Pathways and Hot Spots of Floating and Submerged Microplastics in Atlantic Iberian Marine Waters: A Modelling Approach

Round 1

Reviewer 1 Report

The works reads well, the methods are robust, and the manuscript is of interest to the scientific community. Please revise some minor spelling issues and font consistency. I have no further suggestions.

Author Response

Dear Dr. Everaert and Dr.Catarino ,

Thank you for giving us the opportunity to submit a revised draft of the manuscript “Pathways and hot spots of floating and submerged microplastics in Atlantic Iberian marine waters: a modelling approach.” for publication in the Journal of Poetry and Psychology. We appreciate the time and effort that you and the reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Those changes are highlighted within the manuscript, please see the attachment.

Please see below, for a point-by-point response to the reviewers’ comments and concerns. All page numbers refer to the revised manuscript file with tracked changes

Reviewer 1

The works reads well, the methods are robust, and the manuscript is of interest to the scientific community.

Authors. Thank you.

Please revise some minor spelling issues and font consistency

Authors: Thank you for point out. The font inconsistency has been correct as well as the minor spelling issues. The manuscript has been reviewed again by two English native speakers.

Reviewer 2

Please revise the chapter numbering. 

Authors: Thank you for point out.  The chapter numbering has been corrected on the methodology and results.

My main concern with this study is that sinking of microplastic particles was not considered. 

Authors: We appreciate your suggestion. It would be interesting to explore the sinking aspect of microplastics in this work. However, we still believe that the optimal approach for this study was to use a sensitive test that simulates microplastic pathways in various circulations along the Iberian Peninsula without incorporating any of the microplastic behaviour processes. This is because, despite the fact that several processes, including sinking, settling, and biofouling, are necessary for the transport of microplastics and that a lot of study has been conducted recently to understand how these processes affect the microplastics in the environment. To the best of our knowledge, the equations developed to described these processes are not robust enough to represent the various characteristics of microplastics, such as their size, form, and type of plastic found in the marine environment.

 However, as many experimental studies have been going on lately, we believe that in future work we will be able to add equations for important processes such as sinking, degradation and biofouling to the models with more confidence.

This explanation was added in a paragraph in the methodology [lines 190-197], as well as a paragraph in the discussion was rewritten [lines 373-393]  to include the significance of the experimental studies in the microplastic dynamic behaviour and the inclusion of sinking, settling, biofouling, and other processes in future models.

why the authors decided to release at each emission point 49 particles.

Authors: Thank you for pointing this out. Since this coast hasn't been extensively researched, we don't know much about how much microplastic enters the SW Iberian coast or how it is distributed throughout the water column.  As a result, the model accuracy and computing effort were used to determine the 49 particles released per day. This justification is added at lines 215–218.

the results should be presented also in written form.

Authors: We think this is an excellent suggestion. We included the explanation of the Figure 3 and 4 in the line 262-673.

Conclusions are too long and partly a repetition of the discussion.

Authors: As suggested by the reviewer, we changed the first paragraph of the conclusion in order to not avoid duplication with the discussion.  In order to make this chapter more succinct, the last paragraph has also been removed. This is because the topic of including sinking, biofouling and others processes in future work has been introduced into the discussion.

Reviewer 3

Excellent work! Only minor changes required, mostly concerning fonts and font sizes

Authors: Thank you for your feedback. We appreciate that you find the work to be interesting, and we have corrected the font type and size.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments on manuscript "Pathways and hot spots of floating and submerged microplastics in Atlantic Iberian marine waters: a modelling approach."

1. Please revise the chapter numbering. Chapter numbers are repeating. Especially for Methods and Results.

2. My main concern with this study is that sinking of microplastic particles was not considered. I understand that it is difficult to estimate, but in recent years a lot of effort was made to estimate sinking behavior of microplastic. From what we know so far is that biofouling and sinking can have a significant impact on the transport and distribution of microplastic particles. I suggest that the authors add more about sinking of microplastic. It would be even better, if they could do some additional test runs including algorithms that consider sinking of microplastic and compare it with their results.

