Identification of Priority Pollutants in Groundwater: A Case Study in Xiong’an New Region, China
Round 1
Reviewer 1 Report
Dear Authors,
This article can be an interesting and useful article. But in some cases it is confusing and not enough explanations are provided. By making the following changes I agree to accept it.
1- On page 2 of the first paragraph, “In addition to pollution by human activities, natural geological environment also can cause the deterioration of groundwater quality [21].” more examples of geological effects on underground water can be provided: for example, the effect of deep injection of gaseous CO2 with geological origin can both destroy the aquifer and cause instability in the aquifer and the occurrence of risks such as karst development:
You can see the following:
https://www.sciencedirect.com/science/article/pii/S1750583619304463
https://link.springer.com/chapter/10.1007/978-3-319-45465-8_25
https://link.springer.com/article/10.1007/s12665-021-09763-8
2- “ underground water pollution” It is not very common, please change to groundwater pollution.
3- In the materials and methods, before the description of the methodology, a summary of the study area should be presented along with a suitable geological map, a land use map to show possible pollutants, the boundary of the area's aquifers and sampling locations. Please, Figure 2 changed and shown before the current Figure 1.
4- “Ranking in multiple indicator system is more preferred and it is a popular way to use the arithmetic sum of indicator scores”: This method has been used by various researchers in other groundwater issues such as assessing the vulnerability or groundwater sustainability:
Please see these works:
https://link.springer.com/article/10.1007/s00267-021-01424-7
https://link.springer.com/article/10.1007/s10040-022-02512-6
5- “ natural component and unnatural component according to the sources of pollutants.” It seems better to be man-made (or anthropogenic) instead of unnatural.
6- It seems that it is better to place supplemental material in appropriate places and in the main text of the article and it makes it easier for the reader to understand the material.
7- Who provided the formulas used in this research? If it is by different researchers, the appropriate reference should be mentioned, and if it is suggested by the authors, it should be mentioned.
8- Please describe the details of the classification of Figure S1 in the form of a table and the method used.
9- This section 3.1.1. Groundwater quality assessment is confusing and the explanation is not enough. What is the role of said formulas in these categories?
10- Please combine figures S2 to S5 as a single figure and bring it in the main text.
11- The results of this section "3.2.2. Assessment of natural components" are not understandable for the reader. Please state in a table the results of the calculations with the mentioned methods and degrees.
12- Figures 4 and 5 can be merged together. Please see the figure below:
Comments for author File: 
Comments.pdf
Author Response
- On page 2 of the first paragraph, “In addition to pollution by human activities, natural geological environment also can cause the deterioration of groundwater quality [21].” more examples of geological effects on underground water can be provided: for example, the effect of deep injection of gaseous CO2 with geological origin can both destroy the aquifer and cause instability in the aquifer and the occurrence of risks such as karst development:
You can see the following:
https://www.sciencedirect.com/science/article/pii/S1750583619304463
https://link.springer.com/chapter/10.1007/978-3-319-45465-8_25
https://link.springer.com/article/10.1007/s12665-021-09763-8
Response: Thank you for the advice. The example has been provided in the manuscript, and relevant literature is also cited in the manuscript.
- “ underground water pollution” It is not very common, please change to groundwater pollution.
Response: Thank you for the advice. The “underground water” has been replaced with “groundwater” in the manuscript.
3.In the materials and methods, before the description of the methodology, a summary of the study area should be presented along with a suitable geological map, a land use map to show possible pollutants, the boundary of the area's aquifers and sampling locations. Please, Figure 2 changed and shown before the current Figure 1.
Response: Thank you for the advice. Figure 2 has been optimized accordingly. As for the placement of relevant content, the paper focuses on the establishment of methodologies for the identification of priority pollutants in groundwater, so we introduced the method first, and then applied the method to an area of interest. We feel as if this is the most appropriate way to present our methods and results.
- “Ranking in multiple indicator system is more preferred and it is a popular way to use the arithmetic sum of indicator scores”: This method has been used by various researchers in other groundwater issues such as assessing the vulnerability or groundwater sustainability:
Please see these works:
https://link.springer.com/article/10.1007/s00267-021-01424-7
https://link.springer.com/article/10.1007/s10040-022-02512-6
Response: Thanks for your sharing. Part of the research results have been included in the manuscript.
