Effects of Domestic Sewage on the Photosynthesis and Chromium Migration of Coix lacryma-jobi L. in Chromium-Contaminated Constructed Wetlands

Round 1

Reviewer 1 Report (Previous Reviewer 2)

This paper reveals some information regarding the management of wetlands for remediating chromium contaminated waste water using a simulated study and the results indicate that addition of municipal sewage can promote transformation of toxic Cr (VI) to non-toxic Cr (III), and subsequently improves the growth of wetland vegetation. This work may be interesting to a spectrum of readers in the environmental management.

English has improved over the original version but there is still redundancy, such as "Under the same Cr treatment, the Cr content in roots, stems, and leaves of Coix lacryma-jobi L. under YCA was the highest, followed by that under WCA and then that under HCA." can be revised as "With the same Cr treatment, the Cr content in the roots, stems, and leaves of Coix lacryma-jobi L. was the highest under YCA, followed by WCA and HCA."

Author Response

Dear reviewer：

Thank you very much for your affirmation of our selection, and we have carefully understood your suggestions for our English presentation and made changes.After careful consideration and taking into account the comments of other reviewers, we have reorganized the data and logic of the article and made significant changes to the abstract and discussion and conclusion sections of the article to make the findings more structured.After sorting out the logic of the article, we found that chromium migration in Coix lacryma-jobi L. plants is an important factor affecting the inhibition of physiological activities of Coix lacryma-jobi L. by Cr (VI), so we revised the title to Effects of Domestic Sewage on the Photosynthesis and Chromium Migration of Coix lacryma-jobi L. in Chromium-Contaminated Constructed Wetlands.

Thank you very much for your recognition and for the very useful suggestions you have given us. We have also double-checked the article, corrected some errors in details, and strived to have the article published in the journal.

Reviewer 2 Report (Previous Reviewer 3)

The authors have done all corrections and the manuscript can be published.

The quality of the English is at an acceptable level to publish.

Author Response

Dear reviewer：

Thank you very much for your confirmation of our revision results.After careful consideration and taking into account the comments of other reviewers, we have reorganized the data and logic of the article and made significant changes to the abstract and discussion and conclusion sections of the article to make the findings more structured.After sorting out the logic of the article, we found that chromium migration in Coix lacryma-jobi L. plants is an important factor affecting the inhibition of physiological activities of Coix lacryma-jobi L. by Cr (VI), so we revised the title to Effects of Domestic Sewage on the Photosynthesis and Chromium Migration of Coix lacryma-jobi L. in Chromium-Contaminated Constructed Wetlands.

We also double-checked the article, corrected some errors in details, and strived for the article to be published in the journal.

Thank you again for your dedicated work, we have benefited greatly from your comments.

Wishing you all the best

Reviewer 3 Report (New Reviewer)

Reviewer’s comments to Authors

Authors should revise the manuscript carefully in light of below comments...............

1.   Grammatical errors are present, please revise the whole manuscript to remove any possible grammatical and typos errors.

2.   Error in sentence formation, please revise the whole manuscript to avoid the use of long sentences and confusing sentences/paragraphs.

3.   Please maintain uniformity while in-text citation and referencing in the entire manuscript.

4.   The reference does not meet the format requirements of the Journal so please check the references as per the authors guideline of the Journal.

5.   It is advised to check and avoid too many self-cited papers. Authors are advised to cite maximum two self-papers.

6.   The beginning of a new paragraph should be after some space, check in complete manuscript.

7.      Throughout the whole manuscript the plant names should be in italic format.

8.      This paper lacks final revision by the author as many general repetitions, typos, grammatical, sentence formation errors were found in the manuscript. It is not possible to mention all such errors. Thus revise the manuscript accordingly.

Abstract:

Authors should revise the manuscript carefully in light of below comments...............

1. An abstract must be fully self-contained and make sense by itself, without further reference to outside sources or to the actual paper. It is important to provide the relevance or importance of your work and the main outcomes. Please revise the abstract accordingly.
2. The abstract is not clear and the objective of the paper is not clearly validated from the abstract.
3. The future perspective of the experiment should be mentioned in the abstract.
4. The abstract should appropriately over the contents of the manuscript.
5. In the keywords, it is strongly advisable to use suitable words that can aid in finding out the manuscript in current registers or indexes. Strictly avoid the use of title words in the keywords.

