Organic nitrate contribution to the oxidized nitrogen budget at the 2013 Southern Oxidant and Aerosol Study (SOAS)

Org. nitrates (RONO_2) that are formed from the OH-initiated or NO_3-initiated oxidn. of biogenic alkenes can be important reservoirs and sinks for NO_x (NO + NO_2). Biogenic org. nitrates represent a significant fraction of the total NO_y budget in forested regions. During the 2013 Southern Oxidant and Aerosol Study (SOAS), speciated org. nitrates produced from the oxidn. of isoprene (C_5H_8) and monoterpenes (C_(10)H_(16)) were measured with high temporal resoln. and sensitivity by a time-of-flight chem. ionization mass spectrometer (ToF-CIMS) from a 20 m tower. Both dark and photochem. mechanisms were obsd. to be important for the prodn. of multifunctional org. nitrates at SOAS. The combined vol. mixing ratios of RONO_2 detd. by ToF-CIMS and GC-MS were compared to a thermal-dissocn. laser-induced fluorescence (TD-LIF) measurement of total org. nitrates in the gas and aerosol phase. The mass closure of org. nitrates in the gas-phase and their fractional contributions to the aerosol phase will be presented. The significance of org. nitrates to the overall nitrogen and oxidant budgets at SOAS will be discussed