A lumped species approach for the simulation of secondary organic aerosol production from intermediate-volatility organic compounds (IVOCs): application to road transport in PMCAMx-iv (v1.0)

[摘要] Secondary organic aerosol (SOA) is formed in theatmosphere through the oxidation and condensation of organic compounds.Intermediate-volatility compounds (IVOCs), compounds with effective saturationconcentration ( C ∗ ) at 298 K between 10 3 and 10 6   µg  m −3 , have high SOA yields and can be important SOA precursors. Thefirst efforts to simulate IVOCs in chemical transport models (CTMs) used thevolatility basis set (VBS), a highly parametrized scheme that oversimplifiestheir chemistry. In this work we propose a more detailed approach forsimulating IVOCs in CTMs, treating them as lumped species that retain theirchemical characteristics. Specifically, we introduce four new lumped speciesrepresenting large alkanes, two lumped species representing polyaromatichydrocarbons (PAHs) and one species representing large aromatics, all in theIVOC range. We estimate IVOC emissions from road transport using existingestimates of volatile organic compound (VOC) emissions and emission factorsof individual IVOCs from experimental studies. Over the European domain, forthe simulated period of May 2008, estimated IVOC emissions from roadtransport were about 21 Mmol d −1 , a factor of 8 higher than emissionsused in previous VBS applications. The IVOC emissions from diesel vehicleswere significantly higher than those from gasoline ones. SOA yields underlow-NO x and high-NO x conditions for the lumped IVOC species wereestimated based on recent smog chamber studies. Large cyclic alkanecompounds have both high yields and high emissions, making them animportant, yet understudied, class of IVOCs.

[学科分类] 土木及结构工程学