAQ model simulations. Monitoring data showed that particulate nitrate made up 41% of the PM<small>_2.5</small> during the episode, 2.7 times more than in other periods, and its level was strongly correlated with PM<small>_2.5</small> mass, indicating that the particulate nitrate is the primary cause of the episode. During the episode, eastern China was in slight to moderate ammonia-rich conditions and Seoul had slight ammonia-rich conditions. In contrast, severe ammonia-lean conditions prevailed in the Yellow Sea. Despite the decline of solar radiation at night, the production rate of HNO<small>₃</small> in the Yellow Sea still increased slightly due to the higher nocturnal ozone levels compared to the daytime. On the other hand, it decreased in eastern China and western Korea during the night as O<small>₃</small> dissipated by NO titration, resulting in the conversion rates of NO<small>₂</small> to HNO<small>₃</small> in the Yellow Sea being several times higher than those in eastern China and western Korea. The HNO<small>₃</small> gas formed in the Yellow Sea was transported to Seoul under westerly winds, contributing to particulate nitrate formation. Furthermore, the rate of formation of HNO<small>₃</small> gas in the Yellow Sea was 65% higher than that in Seoul during the night, which indicated that the regional influence dominated the local influence in determining the particulate nitrate concentrations in Seoul.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 6","pages":" 670-684"},"PeriodicalIF":0.0,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d4ea00034j?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interference of sea salt in capture vaporizer-ToF-ACSM measurements of biomass burning organic aerosols in coastal locations†","authors":"Adhitya Sutresna, Melita Keywood, Clare Paton-Walsh, Jack Simmons, Caleb Mynard, Quang Dang, Michihiro Mochida, Sho Ohata, Sonia Afsana, Bhagawati Kunwar, Kimitaka Kawamura, Ruhi Humphries, Erin Dunne, Jason Ward, James Harnwell, Fabienne Reisen, Kathryn Emmerson, Alan Griffiths, Alastair Williams, Robyn Schofield and Peter Rayner","doi":"10.1039/D3EA00171G","DOIUrl":"https://doi.org/10.1039/D3EA00171G","url":null,"abstract":"<p >The capture vaporizer (CV) was developed to reduce uncertainties in non-refractory aerosol composition measurements made using the aerosol mass spectrometer (AMS) and the aerosol chemical speciation monitor (ACSM). Use of the capture vaporizer has achieved this by improving the instruments' collection efficiency to ∼1, but it has also lengthened the aerosol particles' residence times in the instrument, which has changed AMS and ACSM measurements using the standard vaporizer by altering known fragmentation patterns of organic marker species and increasing the likelihood of detecting refractory particles such as sea salt at typical operating temperatures (∼550 °C). This study reports that the changes affected by the capture vaporizer leads to sea salt particles interfering with measurements of biomass burning organic aerosols (BBOA) in environments where both particle sources are present as the ACSM's unit mass resolution is unable to distinguish between different molecules with the same molecular mass. Demonstration of this interference was performed using CV-Time of Flight-ACSM (CV-ToF-ACSM) measurements at two coastal Australian locations: the Kennaook-Cape Grim Baseline Air Pollution Station, Tasmania; and the site of the COALA-2020 (Characterizing Organics and Aerosol Loading over Australia 2020) campaign in New South Wales. Concentrations of BBOA marker ions <em>m</em>/<em>z</em> 60 and <em>m</em>/<em>z</em> 73 were examined at both locations, which showed two distinct branches of points: one where the two marker ions were positively correlated and one that was uncorrelated. This was due to <em>m</em>/<em>z</em> 60 also being a marker for sea salt. A threshold concentration of <em>m</em>/<em>z</em> 73 was established at each location to recognise periods where <em>m</em>/<em>z</em> 60 originated from BBOA. Lower concentrations of <em>m</em>/<em>z</em> 44 and radon when <em>m</em>/<em>z</em> 73 concentration was below the BBOA threshold indicated that <em>m</em>/<em>z</em> 60 concentration during these periods corresponded to inorganic particles of marine origin. Positive Matrix Factorization has also been shown to separate <em>m</em>/<em>z</em> 60 concentration from the two sources. This study suggests that using CV-ToF-ACSMs in coastal locations that are exposed to biomass burning smoke needs to consider sea salt interference when identifying BBOA.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 6","pages":" 634-644"},"PeriodicalIF":0.0,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d3ea00171g?