Heterogeneous conversion of NO2 on secondary organic aerosol surfaces: A possible source of nitrous acid (HONO) in the atmosphere?

R. Bröske, J. Kleffmann, P. Wiesen
2003 Atmospheric Chemistry and Physics  
The heterogeneous conversion of NO 2 on different secondary organic aerosols (SOA) was investigated with the focus on a possible formation of nitrous acid (HONO). In one set of experiments different organic aerosols were produced in the reactions of O 3 with α-pinene, limonene or catechol and OH radicals with toluene or limonene, respectively. The aerosols were sampled on filters and exposed to humidified NO 2 mixtures under atmospheric conditions. The estimated upper limits for the uptake
more » ... icients of NO 2 and the reactive uptake coefficients NO 2 →HONO are in the range of 10 −6 and 10 −7 , respectively. The integrated HONO formation for 1 h reaction time was < 10 13 cm −2 geometrical surface and < 10 17 g −1 particle mass. In a second set of experiments the conversion of NO 2 into HONO in the presence of organic particles was carried out in an aerosol flow tube under atmospheric conditions. In this case the aerosols were produced in the reaction of O 3 with β-pinene, limonene or catechol, respectively. The upper limits for the reactive uptake coefficients NO 2 →HONO were in the range of 7 × 10 −7 − 9 × 10 −6 . The results from the present study show that heterogeneous formation of nitrous acid on secondary organic aerosols (SOA) is unimportant for the atmosphere.
doi:10.5194/acp-3-469-2003 fatcat:ygb2rmpgzzgvzovsah74jypuma