Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Long-distance atmospheric transport of microplastic fibres influenced by their shapes

Nature Geoscience volume 16, pages 863–870 (2023)Cite this article

Subjects

Abstract

Recent studies have highlighted the importance of the atmosphere in the long-range transport of microplastic fibres. However, their dry deposition in the atmosphere is not fully understood, with the common spherical-shape assumption leading to significant uncertainties in predicting their travel distance and atmospheric residence time. Shapes of microplastic fibres vary greatly, which can be as long as 100 μm and as thin as 2 μm. Shapes of microplastic fibres may greatly affect their dry deposition in the atmosphere. Here we develop a theory-based settling velocity model for simulating atmospheric transport of microplastic fibres in different sizes and shapes. The model predicts a smaller aerodynamic size of microplastic fibres than that estimated by using volumetrically equivalent spherical counterparts. We find that the treatment of flat fibres as cylindrical ones, due to uncertainty in dimensions of sampled microplastic fibres, would cause overestimation of their dry deposition rate. Accounting for fibre thickness in sampled microplastic fibres leads to a mean enhancement of residence time by more than 450% compared to cylindrical ones. The results suggest a much more efficient long-range transport of flat fibres than previously thought.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Illustrations of airborne microplastics transport fate and on-site sampled microplastic fibres with various sizes and shapes.
Fig. 2: Impacts of predictive models, geometric configurations and ambient turbulence on the settling velocity of microplastic fibres.
Fig. 3: Geometric configuration, settling velocity, aerodynamic size distributions and enhanced dry deposition lifetimes of collected microplastic fibres.
Fig. 4: Comparative analysis of mass fractions, source contributions and global total emissions for microplastics with varied shapes and sizes.

Similar content being viewed by others

Data availability

Original data underlying the figures are available at https://github.com/a20070348/MPFs_Data.

Code availability

Code for computing the settling velocity given different characteristics of the fibres is available at https://github.com/a20070348/MPs.

References

  1. Yang, L., Zhang, Y., Kang, S., Wang, Z. & Wu, C. Microplastics in soil: Aa review on methods, occurrence, sources, and potential risk. Sci. Total Environ. 780, 146546 (2021).

    Google Scholar 

  2. Horton, A. A. & Dixon, S. J. Microplastics: an introduction to environmental transport processes. Wiley Interdiscip. Rev. Water 5, e1268 (2018).

    Google Scholar 

  3. Allen, S. et al. Atmospheric transport and deposition of microplastics in a remote mountain catchment. Nat. Geosci. 12, 339–344 (2019).

    Google Scholar 

  4. Brahney, J. et al. Constraining the atmospheric limb of the plastic cycle. Proc. Natl Acad. Sci. USA 118, e2020719118 (2021).

  5. Brahney, J., Hallerud, M., Heim, E., Hahnenberger, M. & Sukumaran, S. Plastic rain in protected areas of the United States. Science 368, 1257–1260 (2020).

    Google Scholar 

  6. Abbasi, S., Rezaei, M., Ahmadi, F. & Turner, A. Atmospheric transport of microplastics during a dust storm. Chemosphere 292, 133456 (2022).

    Google Scholar 

  7. Allen, D. et al. Microplastics and nanoplastics in the marine–atmosphere environment. Nat. Rev. Earth Environ. 3, 393–405 (2022).

    Google Scholar 

  8. Rillig, M. C. & Lehmann, A. Microplastic in terrestrial ecosystems. Science 368, 1430–1431 (2020).

    Google Scholar 

  9. Allen, S. et al. Evidence of free tropospheric and long-range transport of microplastic at Pic du Midi observatory. Nat. Commun. 12, 7242 (2021).

    Google Scholar 

  10. Thomas, K. V. Understanding the plastics cycle to minimize exposure. Nat. Sustain. 5, 282–284 (2022).

    Google Scholar 

  11. Zhang, Y., Gao, T., Kang, S. & Sillanpää, M. Importance of atmospheric transport for microplastics deposited in remote areas. Environ. Pollut. 254, 112953 (2019).

