Investigative modeling of new pathways for secondary organic aerosol formation

[摘要] Recent advances in secondary organic aerosol (SOA) research are reviewed andthe status of current understanding is investigated using a box model of SOAformation. Benzene and isoprene are newly identified precursors that areincluded in this SOA model; these precursors form SOA via secondaryproducts. The model is also extended to include some representation ofaqueous partitioning and the formation of high molecular weight products viaoligomerization. Experimental data and empirical relationships are usedwhere possible, because a detailed representation of SOA formation is notsupported by the current state of information. Sensitivity studies areconducted with the SOA model and SOA predictions are found to be verysensitive to the treatment of the interactions between particulate water andorganic compounds. While uncertainties due to model formulation aresignificant, influential model parameters include the aerosol partitioningratios for several small products of isoprene and the partitioning constantsfor unidentified products (currently, the partitioning constants are derivedby fitting experimental data). The pH value used as the reference for theactivation of oligomerization is also a critical parameter. Recommendationsfor future work needed to improve SOA models include the elucidation of thewater-organic relationship, the extent of phase separation, and laboratoryexperiments conducted under conditions more relevant to ambient studies(e.g., lower concentrations, higher relative humidity).

[学科分类] 大气科学