Articles | Volume 23, issue 22
https://doi.org/10.5194/acp-23-14437-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-23-14437-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
22 Nov 2023
Research article |
| 22 Nov 2023
| 22 Nov 2023
pH dependence of brown-carbon optical properties in cloud water
Christopher J. Hennigan
CORRESPONDING AUTHOR
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Michael McKee
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Vikram Pratap
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Bryanna Boegner
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Jasper Reno
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Lucia Garcia
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Madison McLaren
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Sara M. Lance
Atmospheric Sciences Research Center (ASRC), University at Albany, Albany, 12226, USA
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Measurements of aerosol and gas composition were carried out at a land–water transition site near Baltimore, MD. Gas-phase ammonia concentrations were highly elevated compared to measurements at a nearby inland site. Our analysis reveals that NH2 was from both industrial and agricultural sources. This had a pronounced effect on aerosol chemical composition at the site, most notably contributing to episodic spikes of aerosol nitrate.
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This work uses chemical transport and box modeling to study the gas- and aqueous-phase production of organic acid concentrations measured in cloud water at the summit of Whiteface Mountain on 1 July 2018. Isoprene was the major source of formic, acetic, and oxalic acid. Gas-phase chemistry greatly underestimated formic and acetic acid, indicating missing sources, while cloud chemistry was a key source of oxalic acid. More studies of organic acids are required to better constrain their sources.
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Atmospheric aqueous chemistry can have profound effects on our environment, as illustrated by historical data from Whiteface Mountain (WFM) that were critical for uncovering the process of acid rain. The current study updates the long-term trends in cloud water composition at WFM for the period 1994 to 2021. We highlight the emergence of a new chemical regime at WFM dominated by organics and ammonium, quite different from the highly acidic regime observed in the past but not necessarily
clean.
Michael A. Battaglia Jr., Nicholas Balasus, Katherine Ball, Vanessa Caicedo, Ruben Delgado, Annmarie G. Carlton, and Christopher J. Hennigan
Atmos. Chem. Phys., 21, 18271–18281, https://doi.org/10.5194/acp-21-18271-2021, https://doi.org/10.5194/acp-21-18271-2021, 2021
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Nicholas Balasus, Michael A. Battaglia Jr., Katherine Ball, Vanessa Caicedo, Ruben Delgado, Annmarie G. Carlton, and Christopher J. Hennigan
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Measurements of aerosol and gas composition were carried out at a land–water transition site near Baltimore, MD. Gas-phase ammonia concentrations were highly elevated compared to measurements at a nearby inland site. Our analysis reveals that NH2 was from both industrial and agricultural sources. This had a pronounced effect on aerosol chemical composition at the site, most notably contributing to episodic spikes of aerosol nitrate.
Havala O. T. Pye, Athanasios Nenes, Becky Alexander, Andrew P. Ault, Mary C. Barth, Simon L. Clegg, Jeffrey L. Collett Jr., Kathleen M. Fahey, Christopher J. Hennigan, Hartmut Herrmann, Maria Kanakidou, James T. Kelly, I-Ting Ku, V. Faye McNeill, Nicole Riemer, Thomas Schaefer, Guoliang Shi, Andreas Tilgner, John T. Walker, Tao Wang, Rodney Weber, Jia Xing, Rahul A. Zaveri, and Andreas Zuend
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Acid rain is recognized for its impacts on human health and ecosystems, and programs to mitigate these effects have had implications for atmospheric acidity. Historical measurements indicate that cloud and fog droplet acidity has changed in recent decades in response to controls on emissions from human activity, while the limited trend data for suspended particles indicate acidity may be relatively constant. This review synthesizes knowledge on the acidity of atmospheric particles and clouds.
Michael A. Battaglia Jr., Rodney J. Weber, Athanasios Nenes, and Christopher J. Hennigan
Atmos. Chem. Phys., 19, 14607–14620, https://doi.org/10.5194/acp-19-14607-2019, https://doi.org/10.5194/acp-19-14607-2019, 2019
Short summary
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The effects of water-soluble organic carbon (WSOC) on aerosol pH were characterized for aqueous-phase particles containing a mixture of inorganics and organics. The ISORROPIA-II and E-AIM models were used in conjunction with AIOMFAC to quantify the effect of organics on aerosol pH through (1) changes to the aerosol liquid water content and (2) changes to the hydrogen ion activity coefficient. The study included both organic acids and nonacids, at RH levels ranging from 70 to 90 %.
Jie Zhang, Sara Lance, Jeffrey M. Freedman, Yele Sun, Brian A. Crandall, Xiuli Wei, and James J. Schwab
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Preprint retracted
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The impact of fireworks (FW) events on air quality was studied using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and collocated instruments during the Independence Day (July 4) holiday. The Independence Day FW events resulted in significant increases in both organic and inorganic (potassium, sulfate, chloride) chemical components, and the contribution from different aerosol sources was discussed.
