Articles | Volume 26, issue 8
https://doi.org/10.5194/acp-26-5333-2026
© Author(s) 2026. 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-26-5333-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
21 Apr 2026
Research article |
| 21 Apr 2026
| 21 Apr 2026
Isotopic apportionment of sulfate aerosols between natural and anthropogenic sources in the outflow of South Asia
Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden
Henry Holmstrand
Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden
Krishnakant Budhavant
Maldives Climate Observatory at Hanimaadhoo, H. Dh. Hanimaadhoo, Maldives
Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, Karnataka 560012, India
Manoj Remani
Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden
Sophie Haslett
Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden
Katerina Rodiouchkina
Division of Geosciences, Luleå University of Technology, 971 87 Luleå, Sweden
ALS Scandinavia AB, 977 75, Luleå, Sweden
Ellen Kooijman
Department of Geosciences, Swedish Museum of Natural History, Box 50 007, 104 05 Stockholm, Sweden
Örjan Gustafsson
CORRESPONDING AUTHOR
Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden
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Karin Stegelius, Pauline Thompson, Pia Karbiener, Piotr Markuszewski, Andre S. H. Prevot, Sachchida N. Tripathi, Claudia Mohr, Liine Heikkinen, Krishnakant Budhavant, and Sophie L. Haslett
EGUsphere, https://doi.org/10.5194/egusphere-2026-914, https://doi.org/10.5194/egusphere-2026-914, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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High-time-resolution observations in the Maldives indicate that submicron aerosol over the northern Indian Ocean is primarily composed of inorganic sulfate and highly oxidised organic matter, indicative of aged continental outflow. The consistent composition across various air mass origins, alongside identification of sulfur-containing organics, underscores the influence of long-range transport and sulfate-driven secondary chemistry on regional aerosol characteristics and their climate impacts.
Albin Eriksson, Birgit Wild, Wei-Li Hong, Henry Holmstrand, Francisco J. A. Nascimento, Stefano Bonaglia, Denis Kosmach, Igor Semiletov, Natalia Shakhova, and Örjan Gustafsson
Biogeosciences, 23, 1459–1475, https://doi.org/10.5194/bg-23-1459-2026, https://doi.org/10.5194/bg-23-1459-2026, 2026
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Thawing subsea permafrost in the East Siberian Arctic Seas releases methane, a potent greenhouse gas. Using molecular fossils in sediments, we traced aerobic methane oxidation as a proxy of enhanced methane cycling across the Laptev Sea, including in regions once thought low in emissions. This approach captures long-term patterns of methane cycling over years-decades , overcoming limits of short-term seawater measurements and highlights the importance of the Laptev Sea in Arctic methane cycling.
Peng Yao, Katja Belec, Henry Holmstrand, Josh Balacky, Abdus Salam, Krishnakant Budhavant, Mohanan Remani Manoj, Khaled Shaifullah Joy, Md. Alamin Hossain, Atinderpal Singh, Anil Patel, Neeraj Rastogi, Chinmay Mallik, Kirpa Ram, Gyanesh Kumar Singh, and Örjan Gustafsson
EGUsphere, https://doi.org/10.5194/egusphere-2026-411, https://doi.org/10.5194/egusphere-2026-411, 2026
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Methane is a powerful greenhouse gas, but its sources remain uncertain in many regions. The isotope fingerprints of methane are diagnostic of its sources, yet their source end-members are poorly constrained for South Asia. Here we determined the methane isotope signal for major sources in South Asia and found these to differ from global averages. Improved regional-specific isotope source fingerprints will help to improve top-down assessments of methane budgets and climate mitigation strategies.
Lorraine Tual, Christine Authemayou, Caroline Lotout, Matthijs A. Smit, Kira Musiyachenko, Denise Bussien Grosjean, Ellen Kooijman, and Emilie Bruand
Eur. J. Mineral., 37, 639–666, https://doi.org/10.5194/ejm-37-639-2025, https://doi.org/10.5194/ejm-37-639-2025, 2025
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The Léon region in France offers a window into the dramatic geological processes that shaped continents. Studying ancient rocks called eclogite, we uncovered a history of magma generation, deep burial and rapid crustal movement between 390 million and 300 million years ago. The area was shaped by subduction dynamics, where shifting tectonic plates stretched and compressed the crust. These findings help us understand how ancient geological processes continue to influence the Earth’s surface today.
