Distribution of Groundwater Hydrochemistry and Quality Assessment in Hutuo River Drinking Water Source Area of Shijiazhuang (North China Plain)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The study investigated 160 groundwater samples in the Hutuo River Drinking Water Source Area in North China to characterize the distribution of groundwater hydrochemistry and associated controlling factors using the hydrogeological and multivariate analysis, and the quality assessment. The findings of the study are helpful for understanding the geochemical status of the groundwater and for protecting and managing the groundwater in the area. The article is interesting and of scientific values. However, some problems in the current manuscript need to be revised.

 

1. The abstract should be reorganized to illustrate the significance and the novelty of this study. Authors are suggested to tell the main and key findings of the present study in the Abstract Section.

 

2. Please add as a sentence or two in Introduction to recap how your study differs from what has already been done in the literature to ascertain the contributions more strongly.

 

3. Please verify if the scale in Figure 1 is correct? And authors are suggested to add the scale in the lower left corner illustration.

 

4. Line Please add more details for HCO₃⁻ and CO₃²⁻ testing in "2.2. Sample collection and analysis".

 

Line 130-135: The authors should provide a detailed information on the software used for principal component analysis (PCA).

 

Line 140: Please write the formula for SAR according to standard specifications.

 

Line 158-169: What are the advantages of the EWQI method compared to traditional evaluation methods? It is recommended to strengthen the research and discussion on the significance of the  EWQI classification.

 

Please carefully review the entire manuscript, many ion valence states are missing.

 

Line 189: The authors should note the criteria used for “Allowable Limits” values in Table 1.

 

Line 189: Please verify whether the "%" in Table 1 should be retained.

 

Line306-308: You write: “…, there are 49 samples with a concentration of NO₃⁻ higher than the maximum permissible limit of the groundwater quality standard grade III limits of the People’s Republic of China (20 mg/L).” I noticed that the concentration range of NO₃⁻ is 1.79~104mg/L, with an average concentration of 17.23mg/L. The concentration of NO₃⁻ in grade III limits of the standard for groundwater quality in China (20 mg/L) is calculated in NO₃−N, now you need to verify whether 49 samples have indeed exceeded the allowable limit.

 

In the Conclusion Section, it would be valuable to add suggestions to policymakers or local authorities based on the study's findings.

Comments on the Quality of English Language

English Language should be revised throughout the manuscript to avoid minor grammatical errors and word typing mistakes in the manuscript.

Author Response

Dear Reviewers,

Thanks very much for taking your time to review this manuscript. I really appreciate all your comments and suggestions! Please find my itemized responses in below and my revisions/corrections in the re-submitted files.

Thanks again!

Responses to Reviewers

Responses to Reviewer #1

General Comments: The study investigated 160 groundwater samples in the Hutuo River Drinking Water Source Area in North China to characterize the distribution of groundwater hydrochemistry and associated controlling factors using the hydrogeological and multivariate analysis, and the quality assessment. The findings of the study are helpful for understanding the geochemical status of the groundwater and for protecting and managing the groundwater in the area. The article is interesting and of scientific values. However, some problems in the current manuscript need to be revised.

Response: Thank you very much for your insightful review. The provided comments contribute to further polish the finding and innovation of our research. We’ve addressed the concerns you raised in the revision of our manuscript (presented in red color in manuscript with changes), as explained below.

 

 

Comment 1: The abstract should be reorganized to illustrate the significance and the novelty of this study. Authors are suggested to tell the main and key findings of the present study in the Abstract Section.

Response: We appreciate the reviewer’s professional comment. We haven’t conveyed the novelty and key findings of this study in the original version. Accordingly, we have rewritten the “Abstract”. In the current version, the significance and main findings of this study are illustrated. In detail, the revised part (Lines 16-17, 25-30, and 31-33) is as follows:

Lines 16-17: “However, there are few studies focused on the groundwater chemistry evolution over the drinking water area.” is added.

Lines 25-30:” The principal component (PC) analysis translates the hydrochemical components into five PCs, which represent the rock-water interaction and agricultural return, redox environment, geogenic sources, the utilization of agricultural fertilizer, and the weathering of aluminum silicates and dissolution of carbonates, respectively.” are refined into “Five principal components separated from the principal component (PC) analysis represent the rock-water interaction and agricultural return, redox environment, geogenic sources, the utilization of agricultural fertilizer, and the weathering of aluminum silicates and dissolution of carbonates, respectively.”

