Risk Assessment of Nitrate Pollution in the Shallow Groundwater of the Mihe Alluvial–Diluvial Fan Based on a DEA Model

Round 1

Reviewer 1 Report

The manuscript needs extensive editing and corrections and is not suitable for publication in the present form.

1. Please explain briefly (or present in a table) the Groundwater Quality Standard for different contaminant limits.
2. Lines 48 - 51: Please mention the authors who used these methods. Don't write "Lots of scholars...." Mention the specific authors who used it.
3. Line 55: HydrUS-1D is wrong. It's HYDRUS-1D or Hydrus-1D.
4. Line 100: What is index IV and V water of nitrate?
5. Line 127: PH value is wrong? It is pH.
6. Line 128-131: "....standard of III water" what does this mean?
7. Line 141: Correction needed in the section heading
8. Ammonia should be written as NH₄⁺, and not NH₄+ as written in the manuscript.
9. Lines 212: the comma (,) is twisted. Please correct.

Author Response

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Reviewer 2 Report

In my opinion, the authors intend to discuss a current topic, however the presentation of the data and structure of the manuscript are not sufficient. Figures are not carefully created, containing serious problems.

The content of the article is very limited, the literature review is extremely incomplete containing only 18 references, almost all of them from China. The authors are advised to complete this part and use more international references.

The materials and methods / results / discussion / conclusions parts are not correct in many cases, since the content of its is mixed:

- Chapter 2.2 Water quality characteristics   contains results, so it would belong to the result part. If these data are not own data why are these not referenced? If these are own data, why are the sampling and analytical measurements not described. Which year/season was the sampling?

- Chapter 3.1 Calculation would belong to the Materials and methods part, sincet he authors does not developed the new model, they are using the DEA model (A.Charnes in 1978).

- In discussion part, it is needed to compare the own results with the literature data, which is missing in this manuscript. So this part is not acceptable.

- Conclusions part contains tables and figures, which is not correct, this part cannot have this content. Also the text belongs mostly to results.

All figures need to be revised and corrected:

Figure 1. Is not informative enough. Overview map is missing: which part of the country. in the legend “water system” is not understandable, it seems to be indicate lakes and rivers, however other rivers in the area are not marked with blue. What is “STREET (TWON)” in the legend? Not town? these are cities as I see.

Figure 2. belongs to the results part, and it has no legend, so what is the meaning of the different symbols?

Figure 3. Title of X axis is wrong because of not careful preparation of the manuscript:

X axis title: (nitrate contentnitrate contentmg/L)

Figure 4 need to be revised. Sampled areas are not part of the interpolations, but unsampled areas (southwest) are part of the map, which is wrong. Authors should remove the unsampled area from the interpolation. Categories are also problematic.

The quality of the paper does not reach the standards of the journal Water. Therefore, my evaluation is: reject.

However the authors are encouraged to resubmit the manuscript after rewriting the manuscript.

Author Response

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Reviewer 3 Report

The paper attempts to assess the risk of groundwater pollution of Mihe Alluvial-diluvial Fan.

The paper seems to be rather chaotic, due to the improper structure.

Groundwater quality and quantity result from many processes, among which precipitation and infiltration are of the highest importance. The latter is shaped by the geological structure of the area. However, there is no geological setting in the paper. The type of groundwater is Mg Hco3, but there is no explanation why?

There is no mention of the sampling period (how many samples were collected and when?).

Both Equations 3 and 4 are methods, not results. Actual results are practically non-existent in the present version of the paper. Please rewrite this section.

The discussion section discusses nothing. There is no reference to other findings. There should be in the introduction section, or after review, presented as conclusions.

On the other hand, the conclusion section presents results. Please revise the section.

The paper is based on very few references, which brings a question of its relevance.

References are presented as superscripts in the manuscript. Please correct this problem.

All symbols in equations should be explained, e.g. d_j, s.t…

Author Response

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Reviewer 4 Report

The evaluated article was prepared at a high substantive and scientific level, based on a well-selected set of source materials. The assumed research goal was basically achieved. The results are well presented in four figures and two tables. However, the conclusions are too general and in large part, together with Table 2 and Fig. 4, essentially constitute research results and should be included in this part of the article. Conclusions should be a brief but concrete summary of two issues: 1. Analysis of the traceability of nitrate pollution in groundwater. 2. Risk grade of nitrate pollution in shallow groundwater.

Author Response

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Reviewer 5 Report

Groundwater pollution with NO3 and other forms of nitrogen is a major problem in the world, and therefore this article can be recommended to be published in the WATER journal, after incorporating the following comments. Below are technical comments on the manuscript.