Marwa M. H. El-Sayed, Diana L. Ortiz-Montalvo, and Christopher J. Hennigan
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C. J. Hennigan, J. Izumi, A. P. Sullivan, R. J. Weber, and A. Nenes
Atmos. Chem. Phys., 15, 2775–2790, https://doi.org/10.5194/acp-15-2775-2015, https://doi.org/10.5194/acp-15-2775-2015, 2015
Short summary
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We show that the ion balance and molar ratio methods are unsuitable for use as aerosol pH proxies. Our recommendation is that 1) thermodynamic equilibrium models constrained by both gas and aerosol inputs run in the forward (open) mode, and 2) the phase partitioning of ammonia provides the best predictions of aerosol pH. Given the significance of acidity for numerous chemical processes in the atmosphere, the implications of this study are important and far reaching.
R. Saleh, C. J. Hennigan, G. R. McMeeking, W. K. Chuang, E. S. Robinson, H. Coe, N. M. Donahue, and A. L. Robinson
Atmos. Chem. Phys., 13, 7683–7693, https://doi.org/10.5194/acp-13-7683-2013, https://doi.org/10.5194/acp-13-7683-2013, 2013
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Subject: Aerosols | Research Activity: Field Measurements | Altitude Range: Troposphere | Science Focus: Chemistry (chemical composition and reactions)
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The daily concentrations of Polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (OPAHs), and nitrated phenols (NPs) in PM2.5 were all increased during the heating season. Biomass burning was identified to be the primary source of these aromatic compounds, particularly for PAHs. Phenol and nitrobenzene are two main primary precursors for 4NP, with phenol showing lower reaction barriers. P-Cresol was identified as the primary precursor for the formation of 4-methyl-5-nitrocatechol.
Lise Le Berre, Brice Temime-Roussel, Grazia Maria Lanzafame, Barbara D'Anna, Nicolas Marchand, Stéphane Sauvage, Marvin Dufresne, Liselotte Tinel, Thierry Leonardis, Joel Ferreira de Brito, Alexandre Armengaud, Grégory Gille, Ludovic Lanzi, Romain Bourjot, and Henri Wortham
Atmos. Chem. Phys., 25, 6575–6605, https://doi.org/10.5194/acp-25-6575-2025, https://doi.org/10.5194/acp-25-6575-2025, 2025
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A summer campaign in a Mediterranean port examined pollution caused by ships. Two stations in the port measured pollution levels and captured over 350 ship plumes to study their chemical composition. Results showed that pollution levels, such as ultra-fine particles, were higher in the port than in the city and offer strong support to improve emission inventories. These findings may also serve as reference to assess the benefits of a sulfur Emission Control Area in the Mediterranean in 2025.
Jiayin Li, Tianyu Zhai, Xiaorui Chen, Haichao Wang, Shuyang Xie, Shiyi Chen, Chunmeng Li, Yuanjun Gong, Huabin Dong, and Keding Lu
Atmos. Chem. Phys., 25, 6395–6406, https://doi.org/10.5194/acp-25-6395-2025, https://doi.org/10.5194/acp-25-6395-2025, 2025
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We directly measured the dinitrogen pentoxide (N2O5) uptake coefficient using an aerosol flow tube, which critically impacts the NOx fate and particulate nitrate formation in a typical highland city, Kunming, in China. We found that the performance of current γ (N2O5) parameterizations showed deviations with the varying aerosol liquid water content (ALWC). Such differences would lead to biased estimation of particulate nitrate production potential. We give suggestions for future research directions.
Jishnu Pandamkulangara Kizhakkethil, Zongbo Shi, Anna Bogush, and Ivan Kourtchev
Atmos. Chem. Phys., 25, 5947–5958, https://doi.org/10.5194/acp-25-5947-2025, https://doi.org/10.5194/acp-25-5947-2025, 2025
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Pollution with per- and polyfluoroalkyl substances (PFAS) has received attention due to their environmental persistence and bioaccumulation, but their sources remain poorly understood. PM10 (particulate matter) collected above a scaled-down activated sludge tank treating domestic sewage in the UK was analysed for a range of short-, medium-, and long-chain PFAS. Eight PFAS were detected in the PM10. Our results suggest that wastewater treatment processes, i.e. activated sludge aeration, could aerosolise PFAS into airborne PM.
Haley M. Royer, Michael T. Sheridan, Hope E. Elliott, Edmund Blades, Nurun Nahar Lata, Zezhen Cheng, Swarup China, Zihua Zhu, Andrew P. Ault, and Cassandra J. Gaston
Atmos. Chem. Phys., 25, 5743–5759, https://doi.org/10.5194/acp-25-5743-2025, https://doi.org/10.5194/acp-25-5743-2025, 2025
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Saharan dust transported across the Atlantic to the Caribbean, South America, and North America is hypothesized to undergo chemical processing by acids that enhances cloud droplet formation and nutrient availability. In this study, chemical analysis performed on African dust deposited over Barbados shows that acid tracers are found mostly on sea salt and smoke particles, rather than dust, indicating that dust particles undergo minimal chemical processing.