6.      A graphical abstract is recommended for better perception of the present study.

7.      A novelty statement is also encouraged to be added in the manuscript for bringing out the uniqueness of your study and its importance.

8.      Please ensure that “Highlights” of the present work should be clearly mentioned in the manuscript.

Introduction:

Authors should revise the manuscript carefully in light of below comments...............

1.   The literature from past work done in the same field missing to strengthen the introduction section. The need and importance of the present work should be clearly written in the introduction section.

2.   The new aspects and innovations of this manuscript should be clearly and briefly described in this section.

3.   The present state of knowledge in the subject should be described in introduction.

4.   The literature should be sufficiently critical, current, and internationally evaluated.

Materials and Methods:

Authors should revise the manuscript carefully in light of below comments...............

1.         Please try to merge the different sub-sections of the methodology as an individual mention for each component seems a bit unscientific method.

2.         The size of manuscript seems to be large. It should be crisp and appropriate. Please revise it.

3.         The text presented across the manuscript should be simple so that the scientist/workers in other disciplines will understand. Please revise it.

4.         Introduction, Result, and Discussion sections are poorly cited with the references and required to update and validation with previous studies. The relevant papers listed below may be considered to enhance the scientific quality of manuscript significantly.

·         Kumar, D. et al. (2023). Titanium dioxide nanoparticles potentially regulate the mechanism (s) for photosynthetic attributes, genotoxicity, antioxidants defense machinery, and phytochelatins synthesis in relation to hexavalent chromium toxicity in Helianthus annuus L. Journal of Hazardous Materials, 454, p.131418.

 

·         Gupta, P. et al. (2022). 24-Epibrassinolide Regulates Functional Components of Nitric Oxide Signalling and Antioxidant Defense Pathways to Alleviate Salinity Stress in Brassica juncea L. cv. Varuna. Journal of Plant Growth Regulation, pp.1-16.

.

Results and Discussion:

Authors should revise the manuscript carefully in light of below comments...............

1. The results and discussion section needs to be elaborated more. The results should be clearly described in light of available knowledge and hypothesis and must be strongly validated with previous reports in the related subject area.
2. The non-significant results was not clearly validated from the previous papers.
3. Please carefully check, verify, and correct the results of the present experiments from the tables/figures/graphs provided in the manuscript.
4. The discussion does not describe the results with proper facts and even does not validate the result with appropriate references. Please enrich it significantly.
5. The discussion did not provide a specific reasons for the results. The provided explanation should be strengthen significantly.
6. The strong hypothesis, scientific facts, and validation of previous reports are entirely missing. Please revise it. 

Conclusion:

Authors should revise the manuscript carefully in light of below comments...............

1. The conclusion section failed to enlighten the spirit of the present finding or work so required to revise it accordingly.
2. In the conclusion section the authors have only mentioned the data but major finding is missing from the conclusion part. Need to revise and incorporate this important concern of reviewer.
3. The conclusion section seems like abstract so there is a need to revise the conclusion part accordingly.

Figures and Tables:

Authors should revise the manuscript carefully in light of below comments...............

·         Please provide the clear figures and tables.

·         The authors should write the descriptive, elaborated legends for the figures and the tables.

·         Please remove the redundancy from the legends of the figures and tables.

·         The legends of the figures and tables are not crisp and not completely bringing out the sense of the figures and tables. Rewrite it accordingly.

·         The placement of tables and figures in the manuscript should be done appropriately, which is missing in this manuscript. Please revise it.

·         The figures are overlapping the legends, the editing needs to be done.

·         The proper explanation of statistical analysis and its importance for describing the results should be mentioned.

·         There should not be monotony in representation of the results for instance all should not be represented in bar graph form vise-versa.

 

No comments

Author Response

Dear reviewer：

Thank you very much for reviewing our article in your busy schedule.

Your comments and suggestions allow us to better review the problems with our articles and allow us to benefit greatly from them.

