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Title: Observation of isoprene hydroxynitrates in the southeastern United States and implications for the fate of NOx

Isoprene hydroxynitrates (IN) are tracers of the photochemical oxidation of isoprene in high NOx environ-ments. Production and loss of IN have a significant influ-ence on the NOx cycle and tropospheric O3 chemistry. To better understand IN chemistry, a series of photochemical re-action chamber experiments was conducted to determine the IN yield from isoprene photooxidation at high NO concentra-tions (> 100 ppt). By combining experimental data and cal-culated isomer distributions, a total IN yield of 9(+4/-3) %was derived. The result was applied in a zero-dimensional model to simulate production and loss of ambient IN ob-served in a temperate forest atmosphere, during the Southern Oxidant and Aerosol Study (SOAS) field campaign, from 27 May to 11 July 2013. The 9 % yield was consistent with the observed IN/(MVK+MACR) ratios observed during SOAS. By comparing field observations with model simulations, we identified NO as the limiting factor for ambient IN produc-tion during SOAS, but vertical mixing at dawn might also contribute (~ 27 %) to IN dynamics. A close examination of isoprene’s oxidation products indicates that its oxidation transitioned from a high-NO dominant chemical regime in the morning into a low-NO dominant regime in the after-noon. A significant amount of IN produced inmore » the morning high NO regime could be oxidized in the low NO regime, and a possible reaction scheme was proposed.« less
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  1. Purdue Univ., West Lafayette, IN (United States)
  2. Purdue Univ., West Lafayette, IN (United States); Univ. of Michigan, Ann Arbor, MI (United States)
  3. West Chester Univ., PA (United States)
  4. Oakland Univ., Rochester, MI (United States)
  5. Western Michigan Univ., Kalamazoo MI (United States)
  6. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  7. Univ. of California, Berkeley, CA (United States)
  8. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  9. Univ. of Colorado, Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences (CIRES); NOAA Earth System Research Lab., Boulder, CO (United States)
  10. Atmospheric Research and Analysis, Inc., Cary, NC (United States)
  11. Pennsylvania State Univ., University Park, PA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1680-7316; KP1704020
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Atmospheric Chemistry and Physics; Journal Volume: 15; Journal Issue: 19
European Geosciences Union
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States