Zhao Wei, Shohei Hattori, Asuka Tsuruta, Zhuang Jiang, Sakiko Ishino, Koji Fujita, Sumito Matoba, Lei Geng, Alexis Lamothe, Ryu Uemura, Naohiro Yoshida, Joel Savarino, and Yoshinori Iizuka
Atmos. Chem. Phys., 25, 5727–5742, https://doi.org/10.5194/acp-25-5727-2025, https://doi.org/10.5194/acp-25-5727-2025, 2025
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Nitrate isotope records in ice cores reveal changes in NOₓ emissions and atmospheric oxidation chemistry driven by human activity. However, UV-driven postdepositional processes can alter nitrate in snow, making snow accumulation rates critical for preserving these records. This study examines nitrate isotopes in a southeastern Greenland ice core, where high snow accumulation minimizes these effects, providing a reliable archive of atmospheric nitrogen cycling.
Genevieve Rose Lorenzo, Luke D. Ziemba, Avelino F. Arellano, Mary C. Barth, Ewan C. Crosbie, Joshua P. DiGangi, Glenn S. Diskin, Richard Ferrare, Miguel Ricardo A. Hilario, Michael A. Shook, Simone Tilmes, Jian Wang, Qian Xiao, Jun Zhang, and Armin Sorooshian
Atmos. Chem. Phys., 25, 5469–5495, https://doi.org/10.5194/acp-25-5469-2025, https://doi.org/10.5194/acp-25-5469-2025, 2025
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Novel aerosol hygroscopicity analyses of CAMP2Ex (Cloud, Aerosol, and Monsoon Processes Philippines Experiment) field campaign data show low aerosol hygroscopicity values in Southeast Asia. Organic carbon from smoke decreases hygroscopicity to levels more like those in continental than in polluted marine regions. Hygroscopicity changes at cloud level demonstrate how surface particles impact clouds in the region, affecting model representation of aerosol and cloud interactions in similar polluted marine regions with high organic carbon emissions.
Yunfeng He, Xiang Ding, Quanfu He, Yuqing Zhang, Duohong Chen, Tao Zhang, Kong Yang, Junqi Wang, Qian Cheng, Hao Jiang, Zirui Wang, Ping Liu, Xinming Wang, and Michael Boy
EGUsphere, https://doi.org/10.5194/egusphere-2025-2204, https://doi.org/10.5194/egusphere-2025-2204, 2025
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The long-term field measurements in the Pearl River Delta revealed a significant decline in PM2.5 main components. As air quality improved, secondary species became more dominant. In addition, the proportion of nitrate had doubled. The changes in chemical composition led to the reductions in aerosol acidity, liquid water content and light extinction coefficient. Our results help to improve understanding of the secondary species formation under decreasing anthropogenic emissions.
Shubin Li, Yujue Wang, Yiwen Zhang, Yizhe Yi, Yuchen Wang, Yuqi Guo, Chao Yu, Yue Jiang, Jinhui Shi, Chao Zhang, Jialei Zhu, Wei Hu, Jianzhen Yu, Xiaohong Yao, Huiwang Gao, and Min Hu
EGUsphere, https://doi.org/10.5194/egusphere-2025-2154, https://doi.org/10.5194/egusphere-2025-2154, 2025
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Organosulfates (OSs) are an unrecognized and potentially important component in marine organic aerosols. In this study, we quantified and characterized the OSs over East Asian marginal seas. The chemical nature and spatiotemporal distribution of OSs were modified by the joint influence of marine emissions and transported terrestrial pollutants. The results highlight the vital roles of OSs in shaping organic aerosol formation and sulfur cycle during summer in marine boundary layer.
Kouji Adachi, Atsushi Yoshida, Tatsuhiro Mori, Nobuhiro Moteki, Sho Ohata, Kazuyuki Kita, Yoshimi Kawai, and Makoto Koike
EGUsphere, https://doi.org/10.5194/egusphere-2025-2230, https://doi.org/10.5194/egusphere-2025-2230, 2025
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This study measured the compositions and mixing states of individual aerosol particles collected at different altitudes over the western North Pacific by simultaneous sampling from an aircraft and a research vessel. The results showed that they were strongly influenced by Siberian Forest biomass burning and mixed with sea spray, and identified various aerosol compositions at different altitudes, sizes, and aerosol sources, highlighting a wide range of individual particle compositions.