We have carefully considered your review comments and those of other reviewers and have revised the article.

Our response to your review comments is attached in the attached word document, which we hope you will review.

Thank you again for your dedicated work, we have benefited greatly from your comments.

Wishing you all the best

 

Attached File: 

Response to Reviewer Comments

Thank you very much for your practical suggestions to revise our paper in your busy schedule. This would make our paper more comprehensive and we are willing to make corrections and work on publishing in journals. We have carefully considered the comments made by the reviewers, reorganized the logic of the article, further explored what the data can tell us, and made minor changes to the introduction, materials and methods, and data analysis sections of the article, and major changes to the abstract, discussion, and conclusion sections of the article.After sorting out the logic of the article, we found that chromium migration in Coix lacryma-jobi L. plants is an important factor affecting the inhibition of physiological activities of Coix lacryma-jobi L. by Cr (VI), so we revised the title to Effects of Domestic Sewage on the Photosynthesis and Chromium Migration of Coix lacryma-jobi L. in Chromium-Contaminated Constructed Wetlands.

In the following, I would like to answer the following questions:

Reviewer’s comments to Authors

Point 1: Grammatical errors are present, please revise the whole manuscript to remove any possible grammatical and typos errors.

Response 1:We have rechecked the entire manuscript and corrected the grammatical errors that were found.

Point 2:Error in sentence formation, please revise the whole manuscript to avoid the use of long sentences and confusing sentences/paragraphs.

Response 2:We have rechecked the entire manuscript, revised the identified sentence construction errors, and changed some of the long sentences to short sentences to avoid sentence construction errors.

Point 3:Please maintain uniformity while in-text citation and referencing in the entire manuscript.

Response 3:We have rechecked the entire manuscript to fix inconsistencies in citation and reference formatting.

Point 4: The reference does not meet the format requirements of the Journal so please check the references as per the authors guideline of the Journal.

Response 4:We carefully checked and revised the formatting issues that existed according to the reference formatting requirements provided by the journal.

Point 5: It is advised to check and avoid too many self-cited papers. Authors are advised to cite maximum two self-papers.

Response 5:After carefully examining the full text, we reduced the number of self-cited papers, cited more relevant articles to illustrate the problem, and avoided citing our own articles whenever possible.

Point 6: The beginning of a new paragraph should be after some space, check in complete manuscript.

Response 6:We have rechecked the entire manuscript for formatting issues and made changes.

Point 7:Throughout the whole manuscript the plant names should be in italic format.

Response 7:The entire manuscript has been rechecked for italicized plant name issues and has been revised.

Point 8:This paper lacks final revision by the author as many general repetitions, typos, grammatical, sentence formation errors were found in the manuscript. It is not possible to mention all such errors. Thus revise the manuscript accordingly.

Response 8:We carefully proofread the article for grammar, formatting, general repetition, typos, and sentence construction problems and made corrections before submitting the manuscript.

Abstract:

Point 1:An abstract must be fully self-contained and make sense by itself, without further reference to outside sources or to the actual paper. It is important to provide the relevance or importance of your work and the main outcomes. Please revise the abstract accordingly.

Response 1:We reorganized the logic and data of the article and rewrote the abstract to make it more logical and express the main work and main results of this study. The abstract was carefully revised according to the suggestions of the reviewers.

Point 2:The abstract is not clear and the objective of the paper is not clearly validated from the abstract.

Response 2:We reorganized the content and logic of the article based on the reviewers' comments, clarified the purpose of the study, and reflected it in the abstract.

Point 3:The future perspective of the experiment should be mentioned in the abstract.

Response 3:This study mainly investigates the mechanism of action of domestic wastewater, and the abstract mainly describes our results. We have carefully incorporated the comments of the reviewers and will be able to conduct more in-depth studies in the future as already mentioned in the preface and discussion.

Point 4:The abstract should appropriately over the contents of the manuscript.

Response 4:We covered the study in a newly written abstract after listening carefully to the reviewers' comments.

Point 5:In the keywords, it is strongly advisable to use suitable words that can aid in finding out the manuscript in current registers or indexes. Strictly avoid the use of title words in the keywords.

