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

我们提出用气相色谱-燃烧同位素比质谱仪(GCC-IRMS)测量挥发性有机化合物(VOC)的稳定碳、氢同位素比值及其在大气中的浓度。该方法是一种灵敏的工具，可用于确定VOC的来源、研究其大气过程、调查输送过程对其分布的影响、推断输送路径、区分混合和化学过程的影响以及估计化合物的混合程度和停留时间。研究与VOC的生成和损失反应相关的同位素分馏效应有助于更好地理解二次VOC的大气化学与颗粒有机质的形成之间的复杂相互作用。挥发性有机化合物将被用作示踪剂，在不同的空间和时间尺度上研究大气中的化学和物理过程。我们团队专门为Halo设计的自动高容量空气采样系统(MIRAA)将用于分析VOC的同位素比率，并检测影响个别化合物的过程的“指纹”。Mirah IS将部署在Halo飞行任务OMO(2011)、TACTS(2011)、SALSA(2011/12)和SHIVA(2012/13)上，以提供关于动力学、气团特征和光化学过程的详细和准确信息，这些信息对于解释伴随的测量和研究主题至关重要。

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.