Collaborative Research: Laboratory and Theoretical Studies of Mineral Aerosol Heterogeneous Interactions with Mixtures of Atmospheric Gases at Relevant Temperatures and Humidities

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The objective of this project is to determine the heterogeneous reactivity of natural mineral aerosol components, representative of chemically-processed and freshly-emitted mineral aerosol, with single atmospheric gases and with gaseous mixtures over atmospherically relevant temperature and humidity ranges. A low-pressure, low-temperature Diffuse Reflectance Infrared Fourier Transform Spectrometer (DRIFTS) equipped reaction chamber will be used to carry out laboratory studies. The chamber system allows for in situ, simultaneous gas- and condensed-phase measurements of the heterogeneous uptake of reactive gases and gaseous mixtures on thin films of mineral components representative of those observed in the atmosphere. Heterogeneous uptake will be studied experimentally as a function of temperature, relative humidity and reactive gas concentration. Associated theoretical studies will (a) complement experiments by interpreting infrared spectra and identifying intermediate and terminal adsorbed reaction products, providing additional mechanistic detail, (b) model electronic properties of the mineral dust components studied and determine the effects of metal impurities on surface reactivity, and (c) determine how heterogeneous reactions on mineral dust surfaces alter these electronic properties.Results of the studies will provide important mechanistic, kinetic and thermodynamic details needed for incorporation into current atmospheric chemistry models in order to more accurately model the effects of heterogeneous reactivity (impacts on tropospheric chemistry), surface composition (impacts on health, climate and further reactivity) and water adsorption (impacts on visibility and climate) in the Earth's atmosphere. The work will extend beyond previous studies of mineral dust aerosol heterogeneous chemistry that were limited to heterogeneous uptake under dry conditions, room temperature and in the presence of only a single reactive gas. The project will foster a unique partnership between a large university and a small liberal arts college. This relationship will cultivate experiential learning via active educational research opportunities for undergraduate students and aid in the recruitment of well-trained, science-oriented students at the undergraduate and graduate levels. Beyond traditional dissemination, research results will be incorporated into undergraduate teaching curricula at Hendrix College. Additionally, hands-on workshops and laboratory experiments will be conducted at Hendrix College using the DRIFTS system.