- “ natural component and unnatural component according to the sources of pollutants.” It seems better to be man-made (or anthropogenic) instead of unnatural.
Response: Thank you for the advice. The term “artificial components” used at the beginning has been changed to“unnatural component”，which corresponds to “natural component”.
- t seems that it is better to place supplemental material in appropriate places and in the main text of the article and it makes it easier for the reader to understand the material.
Response: Thank you for the advice. In order to simplify the article, part of the content was placed in the supplementary materials. To make the content of the article easier to understand, we have made corresponding adjustments according to your suggestions, and the changes have been marked in the article.
- Who provided the formulas used in this research? If it is by different researchers, the appropriate reference should be mentioned, and if it is suggested by the authors, it should be mentioned.
Response: Thank you for the reminder. The formula source has been added and marked in the paper.
- Please describe the details of the classification of Figure S1 in the form of a table and the method used.
Response: Thank you for the advice. The current water quality assessment is based on the single factor method of Groundwater Quality Standard (GB/T 14848-2017) in China, intended to represent the current groundwater quality status of the Xiongan New Area. Figure S1 has been optimized with a table of exceedance points and indicators and is referenced in the main text of the article. The classification method is also now included in the manuscript.
9.This section 3.1.1. Groundwater quality assessment is confusing and the explanation is not enough. What is the role of said formulas in these categories?
Response: Thank you for your question. In 3.1.1 Groundwater quality assessment, only formula 1 was used. According to Groundwater Quality Standard (GB/T 14848-2017), Cij is the monitoring concentration of each index for the 60 samples, and Bj is the Standard limit value for Class Ⅲ water of each index. Formula 2~4 were used in the following parts 3.2 and 3.3.
10.Please combine figures S2 to S5 as a single figure and bring it in the main text.
Response: Thank you for the advice. Figure S2 to S5 has been grouped together and added in the manuscript.
- The results of this section "3.2.2. Assessment of natural components" are not understandable for the reader. Please state in a table the results of the calculations with the mentioned methods and degrees.
Response: Thank you for the advice. To make the content of the article easier to understand. Related charts are placed in the main text. The calculation method is also explained and marked.
- Figures 4 and 5 can be merged together.
Response: Thank you for your suggestions and sharing. Figures 4 and 5 were merged together as suggested.
Author Response File: 
Author Response.docx
Reviewer 2 Report
It is an interesting manuscript. This subject addressed is within the scope of the journal. Appropriate revisions should be undertaken in order to justify the recommendation for publication. For readers to quickly catch your contribution, it would be better to highlight significant difficulties and challenges and your original achievements to overcome them, in a more straightforward way in the abstract and introduction. The syntax and grammar of the text should be improved. It may need the attention of someone fluent in the English language to enhance readability. The Introduction section should be improved by adding references dealing with contamination issues in groundwater. The Introduction section needs a short paragraph at the beginning to discuss elements distribution issues in groundwater worldwide. I suggest a major revision for this manuscript. Additional comments are included in the attached .pdf file.
Regards,
Comments for author File: Comments.pdf
Author Response
- Additional comments are included in the attached PDF file.
Response: Thank you for your kind suggestion and advice. The comments were all carefully studied and modified as suggested.
- the key word repetitions. Also included in the title.
Response: Thank you for the reminder. The key word has been replaced with“index classification”and “toxicity quantification”.
- The Introduction section should be improved by adding references dealing with contamination issues in water resources. The Introduction section needs a short paragraph at the beginning to discuss water quality issues in water bodies worldwide. More papers related to this paragraph will be beneficial for the paper. Some references dealing with trace elements contamination would be helpful in this context, e.g.:
1) Forecasting discharge rate and chloride content of karstic spring water by applying the Levenberg–Marquardt algorithm. Environmental Earth Sciences, 80, 404, https://doi.org/10.1007/s12665-021-09685-5
2) Origin of Groundwater Salinity in the Draa Sfar Polymetallic Mine Area Using Conservative Elements (Morocco). Water 2023, 15, 82. https://doi.org/10.3390/w15010082
Response: Thank you for sharing. Relevant literature is cited in the manuscript.
