Estimating Macroplastic Mass Transport from Urban Runoff in a Data-Scarce Watershed: A Case Study from Cordoba, Argentina

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

The manuscript has been carefully revised, here are some minor comments for further improvement:

Please rewrite the sentence in lines 201-203 for a clear statement.

Line 265: Street litter could become subsection 2.5.1.

The title of Figure 3 would be rendered as "Figure 3. Example of plastic bags", line 279.

Line 280: Landfills and Dumping Sites could be better addressed as subsection 2.5.2.

Figure 4: please improve the image quality and zoom in for better viewing.

Figure 6: rewrite the title for better understanding.

Please cite the sentence in lines 365-367.

The survey results are addressed from lines 448 to 464, the author may be considered to provide an additional table to present the results comprehensively.

Author Response

We thank the reviewers for their constructive and insightful feedback. We have addressed all comments carefully and revised the manuscript accordingly. Below are our detailed responses, with corresponding changes highlighted in the revised manuscript.

• The sentence in lines 201–203 has been rewritten for clarity.
• “Street litter” has been reorganized as subsection 2.5.1, as suggested.
• The title of Figure 3 has been updated to “Example of plastic litter observed during field visits: a 90×60×20 cm plastic bag...”
• “Landfills and Dumping Sites” is now addressed as subsection 2.5.2 with improved description and clarity.
• Figure 4 has been improved in quality and zoomed in for better visualization.
• The title of Figure 6 has been rewritten to enhance clarity.
• The sentence in lines 365–367 has been properly cited.

• Survey results were rewritten in narrative form and a supporting table was added to improve readability.

Reviewer 2 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

Thank you for the opportunity for the invitation to review the paper entitled “Estimation of macroplastic litter volumes on urban water courses for sustainable management”. The authors have used field surveys and the interpretation of Google Open Street Maps to overcome the problem of data scarcity in modeling macroplastic generation during storms. Modelling results indicate that the mobilization of macroplastics occur at low flow rates and a 10-year return period flood significantly increased the drag of macroplastics.

 

The results are interesting, however, the discussion lacks depth. The authors should focus on further implications of the modeling results. The comparison with existing literature should also be improved.

 

The authors mention in the abstract that they used satellite images:  “For the integration satellite images and Google Street View tours”. In the methods section, there is a short explanation “Based on the survey conducted in the neighborhood, site visits and the analysis of satellite images and images of Google Street View application” that indicate that they observed “two open dumps and eight dumping points”. It is important to explain what satellite imagery was used and what methods were used to find the dumpling points and landfills.

 

Figure 3 lacks description in the caption. After reading the manuscript I am still not sure if the image comes from Google Satellite or if it was an outcome of the field observation. Regarding the field observations, Regarding the field observations, it is not clear in the manuscript what was observed. The authors should provide a clear description of the field visits, what was observed, the date that the observations were made. The number of antecedent dry days prior to the field observation is also a fundamental information for the interpretation of the results. The number of dry days also plays a role in the accumulation of pollutants in urban areas. I understand that this was considered for modeling.

 

Lines 387 - 403 appear fragmented, with some sentences forming isolated paragraphs. To improve the readability and coherence, the authors should consolidate the steps and equations presented into more cohesive and well-structured paragraphs.

 

L 438 - 439 has an incomplete sentence as a paragraph. Please, observe that a paragraph is a group of sentences.

 

The section presenting the survey results (Lines 448–464) would benefit from improvement. In its current form, the text consists of fragmented points that can be difficult to follow. It would be more helpful to readers if the authors could integrate these findings into a more cohesive narrative.

 

The authors make a point in the conclusion that should be discussed in the discussion section: “To refine the results obtained in this work, the drag coefficients should be adjusted using an approach based on observations or measurements to estimate the constants and thus generate the drag equation that resembles reality for the model”

Author Response

We thank the reviewers for their constructive and insightful feedback. We have addressed all comments carefully and revised the manuscript accordingly. Below are our detailed responses, with corresponding changes highlighted in the revised manuscript.

The discussion lacks depth. The authors should focus on implications and compare more with existing literature

The discussion section was significantly improved with deeper analysis and integration of literature (e.g., Roebroek et al., Penza, van Emmerik, Bagheri).

The conclusion suggests refining drag coefficients, but this should be discussed earlier.