Response 5：After careful consideration of the reviewers' comments, some keywords were added and deleted. The present keywords are: hexavalent chromium; glutathione; domestic sewage; Coix lacryma-jobi L.; constructed wetland; photosynthetic parameter

Point 6:A graphical abstract is recommended for better perception of the present study.

Response 6:We listened carefully to the reviewers' comments and thoughtfully created a graphic abstract that was attached to the article.

Point 7: A novelty statement is also encouraged to be added in the manuscript for bringing out the uniqueness of your study and its importance.

Response 7:After carefully considering the comments of the reviewers, we have presented the uniqueness and importance of our research in a newly written abstract.

Point 8:Please ensure that “Highlights” of the present work should be clearly mentioned in the manuscript.

Response 8:After careful consideration of the reviewers' comments, highlights of our work such as: our research on domestic wastewater mitigation mechanisms are mentioned in the abstract.

Introduction:

Point 1:The literature from past work done in the same field missing to strengthen the introduction section. The need and importance of the present work should be clearly written in the introduction section.

Response 1：After carefully considering the comments of the reviewers, we have described more specifically the lack of work in this research area and the need and importance of our research in the introduction section. The specific changes are in lines 80 and 99~100 of the revised version.

Point 2:The new aspects and innovations of this manuscript should be clearly and briefly described in this section.

Response 2:After we have carefully considered the comments of the reviewers, and after our careful combing, the important role of this study for the development of constructed wetlands for wastewater treatment has been mentioned at the end of the introduction, and the part of this study that we hope to fill the missing research in this field has been mentioned in other parts of the introduction.

Point 3:The present state of knowledge in the subject should be described in introduction.

Response 3:After carefully considering the comments of the reviewers, we have revised our paper to more specifically describe the current state of knowledge in the subject and to reflect the importance of our research.

Point 4:The literature should be sufficiently critical, current, and internationally evaluated.

Response 4: After carefully considering the comments of the reviewers, we have improved the international and critical nature of the article, as shown in lines 47-49 and 55-58 of the revised version.

Materials and Methods:

Point 1:Please try to merge the different sub-sections of the methodology as an individual mention for each component seems a bit unscientific method.

Response 1:After we carefully considered the comments of the reviewers, we combined some of the experimental methods to make their presentation more scientific.

Point 2:The size of manuscript seems to be large. It should be crisp and appropriate. Please revise it.

Response 2:After we carefully considered the comments of the reviewers, we revised some of the content to make it meet the requirements of the reviewers.

Point 3:The text presented across the manuscript should be simple so that the scientist/workers in other disciplines will understand. Please revise it.

Response 3:After carefully considering the comments of our reviewers, we have revised some of the experimental methods to make them easier to understand.

Point 4:Introduction, Result, and Discussion sections are poorly cited with the references and required to update and validation with previous studies. The relevant papers listed below may be considered to enhance the scientific quality of manuscript significantly.

Response 4:Many thanks to the reviewers for the literature, which we read through and found very informative for our study, and we have cited them in the discussion section.

Results and Discussion:

Point 1:The results and discussion section needs to be elaborated more. The results should be clearly described in light of available knowledge and hypothesis and must be strongly validated with previous reports in the related subject area.

Response 1:After carefully considering the comments of the reviewers, we carefully and profoundly sorted out the logic of the article, made a larger scale revision of the discussion section of the article to make the expression of the article clearer and more logical, and deleted the redundant descriptions to make the expression more concise and further enhanced the discussion section.

Point 2:The non-significant results was not clearly validated from the previous papers.

Response 2:After carefully considering the comments of the reviewers, we have sorted out the logic of the article to make it tighter. More relevant literature was used to corroborate our results to make them more logical and credible.

Point 3:Please carefully check, verify, and correct the results of the present experiments from the tables/figures/graphs provided in the manuscript.

Response 3:After careful consideration of the reviewers' comments, we found some errors in the listing of our data and made corrections. Finally, we critically proofread our data to ensure that no more errors were made.

