The impact of multiphase reactions of NO2 with aromatics: a modelling approach

[摘要] The impact of multiphase reactions involving nitrogen dioxide(NO₂) and aromatic compounds was simulated in this study. A mechanism (CAPRAM 2.4, MODAC Mechanism)was applied for the aqueous phase reactions, whereas RACM was applied for the gas phasechemistry. Liquid droplets were considered as monodispersed with a mean radius of0.1 µm and a liquid content (LC) of 50 µg m^-3. The multiphase mechanism has been further extendedto the chemistry of aromatics, i.e. reactions involving benzene, toluene, xylene, phenol andcresol have been added. In addition, reaction of NO₂ with dissociated hydroxyl substitutedaromatic compounds has also been implemented. These reactions proceed through chargeexchange leading to nitrite ions and therefore to nitrous acid formation. The strength of thissource was explored under urban polluted conditions. It was shown that it may increase gasphase HONO levels under some conditions and that the extent of this effect is strongly pHdependent. Especially under moderate acidic conditions (i.e. pH above 4) this source mayrepresent more than 75% of the total HONO/NO₂^- production rate, but this contribution drops down close to zero in acidic droplets (as those often encountered in urban environments).

[学科分类] 大气科学