Round 1

Reviewer 1 Report

The manuscript is very interesting and useful for international readers. I suggest to make some minor revisions to improve the manuscript. 

Comments for author File: Comments.pdf

Author Response

Reviewer #1: 

The manuscript is very interesting and useful for international readers. I suggest to make some minor revisions to improve the manuscript.

 

1. Pag. 1 Line 35: it is suggested to sum up all the garbage patches widespread in the oceans and the relative references.

Response:

We supply detailed information on garbage mass in the Pacific Ocean (line 35, page 1). “Land-based plastic waste flows into oceans and accumulates into large garbage patches, which are found in the Pacific Ocean (at least 79 tonnes) [5]”.

 

2. Pag. 2 Line 46: it could be advisable to indicate also the presence of microplastics in the Mediterranean Sea and the relative references.

Response:

Thank you for your suggestions. We added the data about some oceans, including the Pacific Ocean, the Indian Ocean, and the Mediterranean Sea (line 46, page 2). “for example: microplastics were found in the mid-west Pacific Ocean with a mean concentration of 34,039 ± 25,101 pieces/km² [13]; 50 ± 30 particles/fiber m^-3 in the tropical Indian Ocean [14]; or from 0.029 to 0.310 item/m² in the Mediterranean Sea [15].

 

 

3. Pag. 2 Line 50: it is necessary to speak about the process of bio-accumulation of microplastics in the food chain from the lower levels of planctonic biomass to the upper level of carnivores until the top level of mankind, with their references.

Response:

Thanks for your comment. We add more information to describe the bioaccumulation pathway of microplastics (lines 50, page 2). “The bioaccumulation pathway of microplastics was described by a model marine food web. The model shows that Neocalanus cristatus (0.026 MPs/org) is the prey of Crangon crangon (0.64 ± 0.53 MPs/g w.w.), while Crangon crangon is a type of food for Mixied fish species (0.27 ± 0.63 – 83 MPs/fish).

 

4. Pag. 17 Line 495: it is suggested to insert in the paragraph Discussions a sub-paragraph (4.5) to debate about the possible solutions trying to solve this new knd of marine pollution.

Response:

Thank you for your suggestion. The main objective of our study is the investigation of microplastic in the research area and our results should answer the proposed objectives (presence of microplastics in the sand in the coastal areas), the addition of possible solutions to solve marine pollution problems is not in the study scope. Therefore, our research team finds it unnecessary to add sub-paragraphs to the discussion. However, the results of this study will be useful to contribute to the further research and the authorities to take appropriate management measures to propose solution to the microplastic pollution.

 

5. Pag. 17 Lines-496-512: it is necessary to extend the final paragraph “Conclusions” to make the manuscript better organized and shared out

Response:

Thank you for your comment. We have supplied some solutions for the pollution issue to extend paragraph Conclusion.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

This study investigates the presence of microplastics in the sand of several beach areas in Vietnam. Although the topic of microplastic is timely and the manuscript is well written, this work does not bring any novelty to the field since the conclusions of the study have already been highlighted by numerous papers. I do not recommend the publication of this work.
The study could be improved by considering smaller microplastics (ie nanoplastics), be more accurate in the identification of the plastics (LDPE, HDPE instead of PE, presence of pollutants...) and assessing the impact of weathering events on the spread of microplastics across the beach (rainfalls, floods...).

 

Author Response

We thank all reviewers for their careful comments. Below we include the reviewers’ comments (in black) and our responses to them (in blue).

 

Reviewer #2: 

This study investigates the presence of microplastics in the sand of several beach areas in Vietnam. Although the topic of microplastic is timely and the manuscript is well written, this work does not bring any novelty to the field since the conclusions of the study have already been highlighted by numerous papers. I do not recommend the publication of this work.
The study could be improved by considering smaller microplastics (ie nanoplastics), be more accurate in the identification of the plastics (LDPE, HDPE instead of PE, presence of pollutants...) and assessing the impact of weathering events on the spread of microplastics across the beach (rainfalls, floods...).

Response:

Thank you for your comments. The study was conducted along the coast of the most populous city in Vietnam (Ho Chi Minh City), where receives different sources of microplastics from anthropogenic activities (inland water through many rivers, Can Gio Sea,..). Can Gio sea is also in interaction with other areas in the southern sea of Vietnam. Therefore, the results in this study will contribute to the understanding the microplastic pollution in Vietnam in specific and in the Southeast Asia in general. 

Author Response File: Author Response.pdf

Reviewer 3 Report

In the article submitted for review presents to study examined the abundance, physical characteristics, and chemical composition of microplastics in beach sand from the Can Gio Coast, Ho Chi Minh City, Vietnam for the first time. This is very interesting and important research. Recently, there has been an increased interest in microplastics in the environment and this study confirms that it is a global problem. In my opinion, the research was very well designed and thought out. The results of the research are very well illustrated and described.

In my opinion, however, the article requires a few minor corrections:

·       Please use a uniform font format for chapters 2.1, 2.2 etc.,

·       I suggest introducing additional markings for individual diagrams in Figure 1, e.g. a, b, c,

·       In chapter 2.3, please standardize the font in the text,

·       Please check the entry on line 328 (62,800). This is not as recorded in the table. It is worth using the same provisions.

·       I suggest that you change the quoting method on line 380.

Thank you for considering my opinion. I encourage authors to keep on working to improve the manuscript.

Author Response

We thank all reviewers for their careful comments. Below we include the reviewers’ comments (in black) and our responses to them (in blue).

