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| Titel |
Biotic stress: a significant contributor to organic aerosol in Europe? |
| VerfasserIn |
R. Bergstrom, M. Hallquist, D. Simpson, J. Wildt, T. F. Mentel |
| 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 ; 14, no. 24 ; Nr. 14, no. 24 (2014-12-20), S.13643-13660 |
| Datensatznummer |
250119258
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| Publikation (Nr.) |
 copernicus.org/acp-14-13643-2014.pdf |
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| Zusammenfassung |
We have investigated the potential impact on organic aerosol formation from
biotic stress-induced emissions (SIE) of organic molecules from forests in
Europe (north of lat. 45° N). Emission estimates for
sesquiterpenes (SQT), methyl salicylate (MeSA) and unsaturated
C17 compounds, due to different stressors, are based on experiments in
the Jülich Plant Atmosphere Chamber (JPAC), combined with estimates of
the fraction of stressed trees in Europe based on reported observed tree
damage.
SIE were introduced in the EMEP MSC-W chemical transport model and secondary
organic aerosol (SOA) yields from the SIE were taken from the JPAC
experiments. Based on estimates of current levels of infestation and the JPAC
aerosol yields, the model results suggest that the contribution to SOA in
large parts of Europe may be substantial. It is possible that SIE
contributes as much, or more, to organic aerosol than the constitutive
biogenic VOC emissions, at least during some periods. Based on the
assumptions in this study, SIE-SOA are estimated to constitute between 50 and
70 % of the total biogenic SOA (BSOA) in a current-situation scenario where
the biotic stress in northern and central European forests causes large SIE
of MeSA and SQT. An alternative current-situation scenario with lower SIE,
consisting solely of SQT, leads to lower SIE-SOA, between 20 and 40 % of the
total BSOA.
Hypothetical future scenarios with increased SIE, due to higher degrees of
biotic stress, show that SOA formation due to SIE can become even larger.
Unsaturated C17 BVOC (biogenic volatile organic compounds) emitted by spruce infested by the forest-honey
generating bark louse, Cinara pilicornis, have a high SOA-forming
potential. A model scenario investigating the effect of a regional, episodic
infestation of Cinara pilicornis in Baden-Württemberg,
corresponding to a year with high production of forest honey, shows that
these types of events could lead to very large organic aerosol formation in
the infested region.
We have used the best available laboratory data on biotic SIE applicable to
northern and central European forests. Using these data and associated
assumptions, we have shown that SIE are potentially important for SOA
formation but the magnitude of the impact is uncertain and needs to be
constrained by further laboratory, field and modelling studies. As an
example, the MeSA, which is released as a consequence of various types of
biotic stress, is found to have a potentially large impact on SIE-SOA in
Europe, but different assumptions regarding the nighttime chemistry of
MeSA can change its SOA potential substantially. Thus, further investigations
of the atmospheric chemistry of MeSA and observational field studies are
needed to clarify the role of this compound in the atmosphere. |
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