posted on 2019-06-13, 00:00authored byZachary Finewax, Joost A. de Gouw, Paul J. Ziemann
Resorcinol (1,3-benzenediol) has
been observed in both laboratory
and field studies reporting biomass burning emissions. As a result
of its low vapor pressure, it has been suggested as a secondary organic
aerosol (SOA) precursor, but its gas-phase oxidation has not been
studied previously. Here, the reactions of resorcinol with OH radicals
in the presence of NOx and with NO3 radicals in the presence of NO2 were investigated
to mimic oxidation under daytime and nighttime conditions. When resorcinol
was added to the chamber in the presence of a high concentration of
oxidant, the gas-phase chemistry of this highly reactive, low-volatility
compound was investigated while minimizing its loss to the chamber
walls. Gas- and particle-phase products were identified using a combination
of thermal desorption particle beam mass spectrometry, chemical ionization–ion
trap mass spectrometry, and proton transfer reaction–mass spectrometry.
The major products identified were benzenetriol, nitrobenzenetriol,
and hydroxymuconic semialdehyde in the particle phase and hydroxybenzoquinone
and nitroresorcinol in the gas phase, and a reaction mechanism was
developed to explain their formation. Hydroxybenzoquinone was determined
to form through gas-phase oxidation of resorcinol and by heterogeneous
oxidation of benzenetriol by nitric acid. Reactions with OH and NO3 radicals produced SOA with yields of 0.86 and 0.09, respectively,
but these values should be somewhat lower in the atmosphere where
aerosol mass concentrations are lower and, thus, gas–particle
partitioning is reduced.