ACS ES&T Air最新文献

{"title":"Co-Occurring Extremes of PM2.5 and Ozone in Warm Seasons of the Yangtze River Delta of China: Insights from Explainable Machine Learning","authors":"Yan Lyu*,&nbsp;Danni Wu,&nbsp;Fuliang Han,&nbsp;Huiying Zhang,&nbsp;Fengmao Lv,&nbsp;Azhen Kang,&nbsp;Yijia Hu and Xiaobing Pang,&nbsp;","doi":"10.1021/acsestair.4c0031410.1021/acsestair.4c00314","DOIUrl":"https://doi.org/10.1021/acsestair.4c00314https://doi.org/10.1021/acsestair.4c00314","url":null,"abstract":"<p >Recently, summertime PM_2.5 and ozone extremes were reported to frequently co-occur in southern China. In this study, we further demonstrate that their co-occurring extremes can spread into warm seasons in the Yangtze River Delta (YRD) region of China. The annual co-occurrence frequency ranged from 26% to 50% in the YRD from 2015 to 2022, with higher frequencies observed in coastal cities. Notably, the co-occurrence frequency was higher during the COVID-19 pandemic, implying that such co-occurrence may be more spatially widespread with continuous PM_2.5 reduction in China. Taking the pandemic period as an example, we leveraged a machine learning algorithm (i.e., Random Forest) coupled with SHapley Additive ExPlanation (SHAP) to identify higher relative importance of solar radiation-related variables (e.g., surface net solar radiation) during co-occurrence periods compared to non-co-occurrence periods in the YRD. Additionally, incorporating volatile organic compounds (VOCs) measurements, we further showed the higher relative importance of VOCs to the extremes of ozone and PM_2.5 through a case study at Shaoxing (a typical city in the YRD). Overall, the findings highlight the increasing potentials for co-occurring extremes with ongoing PM_2.5 reductions in the YRD and suggest that reducing VOCs (e.g., halocarbons) may help mitigate these extremes in the future.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"578–588 578–588"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrafine Particle Growth Rate During Biogenic Secondary Organic Matter Formation as a Function of Particle Composition, Size, and Phase","authors":"Michael S. Taylor Jr.,&nbsp;Devon N. Higgins,&nbsp;Justin M. Krasnomowitz and Murray V. Johnston*,&nbsp;","doi":"10.1021/acsestair.4c0033910.1021/acsestair.4c00339","DOIUrl":"https://doi.org/10.1021/acsestair.4c00339https://doi.org/10.1021/acsestair.4c00339","url":null,"abstract":"<p >The growth rate of ultrafine seed particles by uptake of secondary organic matter (SOM) is studied with a flow tube reactor to elucidate key factors that can enhance or inhibit the rate. Through application of a time-dependent kinetic model, the molecular growth factor (GF) associated with SOM formation is determined. GF is defined as the fraction of the oxidation products from a biogenic precursor that contribute to seed particle growth. Two seed particle compositions (ammonium sulfate and ammonium bisulfate) are studied under two phase states (effloresced and deliquesced at either 10% or 60% relative humidity) for growth by two different biogenic precursors (isoprene and α-pinene). The results show: (1) ammonium sulfate seed particles give higher GFs than ammonium bisulfate seed particles, (2) increasing the water content of the seed particle increases the GF, and (3) isoprene and α-pinene show the same dependencies of GF on seed particle composition and water content. These dependencies suggest that physicochemical processes in the aqueous layer at or near the air–particle interface enhance the growth rate of particles in the 40 to 80 nm size range, which is relevant to the formation of cloud condensation nuclei.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"615–624 615–624"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High Abundance of Atmospheric Sulfonates Derived from Light-Duty Gasoline Vehicles","authors":"Shuang Chen,&nbsp;Huixia Han,&nbsp;Lihong Ren,&nbsp;Yisheng Xu*,&nbsp;Libin Wu,&nbsp;Yuanguan Gao,&nbsp;Yuanbi Yi,&nbsp;Xinping Yang,&nbsp;Mingliang Fu,&nbsp;Hang Yin,&nbsp;Yan Ding and Pingqing Fu*,&nbsp;","doi":"10.1021/acsestair.4c0033410.1021/acsestair.4c00334","DOIUrl":"https://doi.org/10.1021/acsestair.4c00334https://doi.org/10.1021/acsestair.4c00334","url":null,"abstract":"<p >Particulate matter (PM) emissions from light-duty gasoline vehicles (LDGV) pose a threat to both air quality and human health. However, the molecular compositions and chemical properties of these complex mixtures are poorly understood. In this study, we performed a detailed characterization of exhaust PM from LDGV at various speed phases at the molecular level by employing ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry. We found that with increasing