Diana L. Pereira, Chiara Giorio, Aline Gratien, Alexander Zherebker, Gael Noyalet, Servanne Chevaillier, Stéphanie Alage, Elie Almarj, Antonin Bergé, Thomas Bertin, Mathieu Cazaunau, Patrice Coll, Ludovico Di Antonio, Sergio Harb, Johannes Heuser, Cécile Gaimoz, Oscar Guillemant, Brigitte Language, Olivier Lauret, Camilo Macias, Franck Maisonneuve, Bénédicte Picquet-Varrault, Raquel Torres, Sylvain Triquet, Pascal Zapf, Lelia Hawkins, Drew Pronovost, Sydney Riley, Pierre-Marie Flaud, Emilie Perraudin, Pauline Pouyes, Eric Villenave, Alexandre Albinet, Olivier Favez, Robin Aujay-Plouzeau, Vincent Michoud, Christopher Cantrell, Manuela Cirtog, Claudia Di Biagio, Jean-François Doussin, and Paola Formenti
Atmos. Chem. Phys., 25, 4885–4905, https://doi.org/10.5194/acp-25-4885-2025, https://doi.org/10.5194/acp-25-4885-2025, 2025
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In order to study aerosols in environments influenced by anthropogenic and biogenic emissions, we performed analyses of samples collected during the ACROSS (Atmospheric Chemistry Of the Suburban Forest) campaign in summer 2022 in the greater Paris area. After analysis of the chemical composition by means of total carbon determination and high-resolution mass spectrometry, this work highlights the influence of anthropogenic inputs on the chemical composition of both urban and forested areas.
Kimmo Teinilä, Sanna Saarikoski, Henna Lintusaari, Teemu Lepistö, Petteri Marjanen, Minna Aurela, Heidi Hellén, Toni Tykkä, Markus Lampimäki, Janne Lampilahti, Luis Barreira, Timo Mäkelä, Leena Kangas, Juha Hatakka, Sami Harni, Joel Kuula, Jarkko V. Niemi, Harri Portin, Jaakko Yli-Ojanperä, Ville Niemelä, Milja Jäppi, Katrianne Lehtipalo, Joonas Vanhanen, Liisa Pirjola, Hanna E. Manninen, Tuukka Petäjä, Topi Rönkkö, and Hilkka Timonen
Atmos. Chem. Phys., 25, 4907–4928, https://doi.org/10.5194/acp-25-4907-2025, https://doi.org/10.5194/acp-25-4907-2025, 2025
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Physical and chemical properties of particulate matter and concentrations of trace gases were measured in a street canyon in Helsinki, Finland, and an urban background site in January–February 2022 to investigate the effect of wintertime conditions on pollutants. State-of-the-art instruments and a mobile laboratory were used, and the measurement data were analysed further with modelling tools like positive matrix factorization and the Pollution Detection Algorithm.
Guilherme Martins Pereira, Leonardo Yoshiaki Kamigauti, Rubens Fabio Pereira, Djacinto Monteiro dos Santos, Thayná da Silva Santos, José Vinicius Martins, Célia Alves, Cátia Gonçalves, Ismael Casotti Rienda, Nora Kováts, Thiago Nogueira, Luciana Rizzo, Paulo Artaxo, Regina Maura de Miranda, Marcia Akemi Yamasoe, Edmilson Dias de Freitas, Pérola de Castro Vasconcellos, and Maria de Fatima Andrade
Atmos. Chem. Phys., 25, 4587–4616, https://doi.org/10.5194/acp-25-4587-2025, https://doi.org/10.5194/acp-25-4587-2025, 2025
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The chemical composition of fine particulate matter was studied in the megacity of São Paulo (Brazil) during a polluted period. Vehicular-related sources remain relevant; however, a high contribution of biomass burning was observed and correlated with sample ecotoxicity. Emerging biomass burning sources, such as forest fires and sugarcane-bagasse-based power plants, highlight the need for additional control measures alongside stricter rules concerning vehicular emissions.
Tao Qiu, Yanting Qiu, Yongyi Yuan, Rui Su, Xiangxinyue Meng, Jialiang Ma, Xiaofan Wang, Yu Gu, Zhijun Wu, Yang Ning, Xiuyi Hua, Dapeng Liang, and Deming Dong
EGUsphere, https://doi.org/10.5194/egusphere-2025-1808, https://doi.org/10.5194/egusphere-2025-1808, 2025
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Our research reveals that some species from biomass burning and coal combustion dominate the light absorption of organic aerosols during winter. Cold weather helps these species accumulate in aerosols by slowing their degradation and altering atmospheric chemical processes. This means colder regions might experience stronger and more persistent climate impacts. Our findings highlight the importance of local temperatures and pollution sources when tackling climate challenges.
Can Wu, Yubao Chen, Yuwei Sun, Huijun Zhang, Si Zhang, Cong Cao, Jianjun Li, and Gehui Wang
EGUsphere, https://doi.org/10.5194/egusphere-2025-1668, https://doi.org/10.5194/egusphere-2025-1668, 2025
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Biogenic secondary organic aerosol (BSOA), as an important atmospheric component, is prevalent within the boundary layer and can influence air quality and human health. Our observations demonstrate that anthropogenic NOx and the enhanced aerosol water driven by sulfate inhibit BSOA formation in lifting air masses, leading to a moderate reduction in the SOA burden in the upper boundary layer.
