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| Titel |
On the relationship between nitryl chloride and molecular chlorine and their relative importance as Cl-atom sources from simultaneous ship-borne observations in coastal California |
| VerfasserIn |
Joel Thornton, Theran Riedel |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051989
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| Zusammenfassung |
| Chlorine atoms are highly reactive oxidants, and can influence the oxidation rates of trace gases such as elemental mercury and volatile organic compounds (VOC). Faster conversion of VOC into organic peroxy radicals under high NOx regimes influences ozone production. Cl-atom sources remain uncertain while having consequences for understanding air quality and climate. Modeling studies and past measurements have implicated molecular chlorine as an important Cl-atom source and nitryl chloride as either not quantified or unimportant in polluted coastal regions. We made simultaneous in situ measurements of nitryl chloride and molecular chlorine aboard the RV Atlantis, which cruised along the California coast during the CALNEX campaign from May – June 2010, that appear counter to these previous findings. Our observations show that in the outflow of the LA Basin, nitryl chloride routinely competes with and typically exceeds molecular chlorine as a Cl-atom source. The instantaneous Cl-atom production rate from nitryl chloride was more than a factor of four greater than that from molecular chlorine on average during morning hours (6-11AM); ranging from a factor less than one to greater than 10. On a few specific nights, nitryl chloride and molecular chlorine appear strongly correlated, while on others there is no discernible relationship. In addition, within polluted regions, molecular chlorine appears more episodic in nature compared to a more persistent source of nitryl chloride at night. These results provide important tests of current mechanisms of chlorine activation and ultimately carry implications for models of Cl-atom sources in polluted regions. |
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