speed, the number of organic compounds increased significantly, especially organic nitrogen-containing and sulfur-containing compounds. Moreover, the increase of speed leads to high temperature and high pressure in the cylinder, which in turn leads to a series of thermal cracking–polymerization–cyclization reactions, resulting in new particulate matter with more aromatic structures. In addition, considerable intermediate volatility organic compounds and semivolatile organic compounds were identified in the exhaust PM. Notably, we observed the presence of sulfonates in tailpipe particulate matter during low- or high-speed phases, which highlights a previously negligible source of organic sulfonates in the atmosphere.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"607–614 607–614"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical Imaging of Atmospheric Biomass Burning Particles from North American Wildfires","authors":"Felipe A. Rivera-Adorno,&nbsp;Jay M. Tomlin,&nbsp;Nurun Nahar Lata,&nbsp;Lisa Azzarello,&nbsp;Michael A. Robinson,&nbsp;Rebecca A. Washenfelder,&nbsp;Alessandro Franchin,&nbsp;Ann M. Middlebrook,&nbsp;Swarup China,&nbsp;Steven S. Brown,&nbsp;Cora J. Young,&nbsp;Matthew Fraund,&nbsp;Ryan C. Moffet and Alexander Laskin*,&nbsp;","doi":"10.1021/acsestair.4c0024210.1021/acsestair.4c00242","DOIUrl":"https://doi.org/10.1021/acsestair.4c00242https://doi.org/10.1021/acsestair.4c00242","url":null,"abstract":"&lt;p &gt;The effects of biomass burning aerosols (BBA) on radiative forcing and cloud formation depend on chemical composition and the internal structures of individual particles within smoke plumes. To improve our understanding of the chemical and physical properties of BBA emitted at different times of the day and their evolution during atmospheric aging, we conducted a study as a part of the Fire Influence on Regional to Global Environments and Air Quality field campaign. Particle samples were collected onboard a research aircraft from smoke plumes from a wildfire in eastern Oregon during late afternoon and nighttime flights on August 28, 2019. A time-resolved aerosol collector was used to collect samples on substrates for offline spectromicroscopic imaging to investigate the single-particle characteristics of BBA particles. Approximately 20,400 individual particles from 10 selected samples were analyzed using computer-controlled scanning electron microscopy coupled with energy-dispersive X-ray microanalysis, revealing their elemental composition, morphology, and viscosity. Elemental microanalysis indicated that aged potassium is likely found in the form of K&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;, KNO&lt;sub&gt;3&lt;/sub&gt;, and possible K-organic salts. Further chemical speciation and carbon bonding mapping within individual particles were conducted using synchrotron-based scanning transmission X-ray microscopy (STXM) coupled with near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Real-time, water-soluble light absorption measurements were acquired using a particle-into-liquid sampler instrument coupled to a liquid waveguide capillary cell and total organic analyzer. In the late afternoon samples, 65% of the total particle number population consisted entirely of organic components, compared to 46% in the nighttime particles. These differences were attributed to discrepancies in composition at the time of emission and to the daytime condensation and accumulation of photochemically formed secondary organic material on existing BBA particles, a process that halts at night. Microscopy images indicated that particle viscosity was lower in the nighttime particles (&lt;10&lt;sup&gt;1&lt;/sup&gt; Pa·s), likely due to increased relative humidity and a higher contribution from hygroscopic inorganic components. The chemical heterogeneity of individual particles was quantified using STXM-derived mixing state parameters. The nature of carbon bonding within individual particles was inferred from the extent of carbon sp&lt;sup&gt;2&lt;/sup&gt; hybridization derived from NEXAFS spectra. Average percentages of sp&lt;sup&gt;2&lt;/sup&gt; hybridization range between 40% and 60%, with no noticeable differences between late afternoon and nighttime flights. These findings were compared with the online optical properties of both late afternoon and nighttime smoke plumes, providing valuable insights into the complex relationship between chemical composition and optical properties of BBA particles at different times","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"508–521 508–521"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiphase Processing of the Water-Soluble and Insoluble Phases of Biomass Burning Organic