Following publications might be helpful as a starting point:

Miao, L., Gao, Y., Adyel, T.M., Huo, Z., Liu, Z., Wu, J., Hou, J., 2021. Effects of biofilm colonization on the sinking of microplastics in three freshwater environments. J Hazard Mater 413, 125370.

Song, Y.K., Hong, S.H., Eo, S., Jang, M., Han, G.M., Isobe, A., Shim, W.J., 2018. Horizontal and Vertical Distribution of Microplastics in Korean Coastal Waters. Environ Sci Technol 52, 12188-12197.

Van Melkebeke, M., Janssen, C., De Meester, S., 2020. Characteristics and Sinking Behavior of Typical Microplastics Including the Potential Effect of Biofouling: Implications for Remediation. Environ Sci Technol 54, 8668-8680.

Karkanorachaki, K., Syranidou, E., Kalogerakis, N., 2021. Sinking characteristics of microplastics in the marine environment. Science of The Total Environment 793, 148526.

Fazey, F.M., Ryan, P.G., 2016. Biofouling on buoyant marine plastics: An experimental study into the effect of size on surface longevity. Environ Pollut 210, 354-360.

3. I am not familiar with this model, so I was wondering why the authors decided to release at each emission point 49 particles. Wouldn’t it be better to have more particles? Or a number of particles that represents the number of microplastic at that location? It would be good to add some explanation to this choice.

4. In chapter 4.1. Pathways and travel time …  (Starting at line 232) the results should be presented also in written form. The text only refers to the maps in figure 3 and 4, but the reader is left on its own to figure out the main result. Additionally, the text in this chapter contains a lot of sentences that belong to methods. Basically, all descriptions how something was calculated should be moved to methods. For examples, lines 251-253, lines 261-268.

5. Discussion is difficult to read. I suggest that the authors structure the text using sub-headings.

6. Conclusions are too long and partly a repetition of the discussion. I suggest to shorten the conclusions to the key points of this study.

Author Response

Dear Dr. Everaert and Dr.Catarino ,

Thank you for giving us the opportunity to submit a revised draft of the manuscript “Pathways and hot spots of floating and submerged microplastics in Atlantic Iberian marine waters: a modelling approach.” for publication in the Journal of Poetry and Psychology. We appreciate the time and effort that you and the reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Those changes are highlighted within the manuscript, please see the attachment.

Please see below, for a point-by-point response to the reviewers’ comments and concerns. All page numbers refer to the revised manuscript file with tracked changes

Reviewer 1

The works reads well, the methods are robust, and the manuscript is of interest to the scientific community.

Authors. Thank you.

Please revise some minor spelling issues and font consistency

Authors: Thank you for point out. The font inconsistency has been correct as well as the minor spelling issues. The manuscript has been reviewed again by two English native speakers.

Reviewer 2

Please revise the chapter numbering. 

Authors: Thank you for point out.  The chapter numbering has been corrected on the methodology and results.

My main concern with this study is that sinking of microplastic particles was not considered. 

Authors: We appreciate your suggestion. It would be interesting to explore the sinking aspect of microplastics in this work. However, we still believe that the optimal approach for this study was to use a sensitive test that simulates microplastic pathways in various circulations along the Iberian Peninsula without incorporating any of the microplastic behaviour processes. This is because, despite the fact that several processes, including sinking, settling, and biofouling, are necessary for the transport of microplastics and that a lot of study has been conducted recently to understand how these processes affect the microplastics in the environment. To the best of our knowledge, the equations developed to described these processes are not robust enough to represent the various characteristics of microplastics, such as their size, form, and type of plastic found in the marine environment.

 However, as many experimental studies have been going on lately, we believe that in future work we will be able to add equations for important processes such as sinking, degradation and biofouling to the models with more confidence.

This explanation was added in a paragraph in the methodology [lines 190-197], as well as a paragraph in the discussion was rewritten [lines 373-393]  to include the significance of the experimental studies in the microplastic dynamic behaviour and the inclusion of sinking, settling, biofouling, and other processes in future models.

why the authors decided to release at each emission point 49 particles.