This point is now clearly included in the discussion section and not only in the conclusion.

Satellite images are mentioned in abstract but not explained in methods.

Section 2.5 now explains the use of Google Street View and satellite images for identifying dumping points and mapping accumulation zones.

Figure 3 lacks description. Clarify source of image.

The image source is now explicitly described as a field observation photo (not Google Satellite).

Field observations unclear: what, when, and how many dry days?

Section 2.5.1 now includes the period of field visits (April–May 2022), a 7-day dry period, and observation methods used.

Lines 387–403 are fragmented.

These lines were consolidated into coherent paragraphs.

Line 438–439 is incomplete.

The incomplete sentence was revised for grammatical and conceptual completeness.

The survey results section is fragmented.

Rewritten into cohesive narrative format with improved flow.

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

Please find the attached reviewer report.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The manuscript is generally comprehensible, but the English quality needs moderate revision to ensure clarity, precision, and adherence to academic standards. Several phrases are awkwardly constructed, overly literal (likely due to translation), or non-standard in technical English—such as "transversal nature" or "hydrological dynamics." Grammatical issues, imprecise terminology, and inconsistent word choices occasionally hinder the readability of the text, particularly in the Introduction, Methods, and Results sections.

I recommend a thorough language edit, preferably by a native English speaker with technical expertise in hydrology or environmental modeling, to enhance sentence structure, terminology usage, and overall readability.

Author Response

With respect to the title the recommendation was considered and now the title is:

“Estimating Macroplastic Mass Transport from Urban Runoff in a Data-Scarce Watershed: A Case Study from Cordoba, Argentina”.

Also, we change the abstract following your recommendation.

With respect to the accumulation parameters, a detailed explanation was added specifying how C1 and C2 were derived for both scenarios. C3 was fixed at 1 following reference [23]. A summary paragraph and table were included.

We clarified that C1 was adopted from [23] under the assumption of high plastic mobilization (95%) due to basin vulnerability. The limitation and absence of sensitivity analysis were acknowledged.

Precipitation duration inconsistency: we reconcile this discrepancy, and we ensure that the figures now match.

We thank the reviewers for their constructive and insightful feedback. We have addressed all comments carefully and revised the manuscript accordingly. Below are our detailed responses, with corresponding changes highlighted in the revised manuscript.

Outlet node locations shown in Figure 2. We included them in figure 2.

Avoid “volume” where “mass” is meant. The manuscript now uses “mass” consistently for pollutant accumulation and transport.

Unclear terms (“transversal nature”): Replaced with clearer terms such as “interdisciplinary” and “hydrologic processes”.

We rename table 1 and table 2 and change surface accumulation to residual accumulation.

Round 2

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

The authors have fully addressed my major and minor comments with substantial revisions and improvements. The manuscript now presents a coherent, transparent, and reproducible methodology appropriate for publication.

Comments on the Quality of English Language

The manuscript is scientifically sound, but it would benefit from light editorial polishing to improve grammar, clarity, and readability. Minor issues include awkward phrasing (e.g., “due to the interdisciplinary of the problem”), inconsistent article and preposition use (e.g., “in Latin-American”), and occasional redundancy or informal word choices. Sentence flow can also be improved in places, and figure captions and table labels would benefit from more informative wording. Overall, a final language edit will enhance the manuscript's professionalism and readability.

Author Response

Thank you for your thorough review and positive feedback on our manuscript. We are pleased to hear that you found our revisions substantial and that the methodology is now coherent, transparent, and reproducible.

We also appreciate your valuable comments regarding the English language quality. We have diligently gone through the manuscript  focusing on improving grammar, clarity, and readability. We specifically addressed awkward phrasing, ensured consistent article and preposition usage, removed redundancies, refined word choices, and enhanced sentence flow throughout the text. Additionally, we have revised the figure captions and table labels to be more informative, as you suggested.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please see the attachment.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Improvements in English language proficiency and adherence to academic writing conventions are necessary to enhance the overall quality of the manuscript.

Author Response

Thank you very much for your valuable recommendations that enrich the work and for the dedication.

