Geochemical Speciation, Ecological Risk and Assessment of Main Sources of Potentially Toxic Elements (PTEs) in Stream Sediments from Nile River in Egypt

Round 1

Reviewer 1 Report

The issue raised by the authors is indeed an important one, and is interesting from both scientific and practical perspectives.

The manuscript is written nicely with detailed methodology and results. However, the manuscript important reconsiderations (specially the introduction and discussion sections) and is not suitable for publication in its present form. I would call for Revisions based on following comments:

1. The introduction does not contain a clear statement of the problem, the relevant literature on the subject, and a proposed approach or solution. The topicality and novelty of the research are not understood from the introduction. It is necessary to bring the reader to the thought of the relevance of this study. There are no literature reviews over the past ten years and findings from other studies to point out the objective and importance of this study. Although we can agree with the authors that there is not enough works on this topic in relation to this river. Nevertheless, this problem is relevant not only for the Nile River. And therefore, there are publications. The literature review refers to the central issue of the paper. The Introduction of the manuscript contains irrelevant information and lacks proper citations. Any peer-reviewed journal paper must have a certain level of literature reviews to justify the contribution of this paper.

2. The conclusion should contain several important scientific results having novelty, future and application in the considered context for the community in globe. And also, how the results obtained can be used not only in science but also in practice. Overall this section requires an in-depth rethink and much further consideration on the results found by the research.

3. The abstract should introduce the reader to the research. The abstract does not convey the content of the paper accurately, though the authors have tried to justify the choice of the topic. We do not see a clear aim of the research. I would recommend that the authors reduce the annotation to 200 words indicate the period of analysis in the abstract, as well as list which research methods were used and some of the conclusions.

The article needs revision.

Author Response

The authors would like to thank the 3 reviewers for theirs thorough reviews and suggestions. They helped improve the quality of the manuscript.

Kind regards,

Reviewer #1:

The issue raised by the authors is indeed an important one and is interesting from both scientific and practical perspectives.

The manuscript is written nicely with detailed methodology and results. However, the manuscript needs important reconsiderations (specially the introduction and discussion sections) and is not suitable for publication in its present form.

Reply: We thank reviewer #1 for his extensive comments and suggestions. Our replies are as follows:

 

1) The abstract should introduce the reader to the research. The abstract does not convey the content of the paper accurately, though the authors have tried to justify the choice of the topic. We do not see a clear aim of the research. I would recommend that the authors reduce the annotation to 200 words indicate the period of analysis in the abstract, as well as list which research methods were used and some of the conclusions.

Replay: Done. The abstract has been completely revised following the suggestions of the reviewer

2) The introduction does not contain a clear statement of the problem, the relevant literature on the subject, and a proposed approach or solution. The topicality and novelty of the research are not understood from the introduction. It is necessary to bring the reader to the thought of the relevance of this study. There are no literature reviews over the past ten years and findings from other studies to point out the objective and importance of this study. Although we can agree with the authors that there is not enough works on this topic in relation to this river. Nevertheless, this problem is relevant not only for the Nile River. And therefore, there are publications. The literature review refers to the central issue of the paper. The Introduction of the manuscript contains irrelevant information and lacks proper citations. Any peer-reviewed journal paper must have a certain level of literature reviews to justify the contribution of this paper.

Reply: Done. As for the abstract, the Introduction has also been completely revised and several new bibliographic references have been added.

3) The conclusion should contain several important scientific results having novelty, future and application in the considered context for the community in globe. And also, how the results obtained can be used not only in science but also in practice. Overall, this section requires an in-depth rethink and much further consideration on the results found by the research.

Replay: Done. The conclusions have been revised trying to highlight the scientific innovations present in the work. I am referring, above all, to the statistical analysis of the data which has allowed us a better and clearer interpretation. Today, in the field of environmental geochemistry, the use of the compositional approach in the statistical analysis of data cannot be ignored. As associate editor of Water (MDPI) and Journal of Geochemical Exploration (Elsevier), I often urge colleagues to use this approach.

Thank you for your review work

Reviewer 2 Report

The manuscript handles with potentially toxic elements in stream sediments from Nile River in Egypt.

In my opinion, the abstract is too long nearly 300 words, the instructions to authors refer 200 as the maximum. In comparison with intro, for example, that has 450 words. In addition, the abstract could have more data numbers.

Section “2.2. Sampling and analysis”:

Insert in what was made the digestion (microwave, plate)? What was the procedure? Also insert all about ICP analysis (like brand?, reagents where they are? Etc….)