Lines 31-33:” The potential salinity assessment indicated the presence of high salt content in groundwater, more than 70% of the samples are not recommended for irrigation. EWQI assessment are demonstrated the groundwater has satisfactory quality and is suitable for drinking” are refined into “More than 70% of the samples are not recommended for irrigation due to the presence of high salt content in groundwater. EWQI assessment demonstrates the quality of the groundwater is good.”

 

 

Comment 2: Please add as a sentence or two in Introduction to recap how your study differs from what has already been done in the literature to ascertain the contributions more strongly.

Response: We have added the difference between our study and the previous literature. In detail, the revised part (Lines 97-98) is as follows:

“However, there are few studies focused on groundwater chemistry evolution on the scale of drinking water area.”

 

 

Comment 3: Please verify if the scale in Figure 1 is correct? And authors are suggested to add the scale in the lower left corner illustration.

Response: The original scale shows the scale of the whole country or North China Plain wrongly. The scale is verified and modified based on the study area, and a digital scale is added as shown in Figure 1 (Line 132).

Figure1. Geographical map of the study area.

 

Comment 4: Line Please add more details for HCO3− and CO32− testing in "2.2. Sample collection and analysis".

Response: We appreciate the reviewer’s careful review and apologize for this oversight. We have added the detection method of HCO₃^- and CO₃^2- in part 2.2. Sample collection and analysis. The revised part (Lines 165-166) is as follows:

“HCO₃^- and CO₃^2- were determined by titration method (Method for Analysis of Groundwater Quality, DZ/T0064.49-2021) using an acid burette.”

 

 

Comment 5: The authors should provide a detailed information on the software used for principal component analysis (PCA).

Response: We appreciate the reviewer’s careful review and apologize for this oversight. We have added detailed information on the software used for principal component analysis (PCA). The revised part (Lines 176-177) is as follows:

“The PCA and Pearson correlation are conducted through IBM SPSS Statistics 24.”

 

 

Comment 6: Line 140: Please write the formula for SAR according to standard specifications.

Response: We wrote the formula for SAR mistakenly, we have written the formula as shown in Line 183 as shown below:

“  ”

 

Comment 7: Line 158-169: What are the advantages of the EWQI method compared to traditional evaluation methods? It is recommended to strengthen the research and discussion on the significance of the  EWQI classification.

Response: The importance of the EWQI method is added in Lines 63-69.

Lines 63-69: “Numerous indices are developed to evaluate water pollution. Among them, the water quality index (WQI) is one of the most widely used indices to determine the overall groundwater quality(Fadel et al., 2021). The combination of entropy weights and the conventional WQI called the entropy water quality index (EWQI) is proposed, it can improve the reliability of the assessment results(Egbueri et al., 2020). EWQI has been used by numerous studies for water quality assess-ment(Masood et al., 2022; Naik et al., 2022).”

 

Comment 8: Please carefully review the entire manuscript, many ion valence states are missing.

Response: We have added all the missing ion valence states, you can find them in the revised manuscript.

 

Comment 9: Line 189: The authors should note the criteria used for “Allowable Limits” values in Table 1.

Response: We have added the criteria used for “Allowable Limits” values in Table 1, the values of grade III standards in the groundwater quality standard limits of the People’s Republic of China are employed in our study. The revised part (Lines 238-239) is as follows:

“a Allowable Limits represent the values of grade III standards in the groundwater quality standard limits of the People’s Republic of China.”

 

 

Comment 10: Line 189: Please verify whether the "%" in Table 1 should be retained.

Response: We appreciate the reviewer’s careful review and apologize for the wrong writing, the “%” has been deleted.

 

Comment 11: Line306-308: You write: “…, there are 49 samples with a concentration of NO₃⁻ higher than the maximum permissible limit of the groundwater quality standard grade III limits of the People’s Republic of China (20 mg/L).” I noticed that the concentration range of NO₃⁻ is 1.79~104mg/L, with an average concentration of 17.23mg/L. The concentration of NO₃⁻ in grade III limits of the standard for groundwater quality in China (20 mg/L) is calculated in NO₃−N, now you need to verify whether 49 samples have indeed exceeded the allowable limit.