Aerosol","authors":"Habeeb H. Al-Mashala,&nbsp;Meredith Schervish,&nbsp;Sithumi M. Liyanage,&nbsp;Jace A. Barton,&nbsp;Manabu Shiraiwa and Elijah G. Schnitzler*,&nbsp;","doi":"10.1021/acsestair.4c0034510.1021/acsestair.4c00345","DOIUrl":"https://doi.org/10.1021/acsestair.4c00345https://doi.org/10.1021/acsestair.4c00345","url":null,"abstract":"<p >Biomass burning is one of the most significant sources of organic aerosol in the atmosphere. Biomass burning organic aerosol (BBOA) has been observed to undergo liquid–liquid phase separation (LLPS) to give core–shell morphology with the hydrophobic phase encapsulating the hydrophilic phase, potentially impacting the evolution of light-absorbing components, i.e., brown carbon (BrC), through multiphase processes. Here, we demonstrate how multiphase processing differs between the water-soluble (i.e., hydrophilic) and insoluble (i.e., hydrophobic) phases of BBOA in terms of reactive uptake of ozone in a coated-wall flow tube. Effects of relative humidity (RH) and ultraviolet (UV) irradiation were investigated. Experimental timeseries were used to inform simulations using multilayer kinetic modeling. Among non-irradiated thin films, the uptake coefficient was greatest for the water-soluble phase at 75% RH (3 × 10^–5, corresponding to a diffusion coefficient of BrC, <i>D</i>_BrC, of 3 × 10^–9 cm² s^–1) and least for the same phase at 0% RH (1 × 10^–5, corresponding to <i>D</i>_BrC of 1 × 10^–10 cm² s^–1). The uptake coefficient for the water-insoluble phase fell between these two (about 1.5 × 10^–5), regardless of RH, and the corresponding <i>D</i>_BrC increased only slightly (8 × 10^–10 cm² s^–1 at 0% RH to 9 × 10^–10 cm² s^–1 at 75% RH). The uptake coefficients of both phases at 0% RH decreased significantly after UV irradiation, consistent with a transition from viscous liquid to solid and supported by qualitative microscopy observations. Modeling multiphase ozone oxidation of primary BrC components in the atmosphere demonstrated, first, that LLPS may extend the lifetime of water-soluble BBOA encapsulated by water-insoluble species by a factor of 1.5 at moderate to high RH and, also, that UV irradiation may extend the lifetime of both phases by more than a factor of 2.5.</p><p >Liquid−liquid phase separation and ultraviolet irradiation may restrict the multiphase processing of biomass burning organic aerosol governing its climate effects.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"637–647 637–647"},"PeriodicalIF":0.0,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsestair.4c00345","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814582","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":"Organic Fingerprints of Condensable Particulate Matter from Ultralow Emission Stationary Sources in China","authors":"Zhaojin An,&nbsp;Dongbin Wang*,&nbsp;Shuwen Yang,&nbsp;Jianguo Deng,&nbsp;Xue Li,&nbsp;Yaowei Li and Jingkun Jiang*,&nbsp;","doi":"10.1021/acsestair.5c0000610.1021/acsestair.5c00006","DOIUrl":"https://doi.org/10.1021/acsestair.5c00006https://doi.org/10.1021/acsestair.5c00006","url":null,"abstract":"<p >Understanding organics in condensable particulate matter (CPM) from stationary sources is crucial for assessing air quality impacts, especially as CPM gains significance due to reductions in regulated PM and the implementation of ultralow emission standards in China. Knowledge of these organics remains limited as traditional targeted analyses potentially overlook important molecules and their atmospheric impacts. Here, we employed comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) to analyze the molecular compositions of organics in CPM from typical ultralow emission coal-fired power plants and iron and steel sintering plants in China. We established a nontargeted screening approach to obtain molecular fingerprints of these organics, identifying more than 180 and 200 compounds from over 1000 peaks from the two types of plants. Key contributors to CPM organics include substituted benzenes, polyfunctional aliphatic compounds, alkanes, and cycloalkanes, differing from the previously reported alkane dominance observed using traditional one-dimensional GC analysis. Intermediate/semivolatile organic compounds (I/SVOCs) dominate organics in CPM, with a significant fraction of low volatile organic compounds detected especially in iron and steel sintering plant emissions. Iron and steel sintering plants emit higher concentrations of organics in CPM, particularly aromatics, due to their lower combustion efficiency in the sintering processes. These findings enhance our understanding of the atmospheric behavior of organics in CPM and their impacts on air quality.