Articles | Volume 25, issue 21
https://doi.org/10.5194/acp-25-14629-2025
© Author(s) 2025. 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-25-14629-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Composition and Formation Mechanism of Brown Carbon: Identification and Quantification of Phenolic Precursors
Md. Al-Amin Hossen
Department of Chemistry, Faculty of Science, University of Dhaka, Dhaka-1000, Bangladesh
Mehedi Hasan Shakil
Department of Chemistry, Faculty of Science, University of Dhaka, Dhaka-1000, Bangladesh
Md. Fahim Ehasan
Environmental and Organic Chemistry Laboratory, Chemistry Division, Atomic Energy Centre Dhaka, Bangladesh
Abu Rayhan Mohammad Tareq
Environmental and Organic Chemistry Laboratory, Chemistry Division, Atomic Energy Centre Dhaka, Bangladesh
Abdus Salam
CORRESPONDING AUTHOR
Department of Chemistry, Faculty of Science, University of Dhaka, Dhaka-1000, Bangladesh
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EGUsphere, https://doi.org/10.5194/egusphere-2026-3224, https://doi.org/10.5194/egusphere-2026-3224, 2026
This preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).
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A high-sensitivity balance, controlled temperature and relative humidity chamber, and filter samples collected around the world were used to develop a mass as a function of relative humidity relationship. We subsequently measured the chemical composition of these same samples. A relationship between the chemical composition and water mass was created and used to calculate aerosol water content showing how composition and water content varies worldwide.
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
Atmos. Chem. Phys., 26, 7765–7787, https://doi.org/10.5194/acp-26-7765-2026, https://doi.org/10.5194/acp-26-7765-2026, 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.
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.
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Short summary
This study provides comprehensive insights into the compositions, surface elements, and formation mechanism of BrC in the atmosphere of Dhaka, Bangladesh, through the identification and quantification of seven key phenolic precursors and a laboratory-based aqueous-phase nitration experiment. We observed that PM2.5 particles predominantly exhibited spherical, irregular, and chain-like morphologies, with carbonaceous species, minerals, and trace elements.
This study provides comprehensive insights into the compositions, surface elements, and...
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