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| Titel |
A possible role of ground-based microorganisms on cloud formation in the atmosphere |
| VerfasserIn |
S. Ekström, B. Nozière, M. Hultberg, T. Alsberg, J. Magnér, E. D. Nilsson, P. Artaxo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 1 ; Nr. 7, no. 1 (2010-01-29), S.387-394 |
| Datensatznummer |
250004389
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| Publikation (Nr.) |
 copernicus.org/bg-7-387-2010.pdf |
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| Zusammenfassung |
The formation of clouds is an important process for the atmosphere, the
hydrological cycle, and climate, but some aspects of it are not completely
understood. In this work, we show that microorganisms might affect cloud
formation without leaving the Earth's surface by releasing biological
surfactants (or biosurfactants) in the environment, that make their way into
atmospheric aerosols and could significantly enhance their activation into
cloud droplets.
In the first part of this work, the cloud-nucleating efficiency of standard
biosurfactants was characterized and found to be better than that of any
aerosol material studied so far, including inorganic salts. These results
identify molecular structures that give organic compounds exceptional
cloud-nucleating properties. In the second part, atmospheric aerosols were
sampled at different locations: a temperate coastal site, a marine site, a
temperate forest, and a tropical forest. Their surface tension was measured
and found to be below 30 mN/m, the lowest reported for aerosols, to our
knowledge. This very low surface tension was attributed to the presence of
biosurfactants, the only natural substances able to reach to such low
values.
The presence of strong microbial surfactants in aerosols would be consistent
with the organic fractions of exceptional cloud-nucleating efficiency
recently found in aerosols, and with the correlations between algae bloom
and cloud cover reported in the Southern Ocean. The results of this work
also suggest that biosurfactants might be common in aerosols and thus of
global relevance. If this is confirmed, a new role for microorganisms on the
atmosphere and climate could be identified. |
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