Anderson Da Silva, Louis Marelle, Jean-Christophe Raut, Yvette Gramlich, Karolina Siegel, Sophie L. Haslett, Claudia Mohr, and Jennie L. Thomas
Atmos. Chem. Phys., 25, 5331–5354, https://doi.org/10.5194/acp-25-5331-2025, https://doi.org/10.5194/acp-25-5331-2025, 2025
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Particle sources in polar climates are unclear, affecting climate representation in models. This study introduces an evaluated method for tracking particles with backward modeling. Tests on simulated particles allowed us to show that traditional detection methods often misidentify sources. An improved method that accurately traces the origins of aerosol particles in the Arctic is presented. The study recommends using this enhanced method for better source identification of atmospheric species.
Krishnakant Budhavant, Mohanan Remani Manoj, Hari Ram Chandrika Rajendran Nair, Samuel Mwaniki Gaita, Henry Holmstrand, Abdus Salam, Ahmed Muslim, Sreedharan Krishnakumari Satheesh, and Örjan Gustafsson
Atmos. Chem. Phys., 24, 11911–11925, https://doi.org/10.5194/acp-24-11911-2024, https://doi.org/10.5194/acp-24-11911-2024, 2024
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The South Asian Pollution Experiment 2018 used access to three strategically located receptor observatories. Observational constraints revealed opposing trends in the mass absorption cross sections of black carbon (BC MAC) and brown carbon (BrC MAC) during long-range transport. Models estimating the climate effects of BC aerosols may have underestimated the ambient BC MAC over distant receptor areas, leading to discrepancies in aerosol absorption predicted by observation-constrained models.
Wei Huang, Cheng Wu, Linyu Gao, Yvette Gramlich, Sophie L. Haslett, Joel Thornton, Felipe D. Lopez-Hilfiker, Ben H. Lee, Junwei Song, Harald Saathoff, Xiaoli Shen, Ramakrishna Ramisetty, Sachchida N. Tripathi, Dilip Ganguly, Feng Jiang, Magdalena Vallon, Siegfried Schobesberger, Taina Yli-Juuti, and Claudia Mohr
Atmos. Chem. Phys., 24, 2607–2624, https://doi.org/10.5194/acp-24-2607-2024, https://doi.org/10.5194/acp-24-2607-2024, 2024
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We present distinct molecular composition and volatility of oxygenated organic aerosol particles in different rural, urban, and mountain environments. We do a comprehensive investigation of the relationship between the chemical composition and volatility of oxygenated organic aerosol particles across different systems and environments. This study provides implications for volatility descriptions of oxygenated organic aerosol particles in different model frameworks.
Leonard Kirago, Örjan Gustafsson, Samuel Mwaniki Gaita, Sophie L. Haslett, Michael J. Gatari, Maria Elena Popa, Thomas Röckmann, Christoph Zellweger, Martin Steinbacher, Jörg Klausen, Christian Félix, David Njiru, and August Andersson
Atmos. Chem. Phys., 23, 14349–14357, https://doi.org/10.5194/acp-23-14349-2023, https://doi.org/10.5194/acp-23-14349-2023, 2023
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This study provides ground-observational evidence that supports earlier suggestions that savanna fires are the main emitters and modulators of carbon monoxide gas in Africa. Using isotope-based techniques, the study has shown that about two-thirds of this gas is emitted from savanna fires, while for urban areas, in this case Nairobi, primary sources approach 100 %. The latter has implications for air quality policy, suggesting primary emissions such as traffic should be targeted.
