Atmos. Chem. Phys. Discuss., 13, 11357-11394, 2013
www.atmos-chem-phys-discuss.net/13/11357/2013/
doi:10.5194/acpd-13-11357-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Stable carbon isotope ratios of toluene in the boundary layer and the lower free troposphere
J. Wintel, E. Hösen, R. Koppmann, and M. Krebsbach
Physics Department, University of Wuppertal, Wuppertal, Germany

Abstract. Measurements of stable carbon isotope ratios in VOC are a powerful tool to identify sources or to track both dynamical and chemical processes.

During the field campaign ZEPTER-2 in autumn 2008 whole air samples were collected on board a Zeppelin NT airship in the planetary boundary layer and the lower free troposphere over south-west Germany. These samples were analysed with respect to VOC mixing ratios and stable carbon isotope ratios using a gas chromatograph combustion isotope ratio mass spectrometer. In this study we present the results for toluene, one of the major anthropogenic pollutants.

In the boundary layer we observed rather fresh emissions mixing into the background and derived a toluene source isotope ratio of δ13C = −28.2 ± 0.5 ‰. Using the concept of the effective kinetic isotope effect, we were able to separate the effects of dilution processes and photochemical degradation in the free troposphere. We estimated the photochemical age of toluene in the atmosphere in two different ways (using isotope ratios and mixing ratios, respectively). The results differ strongly in the planetary boundary layer, probably due to mixing processes, but are compatible with each other in the free troposphere.


Citation: Wintel, J., Hösen, E., Koppmann, R., and Krebsbach, M.: Stable carbon isotope ratios of toluene in the boundary layer and the lower free troposphere, Atmos. Chem. Phys. Discuss., 13, 11357-11394, doi:10.5194/acpd-13-11357-2013, 2013.
 
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