Tracking the sources of atmospheric microplastic using FLEXPART v.

An emerging number of studies highlighted the presence of microplastic in the atmosphere all over the world. The presence of such particles has been observed at the poles, in the marine atmosphere above the surface of the oceans, in clouds, on the fresh snow of high mountains and high concentrations has been observed in the atmospheric fallout in densely populated areas. Despite so, the main sources of atmospheric microplastic are still not well characterized and there are high uncertainties in the attempts of estimating their relative contributions. In addition, the peculiar shape of some of these particles, e.g. the very elongated fibers, complicates tracking their atmospheric transport. In this work, we explore the contribution of different sources adopting a Lagrangian approach to analyze the existing timeseries of microplastic concentrations. To do so, we exploit the new version of the Lagrangian model FLEXPART v11 (L. Bakels et al. 2024, in preparation), which also has the capability of considering the differences in the atmospheric lifetimes of irregular particles such as flattened or elongated plastic film or fibers (D. Tatsii et al. 2023). The results will highlight the areas of main emission for the regions of observations and help advance in our understanding of the sources of atmospheric microplastic pollution.