Nair Krishnan Kala, Narayana Sarma Anand, Mohanan R. Manoj, Srinivasan Prasanth, Harshavardhana S. Pathak, Thara Prabhakaran, Pramod D. Safai, Krishnaswamy K. Moorthy, and Sreedharan K. Satheesh
Atmos. Chem. Phys., 23, 12801–12819, https://doi.org/10.5194/acp-23-12801-2023, https://doi.org/10.5194/acp-23-12801-2023, 2023
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We present a 3D data set of aerosol black carbon over the Indian mainland by assimilating data from surface, aircraft, and balloon measurements, along with multi-satellite observations. Radiative transfer computations using height-resolved aerosol absorption show higher warming in the free troposphere and will have large implications for atmospheric stability. This data set will help reduce the uncertainty in aerosol radiative effects in climate model simulations over the Indian region.
Christoph Heinze, Thorsten Blenckner, Peter Brown, Friederike Fröb, Anne Morée, Adrian L. New, Cara Nissen, Stefanie Rynders, Isabel Seguro, Yevgeny Aksenov, Yuri Artioli, Timothée Bourgeois, Friedrich Burger, Jonathan Buzan, B. B. Cael, Veli Çağlar Yumruktepe, Melissa Chierici, Christopher Danek, Ulf Dieckmann, Agneta Fransson, Thomas Frölicher, Giovanni Galli, Marion Gehlen, Aridane G. González, Melchor Gonzalez-Davila, Nicolas Gruber, Örjan Gustafsson, Judith Hauck, Mikko Heino, Stephanie Henson, Jenny Hieronymus, I. Emma Huertas, Fatma Jebri, Aurich Jeltsch-Thömmes, Fortunat Joos, Jaideep Joshi, Stephen Kelly, Nandini Menon, Precious Mongwe, Laurent Oziel, Sólveig Ólafsdottir, Julien Palmieri, Fiz F. Pérez, Rajamohanan Pillai Ranith, Juliano Ramanantsoa, Tilla Roy, Dagmara Rusiecka, J. Magdalena Santana Casiano, Yeray Santana-Falcón, Jörg Schwinger, Roland Séférian, Miriam Seifert, Anna Shchiptsova, Bablu Sinha, Christopher Somes, Reiner Steinfeldt, Dandan Tao, Jerry Tjiputra, Adam Ulfsbo, Christoph Völker, Tsuyoshi Wakamatsu, and Ying Ye
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-182, https://doi.org/10.5194/bg-2023-182, 2023
Revised manuscript not accepted
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For assessing the consequences of human-induced climate change for the marine realm, it is necessary to not only look at gradual changes but also at abrupt changes of environmental conditions. We summarise abrupt changes in ocean warming, acidification, and oxygen concentration as the key environmental factors for ecosystems. Taking these abrupt changes into account requires greenhouse gas emissions to be reduced to a larger extent than previously thought to limit respective damage.
Sophie L. Haslett, David M. Bell, Varun Kumar, Jay G. Slowik, Dongyu S. Wang, Suneeti Mishra, Neeraj Rastogi, Atinderpal Singh, Dilip Ganguly, Joel Thornton, Feixue Zheng, Yuanyuan Li, Wei Nie, Yongchun Liu, Wei Ma, Chao Yan, Markku Kulmala, Kaspar R. Daellenbach, David Hadden, Urs Baltensperger, Andre S. H. Prevot, Sachchida N. Tripathi, and Claudia Mohr
Atmos. Chem. Phys., 23, 9023–9036, https://doi.org/10.5194/acp-23-9023-2023, https://doi.org/10.5194/acp-23-9023-2023, 2023
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In Delhi, some aspects of daytime and nighttime atmospheric chemistry are inverted, and parodoxically, vehicle emissions may be limiting other forms of particle production. This is because the nighttime emissions of nitrogen oxide (NO) by traffic and biomass burning prevent some chemical processes that would otherwise create even more particles and worsen the urban haze.