1. Nitrate pollution risk – calculates figures must be added to the abstract
2. Page 2, lines 86-87 - big difference between evaporation and precipitation, I recommend commenting on and stating where the next water comes from
3. Page 3, line 100. It is necessary to state what the single index IV and V come from. This is also mentioned in the following text. A reader who does not know Chinese standards does not understand this.
4. Page 4, FIG. 1. I recommend adding a schematic picture of China to this picture and indicating where the area under investigation is located.
5. Page 5, chap. 2.2 Water quality .... I consider it necessary to supplement Table 28 with samples of the chemical composition of water. It can be given as a supplementary material. List macro components, selected microcomponents, pesticides and also borehole depth must be in the table. Piper's diagram is nice, but the reader will not learn anything about NO3 ions, which are the main focus of the work. It can be omitted completely when there is a table on the chemical composition of the evaluated waters. Furthermore, I consider it necessary to add to this chapter a map of the distribution of NO3 ions, possibly NH4, NO2 or pesticides.
6. Page 5, chap. 2.3.2 Mathematic model. Did the mathematical model used be developed by the authors or is it taken from the literature? Answer this question.
7. Page 10, FIG. 4. Move to the Results chapter and, if possible, add the general groundwater flow direction.
8. Page 9-10, chap. Conclusion. Finally, add a comparison of the NO3 distribution map with the map of Fig. 4. How they differ and why the Nitration pollution risk map is more appropriate. The conclusion should also be a sentence: We recommend reducing nitrogen fertilizers by at least 40-50% (?), and why.

Author Response

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Round 2

Reviewer 1 Report

Please add the Table (Sheet 1) which you have given in the response to reviewer, to the Introduction section. 

Author Response

Thank you very much for your time and patience in reviewing the manuscript. In the revision of the manuscript, I added this Table in the introduction according to your suggestion, which makes my manuscript look more complete.

Reviewer 2 Report

The authors have significantly modified the content of the article, which has greatly improved the quality of the manuscript. Many of my suggestions have been incorporated into the new version, therefore now the chapters are much better divided, containing the relevant informations, however modifications/clarifications are still needed.

Introduction

The authors have added some references, but it is still mainly dominated by the articles of the own country. In an international article, it is essential, to have a wider view in this topic. The authors discuss the domestic origin of pollution in this section, but in the introduction part this type of source is not presented detailed enough. Point sources can dominate smaller areas especially the area of different cities. It could be also mentioned, what solutions are extisting to reduce point-sours pollution. The authors could cite following article: Assessment of Shallow Groundwater Purification Processes after the Construction of a Municipal Sewerage Network, https://doi.org/10.3390/w13141946

Materials and methods.

The authors state in Lines 144-145 that the depth of groundwater wells varying between 8-40 meters. In shallow groundwater is a very big difference, which can modify the results significantly. Please provide a table, or information regarding this. It is some correlation regarding nitrate content and groundwater depth? water close to the surface is mostly more contaminated than deeper wells.

Therefore spatial analysis may misleading, because differences may occur not because of the location, it is result of the vertical differences.

What is the typical groundwater level? Are all wells belonging to shallow groundwater? If there are different type, interpolation is not possible! Please clarify it!

The other weakness of the study, which is also stated by the authors in the conclusion part, that only 1 sampling took place. This may not enough to have a comprehensive overview of the area. But I can understand that at this step it is not possible to modify.

Figures still need to be corrected.

Figure 1. Please add a coordinate system to the frames. Use Km instead of miles

Figure 2. Please add the unit to the elevation (meter?) Use Km instead of miles. Increase the size of the monitoring well points and ID-s.

Figure 3. It is better, but hard to recognise all the wells, it would maybe help if the wells would categorized, for example southern and northern fells, or deeper/shallower wells. but it is just a suggestion.

Figure 4. There is no figure 4.

Figure 5. Nitrate pollution risk index distribution and nitrate content distribution. Please add unit to nitrate concentration (mg/L). Use Km instead of miles.  Increase the size of the monitoring well points and ID-s. Reduce the decimals it is not necessary to use 5-6 decimals.

My overall evaluation: Major revision

Author Response

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Reviewer 3 Report

The paper has been improved. It may be published in its current version

Author Response

Thank you very much for your recognition of our work and for your time and patience in reviewing the manuscript. Your suggestions are very helpful to the revision of my manuscript.

Reviewer 5 Report

accept

Author Response

Thank you very much for your recognition of our work and for your time and patience in reviewing the manuscript. Your suggestions are very helpful to the revision of my manuscript.

Round 3

Reviewer 2 Report

The authors have revised their manuscript properly, it is now suitable for publication.

In future publications the authors should consider the vertical differences in monitoring wells. I suggest to make a seasonal sampling as well.