| In comparison to homogeneous processes, heterogeneous reactions of atmospheric aerosols are not well characterized even though aerosols are a ubiquitous component of the earth's atmosphere. Particulates can play significant roles in global chemistry cycles, regional and global climate, and also have implications for human health and quality of life. An increased understanding of aerosols as reactive surfaces is needed for many reasons, such as improving atmospheric models, sharpening climate change prediction and in guiding legislation regarding pollution abatement.; The heterogeneous interactions of trace gas species with metal oxide, carbonate and soot aerosols were investigated. For this purpose, a new experimental system utilizing a large reaction chamber was designed, built and optimized. The systems investigated were studied under relevant tropospheric conditions of humidity and total pressure. A Fourier-transform infrared spectrometer was used to probe the aerosol-gas systems. The resulting infrared spectra can then be used to elucidate kinetic parameters, quantify product species in both the gas and adsorbed phase, and glean information about the optical properties of the reacted aerosols.; Uptake coefficients were measured for three systems involving soot aerosols: NO2 with hexane soot and carbon black, as well as HNO3 with carbon black aerosol. Kinetic parameters were also extracted for alumina, a model mineral dust aerosol, reacting with SO2, NO2 and HNO3. The interaction of HNO3 with calcite was explored and the effects of relative humidity on the reactivity examined. The reaction of HNO3 was not limited to the surface of the particle when water was present. The effect of chemical processing by HNO3 on calcite reactions with SO2 and CH3COOH was also considered. Additionally, the scattering properties of aerosols with various size distributions and differing composition were compared. |