Point 4:The discussion does not describe the results with proper facts and even does not validate the result with appropriate references. Please enrich it significantly.

Response 4:We are very grateful to the reviewers for pointing out our problems, and we have reorganized the discussion section and cited more relevant literature to support our results.

Point 5:The discussion did not provide a specific reasons for the results. The provided explanation should be strengthen significantly.

Response 5:After careful consideration of the reviewers' comments, we strongly acknowledge the problems that the reviewers raised with us. We have revised the discussion section to further explain the reasons for our results and to tighten the logic of the discussion.

Point 6:The strong hypothesis, scientific facts, and validation of previous reports are entirely missing. Please revise it.

Response 6:Many thanks to the reviewers for pointing out the problems of our article. We have made extensive changes to the discussion section after carefully revising it in response to the reviewers' comments. More relevant literature has been cited to support our hypothesis.

Conclusion:

Point 1:The conclusion section failed to enlighten the spirit of the present finding or work so required to revise it accordingly.

Response 1:In conjunction with the comments of the reviewers, in the conclusion section we provide an appropriate summary of the findings.

Point 2:In the conclusion section the authors have only mentioned the data but major finding is missing from the conclusion part. Need to revise and incorporate this important concern of reviewer.

Response 2:Combining the comments of the reviewers, we present the main findings of our study in the conclusion section.

Point 3:The conclusion section seems like abstract so there is a need to revise the conclusion part accordingly.

Response 3:Taking into account the comments of the reviewers, we revised the conclusion section to make it more specific.

Figures and Tables:

Point 1: Please provide the clear figures and tables.

Response 1:In conjunction with the comments of the reviewers, we revised the color scheme of the images and the presentation of the tables to make them more clearly represent the study results.

Point 2:  The authors should write the descriptive, elaborated legends for the figures and the tables.

Response 2:Taking into account the comments of the reviewers, we have added more legends under the necessary detailed figures.

Point 3:  Please remove the redundancy from the legends of the figures and tables.

Response 3:In conjunction with the comments of the reviewers, we have removed redundant legends to make the presentation more concise.

Point 4:    The legends of the figures and tables are not crisp and not completely bringing out the sense of the figures and tables. Rewrite it accordingly.

Response 4:In conjunction with the comments of the reviewers, we have revised some of the figures that were not clearly expressed.

Point 5:The placement of tables and figures in the manuscript should be done appropriately, which is missing in this manuscript. Please revise it.

Response 5:In conjunction with the reviewers' comments, we revised the size and format of the figures.

Point 6:The figures are overlapping the legends, the editing needs to be done.

Response 6:In conjunction with the reviewer's comments, we have revised the graphs to show the problems that existed.

Point 7:The proper explanation of statistical analysis and its importance for describing the results should be mentioned.

Response 7:Many thanks to the reviewers for pointing out our problems, and we have revised the data analysis. A reasonable discussion of the results of the statistical analysis has been made, such as the representation of the significance of differences, etc. Relevant content has been highlighted in the text.

Point 8:There should not be monotony in representation of the results for instance all should not be represented in bar graph form vise-versa.

Response 8:We changed some of the bar charts to make the data display more clear and concise. Because our study deals with more, the bar chart can express our findings very clearly.

 

Reviewer 4 Report (New Reviewer)

Abbreviations presently used in the manuscript create confusion for the reader. it will be better if an alternative used

Use the correct reference of statistical software used in this manuscript

Roundup/down the data

Add a space between values and units

Improve discussion and comparison sections manuscript

 

Typo error need to be corrected

Author Response

Dear reviewer：

Thank you very much for your diligent review.

We have carefully considered your review comments and have revised the article in light of your comments and those of other reviewers.

The content of the response to your review comments is in the word attachment.

We hope you will check out.

Thank you again for your dedicated work, we have benefited greatly from your comments.

Wishing you all the best.

