Measurements of Stable Carbon Isotopes in Volatile Organic Compounds in the Outflow of Megacities. This proposal is a contribution to the HALO missions EMeRGe-EU and EMeRGe-ASIA.
Final Report Abstract
Measurement of stable carbon isotope ratios in VOC is an excellent methodology for indicating different processes in the atmosphere and provides precise add-on information not evident in concentration measurements alone. Due to the complex air matrix, resulting chromatograms are enormously complex and concomitant data analysis is very challenging, making the use of standard software rather impossible. Publication of the methodology and the significant progress in peak integration and analysis of our own developed software is currently in preparation. The whole air sampler MIRAH was deployed with great success during EMeRGe-EU/ASIA, where exhaust air of major population centres (MPC) in Europe and Asia was probed. Through international cooperation, also air samples at specific ground sites in London, Wuppertal, Milan, Rome, Taipeh and Manila for obtaining characteristic signatures of VOC sources in parallel was possible. Carbon isotopes and mixing ratios of specific VOC (alkanes, ketones, alcohols as acetone, methanol, ethanol as well as aldehydes, monoterpenes and aromatic compounds such as benzene, toluene, xylenes) were obtained. Depending on flight tracks pollution plumes of different composition could be identified and classified: anthropogenic, biomass burning, signatures indicative of mixing and dilution. Coupled with specific regional meteorology, transport pathways/patterns in the plumes are studied and will further be contrasted to photochemical ageing and mixing. Potential differences in transport and transformation associated with particular characteristics of European MPCs were inferred. During EMeRGe-ASIA, air pollution over and the outflow of Taiwan, Manila, Japan as well as from Mainland China were probed. Information from ground samples are used to estimate integrated residence times of air sampled aboard HALO. Examples show the photochemical age of air masses derived from the isotope measurements to agree with the age derived from accompanying tracer experiments. The single MPCs occasionally have different chemical composition and the isotope information could help to find out why. Data of the EMeRGe missions still has to be analysed in detail. First results show that a determination of atmospheric residence times and to some extent also a source apportionment is possible. With the data acquired, the very rare coverage of stable carbon isotope data from different sites and atmospheric regions has been extended. The valuable data will help to initialise models and to improve their budget estimations of different compounds as well as the understanding of photochemical and dynamical processes. A series of publications in collaboration with the international groups involved in EMeRGe are in the planning stage.
Publications
- Stable Carbon Isotope Ratios in Atmospheric VOC across the Asian Summer Monsoon Anticyclone obtained during the OMO-ASIA campaign, Geophysical Research Abstracts Vol. 19, EGU2017-5055, 2017 EGU General Assembly 2017
Krebsbach M., R. Koppmann, and T. Meisehen
- Observations of Stable Carbon Isotope Ratios in Atmospheric VOC on HALO during the EMeRGe-EU and ASIA campaigns, Geophysical Research Abstracts Vol. 21, EGU2019-16890, 2019 EGU General Assembly 2019
Krebsbach, M., and Koppmann, R.
- Measurement and model data comparisons for the HALO-FAAM formation flight during EMeRGe on 17 July 2017, DLR-Forschungsbericht 2020-48, ISSN 1434-8454, 2020
Ulrich Schumann (Edt.)
(See online at https://doi.org/10.5281/zenodo.4427965) - Stable Carbon Isotope Ratios in Atmospheric VOC during the EMeRGe-EU and ASIA campaigns, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7597
Krebsbach, M. and Koppmann, R.
(See online at https://doi.org/10.5194/egusphere-egu2020-7597)