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript focuses on a very interesting aspect that influences on the development in urban areas due to wastes. However, the writing of manuscript was not in a good manner, it looks like a report than a scientific manuscript. It is recommended the authors to revise following the suggestions as follows:

1. The affiliation of authors need to be addressed appropriately, e.g., detailed addresses, emails
2. Introduction section: the literature reviews are very poor, they should be addressed following the main subjects and they should not be stated separately, the references must follow the format of the journal, at current state they were written not following any rules (for examples: lines 60, 74). The end of a sentence should be ended by a point (.), referring some lines e.g. 51, 59. Overall, the gap of research and the novelty of this study should be clearly stated in the end of this section.
3. Materials and Methods section: This section was arranged very long and not comprehensive. It is recommended to write it shorter with compacted information and approaches. Specifically, the study area should be moved to Introduction section. Besides, the figure 1 must be improved by providing geospatial references and they should be linked together. Figure 2 could be combined into Figure 1 as well. Figure 3 must be improved to have a better view, a flow chart with steps is recommended. Figure 4 should be added a small scale of Figure 1, therefore readers are easily to locate where it is.
4. Results: The header of Sub-section must be written in a clearer manner, e.g. 3.1. Scenary 1, the figures 7, 8, 9, 10 must be improved for a better view by increasing the quality and larger legends to read.
5. Discussion section can be combined into Results section
6. Recommendations (Outlooks) can be combined into Conclusions

Comments on the Quality of English Language

The revision should be proofread the English language.

Author Response

Thank you very much for your valuable recommendations that enrich the work and for the dedication.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The study addresses an important question in the field of urban water drainage and generation of solid waste during flood events using remote sensing, citizen science and simulations. I appreciate the effort of the authors in proposing a methodology that is applied to data scarce regions that are representative of many cities in the world. In fact, the plastic pollution in aquatic systems is a major concern for society and represents an emerging ecological risk that can be increased by climate change.

The manuscript investigates relationships between the socio-environmental vulnerability of people living in the floodplain area to accumulation and carriage of solid waste during flood events by employing remote sensing analysis, collecting data from citizens and performing rainfall-runoff simulation. The central argument is that the higher the storm event the higher the solid waste carriage, supported by the simulations using EPA SWMM. The authors conclude that there is a lack of georeferenced data that could refine the results of similar studies as well as reinforcing the importance of quali-quantitative studies in hydrology.

There is a major ethical concern related to the survey. Has this survey been approved by the ethical committee of the university? Have you asked for the consent of the participants? These questions are not answered in the manuscript. The authors should prove that they obtained an approval from the university to make the survey.

While the study is promising, there is much improvement to be done in the language editing and clarity of the text. I tried to specify all the major points that could improve the quality of the manuscript, however, the authors should provide a throughout review of the paper to avoid: single sentence paragraphs; paragraphs that are not too much informative or present repetitive information; claims without proper citation; a discussion of the work focused on a wider impact of the research results to the literature and not overfocusing on the study area.

I also have concerns about the objective of the work and the worldwide impact of the research. For example, in Introduction, the authors state that ‘This work seeks to advance plastic pollution studies of the main water courses in the city of Córdoba, Argentina’. To strengthen the paper, the authors might reflect on how the study could be generalized and focus on a global impact of the study. This does not require a significant change in the methodology, but this changes how the problem is framed in the introduction and how the results are discussed. The authors also stated that the main research gap of the paper is that there are few studies on plastic pollution in the province of Cordoba. However, the authors should reflect on the problem of transport of plastic waste from urban basins to rivers and how this impacts the current literature.

Another major concern is the IDF curve adopted in the study. The authors used a curve from a publication from 1994. Precisely, there is a 30 year gap between the year the curve was proposed and the present, which means the IDF curve in the study area must have significantly changed, especially for higher return periods. The authors should justify the validity of the curve and explain why they didn’t fit a new one.

The authors mentioned they made a field inspection of the study area. They should provide photographs of the study area, so we can understand the consortium bag of 90x60x20 cm for every 100 m that they have found.

The results of the survey are just briefly discussed in the text and they are not demonstrated in the results section, they are demonstrated in the Material and Methods sections. This is not common for me, I suggest showing the results of the survey in the results section.

