AS&T Article Highlight

AS&T Article Highlight

By Kristina Wagstrom

Methodology for quantifying the volatile mixing state of an aerosol

M. Dickau, J. Olfert, M. Stettler, A. Boies, A. Momenimovahed, K. Thomson, G. Smallwood, M. Johnson
Aerosol Science and Technology, Vol. 50, 759 -772, 2016.

Quantifying the mixing state of aerosols has important implications for understanding optical, chemical, and hygroscopic properties. A knowledge of these properties is integral to determining the potential impacts on climate and human health from particles of differing composition. This differing composition can result from a variety of factors including particle source, particle age, and particle trajectory. This newsletter’s featured article introduces a new method to determine the volatile versus nonvolatile mixing state using a suite of different aerosol instrumentation. This set-up allows the authors to investigate aerosol composition and mixing state as a function of aerosol size using measured fractions of volatile and nonvolatile components.

The authors have demonstrated the effectiveness of their approach using two different soot mixtures, one high in elemental carbon and the other high in organic carbon. In each case, they were able to determine the fraction of nonvolatile, condensed volatile (on nonvolatile material), and pure volatile material (in independent particles) in each sample. While both samples are primarily composed of non-volatile material, only the high organic carbon sample contained internally mixed particles of volatile and nonvolatile material. The sized resolved fractions of each of the components for both samples are shown in the figure below.

 

The mixing state as a function of mobility diameter for the (a) high elemental carbon and (b) high organic carbon soot samples.

Chart

For more, view the list of 12 notable 2015/2016 papers that the Editors and EIC of AST recently compiled.

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