The relative importance of local climate and land use on the deposition rate of airborne microplastics on terrestrial land

Increasing concentrations of microplastics in the Earth's atmosphere could adversely impact ecosystems when deposited on land and human health when inhaled. The deposition rate of airborne microplastics may vary widely depending on both land use and local climate. While land use affects the pool of microplastics available for entrainment into the atmosphere, climatic conditions such as high wind speed or low humidity could increase the emission potential of the microplastics from land surfaces-both factors can synergistically affect microplastic emission. However, it is unclear which of these factors is more influential in affecting the deposition rate of airborne microplastics. Conducting a global analysis of deposition rates (n m- 2 day- 1) based on 24 studies from 15 countries, we found that the deposition rates could vary by 5 orders of magnitude, but longer sampling durations (10 days) could reduce the uncertainty in the measurement of the deposition rate. The deposition rates were higher in arid and tropical climates, which was attributed to hot weather and wind turbulence. Interestingly, the deposition rates did not vary significantly with land use, possibly due to the long-range atmospheric transport of microplastics. Overall, analysis of available data reveals that climate could have a greater impact than land use on the concentration and deposition rate of airborne microplastics, and a longer sampling duration could minimize measurement variability in deposition rates.

Automated summary

Increasing concentrations of microplastics in the Earth's atmosphere could have adverse effects on ecosystems and human health. The deposition rate of airborne microplastics is influenced by both land use and climate, and a global analysis suggests that climate may have a greater impact on the concentration and deposition rate of microplastics than land use.