A study of organic nitrates formation in an urban plume using a Master Chemical Mechanism

Secondary organic chemistry inside a typical urban plume in the North-East of the United States has been studied using a highly detailed chemical model, based upon the Master Chemical Mechanism (MCM). The model results have been qualitatively compared to measurements taken during three flights of the NOAA WP-3D aircraft, which sampled a plume from the New York City area during the NEAQS 2004 campaign. The model has been used to study the formation processes and photochemical evolution of alkyl nitrates. While long-chain (C5) alkyl nitrates are produced for 90% or more from the oxidation of a single parent alkane, short-chain ( C 4 ) alkyl nitrates can be formed from several precursors. The relative importance of each production route has been quantitatively determined thanks to the high level of chemical detail provided by the MCM. These secondary routes to the formation of alkyl nitrates include the oxidation of longer-chain alkanes and oxygenated intermediates, like carbonyls, peroxides and carboxylic acids.