Development of a mobile photochemical reactor to investigate gas-phase chemistry and aerosol formation in the field
Résumé
The development of innovative tools is important to tackle atmospheric complexity, i.e its composition and future changes. Investigating chemical transformations during intensive field campaigns is not straightforward due to the impact of emissions, vertical dilution, and other meteorological parameters on ambient concentrations of trace gases and aerosols. Investigations of these transformations in the laboratory using smog chambers provide a much more controlled environment but are limited to simple chemical systems, which are not representative of complex atmospheres.
The objective of the current study is to combine both concepts through the construction of a mobile photochemical reactor and its deployment in the field during intensive measurement campaigns. This new tool will allow trapping real air masses, directly on site, to characterize the fate of primary emitted trace gases using all the benefits of a smog chamber, i.e. decoupling the chemistry from other processes (emission, transport…). A 9 m3 photo-reactor was constructed to trap ambient air at atmospheric pressure into a FEP foil bag maintained by an aluminium frame. The reactor allows both solar and artificial irradiations, whose irradiance is monitored by a spectroradiometer. The chemical composition, including volatile organic compounds, oxidants and aerosols, is probed in real time during an oxidation experiment using state-of-the-art instrumentation (FastGC/PTR-ToFMS for VOCs, CRM for OH reactivity, PERCA for peroxy radicals, O3 and NOx analysers, SMPS for particles). This presentation will describe the photo-reactor setup and its first deployment during the summer 2018 CERVOLAND field campaign.
Domaines
Océan, Atmosphère
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