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Primary and secondary organics in tropical rainforest aerosols: Quantitative and qualitative analysis of 2-methyltetrols in the Amazon
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM). (Atmospheric Science)
(English)In: Atmospheric Chemistry and Physics Discussions, ISSN 1680-7367, E-ISSN 1680-7375Article in journal (Refereed) Submitted
Abstract [en]

Ambient aerosol samples from central Amazonia were analyzed for the presence of (2R,3S)- and (2S,3R)- methylerythritol and (2S,3S)- and (2R,3R)- methylthreitol, four stereoisomers that may have primary and secondary origins from the biosynthesis and oxidation processes of isoprene within plants and also in the atmosphere. The 2-methyltetrols were detected in aerosol samples collected at a measurement site near Manaus, Brazil in a remote tropical rainforest environment between June 2008 and June 2009. Average concentrations of 78.2 and 72.8 ng m-3 were observed for (2R,3S)- and (2S,3R)- methylerythritol and 3.1 and 3.3 ng m-3 for (2S,3S)- and (2R,3R)- methylthreitol during the dry season. In the wet season, the average concentrations were 7.1, 6.5, 2.0, and 2.2 ng m-3, respectively. The enantiomer fractions (Ef) were on average 0.52: 0.48 for (2R,3S)- and (2S,3R)- methylerythritol and 0.46: 0.54 for (2S,3S)- and (2R,3R)- methylthreitol. The concentration of these isoprene oxidation products attributed to primary origin ranged between 0.8 and 53.8 ng m-3 for the 2-methylerythritols and between 0.3 and 2.1 ng m-3 for the 2-methylthreitols. The 2-methylerythritols show no correlation with isoprene emission estimates whereas 2-methylthreitol displays a negative correlation. The present study reinforces the importance of the analysis of chiral organic compounds to correctly assess the relative contribution of primary biogenic emissions and isoprene oxidation products to biogenic secondary organic aerosol.

Keyword [en]
2-methyltetrols, isoprene, enantiomeric composition
National Category
Environmental Sciences
Research subject
Atmospheric Sciences
URN: urn:nbn:se:su:diva-89302OAI: diva2:616957
Available from: 2013-04-19 Created: 2013-04-19 Last updated: 2013-04-19Bibliographically approved
In thesis
1. Primary and secondary organics in biogenic atmospheric aerosol: The chiral study of 2-methyltetrols from method development to application
Open this publication in new window or tab >>Primary and secondary organics in biogenic atmospheric aerosol: The chiral study of 2-methyltetrols from method development to application
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Distinguishing between the primary and secondary origin of the organic components in atmospheric aerosols is one of the key parameters in assessing the relevance and role of different chemical species in the overall chemistry of the atmosphere. Currently available methods used in field measurements are not able to fully discriminate between the primary or secondary origin of compounds detected in atmospheric aerosols. This thesis presents a new analytical method for examining the primary and secondary origin of certain organic constituents, 2-methyltetrols, in biogenic atmospheric aerosol based on chirality. Chirality is a molecular structure property that makes a pair of compounds to be mirror images of each other. Consequently, compounds with chirality represent challenges for their study as individual species. This is of importance because 2-methyltetrols have been studied so far solely as two diastereomeric constituents, 2-methylerythritol and 2-methylthreitol, when in reality they are four different compounds: (2R,3S)-methylerythritol, (2S,3R)-methylerythritol, (2S,3S)-methylthreitol and (2R,3R)-mehtylthreitol. Furthermore, 2-methylerythritol and 2-methylthreitol are currently used as the main tracers for the contribution of isoprene to the formation of secondary organic aerosols in the atmosphere. Therefore, a new method directed to the chiral analysis of 2-methyltetrols was developed and applied to atmospheric samples collected at Aspvreten, Sweden, the Amazon, Brazil, and Hyytiälä, Finland. The results indicate that 2-methyltetrols in samples from the three sites have both primary and secondary origins with variability among sites as well as seasons. The estimates of the minimum primary origin contribution represent a significant fraction of the total mass of 2-methyltetrols in the samples. In some samples the contribution was as high as 30% of the total mass of these compounds. Even though 2-methyltetrols have secondary origin, their use as tracers for the atmospheric oxidation of isoprene should be discouraged, unless relative primary contributions are considered, as this study has demonstrated that they have primary origin as well. Moreover, the development and application of chiral analytical methods should be prioritized in order to improve the prevailing understanding of the real chemical composition and origin of chiral compounds in atmospheric aerosols.

Place, publisher, year, edition, pages
Stockholm: Department of Applied Environmental Science (ITM), Stockholm Univeristy, 2013. 63 p.
atmospheric organic aerosols, 2-methyltetrols, isoprene, chiral GC-MS, enantiomeric composition
National Category
Environmental Sciences
Research subject
Applied Environmental Science
urn:nbn:se:su:diva-89233 (URN)978-91-7447-683-5 (ISBN)
Public defence
2013-05-31, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrehnius 12, Stockholm, 10:00 (English)

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Submitted.

Available from: 2013-05-09 Created: 2013-04-17 Last updated: 2013-04-19Bibliographically approved

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Karlsson, Nélida Jocelyn Donají
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