Distribution and Pollution Evaluation of Nutrients, Organic Matter and Heavy Metals in Surface Sediments of Wanghu Lake in the Middle Reaches of the Yangtze River, China

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

The work shows a concise analysis of a topic of notable interest, such as the study of the contamination of nutrients, organic matter and heavy metals in surface sediments in water spaces, specifying its analysis in the study area of Wanghu Lake.

It would be important to improve the specification of the study hypothesis, as well as the objectives (general and specific), pursued with it.

It should be noted that the structure of the work is appropriate, and favors the reading of the study, although the excessive use of acronyms makes it difficult to understand the text, so it would be useful to avoid their repeated use.

It is recommended to improve the quality of the maps, allowing for better reading (specifically, on the location map of the study area).

For its part, the analysis and evaluation of all the graphic material used in the study is encouraged, favoring the understanding of the data collected therein.

Author Response

Dear expert，

Thank you for taking the time to reading our article and put forward many meaningful suggestions. These suggestions help us improve some expressions and further improve our article. Our responses to your suggestions are as follows:

 

It would be important to improve the specification of the study hypothesis, as well as the objectives (general and specific), pursued with it.

Respond: Thank you for your advice. On the basis of the original text, we improve the research hypothesis and further clarify the goal of this study. The last paragraph of the introduction was revised and rewritten ( P2-P3, L88-106 ).

 

It should be noted that the structure of the work is appropriate, and favors the reading of the study, although the excessive use of acronyms makes it difficult to understand the text, so it would be useful to avoid their repeated use.

Respond: Thank you for your reminder. We have tried to reduce the use of abbreviations in the original text. To increase readability and help readers better understand.

 

It is recommended to improve the quality of the maps, allowing for better reading (specifically, on the location map of the study area).

Respond: Thank you for your reminder. We redraw the general map of the study area and improve the quality of other maps in the paper. In order to help readers understand the research results more clearly.

 

For its part, the analysis and evaluation of all the graphic material used in the study is encouraged, favoring the understanding of the data collected therein.

Respond: Thank you for your advice. We conducted a supplementary analysis and evaluation of unused graphic materials. In order to increase the readability of the article content.

 

 

 

 

 

 

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

The manuscript presents a study on pollution by nutrients, organic matter and heavy metals in Wanghu Lake, China. The protection of water resources is an important sustainable development goal, so the topic is fit for the journal.

The introduction is comprehensive and clear, describing well the context of the study.

To be checked:

portant Wetland List,’ with a total protected area of 20495 hm2[27]. 99 (probably km)

In the methodology there's a need to clarify a bit more the formulas.

Equations 1 and 2 are not connected. There should be an additional equation to explain how F is calculated and how it relates to S and C (F is defined as the average of the pollution indices, but it is not clear if they are the same as the single-factor evaluation index S)

Equations 4 and 5 are identical - please check

Table 6 - define toxicity coefficients 

Equation 7 - please explain the variables included in the formula.

The results are well presented and the discussion is also very good, including comparisons with other studies on lakes in China. Perhaps the last part of hte discussion could be moved to conclusions.

The conclusions are very brief and they are basically repeating the results. They could be improved by adding what further studies or pollution prevention measures should be carried out.

 

Comments on the Quality of English Language

There are some minor spelling and grammar mistakes that should be checked.

Author Response

Dear expert，

Thanks for taking the time to reading our article and put forward many meaningful suggestions. Some detailed questions in the article were raised and We have rectified these problems. Our responses to your suggestions are as follows:

 

To be checked:

portant Wetland List,’ with a total protected area of 20495 hm²[27]. 99 (probably km)

Respond: Thank you for your reminder. The total area of lake protection in the original text should be 204.95 km². It has been modified at the original study area.

 

In the methodology there's a need to clarify a bit more the formulas.

Equations 1 and 2 are not connected. There should be an additional equation to explain how F is calculated and how it relates to S and C (F is defined as the average of the pollution indices, but it is not clear if they are the same as the single-factor evaluation index S)

Respond: Thank you for your advise. We have added formula (2) to the original 2.3.1 to explained F, and linked formula 1 and formula 2 in the original.

 

Equations 4 and 5 are identical - please check

Respond: Thank you for your reminder. I am sorry that the repetition of the formula in the original text is a pen error, which has been modified accordingly.(P5, L168-169)

 

Table 6 - define toxicity coefficients 

Respond: Thank you for your reminder. We have added annotations to the original table to explain the toxicity coefficient. Toxicity coefficient is a unified standard method and scale for representing and comparing the toxicity of poisons, that is, reference values or indicator values.

 

Equation 7 - please explain the variables included in the formula.

Respond: Thank you for your reminder. We have explained the variables in the formula in detail and accurately in Section 2.3.4. The text is on P6, L207-211. We will pay attention to in the future.

 

 

 

The results are well presented and the discussion is also very good, including comparisons with other studies on lakes in China. Perhaps the last part of hte discussion could be moved to conclusions.

