AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
React or Evaporate? Atmospheric Aldehydes in Aqueous Droplets Containing Amines or Ammonium Sulfate
MICHELLE POWELSON, Melissa Galloway, David De Haan, University of San Diego
Abstract Number: 703 Working Group: Aerosol Chemistry
Abstract Approximately half the mass of typical aerosol particles consists of organic compounds, which change the radiative properties of aerosol and so contribute to global climate change. Oligomer formation in atmospheric aqueous aerosol is an important formation mechanism for low-volatility organic material. There are several aldehydes present in clouds droplets, including methylglyoxal, glycolaldehyde, hydroxyacetone, glyoxal, and acetaldehyde. These aldehydes have the potential to oligomerize and/or create “brown carbon” products when reacted with ammonium sulfate or primary amines (methylamine and glycine). Physical properties of oligomers, such as mass and volatility, can be determined using Thermogravimetric Analysis (TGA). The change in mass of solutions containing amine and aldehyde compounds was measured as a function of temperature to determine the quantity and stability of compounds that remain in the condensed phase. The mass loss profile after water evaporation varied depending on the aldehyde + amine solution. Aldehyde + glycine mixtures produced the most condensed-phase material with glyoxal and methylglyoxal, as observed by other techniques where aerosol evaporation occurs at room temperature. Aldehyde + methylamine and ammonium sulfate mixtures, however, unexpectedly produced the most condensed-phase material with the smallest aldehydes, formaldehyde and acetaldehyde. . These reactions were likely greatly accelerated by the 105 °C temperature used to evaporate water in this TGA method. Further analysis on room-temperature-evaporated materials by TGA will be reported.