 

Reviewer #3: 

In the article submitted for review presents to study examined the abundance, physical characteristics, and chemical composition of microplastics in beach sand from the Can Gio Coast, Ho Chi Minh City, Vietnam for the first time. This is very interesting and important research. Recently, there has been an increased interest in microplastics in the environment and this study confirms that it is a global problem. In my opinion, the research was very well designed and thought out. The results of the research are very well illustrated and described.

In my opinion, however, the article requires a few minor corrections:

 

1. Please use a uniform font format for chapters 2.1, 2.2 etc.,

Response:

Thank you for your suggestion. We changed as pointed

 

2. I suggest introducing additional markings for individual diagrams in Figure 1, e.g. a, b, c,

Response:

Thank you for your suggestion. We changed as pointed

 

3. In chapter 2.3, please standardize the font in the text,

Response:

Thank you for your suggestion. We changed as pointed

 

4. 4. Please check the entry on line 328 (62,800). This is not as recorded in the table. It is worth using the same provisions.

Response:

Thank you for your suggestion. We changed as pointed

 

5. I suggest that you change the quoting method on line 380.

Response:

Thank you for your suggestion. We changed as pointed

 

Thank you for considering my opinion. I encourage authors to keep on working to improve the manuscript.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The revised version of the manuscript still does not bring novelty to the field of microplastic pollution. Below are some examples of papers already published focusing on the analysis of microplastic in Vietnam beaches, the first one being a previous paper written by the authors in 2020 and presenting similar results. Hence, I do not recommend the publication of this manuscript.

Hien, To Thi, et al. "The Distribution of Microplastics in Beach Sand in Tien Giang Province and Vung Tau City, Vietnam." Journal of Engineering & Technological Sciences 52.2 (2020). https://doi.org/10.5614/j.eng.technol.sci.2020.52.2.6

Tran Nguyen QA et al. “Characteristics of microplastics in shoreline sediments from a tropical and urbanized beach (Da Nang, Vietnam).” Mar Pollut Bull. 2020 Dec;161(Pt B):111768. doi: 10.1016/j.marpolbul.2020.111768. 

 

 

 

Author Response

Below we include the reviewer’s comments (in black) and our responses to them (in blue).

 

Reviewer #2: 

The revised version of the manuscript still does not bring novelty to the field of microplastic pollution. Below are some examples of papers already published focusing on the analysis of microplastic in Vietnam beaches, the first one being a previous paper written by the authors in 2020 and presenting similar results. Hence, I do not recommend the publication of this manuscript.

 

Hien, To Thi, et al. "The Distribution of Microplastics in Beach Sand in Tien Giang Province and Vung Tau City, Vietnam." Journal of Engineering & Technological Sciences 52.2 (2020). https://doi.org/10.5614/j.eng.technol.sci.2020.52.2.6

 

Tran Nguyen QA et al. “Characteristics of microplastics in shoreline sediments from a tropical and urbanized beach (Da Nang, Vietnam).” Mar Pollut Bull. 2020 Dec;161(Pt B):111768. doi: 10.1016/j.marpolbul.2020.111768.

 

Response:

As we explained in the previous response, the study was conducted along the coast of the most populous city in Vietnam (Ho Chi Minh City), where receives different sources of microplastics from anthropogenic activities (inland water through many rivers, Can Gio Sea,..), Can Gio sea is also in interaction with other areas in the southern sea of Vietnam. Vietnam has 3260 km of coastline with many anthropogenic activities happening along the beaches, the coastal Vietnam is also affected heavily by the hydrology of the ocean, each coastal area has different characteristics. Therefore, results of studies in each specific area do bring value and necessary scientific information to authorities and stakeholders to solve the microplastic pollution in Vietnam and the world.

In addition, we do believe that it is very important to highlight the differences between this study and other papers on beach microplastics in Vietnam:

• The study of same authors (Hien et al., 2020), in both studies we use the similar sampling methods to compare the microplastic pollution in different beaches, which is important to agree on one same research method since the results are more reliable and comparable. Moreover, in this study, we have more analysis in microplastic mass (relating to emission mass of microplastic into the environment). Plastic wastes in the same samples were also analyzed to give more insights into microplastic source. We want to declare that this study evolved from previous study to have more informative results.

Reference: Hien, To Thi, et al. "The Distribution of Microplastics in Beach Sand in Tien Giang Province and Vung Tau City, Vietnam." Journal of Engineering & Technological Sciences 52.2 (2020). https://doi.org/10.5614/j.eng.technol.sci.2020.52.2.6

• The study in Danang (Tran et al., 2020), the sampling areas are mainly tourism beaches, these places also receive domestic wastewater. The results also show that fibrous microplastics were dominant in all sampling areas. The results from different research reflect the potential source of microplastics and in the relation with coastal activities. In addition, the sampling methods of our study and this study were not the same. While in Danang, subsamples were mixed to form one representative sample of each beach, in our study, samples were collected in different tidal lines to show the different in spatial distribution. Each study brings more insight into microplastic research; therefore, we need more comparison among microplastic studies to conclude a standardized protocol for microplastic sampling and analysis.

Reference: Tran Nguyen QA et al. “Characteristics of microplastics in shoreline sediments from a tropical and urbanized beach (Da Nang, Vietnam).” Mar Pollut Bull. 2020 Dec;161(Pt B):111768. doi: 10.1016/j.marpolbul.2020.111768.

Finally, we want to confirm that, the results of this study bring values to the microplastic pollution research in Vietnam in specific and in the world in general. The more papers on microplastics were published, the more reliable the data is. Then, more feasible solutions would be proposed for microplastic pollution management.

Author Response File: Author Response.pdf