The lifetime of charged dust in the atmosphere
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Date
2022-10-14
Authors
Harper, Joshua Méndez
Harvey, Dana
Huang, Tianshu
McGrath, Jake, III
Meer, David
Burton, Justin C.
Journal Title
Journal ISSN
Volume Title
Publisher
Oxford Academic
Abstract
Wind-blown dust plays a critical role in numerous geophysical and biological systems, yet current models fail to explain the transport
of coarse-mode particles (>5μm) to great distances from their sources. For particles larger than a few microns, electrostatic effects
have been invoked to account for longer-than-predicted atmospheric residence times. Although much effort has focused on elucidating
the charging processes, comparatively little effort has been expended understanding the stability of charge on particles once
electrified. Overall, electrostatic-driven transport requires that charge remain present on particles for days to weeks. Here,we present
a set of experiments designed to explore the longevity of electrostatic charge on levitated airborne particles after a single charging
event. Using an acoustic levitator,we measured the charge on particles of different material compositions suspended in atmospheric
conditions for long periods of time. In dry environments, the total charge on particles decayed in over 1week. The decay timescale decreased
to days in humid environments. These results were independent of particle material and charge polarity. However, exposure
to UV radiation could both increase and decrease the decay time depending on polarity. Our work suggests that the rate of charge
decay on airborne particles is solely determined by ion capture from the air. Furthermore, using a one-dimensional sedimentation
model, we predict that atmospheric dust of order 10μm will experience the largest change in residence time due to electrostatic
forces.
Description
8 pages
Keywords
Charged dust, Acoustic levitation, Atmospheric electricity
Citation
Joshua Méndez Harper, Dana Harvey, Tianshu Huang, Jake McGrath, David Meer, Justin C Burton, The lifetime of charged dust in the atmosphere, PNAS Nexus, Volume 1, Issue 5, November 2022, pgac220, https://doi.org/10.1093/pnasnexus/pgac220