Breakdown and modification of microplastics beads by aeolian abrasion

Saltation is an important wind erosion process that can cause the modification and breakdown of particles by aeolian abrasion. It is recognised that microplastic particles can be transported by wind but the effect of saltation on microplastic properties is unknown. This study examined the impact of simulated saltation alongside quartz grains on the size, shape and surface properties of spherical microplastic beads. The diameter of the microplastics was reduced by 30-50% over 240-300 hours of abrasion with a mass loss of c.80%. For abrasion periods up to 200 hours the microplastic beads remained spherical with minimal change to overall shape. Over 95% of the fragments of plastic removed from the surface of the microbeads during the abrasion process had a diameter ≤10 μm. In addition, during the abrasion process, fine particles derived from breakdown of the quartz grains became attached to the surfaces of the microbeads resulting in a reduction in carbon and an increase in silicon detected on the particle surface. The results suggest microplastics may be mechanically broken down during aeolian saltation and small fragments produced have the potential for long distance transport as well as being within the size range for human respiration.