There are opportunities to enhance clarity and impact of the paper for instance:

• The introduction could be more concise and focused. Streamlining the content to reach the main point more directly would enhance clarity and engagement. The L28-52 should be rewritten into a single paragraph that is concise and direct to the point. While the description of Suquia River and the problem of the region is interesting the paragraphs from L110-141 should be condensed into one well-written and concise paragraph in the Material and Methods section, where the description of the study area is done. There are several sentences that would benefit from language editing, but I’ll give the specific comments in the next session.
• In Material and Methods the L149-157 are not part of methodology. They seem to be part of the introduction and the problem formulation.
• Figure 3 is not discussed in the text. It seems to me that this is the most important figure of the methodology, because it summarizes all the methodological steps. The L183-207 should be condensed in a single paragraph that is concise and describes what we are seeing in Figure 3.
• The L494-496 is an example of a single sentence paragraph that should be avoided. Moreover, the first and second paragraphs of the discussion present repetitive information that was already given in the introduction. The authors write sentences like “There is waste collection in the neighborhood and the frequency is 6 days”. This is a result from their survey and not a part of discussion.

Comments on the Quality of English Language

L53-55: The clarity of this paragraph could be improved, as some parts are difficult to follow. A rephrasing or slight reorganization may help ensure the key points are more effectively communicated.

The authors state in L 56-57: “most existing models attempt to predict variations in plastic flux solely from river discharge, precipitation, and wind speed.”. However, a model does not attempt to do anything. This statement should be rephrased for clarity. I suggest the authors reading, appreciating and referencing this paper to help to elucidate the current state-of-art of plastic pollution modeling at catchment scale https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14572

L 62: please adjust the unit from km2 to km².

L66-73 should be only one paragraph.

L75-77: The phrase “They use global flood maps and global data on mismanaged plastic waste (MPW). They superimpose both data and from this they approximate the plastic potential that is possible to be mobilized during events with different return periods”. The two sentences should be rewritten for clarity.

L88-89: This paragraph should be joined to the previous paragraph.

In figure 5 the title of the figure is IDT and the correct is IDF.

L271: “The surveys provided an overview of the urban solid waste situation.” Single sentence paragraph that should be avoided.

L443: The authors wrote “Scenary”, but the correct is “Scenario”

L444-446: Should be rephrased for clarity.

L453: “Both basins for return times of 2 years” is a fragment and not a full sentence. Please, rewrite as a complete sentence.

L456-457: This is a one sentence paragraph, please, join with the next one.

L467: The authors wrote “Scenary”, but the correct is “Scenario”

Author Response

Thank you very much for your valuable recommendations that enrich the work and for the dedication.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

thank you for your efforts in revising the manuscript. However, the current state of the revision still requires further improvement, particularly in Section 2, Materials and Methods, which is overly long and contains too many short paragraphs. Below are my suggestions and comments:

• Please carefully check the entire manuscript for typographical consistency. A period should appear at the end of each sentence; for example at lines 45, 55, 69, 80, etc.

• As mentioned in the previous review, the authors must adhere to the journal's reference citation format; please see lines 88, 95, and so on.

• The paragraph from lines 118 to 127 seems more appropriate for the methodology section. Please consider moving it accordingly.

• The heading "2.1. Structure of study" is not accurate. Please consider changing it to a more suitable term, such as "Approach."

• The manuscript contains too many short paragraphs. Please consider combining them into larger, more cohesive sections. For instance, the paragraphs from lines 133 to 149 could be merged into a single paragraph.

• Regarding the study area: It is unclear why the authors have placed "2.2. Study area" after (2.1) in Section "2. Materials and Methods". Given the flow chart, the study area is not mentioned there, so wouldn’t it make more sense to move the study area section earlier? Additionally, Figure 2 needs improvement: the small inset figure is redundant as it replicates the larger figure. It would be more effective to show the country of Argentina with a focus box highlighting the study area. Furthermore, please verify the geographical coordinates of the Villa Páez area. What is the significance of the negative values? Please use degrees and minutes for longitude and latitude.

• Subsection 2.3.4, "Survey results" should be moved to the Results section. In Section "2. Materials and Methods": please focus on describing only the methods and the data collection process used in this study.

• Once again, the methodology section needs further improvement by shortening the text and consolidating topics into fewer paragraphs to reduce redundancy and improve readability, for example from lines 295 to 472.

Author Response

Thank you very much for your valuable recommendations that enrich the work and for the dedication.