    Google Scholar 

  12. Woodward, J., Li, J., Rothwell, J. & Hurley, R. Acute riverine microplastic contamination due to avoidable releases of untreated wastewater. Nat. Sustain. 4, 793–802 (2021).

    Google Scholar 

  13. Zhang, Y. et al. Atmospheric microplastics: a review on current status and perspectives. Earth Sci. Rev. 203, 103118 (2020).

    Google Scholar 

  14. Taylor, M., Gwinnett, C., Robinson, L. F. & Woodall, L. C. Plastic microfibre ingestion by deep-sea organisms. Sci. Rep. 6, 33997 (2016).

    Google Scholar 

  15. Zender, C. S., Bian, H. & Newman, D. Mineral dust entrainment and deposition (dead) model: description and 1990s dust climatology. J. Geophys. Res. Atmos. https://doi.org/10.1029/2002JD002775 (2003).

  16. Huang, Y. et al. Climate models and remote sensing retrievals neglect substantial desert dust asphericity. Geophys. Res. Lett. 47, e2019GL086592 (2020).

    Google Scholar 

  17. Kooi, M. & Koelmans, A. A. Simplifying microplastic via continuous probability distributions for size, shape, and density. Environ. Sci. Technol. Lett. 6, 551–557 (2019).

    Google Scholar 

  18. Evangeliou, N., Tichý, O., Eckhardt, S., Zwaaftink, C. G. & Brahney, J. Sources and fate of atmospheric microplastics revealed from inverse and dispersion modelling: from global emissions to deposition. J. Hazard. Mater. 432, 128585 (2022).

    Google Scholar 

  19. Huang, Y., Qing, X., Wang, W., Han, G. & Wang, J. Mini-review on current studies of airborne microplastics: analytical methods, occurrence, sources, fate and potential risk to human beings. TrAC Trends Anal. Chem. 125, 115821 (2020).

    Google Scholar 

  20. Marchioli, C., Fantoni, M. & Soldati, A. Orientation, distribution, and deposition of elongated, inertial fibers in turbulent channel flow. Phys. Fluids 22, 033301 (2010).

    Google Scholar 

  21. Lopez, D. & Guazzelli, E. Inertial effects on fibers settling in a vortical flow. Phys. Rev. Fluids 2, 024306 (2017).

    Google Scholar 

  22. Dietrich, W. E. Settling velocity of natural particles. Water Resour. Res. 18, 1615–1626 (1982).

    Google Scholar 

  23. Khatmullina, L. & Isachenko, I. Settling velocity of microplastic particles of regular shapes. Mar. Pollut. Bull. 114, 871–880 (2017).

    Google Scholar 

  24. Waldschlager, K. & Schuttrumpf, H. Effects of particle properties on the settling and rise velocities of microplastics in freshwater under laboratory conditions. Environ. Sci. Technol. 53, 1958–1966 (2019).

    Google Scholar 

  25. Zhang, J. & Choi, C. E. Improved settling velocity for microplastic fibers: a new shape-dependent drag model. Environ. Sci. Technol. 56, 962–973 (2021).

  26. Zhao, L., Challabotla, N. R., Andersson, H. I. & Variano, E. A. Rotation of nonspherical particles in turbulent channel flow. Phys. Rev. Lett. 115, 244501 (2015).

    Google Scholar 

  27. Voth, G. A. & Soldati, A. Anisotropic particles in turbulence. Ann. Rev. Fluid Mech. 49, 249–276 (2017).

    Google Scholar 

  28. Kramel, S. Non-spherical Particle Dynamics in Turbulence. PhD thesis, Wesleyan Univ. (2018).

  29. Menon, U. K. Theory and Simulation for the Orientation of High Aspect Ratio Particles Settling in Homogeneous Isotropic Turbulence. PhD thesis, Cornell Univ. (2009).

  30. Marchioli, C., Zhao, L. & Andersson, H. On the relative rotational motion between rigid fibers and fluid in turbulent channel flow. Phys. Fluids 28, 013301 (2016).

