Development of a bench scale method for constant output of mineral dust

Abstract

To realize the environmental impacts of mineral dust from different sources, it is necessary to develop aerosol generation systems that can mimic the processes of aerosolization of sediments into dusts under controlled laboratory settings. Current laboratory dust generation systems would benefit from a critical evaluation of the mechanisms by which they generate dust beyond mere resuspension to include natural eolian processes such as saltation/sandblasting. Without realistically generated aerosols, laboratory-measured dust properties may not capture properties relevant to the natural environment. We describe the development of a benchtop system, the Constant Output Dust Generator (CODG), whose design takes into account the dominant natural physical processes of wind erosion and mineral dust production. The CODG’s major components include a wrist-action shaker, custom-built flask, dilution drum, cyclone, and neutralizer. A carrier gas provides flow through the system resulting in dust entrainment. We achieved constant output, typically <10% variation in aerosol surface area concentration, for both a commercial standard as well as environmental samples (saline crusts and loose sediments). We find that the composition of aerosols generated from the CODG is consistent with the composition of the parent source material. We further show that our system is suitable for determination of reaction rates on suspended dust aerosols. At similar mechanical energy inputs, it generates sufficient material (particle surface area concentrations between 10⁻⁵ − 10⁻³ cm² cm⁻³) for many applications from both loose sandy sediment and cohesive evaporite crusts. The CODG represents a system potentially applicable for numerous applications of dust aerosol research.

Copyright © 2021 American Association for Aerosol Research

Acknowledgments

We thank one anonymous reviewer for comments that improved our manuscript. We are very grateful to the following individuals for collection of samples: Prof. Heather Holmes and Prof. Bernhard Bach (Black Rock Desert playa); Prof. Maura Hahnenberger (Great Salt Lake playa); Prof. Joanna Nield, Jana Lasser, and Lucas Goehring (Owens Lake playa); Prof. Roya Bahreini (Salton Sea playa); and Dr. R. Scott Van Pelt (Sulphur Springs Draw). We thank Prof. Andrew Baker for use of the orbital shaker, and Prof. Kimberly Popendorf for use of the vortex shaker in troubleshooting the development of the CODG.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Science Foundation (USA) under grants AGS-1663740 and AGS-1663726. S.H. and K.A.P. acknowledge the University of Michigan REU Program in the Chemical Sciences (CHE-1460990).