 

Attached File: 

Response to Reviewer Comments

Dear reviewer：

Thank you very much for your practical suggestions to revise our paper in your busy schedule. This would make our paper more comprehensive and we are willing to make corrections and work on publishing in journals. After careful consideration and taking into account the comments of other reviewers, we have reorganized the data and logic of the article and made significant changes to the abstract and discussion and conclusion sections of the article to make the findings more structured.After sorting out the logic of the article, we found that chromium migration in Coix lacryma-jobi L. plants is an important factor affecting the inhibition of physiological activities of Coix lacryma-jobi L. by Cr (VI), so we revised the title to Effects of Domestic Sewage on the Photosynthesis and Chromium Migration of Coix lacryma-jobi L. in Chromium-Contaminated Constructed Wetlands.

In the following, I would like to answer the following questions:

Point 1:Abbreviations presently used in the manuscript create confusion for the reader. it will be better if an alternative used

Response 1:We have reformulated the abbreviations based on the initials of each treatment and have tried to avoid confusion caused by improper abbreviations.

Point 2:Use the correct reference of statistical software used in this manuscript

Response 2: In lines 216 to 219 of the modified version, we have made changes based on the actual software used.

Point 3:Roundup/down the data

Response 3:We have taken the decimal points to the right number of digits according to the requirements of different data.

Point 4:Add a space between values and units

Response 4: We have carefully checked the full text and made changes according to the review comments

Point 5:Improve discussion and comparison sections manuscript

Response 5:We sorted and examined the data and article logic carefully. The data analysis section has been improved to make it more concise and clear. The discussion section has been improved to make it more logical, using more references to support our results and making the expression of redundancies more concise.

We have performed a final check of the article, correcting the errors found in the textual details.

Thank you again for your dedicated work, we have benefited greatly from your comments.

Wishing you all the best

Reviewer 5 Report (New Reviewer)

In this study, small vertical flow constructed wetlands of Coix lacryma-jobi L. were set up, and domestic sewage (WCA), 1/2 Hoagland nutrient solution (YCA), and 1/2 Hoagland nutrient solution prepared with domestic wastewater (HCA) were used to simulate wastewater containing 0, 20, and 40 mg/L of Cr (VI), respectively. These three types of liquids were used to investigate the effect of Cr (VI) on plant growth and physiological indicators in vertical flow constructed wetlands with different types water inflow during the treatment of chromium-containing wastewater in the wetlands. The results are as follows. (1) Indicators such as plant height, stem diameter, root activity, photosynthetic gas exchange, and chlorophyll fluorescence properties of Coix lacryma-jobi L. were inhibited under 20 mg/L and 40 mg/L Cr (VI) treatments., and the degree of inhibition under YCA was higher than that under WCA. (2) Under Cr (VI) stress, the glutathione (GSH) content in roots, stems, and leaves of Coix lacryma-jobi L. under YCA was the highest, followed by that under WCA and then that under HCA. (3) The chromium (Cr) content in each organ of Coix lacryma-jobi L. increased as the Cr concentration increased and the treatment time extended. Under the same Cr treatment, the Cr content in roots, stems, and leaves of Coix lacryma-jobi L. under YCA was the highest, followed by that under WCA and then that under HCA. The Cr content in the substrate significantly increased as the treatment time extended. The total Cr content in the substrate under HCA was the highest, followed by that under WCA and then that under YCA. The total Cr content in the water discharged increased as the treatment time extended. 

I have the following comments:

1. What is the novelty of this work?

2. The abbreviations mentioned in the abstract should be more rational and standard.

3. Please describe the Cr impacts on plants, animals, and humans more clearly. What are its background concentrations in the soil or water?

4. Give reasons for using Coix lacrymal-jobi L in this study. How plant was collected, and under what growth conditions and stage of the plant life cycle it was used for the study?

5. Why you provided the Hoagland solution? We can not manage to provide Hoagland solution to the plants in actual field experiments. What are the other uses of this plant?

6.  What do you mean by 1/2 Hoagland nutrient solution?

7. Equations 1 and 2:What are their sources?

 

 

Must be improved

Author Response

Dear reviewer：

Thank you very much for reviewing our article in your busy schedule.

Your comments and suggestions allow us to better review the problems with our articles and allow us to benefit greatly from them.

We have carefully considered your review comments and those of other reviewers and have revised the article.

Our response to your review comments is attached in the attached word document, which we hope you will review.