Respond: Thank you for your advice. Thank you very much for your advice. This is of considerable help to us. We integrate the results of the comparison with other lakes in China into the conclusion of the article in Part 5.

 

The conclusions are very brief and they are basically repeating the results. They could be improved by adding what further studies or pollution prevention measures should be carried out.

Respond: Thank you for your advice. For the conclusion part mentioned in your suggestion, we have revised and written it according to your suggestion. The research results were summarized and the relevant pollution prevention measures were put forward.

 

 

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

This work reported the nutrients, organic matter (OM) and heavy metals (HMs) in surface lake sediments of a local lake. Similar topic has been widely reported in literature, and this work adopted similar research methods to evaluate the total phosphorus (TP), total nitrogen (TN) and organic matter(OM). And the potential ecological risk index(RI) of HMs was also determined. This work has some value in risk evaluation. However, the novelty is not clear.

 

1. The novelty of this work is not clear, it should be highlighted in the introduction section.

2. What are the differences between this work and previous study in research methods, models and conclusion?

3. Why this lake was chosen?

4. All the figures were not clear, and some data did not contain error bars.

5. Did the authors carry out the quality control and assurance anlalysis throughout the experiments and how?

Author Response

Dear expert,

Thank you for taking the time to reading our article and put forward many meaningful suggestions, these suggestions help us to further improve our article. Our responses to your suggestions are as follows: 

1. The novelty of this work is not clear, it should be highlighted in the introduction section.

Respond: Thank you for your reminder. We have adjusted the relevant content in the introduction part. We understand the previous studies on Wanghu lake and summarized these.

 

2. What are the differences between this work and previous study in research methods, models and conclusion?

Respond: In our research, we selected a variety of methods to make a more comprehensive approach to nutrients, organic matter and heavy metals. We have made corresponding adjustments in the introduction. It mainly shows that we use a variety of methods for an overall evaluation of surface sediments, taking into account heavy metal pollution while understanding nutrient pollution. （P2-3, L65-106）

 

3. Why this lake was chosen?

Respond: We choose the Wanghu lake is that the largest lake in Yangxin County. The west side of the net lake is close to Yangxin County, and the east side is connected to the Yangtze River. It is also a provincial nature reserve in Hubei Province and is listed as an ' List of wetlands of international importance '. Meanwhile as a habitat for migratory birds, it receives international migratory birds every year to overwinter, and also distributes many protected animals.

 

4. All the figures were not clear, and some data did not contain error bars.

Respond: Thank you for your reminder. We have improved the picture quality in the original text. The pollutant content is a spatial interpolation map，however, the broken line and the histogram are both an evaluation result index rather than a content, so that there were no error bars.

 

 

 

 

5. Did the authors carry out the quality control and assurance anlalysis throughout the experiments and how?

Respond: Thank you for your advice. In the process of sample collection, we collected 3 samples from each of the 10 points in the surface sediments of Wanghu Lake. In the process of experimental analysis, two parallel samples were set up for three samples at each point. Therefore, there are 9 samples for each index at each point during the test.

 

 

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

The document details the collection and analysis of surface sediments from Lake Wanghu, with a particular focus on assessing concentrations of nutrients, organic matter and heavy metals. In order to improve its overall consistency, improvements should be made in the following key areas:

Firstly, the executive summary should accurately present the main findings of the study, providing a concise yet comprehensive overview. With regard to the introduction, it is necessary to clearly articulate the purpose of the study and explicitly state its objectives, setting out a clear research direction.

With regard to pollution assessment, the methods used need to be further developed and elaborated. Both the criteria and the methodology for assessing pollution need to be specified in order to guarantee transparency and reproducibility. References and detailed information on the methodologies used should be added to enhance the credibility of the study and facilitate a deeper understanding.

The analysis and interpretation of the results can be strengthened by comparison with recent references. This will provide context and highlight the importance of the results within the current body of knowledge.

In the conclusion, additional context should be provided to explain why pollution is more severe in the north-west and lighter downstream. This will provide a better understanding of regional variations in pollution levels. In addition, it is essential to explore the practical applications of the study results, particularly in the context of pollution control in Lake Wanghu. 

Author Response

Dearexpert,

Thank you for taking the time to reading our article and put forward many meaningful suggestions and reminders, these suggestions and reminders help us to further improve our article. Our responses to your suggestions are as follows:

Firstly, the executive summary should accurately present the main findings of the study, providing a concise yet comprehensive overview. With regard to the introduction, it is necessary to clearly articulate the purpose of the study and explicitly state its objectives, setting out a clear research direction.

Respond: Thank you for your advice. We modified the abstract and the introduction respectively. In the part of abstract, we clarify the main findings of the study and give an overview. And in the part of introduction, the objectives and purpose of the study are clarified. ( P2-3, L88-106 ).

