A Comparative Examination of Atmospheric Models for Studying Airborne Micro- and Nanoplastic Pollution

The apparent omnipresence of plastic waste is a serious global issue. The question of micro- and nanoplastics pollution in the environment has been more widely addressed in recent years, and its occurrence in the oceans, freshwater systems, air, soil and various organisms has been well documented [1]. This widespread pollution not only threatens ecosystems it also raises concerns about potential impacts on human health [2]. Alongside the well-studied transport pathway in marine and freshwater systems, micro- and nanoparticles can also be distributed via airborne pathways [1]. In-situ sampling sites provide only in-direct evidence of some possible pathways. Thus, the use of atmospheric models to study atmospheric pathways of different classes of micro- and nanoplastics can give valuable insights into the atmospheric redistribution and possible sources. Various models can be used to describe the behaviour of airborne particles. Trajectory models, like HYSPLIT [3], trace the path of an air parcel with low computational effort, excluding the effect of diffusion and turbulence. In contrast, the weather forecast model ICON and its aerosol and reactive trace gases module ART account for these factors [4], describing the status and the development of the atmosphere in more detail. Using the data of nanoplastic in-situ measurements at a remote sampling site in the high-altitude Alps [5] and the combination of HYSPLIT backwards and ICON-ART forwards simulations, the two model types are compared and characterized, exploring their potential and limitations in describing airborne micro- and nanoplastic particle distributions and revealing potential pathways and attributing possible source regions. [1] Allen, Steve, et al. "Micro (nano) plastics sources, fate, and effects: What we know after ten years of research." Journal of Hazardous Materials Advances 6 (2022): 100057.[2] Lehner, Roman, et al. "Emergence of nanoplastic in the environment and possible impact on human health." Environmental science & technology 53.4 (2019): 1748-1765.[3] Stein, Ariel F., et al. "NOAA’s HYSPLIT atmospheric transport and dispersion modeling system." Bulletin of the American Meteorological Society 96.12 (2015): 2059-2077.[4] Rieger, Daniel, et al. "ICON-ART 1.0–a new online-coupled model system from the global to regional scale." Geoscientific Model Development Discussions 8.1 (2015): 567-614.[5] Materić, Dušan, et al. "Nanoplastics transport to the remote, high-altitude Alps." Environmental Pollution 288 (2021): 117697.