| The research described herein is an exploratory topic that investigated the formation of brown carbon (BrC) in ice. Brown carbon is a subcategory of secondary organic aerosol (SOA) that absorbs visible light as opposed to traditional SOA that scatter radiation. The climate implications of light absorption by BrC include positive radiative forcing and altering the albedo of the Earth's surface. Formation of BrC in ice would also present various effects on atmospheric processes due to the release of organic compounds from ice pack as global temperatures increase. The research focused on formation of BrC through photochemical oxidation of volatile organic compounds (VOCs) with OH radical in the presence of a nitrogen source. Ammonium and glycine served as the sources of nitrogen in the two types of reactions attempted. Acetophenone, glyoxal, propionic acid, and isoprene served as potential BrC precursors in photochemical reactions with hydrogen peroxide and ammonium. Acetophenone, benzoic acid, glyoxal, methylglyoxal, oxalic acid, and malonic acid served as potential BrC precursors in photochemical reactions with hydrogen peroxide and glycine. Each type of reaction was completed with four conditions: dark control ice, irradiated ice, dark control liquid, irradiated liquid. Results indicated that a yellow-brown BrC product formed most readily from acetophenone and benzoic acid. Reactions occurred at a faster rate in the liquid phase as compared to the ice phase. The presence of nitrogen and the identity of the nitrogen source are related to the formation of BrC. |
