@Article{SantosLGKGOFLHBF:2018:BiBuEm,
author = "Santos, Fernando and Longo, Karla Maria and Gunther, Alex and Kim,
Saewung and Gu, Dasa and Oram, Dave and Forster, Grant and Lee,
James and Hopkins, James and Brito, Joel and Freitas, Saulo",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {NASA
Goddard Space Flight Center} and {University of California} and
{University of East Anglia} and {University of East Anglia} and
{University of York} and {University of York} and {Universidade de
S{\~a}o Paulo (USP)} and {University of York} and {Universidade
de S{\~a}o Paulo (USP)} and {NASA Goddard Space Flight Center}",
title = "Biomass burning emission disturbances of isoprene oxidation in a
tropical forest",
journal = "Atmospheric Chemistry and Physics",
year = "2018",
volume = "18",
number = "17",
pages = "12715--12734",
month = "Sept.",
abstract = "We present a characterization of the chemical composition of the
atmosphere of the Brazilian Amazon rainforest based on trace gas
measurements carried out during the South AMerican Biomass Burning
Analysis (SAMBBA) airborne experiment in September 2012. We
analyzed the observations of primary biomass burning emission
tracers, i.e., carbon monoxide (CO), nitrogen oxides (NOx), ozone
(O-3), isoprene, and its main oxidation products, methyl vinyl
ketone (MVK), methacrolein (MACR), and isoprene hydroxy
hydroperoxide (ISOPOOH). The focus of SAMBBA was primarily on
biomass burning emissions, but there were also several flights in
areas of the Amazon forest not directly affected by biomass
burning, revealing a background with a signature of biomass
burning in the chemical composition due to long-range transport of
biomass burning tracers from both Africa and the eastern part of
Amazonia. We used the [MVK + MACR + ISOPOOH] / [isoprene] ratio
and the hydroxyl radical (OH) indirect calculation to assess the
oxidative capacity of the Amazon forest atmosphere. We compared
the background regions (CO < 150 ppbv), fresh and aged smoke
plumes classified according to their photochemical age ([O-3] /
[CO]), to evaluate the impact of biomass burning emissions on the
oxidative capacity of the Amazon forest atmosphere. We observed
that biomass burning emissions disturb the isoprene oxidation
reactions, especially for fresh plumes ([MVK + MACR + ISOPOOH] /
[isoprene] = 7) downwind. The oxidation of isoprene is higher in
fresh smoke plumes at lower altitudes (similar to 500 m) than in
aged smoke plumes, anticipating near the surface a complex chain
of oxidation reactions which may be related to secondary organic
aerosol (SOA) formation. We proposed a refinement of the OH
calculation based on the sequential reaction model, which
considers vertical and horizontal transport for both biomass
burning regimes and background environment. Our approach for the
[OH] estimation resulted in values on the same order of magnitude
of a recent observation in the Amazon rainforest [OH] congruent to
10(6) (molecules cm(-3)). During the fresh plume regime, the
vertical profile of [OH] and the [MVK + MACR + ISOPOOH] /
[isoprene] ratio showed evidence of an increase in the oxidizing
power in the transition from planetary boundary layer to cloud
layer (1000-1500 m). These high values of [OH] (1.5 x 10(6)
molecules cm(-3)) and [MVK + MACR + ISOPOOH] / [isoprene] (7.5)
indicate a significant change above and inside the cloud decks due
to cloud edge effects on photolysis rates, which have a major
impact on OH production rates.",
doi = "10.5194/acp-18-12715-2018",
url = "http://dx.doi.org/10.5194/acp-18-12715-2018",
issn = "1680-7316 and 1680-7324",
label = "self-archiving-INPE-MCTIC-GOV-BR",
language = "en",
targetfile = "santos_biomass.pdf",
urlaccessdate = "25 abr. 2024"
}