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@ARTICLE{Newland:842440,
author = {Newland, Mike J. and Rickard, Andrew R. and Sherwen, Tomás
and Evans, Mathew J. and Vereecken, Luc and Muñoz, Amalia
and Ródenas, Milagros and Bloss, William J.},
title = {{T}he atmospheric impacts of monoterpene ozonolysis on
global stabilised {C}riegee intermediate budgets and {SO}2
oxidation: experiment, theory and modelling},
journal = {Atmospheric chemistry and physics / Discussions},
volume = {1095},
issn = {1680-7375},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2018-00676},
pages = {1 - 65},
year = {2017},
abstract = {The gas-phase reaction of alkenes with ozone is known to
produce stabilised Criegee intermediates (SCIs). These
biradical/zwitterionic species have the potential to act as
atmospheric oxidants for trace pollutants such as SO2,
enhancing the formation of sulfate aerosol with impacts on
air quality and health, radiative transfer and climate.
However, the importance of this chemistry is uncertain as a
consequence of limited understanding of the abundance and
atmospheric fate of SCIs. In this work we apply
experimental, theoretical and numerical modelling methods to
quantify the atmospheric impacts, abundance, and fate, of
the structurally diverse SCIs derived from the ozonolysis of
monoterpenes, the second most abundant group of unsaturated
hydrocarbons in the atmosphere. We have investigated the
removal of SO2 by SCI formed from the ozonolysis of three
monoterpenes (-pinene, -pinene and limonene) in the presence
of varying amounts of water vapour in large-scale simulation
chamber experiments. The SO2 removal displays a clear
dependence on water vapour concentration, but this
dependence is not linear across the range of [H2O] explored.
At low [H2O] a strong dependence of SO2 removal on [H2O] is
observed, while at higher [H2O] this dependence becomes much
weaker. This is interpreted as being caused by the
production of a variety of structurally (and hence
chemically) different SCI in each of the systems studied,
each displaying different rates of reaction with water and
of unimolecular rearrangement/decomposition. The determined
rate constants, k(SCI+H2O), for those SCI that react
primarily with H2O range from
4–310 × 10−15 cm3 s−1. For those SCI that
predominantly react unimolecularly, determined rates range
from 130–240 s−1. These values are in line with
previous results for the (analogous) stereo-specific SCI
system of syn/anti-CH3CHOO. The experimental results are
interpreted through theoretical studies of the SCI
unimolecular reactions and bimolecular reactions with H2O,
characterised for -pinene and -pinene at the
M06-2X/aug-cc-pVTZ level of theory. The theoretically
derived rates agree with the experimental results within the
uncertainties. A global modelling study, applying the
experimental results within the GEOS-Chem chemical transport
model, suggests that $> 98 \%$ of the total monoterpene
derived global SCI burden is comprised of SCI whose
structure determines that they react slowly with water, and
whose atmospheric fate is dominated by unimolecular
reactions. Seasonally averaged boundary layer concentrations
of monoterpene-derived SCI reach up to
1.2 × 104 cm−3 in regions of elevated monoterpene
emissions in the tropics. Reactions of monoterpene derived
SCI with SO2 account for $< 1 \%$ globally but may
account for up to $50 \%$ of the gas-phase SO2 removal
over areas of tropical forests, with significant localised
impacts on the formation of sulfate aerosol, and hence the
lifetime and distribution of SO2.},
cin = {IEK-8},
ddc = {550},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {243 - Tropospheric trace substances and their
transformation processes (POF3-243)},
pid = {G:(DE-HGF)POF3-243},
typ = {PUB:(DE-HGF)16},
doi = {10.5194/acp-2017-1095},
url = {https://juser.fz-juelich.de/record/842440},
}