Emmanuel Chevassus, Kirsten N. Fossum, Darius Ceburnis, Lu Lei, Chunshui Lin, Wei Xu, Colin O'Dowd, and Jurgita Ovadnevaite
Atmos. Chem. Phys., 25, 4107–4129, https://doi.org/10.5194/acp-25-4107-2025, https://doi.org/10.5194/acp-25-4107-2025, 2025
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This study presents the first source apportionment of organic aerosol at Mace Head via high-resolution mass spectrometry. Introducing transfer entropy as a novel method reveals that aged organic aerosol originates from both open-ocean ozonolysis and local peat-burning oxidation. Methanesulfonic acid and organic sea spray both mirror phytoplankton activity, with the former closely tied to coccolithophore blooms and the latter linked to diatoms, chlorophytes, and cyanobacteria.
Paola Formenti, Chiara Giorio, Karine Desboeufs, Alexander Zherebker, Marco Gaetani, Clarissa Baldo, Gautier Landrot, Simona Montebello, Servanne Chevaillier, Sylvain Triquet, Guillaume Siour, Claudia Di Biagio, Francesco Battaglia, Jean-François Doussin, Anais Feron, Andreas Namwoonde, and Stuart John Piketh
EGUsphere, https://doi.org/10.5194/egusphere-2025-446, https://doi.org/10.5194/egusphere-2025-446, 2025
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The elemental composition and solubility of several metals, including iron, at a coastal site in Namibia in August–September 2017, indicate that natural and anthropogenic dust had different solubility depending on mineralogy but mostly to the processing by fluoride ions from marine emissions, pointing out to the complexity of atmospheric/oceanic interactions in this region of the world influenced by the Benguela current and significant aerosol load.
Jia-Yuan Wang, Meng-Xue Tang, Shan Lu, Ke-Jin Tang, Xing Peng, Ling-Yan He, and Xiao-Feng Huang
EGUsphere, https://doi.org/10.5194/egusphere-2025-1034, https://doi.org/10.5194/egusphere-2025-1034, 2025
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Our study explores how secondary organic aerosols (SOA), a major component of air pollution, form in different particle sizes in a coastal city in China. We found that SOA in fine particles is mainly produced through aqueous chemical reactions, especially those involving iron. In contrast, coarse particles form SOA through reactions with ozone and gases from both fossil fuels and natural sources. These findings highlight the need for size-specific air pollution models.
Ashutosh K. Shukla, Sachchida N. Tripathi, Shamitaksha Talukdar, Vishnu Murari, Sreenivas Gaddamidi, Manousos-Ioannis Manousakas, Vipul Lalchandani, Kuldeep Dixit, Vinayak M. Ruge, Peeyush Khare, Mayank Kumar, Vikram Singh, Neeraj Rastogi, Suresh Tiwari, Atul K. Srivastava, Dilip Ganguly, Kaspar Rudolf Daellenbach, and André S. H. Prévôt
Atmos. Chem. Phys., 25, 3765–3784, https://doi.org/10.5194/acp-25-3765-2025, https://doi.org/10.5194/acp-25-3765-2025, 2025
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Our study delves into the elemental composition of aerosols at three sites across the Indo-Gangetic Plain (IGP), revealing distinct patterns during pollution episodes. We found significant increases in chlorine (Cl)-rich and solid fuel combustion (SFC) sources, indicating dynamic emission sources, agricultural burning impacts, and meteorological influences. Surges in Cl-rich particles during cold periods highlight their role in particle growth under high-relative-humidity conditions.
Ye Kuang, Biao Luo, Shan Huang, Junwen Liu, Weiwei Hu, Yuwen Peng, Duohong Chen, Dingli Yue, Wanyun Xu, Bin Yuan, and Min Shao
Atmos. Chem. Phys., 25, 3737–3752, https://doi.org/10.5194/acp-25-3737-2025, https://doi.org/10.5194/acp-25-3737-2025, 2025
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This research reveals the potential importance of nighttime NO3 radical chemistry and aerosol water in the rapid formation of secondary brown carbon from diluted biomass burning emissions. The findings enhance our understanding of nighttime biomass burning evolution and its implications for climate and regional air quality, especially regarding interactions with background aerosol water and water-rich fogs and clouds.
Rongshuang Xu, Yu-Chi Lin, Siyu Bian, Feng Xie, and Yan-Lin Zhang
EGUsphere, https://doi.org/10.5194/egusphere-2025-683, https://doi.org/10.5194/egusphere-2025-683, 2025
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This work reported the hydroxymethanesulfonate (HMS) level in a continental city and, for the first time, in marine atmosphere. The enhancement by aerosol ionic strength (IS) on HMS formation was quantified which first rise with increasing IS, peaking at 4 mol kg–1 before declining. Given the IS range of marine (2–6) and urban aerosol (6–20 mol kg–1) and the clearly negative correlation between humidity and IS, the moderate IS level under humid condition may notably boost ambient HMS formation.
