the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 24 Feb 2025
The atmospheric settling of commercially sold microplastics
Abstract. The atmosphere plays a major role in the dispersion of microplastics in the environment. The atmospheric transport of large microplastics is strongly influenced by their settling behavior, which depends on their physical properties, including size and shape. However, experimental data on the settling behavior of commercially available microplastics with complex, nonspherical shapes in air are rare. Here we present experiments on the gravitational settling velocity of commercially available glitters (nominal diameters between 0.1 and 3 mm) and fibers (lengths between 1.2 and 5 mm). We observed that glitters and fibers settle up to 74 % and 78 % slower compared to volume-equivalent spheres, respectively. The atmospheric transport of fibers has been studied previously; however, there are no studies on the atmospheric transport potential of glitters. Therefore, we used an atmospheric transport model constrained by our experimental results to assess the transport potential of glitters. Our results reveal that glitters exhibit transport distances 12–261 % greater than volume-equivalent spheres, highlighting their elevated atmospheric transport potential. As a result, the environmental impact of glitter particles, especially following their use in entertainment events, warrants attention and mitigation.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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Supplement
(19699 KB)
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(13489 KB) - Metadata XML
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Supplement
(19699 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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CC1: 'Comment on egusphere-2025-605', Zhongling Guo, 08 Apr 2025
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RC1: 'Reply on CC1', Anonymous Referee #1, 27 Apr 2025
I think this manuscript can be accepted in this version.
Citation: https://doi.org/10.5194/egusphere-2025-605-RC1 -
AC1: 'Reply on RC1', Alina Reininger, 20 Jun 2025
Dear reviewer,
We are truly grateful for your positive evaluation of our manuscript! Thank you for taking the time and carefully reviewing our work.
Kind regards,
Alina Reininger on behalf of all co-authorsCitation: https://doi.org/10.5194/egusphere-2025-605-AC1
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AC1: 'Reply on RC1', Alina Reininger, 20 Jun 2025
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AC2: 'Reply on CC1', Alina Reininger, 20 Jun 2025
Dear reviewer,
We thank you very much for your positive feedback and suggestions that helped us improve the manuscript! Please find the detailed answers to your comments in the supplement.
Kind regards,
Alina Reininger on behalf of all co-authors
-
RC1: 'Reply on CC1', Anonymous Referee #1, 27 Apr 2025
-
RC2: 'Comment on egusphere-2025-605', Anonymous Referee #2, 08 May 2025
This work is an interesting and welcome contribution to investigating the dynamics of airborne microplastics. The scientific approach and the adopted methodologies are robust and sound, both on the experimental and modelling sides. At the same time, the impact of the paper would improve adding some more information and discussion, as detailed hereafter. This, to enable the reproducibility of the research and the comparison with the multiple studies that are emerging in relation to the atmospheric transport of microplastics.
The manuscript can be considered and accepted for publication after (medium) revision.
DETAILED COMMENTS (Lx stands for the line number)
L48-49: The number of publications related to the atmospheric dispersion of microplastics is rapidly increasing, and it is indeed difficult to keep continuously updated. However, some attention should be given to more recent works that might be of interest to this investigation, while here the first and by now ‘classical’ studies are recalled only.
L81-84. Here the details of the experimental setup are kept at their minimum, then referring to two previous publications. Since an article should be as much as possible self-consistent, it would be worth adding some additional details as reported in those publications.
L110-120. A summary of the rationale, of the analytical and experimental approach behind Bagheri and Bonadonna 2016 model would be useful to better appreciate the improvement with respect to other (empirical) relationships.
L126-127. Since one of the main findings of this research is the much slower settling of glitter and fibres when compared to volume-equivalent spheres, it could be of interest for the authors to consider the results also from experimental studies treating fragments, characterised by irregular volume and shapes, for which the volume-equivalent concept may apply. In addition to the work by Preston et al. (2023) see, for instance, studies in a cylinder with water and in a wind tunnel:
http://dx.doi.org/10.1016/j.envres.2023.115783; https://doi.org/10.1016/j.hazadv.2024.100433
L135-138. It is not clear (to me) how the simulations were performed. It is specified that the particles are released each 1st and 15th day of each month in the year 2020 at 03:00 and 15:00 local time: for how long? One time-step as a sort of puff release, or a continuous emission starting at that time and lasting 12 hours, or? How was the emission handled: as point releases centred on the city coordinates and spread along 10 to 100 m agl? As particles distributed in a volume emission, centred in the city area and in a layer between 10 and 100 m agl? More details are needed on the model configuration and runs, so that a reader can better understand and interpret the results of the model simulations.
