Geometrically-Driven Selective Transport of Microplastics Across Atmosphere-Land

Abstract

Atmospheric circulation contributes critically to the transport of microplastics (MPs). However, our limited knowledge regarding the geometric characteristics of deposited MPs hinders the accurate assessment of associated environmental risks. This study explores how the geometrical characteristics influence MPs' selective atmospheric transport and deposition in Shanghai, which highlights MP geometric characteristics as a crucial indicator for understanding atmospheric-terrestrial transport mechanisms. High-density deposited MPs exhibited heterogeneous geometric characteristics, and low-density MPs showed partially homogenized characteristics. Meteorological parameters correlate more significantly with geometric characteristics than with deposition flux in our research. Precipitation significantly promotes deposited MPs characterized by high solidity, high circularity, and low density. Moreover, increased wind speeds driven by atmospheric pressure gradients significantly heightened the deposition of MPs with high solidity. Typhoon events enhance MP deposition by promoting the resuspension of terrestrial MPs and the release of MPs from damaged urban infrastructure. Potential source contribution function (PSCF) analysis indicates that both local and remote transport pathways contribute to MP deposition in Shanghai. These results provide critical insights for refining MP transport models by incorporating geometric features, elucidating the environmental fate of MP, and supporting the development of targeted strategies to mitigate human exposure risks.