Jing Li, Jiaoshi Zhang, Xianda Gong, Steven Spielman, Chongai Kuang, Ashish Singh, Maria A. Zawadowicz, Lu Xu, and Jian Wang
EGUsphere, https://doi.org/10.5194/egusphere-2025-726, https://doi.org/10.5194/egusphere-2025-726, 2025
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Using measurements at a rural coastal site, we quantified aerosols in representative air masses and identified major source of organics in Houston area. Our results show cooking aerosol is likely overestimated by earlier studies. Additionally, diurnal variation of highly oxidized organics is mostly driven by air mass changes instead of photochemistry. This study highlights the impacts of emissions, atmospheric chemistry, and meteorology on aerosol properties in the coastal-rural environment.
Fan Mei, Qi Zhang, Damao Zhang, Jerome D. Fast, Gourihar Kulkarni, Mikhail S. Pekour, Christopher R. Niedek, Susanne Glienke, Israel Silber, Beat Schmid, Jason M. Tomlinson, Hardeep S. Mehta, Xena Mansoura, Zezhen Cheng, Gregory W. Vandergrift, Nurun Nahar Lata, Swarup China, and Zihua Zhu
Atmos. Chem. Phys., 25, 3425–3444, https://doi.org/10.5194/acp-25-3425-2025, https://doi.org/10.5194/acp-25-3425-2025, 2025
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This study highlights the unique capability of the ArcticShark, an uncrewed aerial system, in measuring vertically resolved atmospheric properties. Data from 32 research flights in 2023 reveal seasonal patterns and correlations with conventional measurements. The consistency and complementarity of in situ and remote sensing methods are highlighted. The study demonstrates the ArcticShark’s versatility in bridging data gaps and improving the understanding of vertical atmospheric structures.
Marco Paglione, Yufang Hao, Stefano Decesari, Mara Russo, Karam Mansour, Mauro Mazzola, Diego Fellin, Andrea Mazzanti, Emilio Tagliavini, Manousos Ioannis Manousakas, Evangelia Diapouli, Elena Barbaro, Matteo Feltracco, Kaspar Rudolf Daellenbach, and Matteo Rinaldi
EGUsphere, https://doi.org/10.5194/egusphere-2025-760, https://doi.org/10.5194/egusphere-2025-760, 2025
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A year-long set of PM1 samples from Ny-Ålesund, Svalbard, was analyzed by H-NMR and HR-TOF-AMS for the chemical characterization of the organic fraction. Positive Matrix Factorization allowed to identify five organic aerosol sources with specific seasonality. Winter-spring aerosol is dominated by Eurasian pollution, while summer is characterized by biogenic aerosols from marine sources; occasional summertime high OA loadings are associated with wildfire aerosols.
Ting Yang, Yu Xu, Yu-Chen Wang, Yi-Jia Ma, Hong-Wei Xiao, Hao Xiao, and Hua-Yun Xiao
Atmos. Chem. Phys., 25, 2967–2978, https://doi.org/10.5194/acp-25-2967-2025, https://doi.org/10.5194/acp-25-2967-2025, 2025
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Previous measurement–model comparisons of atmospheric isoprene levels showed a significant unidentified source of isoprene in some northern Chinese cities during winter. Here, the first combination of large-scale observations and field combustion experiments provides novel insights into biomass burning emissions as a significant source of isoprene-derived organosulfates during winter in northern cities of China.
Agnesh Panta, Konrad Kandler, Kerstin Schepanski, Andres Alastuey, Pavla Dagsson Waldhauserova, Sylvain Dupont, Melanie Eknayan, Cristina González-Flórez, Adolfo González-Romero, Martina Klose, Mara Montag, Xavier Querol, Jesús Yus-Díez, and Carlos Pérez García-Pando
EGUsphere, https://doi.org/10.5194/egusphere-2025-494, https://doi.org/10.5194/egusphere-2025-494, 2025
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Iceland is among the most active dust source areas in the world. Dust properties are influenced by particle size, mineralogy, shape, and mixing state. This work characterizes freshly emitted individual aerosol particles of Icelandic dust using electron microscopy. Our study provides insights into critical particle-specific information will contribute to better constraining climate models that consider mineralogical variations in their representation of the dust cycle.
Xueqin Zheng, Junwen Liu, Nima Chuduo, Bian Ba, Pengfei Yu, Phu Drolgar, Fang Cao, and Yanlin Zhang
EGUsphere, https://doi.org/10.5194/egusphere-2025-164, https://doi.org/10.5194/egusphere-2025-164, 2025
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In this study, we present the first report on the annual variation of stable oxygen isotope anomalies (∆17O = δ17O - 0.52 × δ18O) in NO3- collected from the urban area of Lhasa , on the Tibetan Plateau, China. Using a Bayesian isotope mixture model, we found that the relative contribution of the NO3+VOC pathway to NO3- formation in spring in Lhasa was several times higher than in urban cities, highlighting the significant influence of VOC transported from outside the Tibetan Plateau.
