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@ARTICLE{Eger:902295,
author = {Eger, Philipp G. and Vereecken, Luc and Sander, Rolf and
Schuladen, Jan and Sobanski, Nicolas and Fischer, Horst and
Karu, Einar and Williams, Jonathan and Vakkari, Ville and
Petäjä, Tuukka and Lelieveld, Jos and Pozzer, Andrea and
Crowley, John N.},
title = {{I}mpact of pyruvic acid photolysis on acetaldehyde and
peroxy radical formation in the boreal forest: theoretical
calculations and model results},
journal = {Atmospheric chemistry and physics},
volume = {21},
number = {18},
issn = {1680-7324},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2021-04158},
pages = {14333 - 14349},
year = {2021},
abstract = {Based on the first measurements of gas-phase pyruvic acid
(CH3C(O)C(O)OH) in the boreal forest, we derive effective
emission rates of pyruvic acid and compare them with
monoterpene emission rates over the diel cycle. Using a
data-constrained box model, we determine the impact of
pyruvic acid photolysis on the formation of acetaldehyde
(CH3CHO) and the peroxy radicals CH3C(O)O2 and HO2 during an
autumn campaign in the boreal forest.The results are
dependent on the quantum yield (φ) and mechanism of the
photodissociation of pyruvic acid and the fate of a likely
major product, methylhydroxy carbene (CH3COH). With the box
model, we investigate two different scenarios in which we
follow the present IUPAC (IUPAC Task Group on Atmospheric
Chemical Kinetic Data Evaluation, 2021) recommendations with
φ = 0.2 (at 1 bar of air), and the main photolysis
products $(60 \%)$ are acetaldehyde + CO2 with
$35 \%$ C–C bond fission to form HOCO and CH3CO
(scenario A). In the second scenario (B), the formation of
vibrationally hot CH3COH (and CO2) represents the main
dissociation pathway at longer wavelengths $(∼ 75 \%)$
with a $∼ 25 \%$ contribution from C–C bond fission
to form HOCO and CH3CO (at shorter wavelengths). In scenario
2 we vary φ between 0.2 and 1 and, based on the results of
our theoretical calculations, allow the thermalized CH3COH
to react with O2 (forming peroxy radicals) and to undergo
acid-catalysed isomerization to CH3CHO.When constraining the
pyruvic acid to measured mixing ratios and independent of
the model scenario, we find that the photolysis of pyruvic
acid is the dominant source of CH3CHO with a contribution
between $∼ 70 \%$ and $90 \%$ to the total
production rate. We find that the photolysis of pyruvic acid
is also a major source of the acetylperoxy radical, with
contributions varying between $∼ 20 \%$ and $60 \%$
dependent on the choice of φ and the products formed. HO2
production rates are also enhanced, mainly via the formation
of CH3O2. The elevated production rates of CH3C(O)O2 and HO2
and concentration of CH3CHO result in significant increases
in the modelled mixing ratios of CH3C(O)OOH, CH3OOH, HCHO,
and H2O2.},
cin = {IEK-8},
ddc = {550},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {2111 - Air Quality (POF4-211)},
pid = {G:(DE-HGF)POF4-2111},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000703045500001},
doi = {10.5194/acp-21-14333-2021},
url = {https://juser.fz-juelich.de/record/902295},
}