Response: Thank you for your suggestion. The data presented in the table is ammonia nitrogen (measured in N), nitrite (measured in N) actually, we marked them mistakenly in the original manuscript. What we measured are NO₂^-−N and NO₃^-−N, we have changed the expression in the current manuscript, you can find them in the Table 1 and the Lines 258-259.

 

 

Comment 12: In the Conclusion Section, it would be valuable to add suggestions to policymakers or local authorities based on the study's findings.

Response: According to your suggestion, we added the advice for policymakers or local authorities. The revised part (Lines 476-478) is as follows:

“Hence, the high concentrations of salinity and nitrate need to be monitored, and a groundwater pollution warning system is suggested to be established on this basis.”

 

Comments on the Quality of English Language

English Language should be revised throughout the manuscript to avoid minor grammatical errors and word typing mistakes in the manuscript.

Response: Thanks for your helpful advice. We have carefully checked the manuscript and corrected the errors accordingly. The typical modifications are as follows:

• Line 13: “in” has been revised to “of”
• Line 15: “is” has been revised to “are”
• Lines 18-21: “to characterize the distribution of groundwater hydrochemistry and associated controlling factors using the hydrogeological and multivariate analysis, and the quality assessment was conducted by the entropy-weighted water quality index (EWQI).” has been revised to “the spatial distribution of groundwater chemistry and related controlling factors are analyzed using the hydrological and multivariate analysis.”
• Lines 71-77: “Groundwater is not only an important source of drinking water for people in Shijiazhuang City but also the key resource for agricultural development (Lu et al., 2008). However, with the development of urbanization and industrialization, increasing pollution emissions take place, and the quantity and quality of groundwater are threatening (Gao et al., 2021).” has been revised to “Groundwater is the dominant source of drinking and irrigation water in Shijiazhuang (Lu et al., 2008). However, the quantity and quality of groundwater are threatened with the development of urbanization and industrialization (Gao et al., 2021).”
• Line 87: “transforming” has been revised to “transformed”
• Line 103: “and their comparison with” has been revised to “based on”
• Line 117: “rainfall” has been revised to “precipitation”
• Line 142: “analyses” has been revised to “analysis”
• Line 172: “were extracted” has been revised to “are calculated”
• Line 173: “were” has been revised to “are”
• Line 226: “revealed” has been revised to “reveal”
• Line 245: “diverged” has been revised to “diverges”
• Lines 255-256: “surpasses” has been revised to “surpass”
• Line 257: “is” has been revised to “are”
• Line 272: “were” has been revised to “are”
• Line 282: “insinuates” has been revised to “imply”
• Lines 295-296: “the groundwater all falls in the rock dominance area” has been revised to “most of the groundwater samples concentrate in the rock dominance area”
• Lines 298-299: “suggesting” has been revised to “indicating”
• Lines 315-316: “which indicates that Ca²⁺ and SO₄^2- do not mainly come from the dissolution gypsum” has been revised to “which indicates that dissolution gypsum is not the main origin of Ca²⁺ and SO₄^2-”
• Line 350: “Spearman correlation” has been revised to “The Pearson correlation coefficient”
• Line 398: “extensive” has been revised to “over-used”
• Line 405: “in” has been revised to “of”
• Line 415: “showed” has been revised to “shows”
• Line 421: “are above” has been revised to “exceed”
• Lines 446-447: “One groundwater sample was found PS value as high as 17” has been revised to “PS value of a groundwater sample reaches 17”

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In my opinion, the study investigates an important and topical issue, the hydrochemical assessment of groundwater in Hutuo river drinking water source area. The results may be of international interest, so the article could valuable addition to the literature, however the article need to be improved significantly.

The authors are advised to make modifications, corrections and additions, as listed below:

 

Abstract:

-        Line 15-18. Add the year/period of sampling

-        what is the reason for the contradiction that 70% of the samples are unsuitable for irrigation due to high salinity, but are suitable for drinking? Please explain and modify or reformulate accordingly. Statement in lines 184, 306 etc. also contradict this.

 

Keywords

The authors could add more keywords e.g. “EWQI” - “multivariate analysis”, and consider to modify the keyword “water sources area”

 

Introduction

This part need to be revised extensively, since it does not give a deep and comprehensive view of the issue investigated. It provides only very general information about groundwater pollution and measurements. Please give more detailed insight to the topic.

Moreover the literature review is extremely short only two paragraphs, the third is about the study area and research goals.

