Collaborative Research: Nitrate (NO3) Induced Nighttime Air Chemistry

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Although normally rapidly removed through daytime photolysis, aqueous phase and aerosol sorption, the reactive NO3 radical plays an elusive role in the oxidation of volatile organic compounds such as biogenic hydrocarbons (e.g. terpenes, alcohols) especially at night, and additionally in the conversion of NOx species to nitric acid (HNO3). Investigators from University of Nevada DRI and Howard University will conduct a four week field measurement campaign together with a series of analysis and modeling efforts to evaluate NO3 radical chemistry in an urban desert setting. It is hypothesized that in low humidity conditions, prevalent in arid regions additionally subject to strong urban sources of NO2 and O3, a more definitive measurement of NO3 and its loss processes will be practicable than can be observed in more humid environments. Both nighttime and daytime chemistry of the urban study site (Reno, NV) will be characterized by a range of direct and indirect chemical measurement techniques allowing the evaluation of NO3 radical budgets. The data, constrained by measured parameters, will be analyzed with box models to see if it is possible to account for known, or postulated, nitrate radical loss mechanisms.