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| Titel |
The influence of natural and anthropogenic secondary sources on the glyoxal global distribution |
| VerfasserIn |
S. Myriokefalitakis, M. Vrekoussis, K. Tsigaridis, F. Wittrock, A. Richter, C. Brühl, R. Volkamer, J. P. Burrows, M. Kanakidou |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 16 ; Nr. 8, no. 16 (2008-08-28), S.4965-4981 |
| Datensatznummer |
250006345
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| Publikation (Nr.) |
 copernicus.org/acp-8-4965-2008.pdf |
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| Zusammenfassung |
Glyoxal, the smallest dicarbonyl, which has recently been observed from
space, is expected to provide indications on volatile organic compounds
(VOC) oxidation and secondary aerosol formation in the troposphere. Glyoxal
(CHOCHO) is known to be mostly of natural origin and is produced during
biogenic VOC oxidation. However, a number of anthropogenically emitted
hydrocarbons, like acetylene and aromatics, have been positively identified
as CHOCHO precursors. The present study investigates the contribution of
pollution to the CHOCHO levels by taking into account the secondary chemical
formation of CHOCHO from precursors emitted from biogenic, anthropogenic and
biomass burning sources. The impact of potential primary land emissions of
CHOCHO is also investigated. A global 3-dimensional chemistry transport
model of the troposphere (TM4-ECPL) able to simulate the gas phase chemistry
coupled with all major aerosol components is used.
The secondary anthropogenic contribution from fossil fuel and industrial
VOCs emissions oxidation to the CHOCHO columns is found to reach 20–70%
in the industrialized areas of the Northern Hemisphere and 3–20% in
the tropics. This secondary CHOCHO source is on average three times larger
than that from oxidation of VOCs from biomass burning sources. The chemical
production of CHOCHO is calculated to equal to about 56 Tg y−1 with
70% being produced from biogenic hydrocarbons oxidation, 17% from
acetylene, 11% from aromatic chemistry and 2% from ethene and
propene. CHOCHO is destroyed in the troposphere primarily by reaction with OH
radicals (23%) and by photolysis (63%), but it is also removed from
the atmosphere through wet (8%) and dry deposition (6%). Potential
formation of secondary organic aerosol through CHOCHO losses on/in aerosols
and clouds is neglected here due to the significant uncertainties associated
with the underlying chemistry. The global annual mean CHOCHO burden and
lifetime in the model domain are estimated to be 0.02 Tg (equal to the global
burden seen by SCIAMACHY over land for the year 2005) and about 3 h,
respectively. The model results are compared with satellite observations of
CHOCHO columns. When accounting only for the secondary sources of CHOCHO in
the model, the model underestimates CHOCHO columns observed by satellites.
This is attributed to an overestimate of CHOCHO sinks or a missing global
source of about 20 Tg y−1. Using the current primary emissions of
CHOCHO from biomass burning together with the anthropogenic combustion
sources of about 7 Tg y−1 leads to an overestimate by the model over
hot spot areas. |
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