Karolina Siegel, Yvette Gramlich, Sophie L. Haslett, Gabriel Freitas, Radovan Krejci, Paul Zieger, and Claudia Mohr
Atmos. Chem. Phys., 23, 7569–7587, https://doi.org/10.5194/acp-23-7569-2023, https://doi.org/10.5194/acp-23-7569-2023, 2023
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Hydroperoxymethyl thioformate (HPMTF) is a recently discovered oxidation product of dimethyl sulfide (DMS). We present a full year of concurrent gas- and particle-phase observations of HPMTF and other DMS oxidation products from the Arctic. We did not observe significant amounts of HPMTF in the particle phase but a good agreement between gas-phase HMPTF and methanesulfonic acid in the summer. Our study provides information about the relationship between HPMTF and other DMS oxidation products.
Emelie L. Graham, Cheng Wu, David M. Bell, Amelie Bertrand, Sophie L. Haslett, Urs Baltensperger, Imad El Haddad, Radovan Krejci, Ilona Riipinen, and Claudia Mohr
Atmos. Chem. Phys., 23, 7347–7362, https://doi.org/10.5194/acp-23-7347-2023, https://doi.org/10.5194/acp-23-7347-2023, 2023
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The volatility of an aerosol particle is an important parameter for describing its atmospheric lifetime. We studied the volatility of secondary organic aerosols from nitrate-initiated oxidation of three biogenic precursors with experimental methods and model simulations. We saw higher volatility than for the corresponding ozone system, and our simulations produced variable results with different parameterizations which warrant a re-evaluation of the treatment of the nitrate functional group.
Yvette Gramlich, Karolina Siegel, Sophie L. Haslett, Gabriel Freitas, Radovan Krejci, Paul Zieger, and Claudia Mohr
Atmos. Chem. Phys., 23, 6813–6834, https://doi.org/10.5194/acp-23-6813-2023, https://doi.org/10.5194/acp-23-6813-2023, 2023
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In this study, we investigate the chemical composition of aerosol particles forming clouds in the Arctic. During year-long observations at a mountain site on Svalbard, we find a large contribution of naturally derived aerosol particles in the fraction forming clouds in the summer. Our observations indicate that most aerosol particles can serve as cloud seeds in this remote environment.
Jing Cai, Kaspar R. Daellenbach, Cheng Wu, Yan Zheng, Feixue Zheng, Wei Du, Sophie L. Haslett, Qi Chen, Markku Kulmala, and Claudia Mohr
Atmos. Meas. Tech., 16, 1147–1165, https://doi.org/10.5194/amt-16-1147-2023, https://doi.org/10.5194/amt-16-1147-2023, 2023
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We introduce the offline application of FIGAERO-CIMS by analyzing Teflon and quartz filter samples that were collected at a typical urban site in Beijing with the deposition time varying from 30 min to 24 h. This method provides a feasible, simple, and quantitative way to investigate the molecular composition and volatility of OA compounds by using FIGAERO-CIMS to analyze offline samples.
Varun Kumar, Stamatios Giannoukos, Sophie L. Haslett, Yandong Tong, Atinderpal Singh, Amelie Bertrand, Chuan Ping Lee, Dongyu S. Wang, Deepika Bhattu, Giulia Stefenelli, Jay S. Dave, Joseph V. Puthussery, Lu Qi, Pawan Vats, Pragati Rai, Roberto Casotto, Rangu Satish, Suneeti Mishra, Veronika Pospisilova, Claudia Mohr, David M. Bell, Dilip Ganguly, Vishal Verma, Neeraj Rastogi, Urs Baltensperger, Sachchida N. Tripathi, André S. H. Prévôt, and Jay G. Slowik
Atmos. Chem. Phys., 22, 7739–7761, https://doi.org/10.5194/acp-22-7739-2022, https://doi.org/10.5194/acp-22-7739-2022, 2022
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Here we present source apportionment results from the first field deployment in Delhi of an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF). The EESI-TOF is a recently developed instrument capable of providing uniquely detailed online chemical characterization of organic aerosol (OA), in particular the secondary OA (SOA) fraction. Here, we are able to apportion not only primary OA but also SOA to specific sources, which is performed for the first time in Delhi.
