Aqueous glyoxal photooxidation in the presence of inorganic nitrogen: A potential source of organic nitrogen in aerosols and wet deposition

The sources of organic nitrogen in aerosols and atmospheric wet deposition are poorly understood, yet are important when assessing potential anthropogenic impacts on global nitrogen budgets. Nitrogen-containing organics are formed through gas phase photochemistry (e.g., involving NOx and isoprene). Imidazoles have been reported to form during smog chamber experiments involving glyoxal and ammonium sulfate seed particles. We hypothesize that nitrogen-containing organic compounds also form during cloud processing of water-soluble organic gases. Specifically, in this work we examine the possibility that organic nitrogen forms from GLY and inorganic nitrogen (NO3- or NH4+) at conditions found in daytime liquid clouds. We conducted batch aqueous reactions of GLY (1 mM) and OH radical (~10^-12 M) with and without nitric acid (1.7 mM) and ammonium sulfate (0.84 mM). OH radical was formed from the continuous photolysis of H2O2. Products were analyzed by ion chromatography (IC) and electrospray ionization mass spectrometry with pre-separation by IC (IC/ESI-MS). The addition of ammonium or nitrate had little effect on the concentrations of major system species (i.e., oxalate, glycolate) in the presence and absence of OH radical. Concentrations of inorganic nitrate and sulfate showed no significant change throughout light and dark experiments. ESI mass spectra with and without pre-separation by IC and ultra high resolution Fourier transform ion cyclotron resonance mass spectral analysis of samples will be examined and any evidence of organic nitrogen products will be discussed.