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-year, high-time resolution aerosol chemical composition and mass measurements from Fairbanks, Alaska†","authors":"Ellis S. Robinson, Michael Battaglia, Jr, James R. Campbell, Meeta Cesler-Maloney, William Simpson, Jingqiu Mao, Rodney J. Weber and Peter F. DeCarlo","doi":"10.1039/D4EA00008K","DOIUrl":"https://doi.org/10.1039/D4EA00008K","url":null,"abstract":"<p >Fairbanks-North Star Borough, Alaska (FNSB) regularly experiences some of the worst wintertime air quality in the United States. Exceedances of the EPA's 24 h fine particulate matter (PM<small>_2.5</small>) rule are common, and can last for weeks-long periods. Here we present sub-hourly measurements of chemically-speciated aerosol measurements over a 25 month span from an Aerosol Chemical Speciation Monitor (ACSM). This dataset includes measurements from all four seasons and over three separate winters (2020, 2021, 2022). It spans a long enough duration to provide an overview of typical seasonal and diurnal variations in aerosol concentrations, composition, and sources in Fairbanks. We observe consistent high PM<small>_2.5</small> concentrations in wintertime, which is dominated by organic aerosol (OA) and, to a lesser extent, sulfate (SO<small>₄</small>). We perform factor analysis of the OA using Positive Matrix Factorization (PMF), which reveals three factors, two of which are attributable to primary sources. These primary OA factors are highest in concentration and fractional contribution during wintertime. We show that high concentration periods are correlated with cold temperatures, and enriched in those organic aerosol components related to primary emissions. High concentration periods are also enriched in SO<small>₄</small>, though we show that some of the “SO<small>₄</small>” measured by the ACSM is very likely organosulfur compounds, which are more prevalent at high concentrations. We also show that within winter, there are significantly different diurnal patterns in PM components depending on meteorological parameters. This analysis is important for understanding air quality patterns in Fairbanks, and as context for the 2022 ALPACA measurement campaign.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 6","pages":" 685-698"},"PeriodicalIF":0.0,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d4ea00008k?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heterogeneous ozonolysis of alkyl substituted-polycyclic aromatic hydrocarbons (AlkPAHs) in the atmosphere†","authors":"Vera Zaherddine, Elisabeth Galarneau and Arthur W. H. Chan","doi":"10.1039/D4EA00024B","DOIUrl":"https://doi.org/10.1039/D4EA00024B","url":null,"abstract":"<p >Polycyclic aromatic compounds (PACs) encompass a range of organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), alkyl-substituted PAHs (AlkPAHs), and others. PAHs have been extensively studied due to their environmental and health implications. AlkPAHs, however, have received relatively less attention, despite recent evidence suggesting their greater abundances in ambient air. Given their prevalence and potential risks, investigating the atmospheric transformation of AlkPAHs is crucial. This work focuses on the heterogeneous oxidation of AlkPAHs, specifically addressing the influence of alkyl groups on reaction kinetics. Oxidation by gas phase ozone was conducted on quartz filters, which serve as models for silica surfaces on which PACs can deposit with minimal chemical interactions. The results reveal that AlkPAHs react faster with ozone than PAHs do, with reaction rates increasing with higher alkyl group substitutions. Furthermore, oxygenated polycyclic aromatic hydrocarbons (OPAHs) were formed during the oxidation of 1-methylpyrene, with greater diversity than those from pyrene. These products are more polar and potentially more toxic than parent compounds. In conclusion, this research advances our understanding of PAC oxidation, focusing on AlkPAHs' heterogeneous oxidation, the influence of alkyl groups, and the formation of OPAHs. These insights have significant implications for air quality, health risk assessments, and the fate of PACs in the environment.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 6","pages":" 645-654"},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d4ea00024b?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatio-temporal changes in the pre-monsoon thunderstorm activities of northeast India over the past four decades†","authors":"Arpita Rastogi, J. Kuttippurath and V. K. Patel","doi":"10.1039/D3EA00133D","DOIUrl":"https://doi.org/10.1039/D3EA00133D","url":null,"abstract":"<p >The development of catastrophic mesoscale convective systems in the atmosphere, such as thunderstorms, is caused by several factors, the most important of which is moisture in the lower troposphere and then the instability and lifting of air parcels. In pre-monsoon, northeast and adjoining eastern India are susceptible to thunderstorms. Herein, we analyse the spatial and temporal changes in thunderstorm activities in terms of convective available potential energy (CAPE) and other parameters during the pre-monsoon period (March, April and May) in northeast (NE) and adjoining eastern India using ground-based and reanalysis data. It is observed that atmospheric instability is relatively higher in southern West Bengal and Tripura compared to the other regions in NE and adjoining eastern India, with a CAPE value of about 1500–3000 J kg<small>⁻¹</small> during pre-monsoon and 2000–3500 J kg<small>⁻¹</small> in May, indicating that these regions are more vulnerable to thunderstorms. Other thunderstorm indicators such as convective inhibition (CIN), <em>K</em>-index (KI) and total totals index (TTI) also exhibit relatively higher values in these regions