Nair K. Kala, Narayana Sarma Anand, Mohanan R. Manoj, Harshavardhana S. Pathak, Krishnaswamy K. Moorthy, and Sreedharan K. Satheesh
Atmos. Chem. Phys., 22, 6067–6085, https://doi.org/10.5194/acp-22-6067-2022, https://doi.org/10.5194/acp-22-6067-2022, 2022
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We present the 3-D distribution of atmospheric aerosols and highlight its variation with respect to longitudes over the Indian mainland and the surrounding oceans using long-term satellite observations and realistic synthesised data. The atmospheric heating due to the 3-D distribution of aerosols is estimated using radiative transfer calculations. We believe that our findings will have strong implications for aerosol–radiation interactions in regional climate simulations.
Cheng Wu, David M. Bell, Emelie L. Graham, Sophie Haslett, Ilona Riipinen, Urs Baltensperger, Amelie Bertrand, Stamatios Giannoukos, Janne Schoonbaert, Imad El Haddad, Andre S. H. Prevot, Wei Huang, and Claudia Mohr
Atmos. Chem. Phys., 21, 14907–14925, https://doi.org/10.5194/acp-21-14907-2021, https://doi.org/10.5194/acp-21-14907-2021, 2021
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Night-time reactions of biogenic volatile organic compounds and nitrate radicals can lead to the formation of secondary organic aerosol (BSOANO3). Here, we study the impacts of light exposure on the BSOANO3 from three biogenic precursors. Our results suggest that photolysis causes photodegradation of a substantial fraction of BSOANO3, changes the chemical composition and bulk volatility, and might be a potentially important loss pathway of BSOANO3 during the night-to-day transition.
Mohanan R. Manoj, Sreedharan K. Satheesh, Krishnaswamy K. Moorthy, Jamie Trembath, and Hugh Coe
Atmos. Chem. Phys., 21, 8979–8997, https://doi.org/10.5194/acp-21-8979-2021, https://doi.org/10.5194/acp-21-8979-2021, 2021
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Vertical distributions of atmospheric aerosols across the Indo-Gangetic Plain (IGP) and their ability to form clouds have been studied based on airborne measurements during the SWAAMI field campaign. The ability of the aerosols to act as cloud-forming nuclei exhibited large spatial variation across the IGP and strong seasonality with increase in this ability with increase in altitude prior to the onset of monsoon and decrease with increase in altitude during the active phase of the monsoon.
Jannik Martens, Evgeny Romankevich, Igor Semiletov, Birgit Wild, Bart van Dongen, Jorien Vonk, Tommaso Tesi, Natalia Shakhova, Oleg V. Dudarev, Denis Kosmach, Alexander Vetrov, Leopold Lobkovsky, Nikolay Belyaev, Robie W. Macdonald, Anna J. Pieńkowski, Timothy I. Eglinton, Negar Haghipour, Salve Dahle, Michael L. Carroll, Emmelie K. L. Åström, Jacqueline M. Grebmeier, Lee W. Cooper, Göran Possnert, and Örjan Gustafsson
Earth Syst. Sci. Data, 13, 2561–2572, https://doi.org/10.5194/essd-13-2561-2021, https://doi.org/10.5194/essd-13-2561-2021, 2021
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The paper describes the establishment, structure and current status of the first Circum-Arctic Sediment CArbon DatabasE (CASCADE), which is a scientific effort to harmonize and curate all published and unpublished data of carbon, nitrogen, carbon isotopes, and terrigenous biomarkers in sediments of the Arctic Ocean in one database. CASCADE will enable a variety of studies of the Arctic carbon cycle and thus contribute to a better understanding of how climate change affects the Arctic.
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Short summary
South Asia has the world's highest loadings of sulfate, scattering sunlight, altering clouds and masking greenhouse warming, yet there are large uncertainties regarding the relative contributions of natural and anthropogenic sources to the receptor atmosphere. Here we use δ34S isotopes to distinguish natural versus anthropogenic sulfate sources, revealing strong seasonal contrasts and quantifying the dominance of anthropogenic contributions.
South Asia has the world's highest loadings of sulfate, scattering sunlight, altering clouds and...
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