- Line 67~69“There is limited data on the priority pol-67 lutants in groundwater. In this study, 60 groundwater samples were collected from the 68 Xiong’an New Region and 156 substances were analyzed.” describes the applied methodology and should be moved to the appropriate sub-section.
Response: Thank you for your suggestion. The description has been integrated into Section 2.2.
- Please add the coordinates, the scale bar and north symbol in Figure 2.
Response: Thank you for your suggestion. Figure 2 has been optimized.
- The discussion section in the present form is relatively weak and should be strengthened with more details and justifications.
Response: Thank you for your kind suggestion. The related charts are put together and place to appropriate position in the main text to support the corresponding description. The calculation method and assessment results are also included in the article.
- The conclusions section is not very successful because it is mostly presentation of methodology and results. Only the most important findings of this study should be presented here which may be interesting for the international audience.
Response: Thank you for your comments. The conclusions have been modified as follows:
Sixty groundwater samples were collected from the Xiong’an New Region. According to the analysis result, 87% of the water can be used as sources of drinking water, and 13% of the water can be used as drinking water only after proper treatment. In addition, 54 of the 60 samples had an ILCR between 10-6~10-4, which is indicative of a potential carcinogenic risk given the concentration of organic pollutants.
An effective screening method for the evaluation of groundwater pollution in the Xiong’an New Region, China was constructed. The degree of pollution and the toxicity level were both taken into consideration in the multiplication method and the weighted summation method, and the assessment results were compared. The unwanted effects caused by the large variation of pollutant evaluation parameters can be effectively avoided when using the weighted summation method. Using the results from comparing different combination of weights, it was more appropriate to use the weighted summation method with weights of 0.5, 0.25, and 0.25 for toxicity, total, and median pollution degrees, respectively. Using the selected screening method to evaluate the 60 groundwater samples, the top 10 pollutants were Benzo[a]pyrene, Hexachlorobenzene, As, Se, Atrazine, Benzo[b]fluoranthene, Ni, Mo, Ti, and Naphthalene. These pollutants require more attention in future pollutant discharge control.
- for the references, please follow the authors instructions given by the journal.
Response: Thank you for your kind suggestion. The references have been modified to conform to the journal format and the references were cited with reference numbers.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors have to carefully check again all my initial comments. Moreover, they have revised Figure 2 by removing two maps instead of adding to them the scale bar. They have to place again the initial figure and simply follow my instructions. Another point is that the conclusions section is not very successful. It still contains some parts which are the description of the methodology. The authors have to revise again this section.
Author Response
- they have revised Figure 2 by removing two maps instead of adding to them the scale bar. They have to place again the initial figure and simply follow my instructions.
Response: Thank you for your instructions. The Figure 2 has been optimized .
- the conclusions section is not very successful. It still contains some parts which are the description of the methodology. The authors have to revise again this section.
Response: Thank you for your comments. The conclusions have been modified as follows:
An efficient priority ranking list is required to focus on the compounds in groundwater that are predicted to be the most hazardous to the environment. The main objective of this study was to develop a screening method for major pollutants based on groundwater pollution assessment. By using this method, the evaluation indexes were divided into natural and man-made components, and pollution evaluation was realized based on the apparent background value and inspection limit, respectively. Additionally, the mean and median of pollution degree were selected, and combined with the toxicity parameters of each component, the product method and hierarchical scoring method were used for coupling calculation. According to the calculated score, the main pollutants in groundwater could be sorted.
Assessment results by using the multiplication method and the weighted summation method were also compared. The unwanted effects caused by the large variation of pollutant evaluation parameters can be effectively avoided when using the weighted summation method. Using the results from comparing different combination of weights, it was more appropriate to use the weighted summation method with weights of 0.5, 0.25, and 0.25 for toxicity, total, and median pollution degrees, respectively. Ten pollutants including Benzo[a]pyrene, Hexachlorobenzene, As, Se, Atrazine, Benzo[b]fluoranthene, Ni, Mo, Ti, and Naphthalene, were selected as priority pollutants in Xiong’an New Region by using the selected screening method, which means more concern is required to strengthen pollution prevention and control of these pollutants.
Author Response File: Author Response.docx
Round 3
Reviewer 2 Report
It has reached the level of acceptance for publication in Water.