Thank you again for your dedicated work, we have benefited greatly from your comments.

Wishing you all the best

 

Attached File: 

Response to Reviewer Comments

Thank you very much for your practical suggestions to revise our paper in your busy schedule.This would make our paper more comprehensive and we are willing to make corrections and work on publishing in journals.After careful consideration and taking into account the comments of other reviewers, we have reorganized the data and logic of the article and made significant changes to the abstract and discussion and conclusion sections of the article to make the findings more structured.After sorting out the logic of the article, we found that chromium migration in Coix lacryma-jobi L. plants is an important factor affecting the inhibition of physiological activities of Coix lacryma-jobi L. by Cr (VI), so we revised the title to Effects of Domestic Sewage on the Photosynthesis and Chromium Migration of Coix lacryma-jobi L. in Chromium-Contaminated Constructed Wetlands.

In the following, I would like to answer the following questions:

Point 1:What is the novelty of this work?

Response 1:We reorganized the logic of the article and clarified that the novelty of the article is "we studied the effect of domestic wastewater on photosynthesis and chromium transport in chromium-contaminated constructed wetland plants, and investigated the reasons that contribute to the long-term sustainable and efficient operation of constructed wetlands", which is mentioned in the abstract and conclusion of the article.

Point 2:The abbreviations mentioned in the abstract should be more rational and standard.

Response 2:We reorganized the logic of the article and clarified that the novelty of the article is "the effect of domestic wastewater on the photosynthesis and chromium transport of chromium-contaminated constructed wetland plants was investigated, and the reasons why it contributes to the long-term sustainable and efficient operation of the constructed wetland", which is mentioned in the abstract and conclusion of the article.

Point 3:Please describe the Cr impacts on plants, animals, and humans more clearly. What are its background concentrations in the soil or water?

Response 3:We improved the description of Cr effects on plants in the preface to make it more relevant to the content of our study.In the present study the background values of Cr in the matrix were represented in the control.

Point 4:Give reasons for using Coix lacrymal-jobi L in this study. How plant was collected, and under what growth conditions and stage of the plant life cycle it was used for the study?

Response 4:In this study, the experimental material, Coix lacryma-jobi L. was provided by the Guangxi Academy of Agricultural Sciences, which can be used to study the stress study of heavy metals under different moisture conditions because it is resistant to flooding throughout the reproductive period and can also be drought-long, and in our preliminary study, it was found that the constructed wetland of Coix lacryma-jobi L. has a better purification effect on Cr (VI)-containing wastewater, therefore, we chose it as the study material.

Point 5:Why you provided the Hoagland solution? We can not manage to provide Hoagland solution to the plants in actual field experiments. What are the other uses of this plant?

Response 5:Usually, the use of nutrient culture is an important tool to study the mechanism of nutrient uptake by plants.The nutrient content of wastewater containing chromium is usually not high, but it is often discharged mixed into domestic wastewater, but after preliminary treatment, the nutrient content of domestic wastewater we obtained was also low. Therefore, in order to better study the migration pattern of different chromium in constructed wetlands and the response of constructed wetlands to chromium stress, we used Hoagland nutrient solution as the study material and used pure domestic wastewater, nutrient solution and nutrient solution prepared from domestic wastewater.

Point 6:What do you mean by 1/2 Hoagland nutrient solution?

Response 6:1/2 Hoagland Nutrient Solution means that the standard Hoagland Nutrient Solution is configured by reducing each nutrient element to 1/2 of the standard.The nutrient content in general chromium-containing wastewater is not high, and if the nutrient solution concentration is too high, it is too far from the actual nutrients of the wastewater, and the obtained results may not reflect the actual situation, therefore, 1/2 Hoagland Nutrient Solution was used for the study.

Point 7:Equations 1 and 2:What are their sources?

Response 7:In lines 162 to 164 of the revised version of the article, we have added the literature referenced by the formula.

We have improved the English and Chinese presentation of the article.

Thank you again for your dedicated work, we have benefited greatly from your comments.

Wishing you all the best

Round 2

Reviewer 3 Report (New Reviewer)

Comments have been addressed. 

