air-sea exchanges driven by light: functionalized VOC and particle formation
Résumé
The sea surface is characterized by an organic enriched microlayer. Exposed to solar radiation, it has been demonstrated that the surface is a source of volatile organic compounds (VOC) as well as highly functionalized VOCs. Therefore, it is thought that photochemical processes occurring at air-sea interface lead to the formation of low molecular weight organic compounds able to condense, leading to SOA formation and growth. The aim of this study is centred to the following question: can photo-induced chemical processes under relevant atmospheric conditions lead to the aerosol loading in the marine boundary layer? Previous works have shown that photochemical processing led to the formation of highly functionalized VOCs which may be potential candidates to the SOA loading. In order to bring further comprehension, a multiphase atmospheric simulation chamber has been developed and used in order to study the chemical processes occurring at the air-sea interface. Experiments were performed with synthetic sea surface microlayers but also authentic samples from the Cape Verde Atmospheric Observatory. The formation of unexpected highly functionalized and oxygenated VOCs was observed, leading to the formation of organic aerosols from a quite surface i.e., without any bubble bursting aerosol production. These photosensitized processes at the air/sea surface will be presented and discussed in terms of chemical processing and impact of organic aerosol formation in the marine boundary layer.