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The influence of bi...
The influence of biogenic organic compounds on cloud formation
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- Ekström, Sanna, 1980- (author)
- Stockholms universitet,Institutionen för tillämpad miljövetenskap (ITM)
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- Nozière, Barbara, Professor (thesis advisor)
- Stockholms universitet,Institutionen för tillämpad miljövetenskap (ITM)
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- Alsberg, Tomas, PhD (thesis advisor)
- Stockholms universitet,Institutionen för tillämpad miljövetenskap (ITM)
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- Hansson, Hans-Christen, Professor (thesis advisor)
- Stockholms universitet,Institutionen för tillämpad miljövetenskap (ITM)
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- Weingartner, Ernest, PhD (opponent)
- Paul Sherrer Institut, Laboratory of Atmospheric Chemistry
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(creator_code:org_t)
- ISBN 9789174471755
- Stockholm : Department of Applied Environmental Science (ITM), Stockholm University, 2010
- English 43 s.
- Related links:
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Abstract
Subject headings
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- Aerosols and clouds provide the largest uncertainty in the atmospheric radiation budget. The main focus of this thesis was to investigate the ability of organic compounds in aerosol particles to form clouds, and more specifically those emitted by living organisms. The cloud forming properties of the highly water-soluble methyltetrols and polyols, which are compounds produced by plants and fungi that are common in aerosol, were studied. All compounds and their salt mixtures have a moderate potential to serve as cloud condensation nuclei (CCN). They are thus not likely to have a significant global impact on cloudiness. The potential presence of surfactants released by microorganisms was investigated for aerosols sampled at different locations. Very low surface tension values were measured for these aerosol extracts (30 mN/m), which implies that these aerosols have good CCN properties and indicate the presence of biosurfactants. Their occurrence in aerosols still needs to be confirmed directly by chemical identification. Reactions of organic compounds in sulfate salt solutions exposed to UV-light were studied and found to produce surface active compounds. Thus, mixed sulfate/organic aerosol could have more favourable CCN properties after exposure to light than when kept in the dark. The surface active compounds were proposed to be long-chained organosulfates with hydrophilic and hydrophobic parts, similar to other amphiphilic surfactants. Mixtures of salt and strong surfactants formed by bacteria were studied using two different techniques for determining their CCN properties. There were inconsistencies between the two methods which could be accounted for by surface partitioning. The studied mixtures were determined to be good potential CCN material in both techniques. All these aspects require further investigation, but if the impact of strong biogenic surfactants on cloud formation is confirmed, a new link between living organisms and climate would be identified.
Keyword
- biogenic
- aerosol
- CCN
- water-soluble
- microorganisms
- surfactant
- organosulfate
- NATURAL SCIENCES
- NATURVETENSKAP
- Applied Environmental Science
- tillämpad miljövetenskap
Publication and Content Type
- vet (subject category)
- dok (subject category)
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