Secondary organic aerosol formation in the atmosphere by new aerosol-based photo-induced processes

KIFLE Z AREGAHEGN; MARÍA EUGENIA MONGE; CHRISTIAN GEORGE; BARBARA D'ANNA; BARBARA NOZIÈRE

Philadelphia

Encuentro; 240th American Chemical Society National Meeting & Exposition; 2012

ACS

The formation mechanisms currently considered for Secondary Organic Aerosols (SOA) in the atmosphere, mostly taking into account the gas precursor volatility, underestimate atmospheric SOA masses. Reactivity inside the aerosol particles was shown to potentially account for the missing masses but exact reactions remained to be identified until now. Here we report new aerosol-based photo-induced processes producing SOA at atmospheric growth rates from a range of gas precursors (isoprene, limonene, butanol, toluene) (Monge et al., PNAS, in press 2012). Unlike in the current mechanisms the precursors are oxidized in the aerosol particles, not the gas, by radicals produced by the excitation of a photosentisizer by sunlight. The resulting SOA yields are thus strongly enhanced by the reactive uptake and by the contribution of a much wider range of precursors. Such photosentisizers were also identified among the multiphase products of common atmospheric gases, increasing the importance of these processes in the atmosphere.