Importance of biogenic precursors to the budget of organic nitrates: observations of multifunctional organic nitrates by CIMS and TD-LIF during BEARPEX 2009 1California Institute of Technology, Pasadena, CA, USA
03 Jul 2012
2University of California, Berkeley, CA, USA
3Texas A&M University, College Station, TX, USA
*now at: National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, NC, USA
**now at: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA, USA
***now at: University of California, Los Angeles, CA, USA
Received: 11 Nov 2011 – Published in Atmos. Chem. Phys. Discuss.: 04 Jan 2012Abstract. Alkyl and multifunctional organic nitrates, molecules of the chemical
form RONO2, are products of chain terminating reactions
in the tropospheric HOx and NOx catalytic
cycles and thereby impact ozone formation locally. Many of the molecules
in the class have lifetimes that are long enough that they can be
transported over large distances. If the RONO2 then decompose
to deliver NOx to remote regions they affect ozone production
rates in locations distant from the original NOx source.
While measurements of total RONO2 (ΣANs) and
small straight chain alkyl nitrates are routine, measurements of the
specific multifunctional RONO2 molecules that are believed
to dominate the total have rarely been reported and never reported
in coincidence with ambient ΣANs measurements. Here we describe
observations obtained during the BEARPEX 2009 experiment including
ΣANs and a suite of multifunctional nitrates including isoprene
derived hydroxynitrates, oxidation products of those nitrates, 2-methyl-3-buten-2-ol
(MBO) derived hydroxynitrates, and monoterpene nitrates. At the BEARPEX
field site, the sum of the individual biogenically derived nitrates
account for two-thirds of the ΣANs, confirming predictions
of the importance of biogenic nitrates to the NOy budget.
Isoprene derived nitrates, transported to the site, are a much larger
fraction of the ΣANs at the site than the nitrates derived
from the locally emitted MBO. Evidence for additional nitrates, possibly
from nocturnal chemistry of isoprene and α-pinene, is presented.
Revised: 23 May 2012 – Accepted: 06 Jun 2012 – Published: 03 Jul 2012
Citation: Beaver, M. R., Clair, J. M. St., Paulot, F., Spencer, K. M., Crounse, J. D., LaFranchi, B. W., Min, K. E., Pusede, S. E., Wooldridge, P. J., Schade, G. W., Park, C., Cohen, R. C., and Wennberg, P. O.: Importance of biogenic precursors to the budget of organic nitrates: observations of multifunctional organic nitrates by CIMS and TD-LIF during BEARPEX 2009, Atmos. Chem. Phys., 12, 5773-5785, doi:10.5194/acp-12-5773-2012, 2012.