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"692–699 692–699"},"PeriodicalIF":0.0,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dominant Role of NO2 Oxidation in SO2 Conversion to Sulfate Revealed by Synchronous Measurements of Gas and Particle Sulfur Isotopes in Haze Episodes","authors":"Xinxin Feng,&nbsp;Yingjun Chen*,&nbsp;Zeyu Liu,&nbsp;Hongxing Jiang,&nbsp;Yanli Feng and Tian Chen*,&nbsp;","doi":"10.1021/acsestair.4c0023910.1021/acsestair.4c00239","DOIUrl":"https://doi.org/10.1021/acsestair.4c00239https://doi.org/10.1021/acsestair.4c00239","url":null,"abstract":"<p >The oxidation pathways of SO₂ conversion to sulfate remain controversial. Sulfur isotope (δ³⁴S) has been used to trace the SO₄^2– formation pathways based on sulfur fractionation. Accurately assessing δ³⁴S fractionation is crucial to quantify SO₄^2– formation pathways. However, previous studies have used particle-phase δ³⁴S to estimate δ³⁴S fractionation (α³⁴S_g→p-estimated) in SO₄^2– formation, leading to significant uncertainties. δ³⁴S values of gas-to-particle (δ³⁴SO₂ and δ³⁴SO₄^2–) were synchronously measured to uncover isotope fractionation (α³⁴S_g→p). Results found that α³⁴S_g→p (−3.7‰ to +9.9‰) obtained by gas-to-particle δ³⁴S showed a significant difference with α³⁴S_g→p-estimated(−6.4‰ to +1.4‰) obtained by δ³⁴SO₄^2–, implying different results for SO₄^2– formation using the two methods. Among them, α³⁴S_g→p results indicated the prominent pathway of NO₂ oxidation (48–56%), while α³⁴S_g→p-estimated suggested the dominant role of transition metal ion (TMI)-catalyzed O₂ (54–80%). Additionally, α³⁴S_g→p results show a more reasonable response to SO₄^2– formation and consistent trends with oxidant concentrations. α³⁴S_g→p-estimated overestimated the TMI-catalyzed O₂ pathway contribution (38–47%) to SO₄^2– formation. This is the first study to employ gas-to-particle δ³⁴S to demonstrate the dominant role of NO₂ oxidation in SO₄^2– formation. This approach provides new insight into using δ³⁴SO₄^2– for the analysis of SO₄^2– formation.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"498–507 498–507"},"PeriodicalIF":0.0,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical Evolution of Biomass Burning Aerosols across Wildfire Plumes in the Western U.S.: From Near-Source to Regional Scales","authors":"Ryan Farley,&nbsp;Shan Zhou,&nbsp;Sonya Collier,&nbsp;Wenqing Jiang,&nbsp;Timothy B. Onasch,&nbsp;John E. Shilling,&nbsp;Lawrence Kleinman,&nbsp;Arthur J. Sedlacek III and Qi Zhang*,&nbsp;","doi":"10.1021/acsestair.5c0000210.1021/acsestair.5c00002","DOIUrl":"https://doi.org/10.1021/acsestair.5c00002https://doi.org/10.1021/acsestair.5c00002","url":null,"abstract":"<p >The atmospheric processing of biomass burning organic aerosol (BBOA) and its implications for tropospheric aerosol physicochemical properties remain uncertain. To address this gap, we investigate the chemical transformation of BBOA from wildfire events in the western U.S., using data from aerosol mass spectrometers aboard the DOE G-1 aircraft and at the Mt. Bachelor Observatory (∼2800 m a.s.l.) during the summers of 2013 and 2019. This study captures dynamic changes in submicron particulate matter (PM₁) concentrations and chemical profiles within wildfire plumes that span a broad range of atmospheric ages, from fresh emissions (&lt;30 min) to plumes transported for several days. As plumes age, the oxidation state of organic aerosols (OA) increases, accompanied by the formation of secondary aerosol components such as phenolic secondary OA (SOA) species, carboxylic acids, and potassium sulfate. Early plume evolution is marked by the evaporation of semivolatile components and the formation of alcohol and peroxide functional groups, while extended aging produces more oxidized species, including carboxylic acids and carbonyl compounds. Normalized excess mixing ratios (NEMRs) of OA to CO demonstrate a complex interplay between evaporation, SOA formation, and oxidative loss. Using positive matrix factorization (PMF), we identify distinct BBOA types representing various stages of atmospheric processing and assess the contributions of primary BBOA and secondary BBOA formed through atmospheric reactions. These findings shed light on the intricate mechanisms governing the evolution of BBOA characteristics within wildfire plumes, providing critical insights to improve atmospheric modeling of BBOA and better assess the environmental and climatic impacts of wildfire emissions.</p><p >This study integrates aircraft and mountaintop observatory measurements of wildfire emissions to analyze the chemical characteristics of aerosols and their transformation processes across a wide range of atmospheric ages.