during pre-monsoon. Causal discovery and correlation analysis reveal a positive association of thunderstorm days with CAPE and TTI, but a negative link with CIN. A significant negative trend is estimated in CAPE and other parameters in NE and eastern India during May, which is more dominant in southern West Bengal and Tripura (about −8 to −12 J per kg per year). Stability indices such as KI and TTI also show significant negative trends in NE India. There is a negative trend in thunderstorm days at Mohanbari, Barapani, Jorhat, Pasighat and Silchar, while positive trends at Dhubri, Imphal, Tezpur and Lengpui in the recent decade (2011–2020), which is consistent with the changes in thunderstorm indicators at these stations. This study provides an important insight into thunderstorm activity in areas susceptible to extreme weather events in the context of recent climate change and global warming.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 5","pages":" 557-570"},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d3ea00133d?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140949104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Antimicrobial activity of safe concentrations of ozone, hydrogen peroxide, and triethylene glycol in air and surfaces","authors":"Joan Truyols-Vives, Salut Botella-Grau, Josep Mercader-Barceló and Herme G. Baldoví","doi":"10.1039/D3EA00156C","DOIUrl":"https://doi.org/10.1039/D3EA00156C","url":null,"abstract":"<p >Monitoring and control of indoor air hygiene has gained much interest since the COVID-19 pandemic because the airborne route is the main pathway for the spread of SARS-CoV-2 and other pathogens, making it necessary to develop strategies to mitigate airborne transmission of diseases. This work addresses indoor breathable air hygiene by proposing the “<em>in situ</em>” reduction of airborne microorganisms with the nebulization of low and safe concentrations of hydrogen peroxide (H<small>₂</small>O<small>_2,</small> 0.5 and 1 ppm), ozone (O<small>_3,</small> 0.06 and 0.2 ppm), triethylene glycol (TEG, 17.1, 52 and 171.2 ppm), and their combinations. The antimicrobial activity was evaluated in an office room by assessing the viability of commercial extremophile sporulated bacteria and naturally present bacteria and fungi in surfaces and air. All three chemicals individually dispersed reduced the viability of sporulated bacteria and naturally occurring microorganisms. Binary combinations were more effective than individual agents in the case of the H<small>₂</small>O<small>₂</small> and O<small>₃</small> mixture against sporulated bacteria, and the O<small>₃</small> and TEG mixture against airborne and surface bacteria. The ternary mixture was the most effective against commercial sporulated bacteria and airborne microorganisms. These results illustrate that the application of low and safe concentrations of antimicrobial compounds in indoor air could be an interesting strategy to reduce infection risk.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 6","pages":" 620-633"},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d3ea00156c?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Singlet oxygen is produced from brown carbon-containing cooking organic aerosols (BrCOA) under indoor lighting†","authors":"Nadine Borduas-Dedekind, Keighan J. Gemmell, Madushika Madri Jayakody, Rickey J. M. Lee, Claudia Sardena and Sebastian Zala","doi":"10.1039/D3EA00167A","DOIUrl":"https://doi.org/10.1039/D3EA00167A","url":null,"abstract":"<p >Light absorbing organic molecules known as brown carbon (BrC) can be emitted during processes such as cooking and combustion in indoor environments. We hypothesized that indoor BrC-containing cooking organic aerosols, or BrCOA, can act as sensitizers to generate the first excited state of molecular oxygen, singlet oxygen (<img>), under indoor lighting conditions. Here, we used an impinger to collect aerosols from a range of cooking dishes, including pancakes, pan-fried Brussels sprouts and vegetable stir-fries, and irradiated these samples in a photoreactor with UVA and fluorescent lights and on a sunlit windowsill. Using furfuryl alcohol as a probe for <img>, we determined steady-state concentrations of <img> using liquid chromatography and calculated apparent quantum yields for each BrCOA sample. Our results show that under all indoor lighting conditions tested, BrCOA can indeed sensitize <img>. Specifically, in solutions of BrCOA from pancakes, pan-fried Brussels sprouts, and vegetable stir-fries under UVA light, the <img> concentrations were 2.56 ± 1.24 × 10<small>⁻¹³</small> M, 2.24 ± 1.51 × 10<small>⁻¹³</small> M, and 3.12 ± 0.86 × 10<small>⁻¹³</small> M, respectively. These results suggest that <img> production is not dish-dependent, but rather produced across a range of BrCOA samples. We then normalized the <img> concentrations to the rate of absorbance to obtain apparent quantum yields up to 6.1%. Both the quality and the quantity of the chromophoric BrCOA were important for predicting the apparent quantum yield. Moreover, the indoor sunlit experiments led to the highest <img> concentrations observed, with important implications on the formation of oxidants in sunlit kitchens. These results demonstrate the ability of BrCOA to produce <img> in indoor environments, and thus for <img> to be a competitive indoor oxidant.