Yi-Jia Ma, Yu Xu, Ting Yang, Lin Gui, Hong-Wei Xiao, Hao Xiao, and Hua-Yun Xiao
Atmos. Chem. Phys., 25, 2763–2780, https://doi.org/10.5194/acp-25-2763-2025, https://doi.org/10.5194/acp-25-2763-2025, 2025
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The abundance, potential precursors, and main formation mechanisms of nitrogen-containing organic compounds (NOCs) in PM2.5 during winter were compared among cities with different energy consumption patterns. The aerosol NOC pollution during winter in China is closely associated with the intensity of precursor emissions and the aqueous-phase processes. Our results highlight the importance of emission reduction strategies in controlling aerosol NOCs pollution during winter in China.
Dane Blanchard, Mark Gordon, Duc Huy Dang, Paul Andrew Makar, and Julian Aherne
Atmos. Chem. Phys., 25, 2423–2442, https://doi.org/10.5194/acp-25-2423-2025, https://doi.org/10.5194/acp-25-2423-2025, 2025
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This study offers the first known evaluation of water-soluble brown carbon aerosols in the Athabasca oil sands region (AOSR), Canada. Fluorescence spectroscopy analysis of aerosol samples from five regional sites (collected during the summer of 2021) identified oil sands operations as a measurable brown carbon source. Industrial aerosol emissions were unlikely to impact regional radiative forcing. These findings show that fluorescence spectroscopy can be used to monitor brown carbon in the AOSR.
Kira Zeider, Kayla McCauley, Sanja Dmitrovic, Leong Wai Siu, Yonghoon Choi, Ewan C. Crosbie, Joshua P. DiGangi, Glenn S. Diskin, Simon Kirschler, John B. Nowak, Michael A. Shook, Kenneth L. Thornhill, Christiane Voigt, Edward L. Winstead, Luke D. Ziemba, Paquita Zuidema, and Armin Sorooshian
Atmos. Chem. Phys., 25, 2407–2422, https://doi.org/10.5194/acp-25-2407-2025, https://doi.org/10.5194/acp-25-2407-2025, 2025
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In situ aircraft data collected over the northwest Atlantic Ocean are utilized to compare aerosol conditions and turbulence between near-surface and below-cloud-base altitudes for different regimes of coupling strength between those two levels, along with how cloud microphysical properties vary across those regimes. Stronger coupling yields more homogenous aerosol structure vertically along with higher cloud drop concentrations and sea salt influence in clouds.
Junke Zhang, Xinyi Fu, Chunying Chen, Yunfei Su, Siyu Liu, Luyao Chen, Yubao Chen, Gehui Wang, and Andre S. H. Prevot
EGUsphere, https://doi.org/10.5194/egusphere-2025-92, https://doi.org/10.5194/egusphere-2025-92, 2025
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The 125 organic aerosol (OA) compounds in PM2.5 in winter in Chengdu were measured at the molecular level. OA was dominated by fatty acids, phthalate esters, and anhydrosugars, and were deeply influenced by anthropogenic sources. As pollution worsens: secondary inorganic species and secondary organic carbon (OC) dominated the increase in PM2.5; fatty acids and anhydrosugars dominated the increase in OA; and the contribution of secondary formation and biomass burning to OC increased markedly.
Amie Dobracki, Ernie R. Lewis, Arthur J. Sedlacek III, Tyler Tatro, Maria A. Zawadowicz, and Paquita Zuidema
Atmos. Chem. Phys., 25, 2333–2363, https://doi.org/10.5194/acp-25-2333-2025, https://doi.org/10.5194/acp-25-2333-2025, 2025
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Biomass-burning aerosol is commonly present in the marine boundary layer over the southeast Atlantic Ocean between June and October. Our research indicates that burning conditions, aerosol transport pathways, and prolonged oxidation processes (heterogeneous and aqueous phases) determine the chemical, microphysical, and optical properties of the boundary layer aerosol. Notably, we find that the aerosol optical properties can be estimated from the chemical properties alone.
Benjamin Heutte, Nora Bergner, Hélène Angot, Jakob B. Pernov, Lubna Dada, Jessica A. Mirrielees, Ivo Beck, Andrea Baccarini, Matthew Boyer, Jessie M. Creamean, Kaspar R. Daellenbach, Imad El Haddad, Markus M. Frey, Silvia Henning, Tiia Laurila, Vaios Moschos, Tuukka Petäjä, Kerri A. Pratt, Lauriane L. J. Quéléver, Matthew D. Shupe, Paul Zieger, Tuija Jokinen, and Julia Schmale
Atmos. Chem. Phys., 25, 2207–2241, https://doi.org/10.5194/acp-25-2207-2025, https://doi.org/10.5194/acp-25-2207-2025, 2025
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Limited aerosol measurements in the central Arctic hinder our understanding of aerosol–climate interactions in the region. Our year-long observations of aerosol physicochemical properties during the MOSAiC expedition reveal strong seasonal variations in aerosol chemical composition, where the short-term variability is heavily affected by storms in the Arctic. Local wind-generated particles are shown to be an important source of cloud seeds, especially in autumn.