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"677–691 677–691"},"PeriodicalIF":0.0,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsestair.5c00002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814372","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":"Ethanol and Methanol in South Korea and China: Evidence for Large Anthropogenic Emissions Missing from Current Inventories","authors":"Ellie Beaudry*,&nbsp;Daniel J. Jacob,&nbsp;Kelvin H. Bates,&nbsp;Shixian Zhai,&nbsp;Laura H. Yang,&nbsp;Drew C. Pendergrass,&nbsp;Nadia Colombi,&nbsp;Isobel J. Simpson,&nbsp;Armin Wisthaler,&nbsp;James R. Hopkins,&nbsp;Ke Li and Hong Liao,&nbsp;","doi":"10.1021/acsestair.4c0021010.1021/acsestair.4c00210","DOIUrl":"https://doi.org/10.1021/acsestair.4c00210https://doi.org/10.1021/acsestair.4c00210","url":null,"abstract":"<p >Observations during the KORUS-AQ, MAPS-Seoul, and APHH-Beijing field campaigns of 2015–2017 reveal high concentrations of ethanol and methanol in urban air over South Korea and China, with median concentrations of 2–4 ppb for ethanol and 12–18 ppb for methanol. Simulations with the GEOS-Chem model show that these values cannot be captured by current emission inventories. They could originate from volatile chemical products (VCPs). Fitting observed ethanol concentrations with GEOS-Chem would imply per capita VCP emissions 2.4 times higher in South Korea and 1.5 times higher in China than in the U.S. The strong ethanol–methanol correlation suggests a major methanol component in VCP emissions, unlike in the U.S. where methanol use is largely banned. Including these emissions in GEOS-Chem increases the level of surface ozone over South Korea and China by 1–3 ppb. KORUS-AQ aircraft profiles also indicate a high free tropospheric methanol background of 3.2 ppb, which appears to be of terrestrial biospheric origin but cannot be reproduced by GEOS-Chem.</p><p >Atmospheric measurements of ethanol and methanol in South Korea and China indicate large emissions of these species from volatile chemical products.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"456–465 456–465"},"PeriodicalIF":0.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acsestair.4c00210","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814494","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":"Downdrafts of Biomass Burning to Houston Enhanced by Local Convective Activity","authors":"Rebecca J. Sheesley*,&nbsp;Mackenzie T. S. Ramirez,&nbsp;Jeewan Poudel,&nbsp;Travis Griggs,&nbsp;Manisha Mehra,&nbsp;Sujan Shrestha,&nbsp;Yang Li,&nbsp;Lucas Senkbeil and James Flynn,&nbsp;","doi":"10.1021/acsestair.4c0023210.1021/acsestair.4c00232","DOIUrl":"https://doi.org/10.1021/acsestair.4c00232https://doi.org/10.1021/acsestair.4c00232","url":null,"abstract":"<p >In June 2023, an elevated smoke layer from record-breaking Canadian wildfires was transported across the eastern half of the United States, impacting air quality for millions of people. Houston, TX experienced a notable biomass burning (BB) event associated with this wildfire smoke from Jun 4 to 9, 2023. The vertical transport of this smoke layer down to the surface followed afternoon convective activity in the Houston urban area on Jun 6–8. Our monitoring sites at urban, rural, and coastal locations around Houston experienced different levels of wildfire smoke. Carbon monoxide, aerosol absorption, and the Absorption Ångström Exponent (AAE) revealed stronger smoke incursions overnight at the urban site. The average nighttime AAE during the BB event period was 1.28 with 384 ppbv of CO; by comparison, the monthly nighttime averages for Jun 2023 were 1.03 and 172 ppbv, respectively. Enhanced PM_2.5 and NO₂ coincided with BB tracers while higher ozone concentrations were observed the following day at downwind sites relative to the peak observed BB smoke sites. The nighttime NO₂ for the BB event was also significantly higher than the monthly average with standard deviation for Jun 2023 (14.5 ppbv versus 5.19 ± 4.61 ppbv, respectively). Ozone concentrations peaked over 100 ppbv on Jun 9 driven by clear skies after the overnight high BB. Understanding the role of convective activity in enhancing the downdraft of BB plumes to the surface will improve assessment of the long-range impacts of wildfire smoke on urban populations.</p><p >Smoke from the June 2023 wildfires in Eastern Canada was transported at elevated layers to Houston, TX. Afternoon storms enhanced the downward mixing of this smoke to surface monitors.</p>","PeriodicalId":100014,"journal":{"name":"ACS ES&T Air","volume":"2 4","pages":"486–497 486–497"},"PeriodicalIF":0.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143814492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}