    Google Scholar 

  31. Zhao, L., Marchioli, C. & Andersson, H. I. Slip velocity of rigid fibers in turbulent channel flow. Phys. Fluids 26, 063302 (2014).

    Google Scholar 

  32. Jayaweera, K. & Cottis, R. Fall velocities of plate-like and columnar ice crystals. Q. J. R. Meteorolog. Soc. 95, 703–709 (1969).

    Google Scholar 

  33. Yang, X., Wang, Y., Yang, H. & Yang, Y. Experimental research on free settling properties of different types of single fiber particle in air. Build. Environ. 185, 107300 (2020).

    Google Scholar 

  34. Khayat, R. & Cox, R. Inertia effects on the motion of long slender bodies. J. Fluid Mech. 209, 435–462 (1989).

    Google Scholar 

  35. Muñoz-Esparza, D., Sharman, R. D. & Lundquist, J. K. Turbulence dissipation rate in the atmospheric boundary layer: observations and WRF mesoscale modeling during the XPIA field campaign. Mon. Weather Rev. 146, 351–371 (2018).

    Google Scholar 

  36. Batchelor, G. Slender-body theory for particles of arbitrary cross-section in Stokes flow. J. Fluid Mech. 44, 419–440 (1970).

    Google Scholar 

  37. Ni, R., Kramel, S., Ouellette, N. T. & Voth, G. A. Measurements of the coupling between the tumbling of rods and the velocity gradient tensor in turbulence. J. Fluid Mech. 766, 202–225 (2015).

    Google Scholar 

  38. Clift, R., Grace, J. R. & Weber, M. E. Bubbles, Drops, and Particles (Dover Publications, 2005).

  39. Huang, Y., Adebiyi, A. A., Formenti, P. & Kok, J. F. Linking the different diameter types of aspherical desert dust indicatesthat models underestimate coarse dust emission. Geophys. Res. Lett. 48, e2020GL092054 (2021).

    Google Scholar 

  40. Evangeliou, N. et al. Atmospheric transport is a major pathway of microplastics to remote regions. Nat. Commun. 11, 3381 (2020).

    Google Scholar 

  41. Allen, S. et al. Examination of the ocean as a source for atmospheric microplastics. PloS ONE 15, 0232746 (2020).

    Google Scholar 

  42. Yang, S. et al. Constraining microplastic particle emission flux from the ocean. Environ. Sci. Technol. Lett. 9, 513–519 (2022).

  43. Oehmke, T. & Variano, E. A new particle for measuring mass transfer in turbulence. Exp. Fluids 62, 16 (2021).

  44. Cheng, K.-Y., Wang, P. K. & Hashino, T. A numerical study on the attitudes and aerodynamics of freely falling hexagonal ice plates. J. Atmos. Sci. 72, 3685–3698 (2015).

    Google Scholar 

  45. Roy, A., Hamati, R. J., Tierney, L., Koch, D. L. & Voth, G. A. Inertial torques and a symmetry breaking orientational transition in the sedimentation of slender fibres. J. Fluid Mech. 875, 576–596 (2019).

    Google Scholar 

  46. Jeffery, G. B. The motion of ellipsoidal particles immersed in a viscous fluid. Proc. R. Soc. Lond. A 102, 161–179 (1922).

    Google Scholar 

  47. Ravnik, J., Marchioli, C. & Soldati, A. Application limits of jeffery’s theory for elongated particle torques in turbulence: a DNS assessment. Acta Mech. 229, 827–839 (2018).

    Google Scholar 

  48. Sabban, L., Cohen, A. & van Hout, R. Temporally resolved measurements of heavy, rigid fibre translation and rotation in nearly homogeneous isotropic turbulence. J. Fluid Mech. 814, 42–68 (2017).