L145-148. FLEXPART is a well-known and largely used model, so it can be accepted that no specific details are provided on the physics in the model. However, here the total mass deposited plays an important role, as in eq. (2), and briefly recalling how the dry and wet depositions are treated in the model would be useful.
L151-152 and 182-183. In general, and given all potential uncertainties, I wonder whether three decimals are truly significant/substantial to distinguish the measured and calculated settling velocities.
L168-169 and 196-198. A partial interpretation of the discrepancies between the model and the measurements is attributed to the imperfections in the shape and size of the glitter particles or fibres. A discussion on the possible uncertainties related to the experimental approach, leading to uncertainties also in the observed data, would be worth it. The experiments are conducted in quiet air. It would be interesting to provide some comments on the potential/expected effect of turbulence on the settling dynamics.
L239-247. Consider comparing the distances travelled by the particles and fibres in your study with findings from other studies in the literature. In this relatively recent field of study, it is important to verify similarities, convergences and differences, to evaluate whether the scientific community is following a sensible research path.
Supplementary material: please note that the citation of Bagheri and Bonadonna (2016, 2019) is repeated twice every time (a latex trap, I guess).
Citation: https://doi.org/10.5194/egusphere-2025-605-RC2 -
AC3: 'Reply on RC2', Alina Reininger, 20 Jun 2025
Dear reviewer,
We sincerely thank you for your positive evaluation and for pointing out some important issues in the manuscript! Please find the detailed answers to your comments in the supplement.
Kind regards,
Alina Reininger on behalf of all co-authors
-
AC3: 'Reply on RC2', Alina Reininger, 20 Jun 2025
Interactive discussion
Status: closed
-
CC1: 'Comment on egusphere-2025-605', Zhongling Guo, 08 Apr 2025
General comments:
The current manuscript focused on a thorough investigation of the atmospheric settling behavior of microplastics, particularly glitters and fibers. The study is well-designed and well-written. And the authors have carried out extensive experimental work. In my view, the study would be highly valuable for publication. However, prior to a successful publication, I would recommend some changes to the manuscript.
Specific comments:
1.There are many abbreviations in the manuscript, please provide an abbreviation list at the begin of the paper.
2. A schematic diagram of the experimental setup is necessary in the ‘2.2 Experimental setup’.
3. Please include a sensitivity analysis or error quantification in FLEXPART simulation.
Citation: https://doi.org/10.5194/egusphere-2025-605-CC1 -
RC1: 'Reply on CC1', Anonymous Referee #1, 27 Apr 2025
I think this manuscript can be accepted in this version.
Citation: https://doi.org/10.5194/egusphere-2025-605-RC1 -
AC1: 'Reply on RC1', Alina Reininger, 20 Jun 2025
Dear reviewer,
We are truly grateful for your positive evaluation of our manuscript! Thank you for taking the time and carefully reviewing our work.
Kind regards,
Alina Reininger on behalf of all co-authorsCitation: https://doi.org/10.5194/egusphere-2025-605-AC1
-
AC1: 'Reply on RC1', Alina Reininger, 20 Jun 2025
-
AC2: 'Reply on CC1', Alina Reininger, 20 Jun 2025
Dear reviewer,
We thank you very much for your positive feedback and suggestions that helped us improve the manuscript! Please find the detailed answers to your comments in the supplement.
Kind regards,
Alina Reininger on behalf of all co-authors
-
RC1: 'Reply on CC1', Anonymous Referee #1, 27 Apr 2025
-
RC2: 'Comment on egusphere-2025-605', Anonymous Referee #2, 08 May 2025
This work is an interesting and welcome contribution to investigating the dynamics of airborne microplastics. The scientific approach and the adopted methodologies are robust and sound, both on the experimental and modelling sides. At the same time, the impact of the paper would improve adding some more information and discussion, as detailed hereafter. This, to enable the reproducibility of the research and the comparison with the multiple studies that are emerging in relation to the atmospheric transport of microplastics.
The manuscript can be considered and accepted for publication after (medium) revision.
