Microplastic particles resuspensions in bare soils and global atmospheric transport

Microplastics (MPs), which are synthetic polymer particles with sizes from 1 µm to 1 mm, are considered as an emerging pollutant. It has been proposed that the atmosphere has a significant role in the transport of MPs. Atmospheric MPs can originate from primary sources, such as population activities, or secondary sources, like the ocean and soils. In this study, we estimate the secondary MPs that are resuspended in bare soils together with mineral dust, using measurements of MP soil mass fractions, the MP enrichment in wind-eroded sediments relative to the original soil, and spatiotemporally resolved dust emissions calculated with the dust mobilization scheme FLEXDUST (Groot Zwaaftink et al., 2016). Using the Lagrangian atmospheric dispersion model FLEXPART (Pisso et al., 2019), we simulate the global transport of resuspended MPs for a range of sizes and morphologies (spheres, fibers) based on our estimated emissions. We perform a ten-thousand-member Monte Carlo (MC) simulation in which the parameters affecting the resuspensions are perturbed, and an extended MC by varying further the assumed MP size distributions to estimate the resuspension and transport uncertainties, respectively.