 

With regard to pollution assessment, the methods used need to be further developed and elaborated. Both the criteria and the methodology for assessing pollution need to be specified in order to guarantee transparency and reproducibility. References and detailed information on the methodologies used should be added to enhance the credibility of the study and facilitate a deeper understanding.

Respond: Thank you for your reminder. We have improved the pollution assessment method in part of 2.2. Add the corresponding information as much as possible to improve the credibility of the text.

 

The analysis and interpretation of the results can be strengthened by comparison with recent references. This will provide context and highlight the importance of the results within the current body of knowledge.

Respond: Thank you for your advice. In the original text, we have appropriately added the latest references to strengthen the analysis and interpretation of the results. And summarizes the previous research on the Wanghu lake.

 

 

 

 

 

 

In the conclusion, additional context should be provided to explain why pollution is more severe in the north-west and lighter downstream. This will provide a better understanding of regional variations in pollution levels. In addition, it is essential to explore the practical applications of the study results, particularly in the context of pollution control in Lake Wanghu.

Respond: According to your advice, we have revised the conclusion and provided corresponding support for the conclusion. According to the results of this study, we believe that the reduction of internal pollution and the control of external pollution should be carried out for the pollution of TP, Hg and Cd in Wanghu lake. It is necessary to take the northwest and central parts of the lake as the key areas for pollution control and remediation. ( P14, L442-455 )

 

 

 

 

 

 

 

Round 2

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

Accept.

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

The overall structure of the manuscript is very simple, and there are only 10 sampling points, which is too small and lacks representativeness for a lake area of 204.95 km2. Especially for sampling point w5, there is a significant difference between it and adjacent sampling points. The text cannot accurately explain whether the data is caused by sampling errors or something else, which needs to be verified. The detailed comments are as follows. In order to increase the depth of the text, it is recommended to add a method for identifying the source of pollutants to explain the reasons for the discussion section, rather than citing information from other rivers to explain the reasons for river pollution in the region, which is too farfetched.

1. The best pattern in the last paragraph of the introduction is what kind of experimental design and research methods you use to explain those assumptions and predictions, and thus what kind of contribution you make through the manuscript.

2. Section 2.1 can supplement basic data such as precipitation, temperature, and evaporation to facilitate readers' understanding of the environmental situation in the region. In addition, the explanation in the discussion was that the impact of urban population sewage, aquaculture, etc. was mentioned. Please supplement the location of the city and the distribution of aquaculture in this section, as well as the greening situation around the lake.

3. In the part of 2.2. Clarify the sampling time and sampling point coordinates, and supplement the detailed process and quantity of sample collection.

4. The standards used in Tables 3 and 4 should be supplemented with references. Similarly, all standards used below need to be supplemented with references.

5. In the part of 2.4. Add basic information about using the software, such as country, etc.

6. The distance between sampling point 5 and 9.7.6 is relatively close, but the variation of sampling point 5 is significant. The author needs to clarify whether the data at sampling point 5 is caused by sampling errors or real data. This will also be emphasized in the subsequent discussion.

7. In the lines of 269-273. Explain that organic pollutants may be related to aquatic plants, but the results section shows that the organic matter content in the center of the lake is also high. Please explain the reason.

8. In the lines of 281-282. Explanation: The research area is a national wetland forest park. So, as you explained earlier, the increase in the discharge of domestic sewage into the lake may be the cause of pollution. Is there a contradiction between the two? Please consider giving an explanation.

9. The explanation in Table 8 is more appropriate in the results section.

 

  

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editor,

Thanks for the opportunity to review the manuscript entitled “Distribution and pollution evaluation of nutrients, organic matter and heavy metals in surface sediments of Wanghu Lake 3 in the middle reaches of the Yangtze River, China”. The paper qualifies the title and scope of the study; however, this manuscript is not ready for publication yet. Below, I have listed some major weaknesses that need to be addressed.

* The abbreviation must be introduced the first time it is used in the paper, e.g., RI, Igeo, etc.

* The study area section is poorly cited. There are often statements with no reference.

* The results section must be improved (statistical analysis).

* Please re-check the conclusion. The conclusion is a direct presentation of the results without any indication of implications drawn from the findings, put detail of any limitations of this study, describe implications of this study and provide recommendations for future perspectives.

 

* L87, P 2: There seems to be a mistake in the area unit.

* In every table and figure always show the units of the parameters.

* Please provide the original source in the table caption (cf. tables 2,3,4 and 7).

Comments on the Quality of English Language

English should be checked. There are some typos and grammatical errors in the text.

Reviewer 3 Report

Comments and Suggestions for Authors

The results presented in this paper are indeed very interesting, especially in the context of pollution assessment in the surface sediments of Wanghu Lake. The comprehensive analysis of organics, nutrients, and heavy metals has been methodically conducted. I thoroughly enjoyed reading this manuscript. From a reviewer's perspective, the manuscript holds promise for publication without any alterations.

Comments on the Quality of English Language

Few minor changes