    Google Scholar 

  49. Bréon, F.-M. & Dubrulle, B. Horizontally oriented plates in clouds. J. Atmos. Sci. 61, 2888–2898 (2004).

    Google Scholar 

  50. Klett, J. D. Orientation model for particles in turbulence. J. Atmos. Sci. 52, 2276–2285 (1995).

    Google Scholar 

  51. Siewert, C., Kunnen, R., Meinke, M. & Schröder, W. Orientation statistics and settling velocity of ellipsoids in decaying turbulence. Atmos. Res. 142, 45–56 (2014).

    Google Scholar 

Download references

Acknowledgements

We thank D.L. Koch for insightful scientific discussions and comments concerning this work. Our thanks also extend to Y. Guo and S. Yin for assistance with the illustrative figures. Q.L. acknowledges support from the US National Science Foundation (NSF-CAREER-2143664, NSF-AGS-2028633, NSF-CBET-2028842) and computational resources from the National Center for Atmospheric Research (UCOR-0049). J.B. acknowledges support from the US National Science Foundation (NSF-MSB-1926559).

Author information

Authors and Affiliations

  1. School of Civil and Environmental Engineering, Cornell University, Ithaca, NY, USA

    Shuolin Xiao, Yuanfeng Cui & Qi Li

  2. Department of Watershed Sciences, Utah State University, Logan, UT, USA

    Janice Brahney

  3. Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA

    Natalie M. Mahowald

Authors
  1. Shuolin Xiao
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yuanfeng Cui
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Janice Brahney
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Natalie M. Mahowald
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Qi Li
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

S.X. and Q.L. designed this research. Y.C. helped with the data preparation and documentation of data and code. J.B. generated the data from on-site measurements. N.M.M. carried out large-scale climate modelling. S.X., Q.L. and N.M.M. wrote the manuscript draft. S.X., Q.L., N.M.M., J.B. and Y.C. revised the manuscript.

Corresponding author

Correspondence to Qi Li.

Ethics declarations

Competing interests

The authors declare no competing interests.

Inclusion and ethics

All authors are committed to fostering an inclusive and ethical environment in all aspects of our work.

Peer review

Peer review information

Nature Geoscience thanks Sajjad Abbasi, Cristian Marchioli, Masanori Saito, and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Xujia Jiang, in collaboration with the Nature Geoscience team.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1

Settling velocity for round fiber and flat fiber with l = 1 mm and different β definition.

Extended Data Fig. 2

Settling velocity distribution for flat fiber with different β definition for field measurement data.

Extended Data Fig. 3

Comparison of aerodynamic size distributions for flat fibers with different prescribed thicknesses.

Extended Data Fig. 4 Cumulative probability distributions of reduction in dry deposition rate.

(a) the reduction in dry deposition rate for MPF with a flat bottom and (b) the reduction in dry deposition rate for MPF with round cross-section. Note that the reduction in a dry deposition for MPF with a flat bottom is evaluated between ws calculated from our model for MPF with a flat bottom and the one obtained from our model but with a presumption that the cross section is in a round shape based on the sampled fiber on site. The reduction in dry deposition for MPF with a round cross section is compared between ws calculated from our model and the one obtained from the volumetric spherical particle model. For all the subfigures, red dash–dot lines denote the mean quantities and black solid lines represent the median values.

Extended Data Fig. 5

Figure showing the size of the ocean source (Tg on the y axis) as a function of the size of plastics (um on x-axis) in sensitivity studies where all plastics are assumed to be one size for each sensitivity study.

Extended Data Fig. 6

Flowchart for implementing the proposed model for large-scale climate model.

Extended Data Fig. 7

Framework of our proposed settling velocity model for microplastic fiber.

Supplementary information

Supplementary Information

Supplementary Notes 1–5.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Xiao, S., Cui, Y., Brahney, J. et al. Long-distance atmospheric transport of microplastic fibres influenced by their shapes. Nat. Geosci. 16, 863–870 (2023). https://doi.org/10.1038/s41561-023-01264-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41561-023-01264-6

Search

Advanced search

Quick links

Nature Briefing Anthropocene

Sign up for the Nature Briefing: Anthropocene newsletter — what matters in anthropocene research, free to your inbox weekly.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing: Anthropocene