Thermodynamic properties and gas/particle partitioning of atmospheric amines

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Description

Amines can be emitted into the atmosphere from a variety of sources, such as animal husbandry, industrial operations, and oceans. They are also among one of the important groups of organic species in atmospheric aerosols and a rare class of bases (Saxena and Hildemann 1996). However, relatively little is known about the atmospheric chemistry of amines and how they may lead to particle formation. We present a general overview of the present knowledge of amines, with respect to atmospheric sources, emission fluxes, detection in ambient air, and atmospheric behaviors such as gas-phase reactions, gas-to-particle conversion, wet deposition processes, and health effects. Additionally, information about atmospheric occurrence and reactivity of amino acids and urea in the atmosphere are also reviewed since these are closely related compounds. 154 amines and 32 amino acids have been identified in the atmosphere. We evaluate the thermodynamic properties of atmospherically relevant amines with special regard to the gas/particle partitioning, such as Henry Law’s constant, acid-dissociation constant, vapor pressure, solubility, and activity coefficient. Those data will be incorporated into our E-AIM web interface (Extended Aerosol Inorganic Model, Wexler and Clegg 2002), so that users can add additional amines to the model for the gas/aerosol partitioning calculations of their interests. Finally, we estimated the dissociation constants and their variation with temperature and relative humidity (RH) of atmospherically relevant aminium salts, such as aminium chloride and nitrates, and their likely competition with ammonium salts on gas/aerosol partitioning. Saxena, P, and LM Hildemann. 1996. “Water-soluble organics in atmospheric particles: A critical review of the literature and application of thermodynamics to identify candidate compounds.” Journal of Atmospheric Chemistry, 24, 57-109. Wexler, AS and SL Clegg. 2002. “Atmospheric aerosol models for systems including the ions H+, NH4+, Na+, SO42-, NO3-, Cl-, Br- and H2O.” Journal of Geophysical Research, 107(D14), 4207.