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 6","pages":" 611-619"},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d3ea00167a?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights into size-segregated distribution of benzothiazoles in indoor aerosol from office environments†","authors":"Matteo Feltracco, Giovanna Mazzi, Elena Barbaro, Elena Gregoris, Mara Bortolini, Carlo Barbante and Andrea Gambaro","doi":"10.1039/D4EA00031E","DOIUrl":"https://doi.org/10.1039/D4EA00031E","url":null,"abstract":"<p >Understanding the impact of rubber-derived particles on indoor environmental quality is crucial for effective environmental management. Emissions from both roads and textiles are recognized contributors to pollution across diverse environments, including indoor spaces. Benzothiazoles and their derivatives serve as valuable tracers for identifying pollutant sources. In this study, a total of eight benzothiazoles were determined in indoor size-segregated aerosol samples collected from 6th November to 11th December 2023 in Mestre-Venice. The selected offices host both university personnel and students. The results indicate that SO<small>₃</small>H-BTH, SH-BTH and OH-BTH were the most concentrated benzothiazoles in aerosol samples. The inhaled daily intake remained low if compared with previous studies, but higher values were found in fine particles (&lt;0.56 μm). Despite the presence of an advanced filtration system, BTHs have been detected across various dimensional fractions, indicating an internal source. Considering that most of the benzothiazoles were distributed in the finest fraction, the findings raise concerns about their capability to reach alveoli and causing health issues.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 5","pages":" 571-577"},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d4ea00031e?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140949099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of relative humidity on the molecular composition of secondary organic aerosols from α-pinene ozonolysis†","authors":"Hao Luo, Yindong Guo, Hongru Shen, Dan Dan Huang, Yijun Zhang and Defeng Zhao","doi":"10.1039/D3EA00149K","DOIUrl":"https://doi.org/10.1039/D3EA00149K","url":null,"abstract":"<p >Secondary organic aerosols (SOAs) originating from the oxidation of biogenic volatile organic compounds such as monoterpenes by atmospheric oxidants (<em>e.g.</em> OH, ozone, and NO<small>₃</small>), constitute a widespread source of organic aerosols in the atmosphere. Among monoterpenes, α-pinene has the highest emission rates and its ozonolysis is often used as a canonical SOA system. However, the molecular composition of SOAs obtained from monoterpene ozonolysis as a function of relative humidity (RH) remains unclear. Herein, we investigated the real-time molecular composition of SOAs obtained from the ozonolysis of α-pinene using extractive electrospray ionization coupled with long time-of-flight mass spectrometry (EESI-LTOF-MS). We investigated the dependence of the molecular composition on RH in the presence and absence of seed aerosols. We characterized a large number of organic compounds, including less oxygenated and highly oxygenated organic molecules (HOMs). In the presence of a ammonium sulfate (AS) seed aerosol, the fractions of both monomers and dimers in the SOAs from α-pinene ozonolysis remained largely unchanged as RH increased from 3% to 84%, which can be attributed to a similar extent of increase in the absolute abundance of both dimers and monomers with increasing RH. The increase of the absolute abundance of monomers is likely due to the enhanced partitioning of less oxygenated semi-volatile monomer products (such as C<small>₁₀</small>H<small>₁₆</small>O<small>_{<em>x</em>≤6}</small>) at higher RH. The increase in the absolute abundance of dimers may be attributed to acid-catalyzed reactions, which is corroborated by a marked change in the distribution pattern of dimers. The average O/C of the most abundant product families in the SOAs, such as C<small>₁₀</small>H<small>₁₆</small>O<small>_<em>x</em></small>, decreased with increasing RH due to the decreasing fractions of more oxygenated products (C<small>₁₀</small>H<small>₁₆</small>O<small>_{<em>x</em>&gt;6}</small>). However, the elemental composition (O/C and H/C) of the total SOA remained stable with increasing RH. In contrast, in the absence of the seed aerosol, an increase in the monomer fraction and a decrease in the dimer fraction were observed with increasing RH. These changes were attributed to a combination of different extents of condensation enhancement of monomer and dimer vapors by increasing RH and different vapor wall losses of monomers and dimers. Our results provide new insights into the RH-dependent molecular chemical composition of α-pinene SOAs. We also highlight the necessity to characterize the composition of SOAs at the molecular level.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 5","pages":" 519-530"},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ea/d3ea00149k?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140949101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}