Yifan Zhang, Rui Li, Zachary B. Bunnell, Yizhu Chen, Guanhong Zhu, Jinlong Ma, Guohua Zhang, Tim M. Conway, and Mingjin Tang
EGUsphere, https://doi.org/10.5194/egusphere-2025-474, https://doi.org/10.5194/egusphere-2025-474, 2025
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The sources of aerosol Fe, especially soluble aerosol Fe, remain to be constrained. The stable isotope ratio of Fe (δ56Fe) has emerged as a potential tracer for discriminating and quantifying sources of aerosol Fe. In this review, we examine the state of the field for using δ56Fe as an aerosol source tracer, and constraints on endmember signatures.
Feng Jiang, Harald Saathoff, Uzoamaka Ezenobi, Junwei Song, Hengheng Zhang, Linyu Gao, and Thomas Leisner
Atmos. Chem. Phys., 25, 1917–1930, https://doi.org/10.5194/acp-25-1917-2025, https://doi.org/10.5194/acp-25-1917-2025, 2025
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The chemical composition of brown carbon in the particle and gas phase was determined by mass spectrometry. BrC in the gas phase was mainly controlled by secondary formation and particle-to-gas partitioning. BrC in the particle phase was mainly from secondary formation. This work helps to get a better understanding of diurnal variations and the sources of brown carbon aerosol at a rural location in central Europe.
Kohei Sakata, Shotaro Takano, Atsushi Matsuki, Yasuo Takeichi, Hiroshi Tanimoto, Aya Sakaguchi, Minako Kurisu, and Yoshio Takahashi
EGUsphere, https://doi.org/10.5194/egusphere-2025-161, https://doi.org/10.5194/egusphere-2025-161, 2025
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Deposition of aerosol iron (Fe) into the ocean stimulates primary production and influences the global carbon cycle, although the factors governing the aerosol Fe solubility remain uncertain. Our observations in Japan revealed that both mineral dust and anthropogenic aerosols are significant sources of dissolved Fe, and that atmospheric chemical weathering enhances their solubility. This finding is expected to play a crucial role in estimating the supply of dissolved iron to the ocean.
Rui Li, Yubing Shen, Yumeng Shao, Yining Gao, Ziwei Yao, Qian Liu, Xing Liu, and Guitao Shi
EGUsphere, https://doi.org/10.5194/egusphere-2024-3740, https://doi.org/10.5194/egusphere-2024-3740, 2025
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It is the first time to reveal the global variations of PAHs derivatives in the marine air. We found that marine aerosols in East China Sea (ECS) and Western Pacific (WP) were significantly affected by coal and engine combustion, while those in Bismarck Sea (BS) and East Australian Sea (EAS) were mainly influenced by wildfire and coal combustion. Antarctic Ocean (AO) was dominated by biomass burning and local shipping emissions. This finding help elucidate the mechanism of global PAH cycle.
James Brean, David C. S. Beddows, Eija Asmi, Aki Virkkula, Lauriane L. J. Quéléver, Mikko Sipilä, Floortje Van Den Heuvel, Thomas Lachlan-Cope, Anna Jones, Markus Frey, Angelo Lupi, Jiyeon Park, Young Jun Yoon, Rolf Weller, Giselle L. Marincovich, Gabriela C. Mulena, Roy M. Harrison, and Manuel Dall'Osto
Atmos. Chem. Phys., 25, 1145–1162, https://doi.org/10.5194/acp-25-1145-2025, https://doi.org/10.5194/acp-25-1145-2025, 2025
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Our results emphasise how understanding the geographical variation in surface types across the Antarctic is key to understanding secondary aerosol sources.
Adam E. Thomas, Hayley S. Glicker, Alex B. Guenther, Roger Seco, Oscar Vega Bustillos, Julio Tota, Rodrigo A. F. Souza, and James N. Smith
Atmos. Chem. Phys., 25, 959–977, https://doi.org/10.5194/acp-25-959-2025, https://doi.org/10.5194/acp-25-959-2025, 2025
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We present measurements of the organic composition of ultrafine particles collected from the eastern Amazon, an understudied region that is subjected to increasing human influence. We find that while isoprene chemistry is likely significant for ultrafine-particle growth throughout the year, compounds related to other sources, such as biological-spore emissions and biomass burning, exhibit striking seasonal differences, implying extensive variation in regional ultrafine-particle sources.
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Short summary
This study characterized the optical properties of light-absorbing organic compounds, called brown carbon (BrC), in atmospheric cloud water samples. In all samples, light absorption by BrC increased linearly with increasing pH. There was variability in the sensitivity of the absorption–pH relationship, depending on the degree of influence from fire emissions. Overall, these results show that the climate forcing of BrC is quite strongly affected by its pH-dependent absorption.
This study characterized the optical properties of light-absorbing organic compounds, called...
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