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Shape, Structure, and Chemical Analysis of Mineral Dust Aerosol and Its Impact on IN activity

EMSL Project ID


A significant amount of atmospheric aerosol particles are aspherical, with complex shapes and morphological distributions of chemical components. This can greatly affect their climate relevant properties such as optical properties, ice nucleation (IN) activity and cloud condensation nuclei (CCN) activity. However, the relationship between aerosol particle shape and their climate relevant properties remains poorly understood. More specifically, mineral dust is an important atmospheric aerosol whose properties strongly depend on particle shape. The proposed work will investigate the particle shapes of several atmospherically relevant mineral dust samples and the effects that particle shape has on the optical properties, IN activity, and CCN activity.
EMSLs advanced microscopy capabilities and APM/DMA/SPLAT (ADS) system will allow us to characterize particle shape in great detail. The ADS is capable of selecting particles with a specific mass, size, and shape from a complex sample. It can then measure the dynamic shape factors (DSFs), porosity, density, morphology, and composition of the resulting selected aerosol. One example of the unique capabilities of the ADS system that our studies will utilize is the ability to measure aerosol composition and shape as a function of size. Studies have found that ground samples of mineral dust can differ from aerosol samples because composition varies with particle size. Furthermore, many minerals, such as clays, have been found to have particles whose shape varies with size. Therefore by understanding the relationship between size, shape and composition of mineral dust we can greatly improve models of atmospheric mineral dust. All of these properties have an effect on climate and need to be understood in order to develop future climate models.
Important climate factors such as IN and CCN activity can also be measured using EMSLs technology and advanced microscopy instrumentation and the optical properties can be measured using our home built laser scattering CCD instrument. Once the particles have been size and shape selected by the ADS system they are ready for characterization by any application or analytical tool, including measurements of the optical properties and IN and CCN activity. Combining these capabilities, the effects that particle size, shape, and composition have on the different physiochemical properties of interest can be differentiated between which would otherwise be extremely difficult.
Additionally, many studies have found that mineral dust is often reacted or coated with organic material. Clearly this interaction can affect the particle size, shape and composition, which can in turn affect the optical properties and IN and CCN activity. Therefore we will investigate the physical and chemical changes caused by the interaction of mineral dust and organic material and its effect on climate relevant properties.
The work proposed here is necessary to not only understand the physical, optical, and chemical properties of atmospheric mineral dust but also their interaction with organic material. In addition, this work will include characterizing the molecular-scale processes by which aerosol particles control ice nucleation and crystal formation. These studies will further the understanding of the impact that atmospheric mineral dust aerosol has on the climate so as to develop better climate models.

Project Details

Project type
Large-Scale EMSL Research
Start Date
End Date


Principal Investigator

Vicki Grassian
University of Iowa


Paul Kleiber
University of Iowa

Team Members

Jennifer Alexander
University of Iowa

David Bell
Pacific Northwest National Laboratory

Jacqueline Wilson
Pacific Northwest National Laboratory

Related Publications

Alexander JM, DM Bell, D Imre, P Kleiber, VH Grassian, and A Zelenyuk. 2016. "Measurement of Size-dependent Dynamic Shape Factors of Quartz Particles in Two Flow Regimes." Aerosol Science and Technology 50(8):870-879. doi:10. 1080/02786826. 2016. 1200006