Index Geophysics

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

The heterogeneous conversion of NO₂ 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 O₃ with alpha-pinene, limonene or catechol and OH radicals with toluene or limonene, respectively. The aerosols were sampled on filters and exposed to humidified NO₂  mixtures under atmospheric conditions. The estimated upper limits for the uptake coefficients of NO₂  and the reactive uptake coefficients NO_2  -> HONO are in the range of 10^-6and 10^-7, respectively. The integrated HONO formation for 1 h reaction time was <10¹³ cm^-2 geometrical surface and <10¹⁷ g^-1 particle mass. In a second set of experiments the conversion of NO₂ 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 O₃ with beta-pinene, limonene or catechol, respectively. The upper limits for the reactive uptake coefficients NO₂-> HONO were in the range of 7 x 10^-7- 9 x 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.

Bröske, R.

Kleffmann, J.

Wiesen, P.

2018-06-29

Text

application/pdf

10.5194/acp-3-469-2003

https://acp.copernicus.org/articles/3/469/2003/

eISSN: 1680-7324

eng