International literature review is completely missing, only Chinese studies are presented. It is essential to review the existing and current finding of similar studies, not only made in china.

Line 36-37. ‘The hydrochemical composition characteristic of groundwater is controlled by sedimentary conditions and human activities.’ This is very general pleas give more information about the forms of human impacts of groundwater and use several international examples. You can see following article:

Environmental Hazards of an Unrecultivated Liquid Waste Disposal Site on Soil and Groundwater. https://doi.org/10.3390/w14020226

 

Also important to reflect the used methods, like statistical analysis, WQI in other studies.

 

Line 45-46. Reformulate, since this information are not only useful for your study area.

Line 50-52. This is very important, but very general statement. Please describe the environmental status and the findings of other studies about this area.

You could add also some hypothesises at the end of this chapter.

 

Materials and Methods.

Lines 80-81. ‘The maximum temperature of the study area is 42.7 ℃., and the lowest is -24.5 ℃, with an average annual temperature of 13 ℃.’

I don’t really understand these values. 42.7°C is that maximum of what? Normally we use average values of the months. So these values are not saying to much, and may be some extreme values. Please modify it accordingly.

Line 88-92. Please explain the meaning of the terms first and second level protected area. For international readers may not be obvious. What environmental measures come with these levels?

Line 85. “The topography is low” once again a very general statement, pleas add exact details to this.

Figure 1. I don’t see the location of the monitoring wells, please modify it, or add a new map. As I see, your study area does not only belongs to the North China Plain, what is the name of the surrounding are? Please indicate in the map. Also indicate the name of the city in the south, and the river.

Lines 101-102. “Samples were collected from private wells with sampling depths below 0.5 m.”

Sampling depth from the water level or from the ground? Please also provide information about the groundwater level in the study area. Did you measure it?

Why did you not measure Ammonium? This is key parameter in water quality assessment. Also phosphate is very important, but this is also not included, why?

 

Results

Table 1. You could add the upper and lower quartile values to each parameter.

The authors present the results of the Spearman correlation, but it is not mentioned in the materials and methods, please add information to the relevant subchapter.

Moreover in Figure 5. you write about Pearson correlation. Pleas clarify which did you use. Also add the results of the normality tests, and the chosen correlation method according to this.

In Figure 5.b. The correlation values are not readably, please modify. You can divide it into two figures, so you will be able the enlarge it.

 Figure 6. Important diagram, please provide references in the text for the interpration and to the design of the chart.

 

The discussion is missing. The own results should be evaluated and compared with the international literature.

 

3.4. Groundwater Quality Assessment part is very weak, and does not support the study very well.

Even the authors stat in line 356 “These results demonstrate that only using limited parameters cannot estimate the real groundwater quality comprehensively”

The problem may arise also because you did not included important parameters. And did not consider Ammonium and phosphate for example. This is the researchers responsibility to include the proper parameters, and may not the fault of the index method. Also can be an addition the your country use sometimes higher limits than the international standars. Like Nitrite, international standard is 0.5, your standard is 1 mg/L.

So I suggest to modify, or remove, or see other studies and compare. You can try other more easy water quality indicators.

 

Conclusion

Need to be modified according the modifications suggested before, especially after reconsideding the result of the EWQI.

 

My overall evaluation is, that the manuscript needs major scientific revisions.

Comments on the Quality of English Language

Minor modifications are needed.

Author Response

Dear Reviewers,

Thanks very much for taking your time to review this manuscript. I really appreciate all your comments and suggestions! Please find my itemized responses in below and my revisions/corrections in the re-submitted files.

Thanks again!

 

Responses to Reviewers

Responses to Reviewer #2

General Comments: In my opinion, the study investigates an important and topical issue, the hydrochemical assessment of groundwater in Hutuo river drinking water source area. The results may be of international interest, so the article could valuable addition to the literature, however the article need to be improved significantly.

The authors are advised to make modifications, corrections and additions, as listed below:

Response: Thank you so much for the valuable suggestions, which contribute to further polish the finding of our research. We’ve addressed the concerns you raised in the revision of our manuscript (presented in red color), as explained below.

Comment 1: Abstract: Line 15-18. Add the year/period of sampling.

Response: The sampling time is added in Lines 17-18, the revised part (Lines 17-21) is as follows:

“In this study, total of 160 groundwater samples were collected in November 2021, to characterize the spatial distribution of groundwater hydrochemistry and associated related controlling factors are analyzed using the hydrological and multivariate analysis. using the hydrogeological and multivariate analysis, and the quality assessment was conducted by the entropy-weighted water quality index (EWQI).”

