10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Simulation of Heterogeneous Oxidation of SO2 and NOx in the Presence of Gobi Desert Dust Particles under Urban Environments
ZECHEN YU, Myoseon Jang, University of Florida
Abstract Number: 536 Working Group: Aerosol Transport and Transformation
Abstract Large quantities of mineral dust particles are frequently ejected into the atmosphere through wind action. The surface of mineral dust particles can act as an import sink for atmospheric tracers (i.e., O3, SO2, NOx and hydrocarbons) and photochemically enhance the production of oxygenated compounds. The photochemically oxidized hydrocarbons in the gas phase partition onto dust particles and involve in dust-phase heterogeneous reactions. These products modulate the characteristics of dust surfaces. In this study, we simulate the oxidation of SO2 and NOx in the presence of mineral dust under the ambient conditions using the Atmospheric Mineral Aerosol Reaction (AMAR) model. The model consists of explicit reaction mechanisms in three phases: gas phase, inorganic salted aqueous phase, and dust phase. Dust heterogeneous chemistry begins with a gas-particle partitioning process and is further processed via both autoxidation and photocatalytic oxidation by the dust phase semi-conducting matters. The simulation using the model is compared with UF-APHOR chamber data for the formation of nitrate and sulfate in the presence of Gobi Desert Dust particles and different hydrocarbons (i.e., 2-Methyl-2-butene, alpha-pinene, toluene, isoprene, gasoline and urbane mix hydrocarbons). In the exploratory experiment, the organic compounds formed from the photooxidation of 2-Methyl-2-butene in the presence of NOx showed a negligible effect on dust-phase nitrate formation. However, oxidized compounds formed from the photooxidation of secondary organic aerosol precursor hydrocarbons (i.e., alpha-pinene) depleted dust phase nitrate that formed via the reaction of alkaline carbonates with nitric acid. The adsorbed ozone on dust surfaces can positively modulate the formation of sulfate and nitrate. Using the AMAR model that is integrated with the Carbon Bond mechanism (CB6), the influence of ozone on sulfate and nitrate formation in dust particles will also be simulated under the urban environments that contain various hydrocarbons and NOx.