Authors: Thank you for pointing this out. Since this coast hasn't been extensively researched, we don't know much about how much microplastic enters the SW Iberian coast or how it is distributed throughout the water column.  As a result, the model accuracy and computing effort were used to determine the 49 particles released per day. This justification is added at lines 215–218.

the results should be presented also in written form.

Authors: We think this is an excellent suggestion. We included the explanation of the Figure 3 and 4 in the line 262-673.

Conclusions are too long and partly a repetition of the discussion.

Authors: As suggested by the reviewer, we changed the first paragraph of the conclusion in order to not avoid duplication with the discussion.  In order to make this chapter more succinct, the last paragraph has also been removed. This is because the topic of including sinking, biofouling and others processes in future work has been introduced into the discussion.

Reviewer 3

Excellent work! Only minor changes required, mostly concerning fonts and font sizes

Authors: Thank you for your feedback. We appreciate that you find the work to be interesting, and we have corrected the font type and size.

Author Response File: Author Response.docx

Reviewer 3 Report

Excellent work! Only minor changes required, mostly concerning fonts and font sizes

Comments for author File: Comments.pdf

Author Response

Dear Dr. Everaert and Dr.Catarino ,

Thank you for giving us the opportunity to submit a revised draft of the manuscript “Pathways and hot spots of floating and submerged microplastics in Atlantic Iberian marine waters: a modelling approach.” for publication in the Journal of Poetry and Psychology. We appreciate the time and effort that you and the reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers,. Plese see the attachement. Those changes are highlighted within the manuscript. Please see below, for a point-by-point response to the reviewers’ comments and concerns. All page numbers refer to the revised manuscript file with tracked changes

Reviewer 1

The works reads well, the methods are robust, and the manuscript is of interest to the scientific community.

Authors. Thank you.

Please revise some minor spelling issues and font consistency

Authors: Thank you for point out. The font inconsistency has been correct as well as the minor spelling issues. The manuscript has been reviewed again by two English native speakers.

Reviewer 2

Please revise the chapter numbering. 

Authors: Thank you for point out.  The chapter numbering has been corrected on the methodology and results.

My main concern with this study is that sinking of microplastic particles was not considered. 

Authors: We appreciate your suggestion. It would be interesting to explore the sinking aspect of microplastics in this work. However, we still believe that the optimal approach for this study was to use a sensitive test that simulates microplastic pathways in various circulations along the Iberian Peninsula without incorporating any of the microplastic behaviour processes. This is because, despite the fact that several processes, including sinking, settling, and biofouling, are necessary for the transport of microplastics and that a lot of study has been conducted recently to understand how these processes affect the microplastics in the environment. To the best of our knowledge, the equations developed to described these processes are not robust enough to represent the various characteristics of microplastics, such as their size, form, and type of plastic found in the marine environment.

 However, as many experimental studies have been going on lately, we believe that in future work we will be able to add equations for important processes such as sinking, degradation and biofouling to the models with more confidence.

This explanation was added in a paragraph in the methodology [lines 190-197], as well as a paragraph in the discussion was rewritten [lines 373-393]  to include the significance of the experimental studies in the microplastic dynamic behaviour and the inclusion of sinking, settling, biofouling, and other processes in future models.

why the authors decided to release at each emission point 49 particles.

Authors: Thank you for pointing this out. Since this coast hasn't been extensively researched, we don't know much about how much microplastic enters the SW Iberian coast or how it is distributed throughout the water column.  As a result, the model accuracy and computing effort were used to determine the 49 particles released per day. This justification is added at lines 215–218.

the results should be presented also in written form.

Authors: We think this is an excellent suggestion. We included the explanation of the Figure 3 and 4 in the line 262-673.

Conclusions are too long and partly a repetition of the discussion.

Authors: As suggested by the reviewer, we changed the first paragraph of the conclusion in order to not avoid duplication with the discussion.  In order to make this chapter more succinct, the last paragraph has also been removed. This is because the topic of including sinking, biofouling and others processes in future work has been introduced into the discussion.

Reviewer 3

 Excellent work! Only minor changes required, mostly concerning fonts and font sizes

Authors: Thank you for your feedback. We appreciate that you find the work to be interesting, and we have corrected the font type and size.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Great job! No further comments