The formation, properties and impact of secondary organic aerosol: current and emerging issues
- ISSN: 1680-7316
Secondary organic aerosol (SOA) accounts for a\nsignificant fraction of ambient tropospheric aerosol\nand a detailed knowledge of the formation, properties\nand transformation of SOA is therefore required to\nevaluate its impact on atmospheric processes, climate\nand human health. The chemical and physical processes\nassociated with SOA formation are complex and varied,\nand, despite considerable progress in recent years, a\nquantitative and predictive understanding of SOA\nformation does not exist and therefore represents a\nmajor research challenge in atmospheric science. This\nreview begins with an update on the current state of\nknowledge on the global SOA budget and is followed by\nan overview of the atmospheric degradation mechanisms\nfor SOA precursors, gas-particle partitioning theory\nand the analytical techniques used to determine the\nchemical composition of SOA. A survey of recent\nlaboratory, field and modeling studies is also\npresented. The following topical and emerging issues\nare highlighted and discussed in detail: molecular\ncharacterization of biogenic SOA constituents,\ncondensed phase reactions and oligomerization, the\ninteraction of atmospheric organic components with\nsulfuric acid, the chemical and photochemical\nprocessing of organics in the atmospheric aqueous\nphase, aerosol formation from real plant emissions,\ninteraction of atmospheric organic components with\nwater, thermodynamics and mixtures in atmospheric\nmodels. Finally, the major challenges ahead in\nlaboratory, field and modeling studies of SOA are\ndiscussed and recommendations for future research\ndirections are proposed.