• Please carefully check the entire manuscript for typographical consistency. A period should appear at the end of each sentence; for example at lines 45, 55, 69, 80, etc.

It was checked that all sentences ended in a period.

• As mentioned in the previous review, the authors must adhere to the journal's reference citation format; please see lines 88, 95, and so on.

Citations have been changed to adhere to the journal format.

• The paragraph from lines 118 to 127 seems more appropriate for the methodology section. Please consider moving it accordingly.

The location of the paragraph was changed to the methodology (line 123-132).

• The heading "2.1. Structure of study" is not accurate. Please consider changing it to a more suitable term, such as "Approach."

The title of the study structure section was changed to approach.

• The manuscript contains too many short paragraphs. Please consider combining them into larger, more cohesive sections. For instance, the paragraphs from lines 133 to 149 could be merged into a single paragraph.

The suggestion was taken into account and the short paragraphs were combined to make them longer and more cohesive.

• Regarding the study area: It is unclear why the authors have placed "2.2. Study area" after (2.1) in Section "2. Materials and Methods". Given the flow chart, the study area is not mentioned there, so wouldn’t it make more sense to move the study area section earlier? Additionally, Figure 2 needs improvement: the small inset figure is redundant as it replicates the larger figure. It would be more effective to show the country of Argentina with a focus box highlighting the study area. Furthermore, please verify the geographical coordinates of the Villa Páez area. What is the significance of the negative values? Please use degrees and minutes for longitude and latitude.

Following the recommendation the order of the section was changed. First the approach is presented, then the socio-environmental studies and then the study area following the flow chart.

Figure 2 was changed. Now the country, the province of Cordoba, and the City of Cordoba where the Villa Paez neighborhood is located are also shown.

• Subsection 2.3.4, "Survey results" should be moved to the Results section. In Section "2. Materials and Methods": please focus on describing only the methods and the data collection process used in this study.

The survey results were moved to the results section (line 422-439).

• Once again, the methodology section needs further improvement by shortening the text and consolidating topics into fewer paragraphs to reduce redundancy and improve readability, for example from lines 295 to 472.

This was also taken into account.

Reviewer 3 Report

Comments and Suggestions for Authors

I congratulate the authors for the significant improvement of the manuscript.

 

They successfully answered all my questions and concerns and added valuable information in the manuscript. I particularly appreciated the effort in improving the objectives, focusing on the wider impact of the research, adding Figure 5, and substantially improving the discussion.

There is only one final comment before the paper is published. The authors stated in lines 205-211 that they obtained university approval for conducting the survey; however, it's also important to say the number or any reference to this approval. This will show the scientific community that this study complies with international standards of research integrity and help to raise the impact of the manuscript when published.

 

Other than that, I just have to congratulate the authors for the excellent work done.

 

Author Response

Thank you very much for your valuable recommendations that enrich the work and for the dedication.

• The authors stated in lines 205-211 that they obtained university approval for conducting the survey; however, it's also important to say the number or any reference to this approval. This will show the scientific community that this study complies with international standards of research integrity and help to raise the impact of the manuscript when published.

As recommended, the resolution of the honorable board of directors of the National University of Cordoba was added.

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

thank you for your efforts to revise the paper, however the Figure 2 was not edited following my previous suggestion. Maybe you forgot to replace the figure?

Figure 2 needs improvement: the small inset figure is redundant as it replicates the larger figure. It would be more effective to show the country of Argentina with a focus box highlighting the study area. Furthermore, please verify the geographical coordinates of the Villa Páez area. What is the significance of the negative values? Please use degrees and minutes for longitude and latitude.

Author Response

Figure 2 needs improvement: the small inset figure is redundant as it replicates the larger figure. It would be more effective to show the country of Argentina with a focus box highlighting the study area. Furthermore, please verify the geographical coordinates of the Villa Páez area. What is the significance of the negative values? Please use degrees and minutes for longitude and latitude.

Dear Reviewer,
Yes, there was a confusion, and the figure was not replaced.
The small figure was removed because it was redundant.
Instead, an image of the country of Argentina was added, highlighting the location of the province of Córdoba. An image of the province of Córdoba was also added, identifying the city of Córdoba, where the study basin is located.
The longitude and latitude were changed to degrees and minutes.

Thank you very much for your valuable time reviewing the article, which has led to significant improvements.