Comment 2:  What is the reason for the contradiction that 70% of the samples are unsuitable for irrigation due to high salinity, but are suitable for drinking? Please explain and modify or reformulate accordingly. Statement in lines 184, 306 etc. also contradict this.

Response: The expression is wrong in the original, the EWQI assessment cannot indicate the applicability of drinking water, hence we have reformulated the corresponding expression. In detail, the revised part (Lines 30-33) is as follows:

Lines 30-33: “The potential salinity assessment indicated the presence of high salt content in groundwater, mMore than 70% of the samples are not recommended for irrigation due to the presence of high salt content in groundwater. EWQI assessment are demonstrated demonstrates the quality of the groundwater is good has satisfactory quality and is suitable for drinking.”

Comment 3: Keywords. The authors could add more keywords e.g. “EWQI” - “multivariate analysis”, and consider to modify the keyword “water sources area”

Response: The original version of these keywords cannot illustrate the highlights of the manuscripts. We have revised the keywords as shown in Lines 37-38.

Lines 37-38: “Keywords: Groundwater quality; Hydrochemistry; Multivariate analysis; Water sources area; North China Plain”

 

 Comment 4: Introduction. This part needs to be revised extensively, since it does not give a deep and comprehensive view of the issue investigated. It provides only very general information about groundwater pollution and measurements. Please give more detailed insight to the topic.

Moreover the literature review is extremely short only two paragraphs, the third is about the study area and research goals.

International literature review is completely missing, only Chinese studies are presented. It is essential to review the existing and current finding of similar studies, not only made in china.

Line 36-37. ‘The hydrochemical composition characteristic of groundwater is controlled by sedimentary conditions and human activities.’ This is very general pleas give more information about the forms of human impacts of groundwater and use several international examples. You can see following article:

Environmental Hazards of an Unrecultivated Liquid Waste Disposal Site on Soil and Groundwater. https://doi.org/10.3390/w14020226

 Also important to reflect the used methods, like statistical analysis, WQI in other studies.

 Line 45-46. Reformulate, since this information are not only useful for your study area.

Line 50-52. This is very important, but very general statement. Please describe the environmental status and the findings of other studies about this area.

You could add also some hypothesises at the end of this chapter.

 

Response: According to your suggestions, we have refined the introduction.

1. One paragraph is added to illustrate the current findings of similar studies and the used methods. In detail, the revised part is as follows:

Lines 43-46: “80% of human diseases are induced by water based on the World Health Organization (Mao et al., 2022). The hydrochemical composition characteristic of groundwater is controlled by sedimentary conditions and human activities.”

Lines 56-69: “The chemical evolution assessment is important for the establishment of suitable management policies and groundwater quality improvement. The hydrochemical composition characteristic of groundwater is controlled by sedimentary conditions and human activities(Mester et al., 2022). However, it is difficult to figure out the contributions of geogenic processes and anthropogenic activities. Many analytical methods (multivariate statistical analysis, hydrogeochemical facies, binary diagrams, and correlation analysis, etc.) are used to characterize the evolution processes(Abu Salem et al., 2022; Tiwari et al., 2019; Zhang et al., 2022). Numerous indices are developed to evaluate water pollution. Among them, the water quality index (WQI) is one of the most widely used indexes to determine the overall groundwater quality(Fadel et al., 2021). The combination of entropy weights and the conventional WQI called the entropy water quality index (EWQI) is proposed, it can improve the reliability of the assessment results(Egbueri et al., 2020). EWQI has been used by numerous studies for water quality assessment(Masood et al., 2022; Naik et al., 2022).”

2. More information about the forms of human impacts of groundwater is confirmed using the international examples, the revised part is as follows:

“The hydrochemical composition characteristic of groundwater is controlled by sedimentary conditions and human activities(Mester et al., 2022).”

Mester T., Szabo G., Sajtos Z., Baranyai E., Szabo G., Balla D. Environmental Hazards of an Unrecultivated Liquid Waste Disposal Site on Soil and Groundwater. Water 2022, 14.

