Chloramine chemistry as a missing link in atmospheric chlorine cycling.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41160677.
- Also identified by DOI 10.1126/sciadv.adv4298 and PMC identifier 12571055.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
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.