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Epoxide Pathways Improve Model Predictions of Isoprene Markers and Reveal Key Role of Acidity in Aerosol Formation

2013; American Chemical Society; Volume: 47; Issue: 19 Linguagem: Inglês

10.1021/es402106h

1520-5851

Havala O. T. Pye, R. W. Pinder, Ivan R. Piletic, Ying Xie, Shannon L. Capps, Ying‐Hsuan Lin, Jason D. Surratt, Zhenfa Zhang, Avram Gold, D.J. Luecken, William T. Hutzell, Mohammed Jaoui, John H. Offenberg, Tadeusz E. Kleindienst, Michael Lewandowski, Edward O. Edney,

Air Quality and Health Impacts

Isoprene significantly contributes to organic aerosol in the southeastern United States where biogenic hydrocarbons mix with anthropogenic emissions. In this work, the Community Multiscale Air Quality model is updated to predict isoprene aerosol from epoxides produced under both high- and low-NOx conditions. The new aqueous aerosol pathways allow for explicit predictions of two key isoprene-derived species, 2-methyltetrols and 2-methylglyceric acid, that are more consistent with observations than estimates based on semivolatile partitioning. The new mechanism represents a significant source of organic carbon in the lower 2 km of the atmosphere and captures the abundance of 2-methyltetrols relative to organosulfates during the simulation period. For the parametrization considered here, a 25% reduction in SOx emissions effectively reduces isoprene aerosol, while a similar reduction in NOx leads to small increases in isoprene aerosol.