(593h) The Influence of Increasing Chemical Complexity on the Hygroscopic Properties of Multi-Component Dicarboxylic Acid Aerosols

Significant research in the past two decades has focused on individual particulate constituents and their interactions with water. Previously, the interaction between water and the inorganic fraction of atmospheric aerosols has been well characterized, and the role of organics in aerosols is becoming more fully understood. Most studies to date have examined aerosol mixtures containing only one or a few species; however, such mixtures are unlikely to accurately represent the hygroscopic properties of ambient aerosols, which may contain hundreds of different organic compounds and substantial amounts of inorganic compounds. It is necessary, therefore, to investigate the water interactions of particles containing many inorganic and organic species to develop a more realistic simulation of the complex nature of ambient particulates and to discover the best way to simplify this complexity of natural aerosols for modeling studies. To accomplish this goal, the deliquescence and hygroscopic growth of aerosols containing up to 10 different dicarboxylic acids and common inorganics were observed using tandem differential mobility analysis (TDMA). The results show that while pure-component aerosols and those containing up to 3 different components may exhibit deliquescent behavior, mixtures which are more chemically-complex develop a smooth hygroscopic growth curve and show water uptake even at low relative humidities. Additionally, individual mixture components do not contribute equally to the hygroscopic properties of the overall mixture. The hygroscopic behavior of complex multi-component aerosols will be presented along with some discussion of the contribution of each chemical species present.