EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Constraining the atmospheric limb of the plastic cycle

Natalie Mahowald1, Janice Brahney2, Marje Prank1,3, Gavin Cornwell4, Zbigniew Klimont5, Hitoshi Matsui6, and Kim Prather7
Natalie Mahowald et al.
  • 1Department of Earth and Atmospheric Sciences, Atkinson Center for Sustainability, Cornell University, Ithaca, NY 14853, U.S.A
  • 2Department of Watershed Sciences, Utah State University, Logan UT 84322, U.S.A
  • 3Finnish Meteorological Institute, Department of Climate System Research, Climate System Modelling Group, Erik Palmenin Aukio 1, Helsinki, 00560, Finland
  • 4Pacific Northwest National Laboratory, Richland WA 99352, U.S.A
  • 5International Institute for Applied Systems Analysis (IIASA), 2361 Laxenburg, Austria
  • 6Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
  • 7Scripps Institution of Oceanography and Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, A92093, U.S.A

Plastic pollution is one of the most pressing environmental and social issues of the 21st century. Recent work has highlighted the atmosphere’s role in transporting microplastics to remote locations. Here we use in situ observations of microplastic deposition combined with an atmospheric transport model and optimal estimation techniques to test hypotheses of the most likely sources of atmospheric plastic. Results suggest that atmospheric microplastics in the western USA are primarily derived from secondary re-emission sources including roads, the ocean and agricultural soil dust. Using our best estimate of plastic sources and modeled transport pathways, most continents were net importers of plastics from the marine environment, underscoring the cumulative role of legacy pollution in the atmospheric burden of plastic. This effort is the first to use high resolution spatial and temporal deposition data along with several hypothesized emission sources to constrain atmospheric plastic. Akin to global biogeochemical cycles, plastics now spiral around the globe with distinct atmospheric, oceanic, cryospheric, and terrestrial lifetimes. Though advancements have been made in the manufacture of biodegradable polymers, our data suggest that extant non-biodegradable polymers will continue to cycle through the Earth’s systems. Due to limited observations and understanding of the source processes, there remain large uncertainties in the, transport, deposition, and source attribution of microplastics. Thus, we prioritize future research directions for understanding the plastic cycle.

How to cite: Mahowald, N., Brahney, J., Prank, M., Cornwell, G., Klimont, Z., Matsui, H., and Prather, K.: Constraining the atmospheric limb of the plastic cycle, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16473,, 2021.

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