Reviewer 5 Report (New Reviewer)

No comments

Suitable

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

In the abstract, the authors mentioned that “this paper aims to investigate the mechanism of domestic sewage mitigating the physiological toxicity of Cr (VI) to plants during the treatment of wastewater by the wetlands”. The authors did observe some alleviation effects of domestic sewage on the toxicities by Cr(VI) on plants. However, to be honest, there are some obvious and serious flaws on the experimental design and measurements. Thus, it’s not scientific to get the conclusions as the authors have made. Also, in my opinion, this paper has not explored any “mechanism”.

1.      The biggest problem is that the authors only measured the total Cr concentrations in plant tissues and water. Thus, we could not know what were the exact levels of Cr(VI) or Cr(III) in the plants or water. Given this, the conclusion demonstrating that “…wastewater can effectively promote the conversion of Cr (VI), reduce Cr effectiveness…” (Lines 456-457) is invalid. No clues for it.

2.      The experimental design is not rigorous and a lot of essential information is lacked. For example, how did you prepare the Cr(VI)-containing solutions (WCA, YCA and HCA)? The solutions reached equilibrium or not? The Cr species is stable in these solutions? The K₂Cr₂O₇ solution was used in the study, so what are the really concentrations of Cr(VI) in the prepared solutions? So, back to the 1^st question.

3.      How did you get the domestic sewage and store it? It seems to be quite unstable, especially for the TN (8.16～12.33 mg/L) and NH₃-N (15.98～22.56 mg/L). Have you ever pretreated the water?

4.      The further question is that how can you make sure that Cr(VI) would not be converted into Cr(III) in the domestic sewage before the experiment was started? As you mentioned in Line 86 “…that the organic matter and microorganisms in domestic sewage may help to convert Cr (VI) into Cr (III) in the substrate…”, if this process was occurred quickly, this treatment would just investigate the toxic effects of Cr(III) on plants. That does not make sense at all.

5.      Some obvious and stupid mistakes or errors can be found in the Figs and Tables. For the different lowercase letters, are they indicate the 5% significant level for each treatment? Or for all the treatments? For all the figures, what do you mean by “processing aime”?

 

Make the descriptions more concise. 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Wetland systems have become an important approach for disposal and remediation of heavy metal-containing wastewater via immobilization and conversion of metals by wetland plants and substrates. However, how to maintain a wetland for sustainable operation without affecting its remediation efficiency requires a lot of studies. This study revealed that adding domestic sewage to chromium-containing wastewater can effectively promote the conversion of Cr (VI) to less available forms and reduce Cr uptake and the damage to wetland plants, and thus increase the treatment efficiency and sustainability of the wetland systems. This work has implications for future management of wetland remediation systems.

The English is generally fine but requires certain refinement to make it concise and clear.

Author Response

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Reviewer 3 Report

Some revisions are required before acceptance of the manuscript:

1- What is the novelty of this study? It should be provided in the abstract as well as at the end of the introduction.

2- Section 2.4.1: The quality of two equations are low. Improve them by writing these relationships with the Equation Software.

3- The section 2.4.2 must be further explained. The authors just mentioned reference [22] without any description. Also, other sections such as 2.4.5 and 2.4.9.

4- The results in section 3.1 should be compared with previous studies and mention pros and cons of your results.

5- The results are discussed with only p-value as a statistic criterion. What about other statistic parameters such as t-statistics, standard deviation, standard error of the mean. I think these data and their interpretation are very necessary for this study.

6- The quality of figures can be improved.

7- The conclusion is written very weak without any serious discussion. Also, the future perspective on this work should be presented and discussed.

8- Old references should be replaced.

9- Some critical articles can be used: https://doi.org/10.1016/j.ecoenv.2023.114566

https://doi.org/10.1016/j.resconrec.2022.106740  https://doi.org/10.1016/j.watres.2022.119258

https://doi.org/10.1016/j.chemosphere.2023.138101

https://doi.org/10.1016/j.jece.2023.109312 

https://doi.org/10.1021/acs.est.8b02213

 

Some minor revision is required

Author Response

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Author Response File: Author Response.docx