Line 195: it´s not clear if the authors used a R package or not.

Why it was named the metals as “potentially toxic elements (PTEs)”?

Author Response

The authors would like to thank the 3 reviewers for theirs thorough reviews and suggestions. They helped improve the quality of the manuscript.

Kind regards,

Reviewer #2:

1) In my opinion, the abstract is too long nearly 300 words, the instructions to authors refer 200 as the maximum. In comparison with intro, for example, that has 450 words. In addition, the abstract could have more data numbers.

Reply: Done. The abstract has been completely revised following the suggestions of the reviewer. The number of words has been shortened and several data have been added.

2) Section “2.2. Sampling and analysis”: Insert in what was made the digestion (microwave, plate)? What was the procedure? Also insert all about ICP analysis (like brand?, reagents where they are? Etc….)

Reply: Done. More information has been added about chemical analyses. The methods used are now well known by the international scientific community and it is useless to dwell too much on them. They do not represent anything new.

3) Line 195: it´s not clear if the authors used a R package or not.

Reply: As specified in the manuscript (line 216): “All statistical analyses were conducted on both databases using the R system for statistical computing”.

4) Why was it named the metals as “potentially toxic elements (PTEs)”?

Reply: As also reported in (Pourret and Hursthouse, 2019) the term metals or heavy metals is not scientifically very correct. Among the studied elements there is, for example, arsenic which is not a metal.

Pourret, O.; Hursthouse, A. It’s time to replace the term “heavy metals” with “potentially toxic elements” when reporting environmental research. Intern. J. Environ. Res. Public Health 2019, 16, 4446. https://doi.org/10.3390/ijerph16224446

Thank you for your review work

Reviewer 3 Report

Please see my comments in the attached file.

Good luck!

Comments for author File: Comments.pdf

Author Response

The authors would like to thank the 3 reviewers for theirs thorough reviews and suggestions. They helped improve the quality of the manuscript.

Kind regards,

Reviewer #3:

1) Abstract: This section can end with some implications of the findings in a broader context. For example, what can others learn from your investigation? How can they apply your findings to their own case studies?

Replay: Done. The abstract has been completely revised following the suggestions of the reviewer.

2) Introduction: the authors should place this work into a broader setting. The literature review does help in this regard. I would suggest the authors to add more conducted studies aimed to investigate heavy metals in water bodies around the world such as:

https://www.tandfonline.com/doi/full/10.1080/26395940.2021.1978868

https://link.springer.com/article/10.1007/s42452-020-03279-9

2) Done. As for the abstract, the Introduction has also been completely revised and suggested bibliographic references have been added.

3) Figure 1. Is it possible to add a new panel showing the land-use in your study area?

Reply: Unfortunately, we could not find this map. It probably does not exist.

4) Line 88: After which river?

Reply: In fact, this issue is somewhat controversial. We have rewritten this sentence as follows: ”With a catchment area of about 3.1 million km² and a length of about 6850 km, it is considered the longest river in the world, contending the primacy with the Amazon River.”

5) Line 171 Need a reference

Replay: We have added the reference

6) Line 183 Please add more description about the TEL, PEL, PEC, TEC. See: https://doi.org/10.2166/nh.2020.160

Reply: Done. See lines 198-204

7) Line 325 Please compare the results with the same studies conducted such as: https://doi.org/10.2166/nh.2020.160

Reply: We thank Prof. Noori for the suggestion. We are preparing a review on this topic where we will compare data from different works. Thank you for reporting this paper to us.

Thank you for your review work

Round 2

Reviewer 1 Report

Dear authors! You have done a lot of work to correct my comments. The issue raised by the authors is indeed an important one, and is interesting from both scientific and practical perspectives. The structure of the article does meet the requirements of the publication (Research Manuscript Sections).

The introduction does contain a clear statement of the problem, the relevant literature on the subject, and a proposed approach or solution. The topicality and novelty of the research are understood from the introduction. The literature review refers to the central issue of the paper, it is quite extensive, relevant and thorough. The review will be of interest to other researchers. I would like to mention that the authors have comprehensively studied the literature on the issue published over the last five years. References are correct. The conclusion is consistent with presented arguments and evidence. The results complete previous results on the matter and are supported by references.

Reviewer 3 Report

Dear Authors;

Thank you for addressing my comments. My suggestion is acceptance. Congratulations.