Constraints on Aerosol Nitrate Photolysis as a Potential Source of HONO and NO x

Paul S. Romer, Paul J. Wooldridge, John D. Crounse, Michelle J. Kim, Paul O. Wennberg, Jack E. Dibb, Eric Scheuer, Donald R. Blake, Simone Meinardi, Alexandra L. Brosius, Alexander B. Thames, David O. Miller, William H. Brune, Samuel R. Hall, Thomas B. Ryerson, Ronald C. Cohen

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


The concentration of nitrogen oxides (NO x ) plays a central role in controlling air quality. On a global scale, the primary sink of NO x is oxidation to form HNO 3 . Gas-phase HNO 3 photolyses slowly with a lifetime in the troposphere of 10 days or more. However, several recent studies examining HONO chemistry have proposed that particle-phase HNO 3 undergoes photolysis 10-300 times more rapidly than gas-phase HNO 3 . We present here constraints on the rate of particle-phase HNO 3 photolysis based on observations of NO x and HNO 3 collected over the Yellow Sea during the KORUS-AQ study in summer 2016. The fastest proposed photolysis rates are inconsistent with the observed NO x to HNO 3 ratios. Negligible to moderate enhancements of the HNO 3 photolysis rate in particles, 1-30 times faster than in the gas phase, are most consistent with the observations. Small or moderate enhancement of particle-phase HNO 3 photolysis would not significantly affect the HNO 3 budget but could help explain observations of HONO and NO x in highly aged air.

Original languageEnglish (US)
Pages (from-to)13738-13746
Number of pages9
JournalEnvironmental Science and Technology
Issue number23
StatePublished - Dec 4 2018

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Environmental Chemistry


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