Measurements of stable isotope ratios in atmospheric trace gases on HALO (MIRAH)

点击翻译按钮获取中文摘要

We propose to measure stable carbon and hydrogen isotope ratios of volatile organic compounds (VOC) as well as their concentrations in the atmosphere using a gas chromatograph combustion isotope ratio mass spectrometer (GCC-IRMS). The proposed methodology is a sensitive tool to identify the origin of VOC, to study their atmospheric processing, to investigate the impact of transport processes on their distribution, to infer transport pathways, to differentiate between impacts of mixing and chemical processes, as well as to estimate the degree of mixing and the residence times of the compounds. Studies of isotope fractionation effects associated with formation and loss reactions of VOC help to better understand the complex interaction between the atmospheric chemistry of secondary VOC and the formation of particulate organic matter. The VOC will be used as tracers to investigate chemical and physical processes in the atmosphere on different spatial and temporal scales. An automated high volume air sampling system (MIRAH) specifically designed by our group for HALO will be used to analyse isotope ratios of VOC and to detect ’fingerprints’ of processes that influenced individual compounds. MIRAH is will be deployed on the HALO missions OMO (2011), TACTS (2011), SALSA (2011/12) and SHIVA (2012/13) to deliver detailed and precise information of dynamics, air mass characteristics and photochemical processing, essential for the interpretation of concomitant measurements and research topics.