Chemical Characterization of Cloudwater Collected at Puy de Dome by FT-ICR MS Reveals the Presence of SOA Components

Secondary organic aerosols (SOA) produced in the atmosphere from sequential oxidation of biogenic or anthropogenic volatile organic compounds (VOC) represent a significant part of the atmospheric organic aerosol. Aerosol particles can act as cloud condensation nuclei or can be scavenged by cloud droplets, where organic carbon undergo chemical and biological transformations. Due to its high complexity, a nontargeted analysis by FT-ICR MS (Fouriertransform ion cyclotron resonance mass spectrometry) has been used to characterize the dissolved organic matter at a molecular level. SOA compounds have been detected in six aqueous samples collected in 2017 at the Puy de DOme station (PUY, France). SOA tracers, produced by VOC oxidation in environmental chambers or in ambient air and characterized in previous studies by mass spectrometry, were searched by FT-ICR MS in cloudwaters. Results clearly indicate the presence of oxidation products of isoprene, alpha- and beta-pinene, and other monoterpenes and sesquiterpenes. Interestingly, a significant number of assigned molecular formulas are attributed to brown carbon and nitroaromatics. Seasonal variabilities are also observed for organonitrates and organosulfates.