Chloramine chemistry as a missing link in atmospheric chlorine cycling
Chlorine radicals (Cl<b>·</b>) profoundly affect atmospheric oxidation capacity. Chloramines, especially trichloramine, are emerging precursors of Cl<b>·</b>. However, their sources and roles in the atmosphere remain elusive. This study presents field evidence of primary emissions and explicit secondary production pathways of atmospheric trichloramine in Beijing, supplemented by observations from New Delhi and reanalysis of measurements in Toronto. We demonstrate that the sequential chlorination reactions initiated by molecular chlorine and ammonia in atmospheric aerosols are a major source of trichloramine. The trichloramine produced in aerosols is a source of gaseous trichloramine and serves as an intermediate during the conversion from molecular chlorine to Cl<b>·</b>, while direct trichloramine emissions constitute a previously overlooked source of Cl<b>·</b>. Overall, chloramine chemistry alters the Cl<b>·</b> production mechanism and represents a crucial missing pathway to Cl<b>·</b> worldwide.
Authors
- Markku Kulmala (ORCID: https://orcid.org/0000-0003-3464-7825)
- Jingkun Jiang (ORCID: https://orcid.org/0000-0001-6172-190X)
- Epameinondas Tsiligiannis (ORCID: https://orcid.org/0000-0002-5100-0858)
- Mattias Hallquist (ORCID: https://orcid.org/0000-0001-5691-1231)
- Kebin He (ORCID: https://orcid.org/0000-0001-6006-9323)
- Douglas R. Worsnop (ORCID: https://orcid.org/0000-0002-8928-8017)
- Cheng Wu (ORCID: https://orcid.org/0000-0001-9648-2865)
- J. N. Zhang
- Chenjie Hua
- Men Xia (ORCID: https://orcid.org/0000-0002-8534-3357)
- Chao Yan (ORCID: https://orcid.org/0000-0002-5735-9597)
- Zongcheng Wang (ORCID: https://orcid.org/0000-0002-0723-4083)
- Runlong Cai (ORCID: https://orcid.org/0000-0002-6630-0896)
- Guangjie Zheng (ORCID: https://orcid.org/0000-0002-8103-2594)
- Zhaojin An
- Lina Cao (ORCID: https://orcid.org/0000-0002-4410-7411)
- Yuyang Li (ORCID: https://orcid.org/0000-0001-6774-5320)
- Shuxiao Wang (ORCID: https://orcid.org/0000-0001-9727-1963)
- Yiran Li (ORCID: https://orcid.org/0000-0001-7232-4969)
- Tao Wang (ORCID: https://orcid.org/0000-0002-4765-9377)
- Junchen Guo
- Xinyan Zhao
- Yijing Chen (ORCID: https://orcid.org/0009-0003-8094-7586)
- Qipeng Qu (ORCID: https://orcid.org/0000-0002-6776-1387)
- Yongchun Liu (ORCID: https://orcid.org/0000-0002-9055-970X)
Institutions
- University of Helsinki (FI)
- Harvard University (US)
- Hong Kong Polytechnic University (HK)
- Fudan University (CN)
- Harvard University Press (US)
- Aerodyne Research (US)
- Cloud Computing Center (CN)
- Beijing University of Chemical Technology (CN)
- University of Gothenburg (SE)
- Nanjing University (CN)
- Tsinghua University (CN)
Publication Details
- Journal
- Science Advances
- Published
- 2025-10-29
- DOI
- https://doi.org/10.1126/sciadv.adv4298
- Citations
- 2
- Primary Topic
- Water Treatment and Disinfection
- Type
- article
- Field-Weighted Citation Impact
- 2.40