Stable isotopes of carbon, hydrogen, nitrogen, sulfur and oxygen in atmospheric gases and aerosols provide a powerful constraint on chemical, physical and biological processes that affect our atmosphere. Measurement of stable isotope ratios is an established tool for investigating the processes that determine the distribution, sources and sinks of important atmospheric gases such as carbon dioxide, carbon monoxide, methane, hydrogen, nitrous oxide, sulfur dioxide and ozone. Recently, the first measurements of carbon isotope ratios in volatile organic compounds (VOCs) have become available. Meanwhile, a number of laboratory studies reported kinetic isotope effects in the reactions of VOCs with OH, Cl, and ozone. Due to the broad spectrum of compounds with a large range of atmospheric life times, the recently developed isotopic hydrocarbon clock concept allows investigation of chemical and physical processes in the atmosphere. These methods have been extended to investigate particulate matter, especially secondary organic aerosols. Moreover, the discovery of non-mass dependent isotope fractionation processes in the laboratory and in nature have revolutionised the way stable isotope measurements are applied. Previously neglected minor isotope ratios such as 17O/16O, 33S/32S, 36S/32S, etc. are establishing themselves as vital tools.

The session is open to all contributions related to stable isotope studies of gases in the atmosphere, field studies, laboratory and simulation experiments, technical developments and modeling activities.

Topics addressed in this session are:
- Stable isotope ratios in atmospheric gases and aerosols
- Kinetic isotope effects
- Field and simulation experiments
- Model studies including stable isotope ratios
- Stable isotope ratios in the formation of aerosols from biogenic and anthropogenic VOC
- Technical developments (sampling techniques, analytical techniques etc.)
- Non-mass dependent isotope fractionation and related isotope anomalies
- Stable isotopes in the past, present and future atmosphere