DETAILED COMMENTS (Lx stands for the line number)
L48-49: The number of publications related to the atmospheric dispersion of microplastics is rapidly increasing, and it is indeed difficult to keep continuously updated. However, some attention should be given to more recent works that might be of interest to this investigation, while here the first and by now ‘classical’ studies are recalled only.
L81-84. Here the details of the experimental setup are kept at their minimum, then referring to two previous publications. Since an article should be as much as possible self-consistent, it would be worth adding some additional details as reported in those publications.
L110-120. A summary of the rationale, of the analytical and experimental approach behind Bagheri and Bonadonna 2016 model would be useful to better appreciate the improvement with respect to other (empirical) relationships.
L126-127. Since one of the main findings of this research is the much slower settling of glitter and fibres when compared to volume-equivalent spheres, it could be of interest for the authors to consider the results also from experimental studies treating fragments, characterised by irregular volume and shapes, for which the volume-equivalent concept may apply. In addition to the work by Preston et al. (2023) see, for instance, studies in a cylinder with water and in a wind tunnel:
http://dx.doi.org/10.1016/j.envres.2023.115783; https://doi.org/10.1016/j.hazadv.2024.100433
L135-138. It is not clear (to me) how the simulations were performed. It is specified that the particles are released each 1st and 15th day of each month in the year 2020 at 03:00 and 15:00 local time: for how long? One time-step as a sort of puff release, or a continuous emission starting at that time and lasting 12 hours, or? How was the emission handled: as point releases centred on the city coordinates and spread along 10 to 100 m agl? As particles distributed in a volume emission, centred in the city area and in a layer between 10 and 100 m agl? More details are needed on the model configuration and runs, so that a reader can better understand and interpret the results of the model simulations.
L145-148. FLEXPART is a well-known and largely used model, so it can be accepted that no specific details are provided on the physics in the model. However, here the total mass deposited plays an important role, as in eq. (2), and briefly recalling how the dry and wet depositions are treated in the model would be useful.
L151-152 and 182-183. In general, and given all potential uncertainties, I wonder whether three decimals are truly significant/substantial to distinguish the measured and calculated settling velocities.
L168-169 and 196-198. A partial interpretation of the discrepancies between the model and the measurements is attributed to the imperfections in the shape and size of the glitter particles or fibres. A discussion on the possible uncertainties related to the experimental approach, leading to uncertainties also in the observed data, would be worth it. The experiments are conducted in quiet air. It would be interesting to provide some comments on the potential/expected effect of turbulence on the settling dynamics.
L239-247. Consider comparing the distances travelled by the particles and fibres in your study with findings from other studies in the literature. In this relatively recent field of study, it is important to verify similarities, convergences and differences, to evaluate whether the scientific community is following a sensible research path.
Supplementary material: please note that the citation of Bagheri and Bonadonna (2016, 2019) is repeated twice every time (a latex trap, I guess).
Citation: https://doi.org/10.5194/egusphere-2025-605-RC2 -
AC3: 'Reply on RC2', Alina Reininger, 20 Jun 2025
Dear reviewer,
We sincerely thank you for your positive evaluation and for pointing out some important issues in the manuscript! Please find the detailed answers to your comments in the supplement.
Kind regards,
Alina Reininger on behalf of all co-authors
-
AC3: 'Reply on RC2', Alina Reininger, 20 Jun 2025
Peer review completion
Journal article(s) based on this preprint
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Alina Sylvia Waltraud Reininger
Daria Tatsii
Taraprasad Bhowmick
Gholamhossein Bagheri
Andreas Stohl
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(13489 KB) - Metadata XML
-
Supplement
(19699 KB) - BibTeX
- EndNote
- Final revised paper
General comments:
The current manuscript focused on a thorough investigation of the atmospheric settling behavior of microplastics, particularly glitters and fibers. The study is well-designed and well-written. And the authors have carried out extensive experimental work. In my view, the study would be highly valuable for publication. However, prior to a successful publication, I would recommend some changes to the manuscript.
Specific comments:
1.There are many abbreviations in the manuscript, please provide an abbreviation list at the begin of the paper.
2. A schematic diagram of the experimental setup is necessary in the ‘2.2 Experimental setup’.
3. Please include a sensitivity analysis or error quantification in FLEXPART simulation.