3. The importances of the used methods (i.e. EWQI) are added in Lines 63-69.

“Numerous indices are developed to evaluate water pollution. Among them, the water quality index (WQI) is one of the most widely used indices to determine the overall groundwater quality(Fadel et al., 2021). The combination of entropy weights and the conventional WQI called the entropy water quality index (EWQI) is proposed, it can improve the reliability of the assessment results(Egbueri et al., 2020). EWQI has been used by numerous studies for water quality assessment(Masood et al., 2022; Naik et al., 2022).”

4. We have reformulated the sentence since this information is not only useful for our study area. In detail, the revised part is as follows:

Lines 53-55: “The results can provide a hydrochemical background for protecting the groundwater source of the North China Plain and the other places.”

 

5. We have added the current research situation of groundwater pollution in the Hutuo River Basin, the revised part is added in Lines 82-84.

“Human activities lead to dramatical increase of the groundwater NO₃^- concentration in pluvial fans of the Hutuo River, which reaches 124.4 mg/L(Zhang et al., 2018).”

 

6. The existing research deficiencies are improved in Lines 97-98.

“However, there are few studies focused on groundwater chemistry evolution on the scale of drinking water area. And tThe hydrochemistry, origin analysis, and quality assessment of the groundwater in the Hutuo River Drinking Water Source Area have not been investigated comprehensively.”

 

Comment 5: Materials and Methods. Lines 80-81. ‘The maximum temperature of the study area is 42.7 ℃., and the lowest is -24.5 ℃, with an average annual temperature of 13 ℃.’

I don’t really understand these values. 42.7°C is that maximum of what? Normally we use average values of the months. So these values are not saying to much, and may be some extreme values. Please modify it accordingly.

Response: The statements about the maximum and the lowest temperature are meaningless, we have reformulated the description as shown below:

Lines 113-114: “The maximum temperature of the study area is 42.7 ℃., and the lowest is -24.5 ℃, with an average annual temperature of the study area is of 13 ℃.”

Comment 6：Line 88-92. Please explain the meaning of the terms first and second level protected area. For international readers may not be obvious. What environmental measures come with these levels?

 

Response: Thanks for the valuable suggestions, the meaning of the terms first and second level protected area are listed below. We have added the corresponding explanation in the current version of the manuscript (Lines 125-128).

Lines 125-128: “According to the Technical Specification for Classification of Drinking Water Source Protection Areas of China (HJ 338-2018), the sewage outlets, the cultivation and stocking of poultry and livestock are prohibited in the first-grade protection zone.”

 

First-level protection zone: The core area that needs to be strictly restricted is designated with the water intake as well as the center, to prevent direct pollution of the water intake by human activities and ensure the water quality safety of the water intake. Within the first level protected area, it is prohibited to build or expand construction projects unrelated to water supply facilities and water source protection; It is prohibited to discharge sewage into the water area, and the sewage outlets that have been set up must be dismantled; No dock unrelated to water supply needs shall be set up, and ships are prohibited from docking; Prohibit the establishment of oil depots; Prohibiting the cultivation and stocking of poultry and livestock, and strictly controlling cage farming activities.

 

Second-level protection zone: A key area designated outside the first level protection zone to prevent the direct impact of pollution sources on the water quality of drinking water sources and ensure the water quality of the first level protection zone for drinking water sources, which requires strict control. Within the second level protection zone: it is not allowed to build or expand construction projects that discharge pollutants into water bodies. The original sewage outlet must reduce the amount of sewage discharge to ensure that the water quality in the protected area meets the prescribed water quality standards; It is prohibited to establish docks for loading and unloading garbage, feces, oil, and toxic substances.

Quasi-protected area: It is designated outside the secondary protected area to conserve water sources, control the impact of pollution sources on the water quality of drinking water sources, and ensure the water quality of the secondary protected area for drinking water sources. It is an area that requires the implementation of total water pollutant control and ecological protection.

Comment 7: Line 85. “The topography is low” once again a very general statement, pleas add exact details to this.

Response: The expression about the topography is not accurate, we have modified the sentence as shown in Lines 118-119.

Lines 118-119: “The topography is low in the east and relatively high in the west part, with a slope of approximately 0.5~1.0 ‰.”

 

Comment 8: Figure 1. I don’t see the location of the monitoring wells, please modify it, or add a new map. As I see, your study area does not only belongs to the North China Plain, what is the name of the surrounding are? Please indicate in the map. Also indicate the name of the city in the south, and the river.

Response: The original map hasn’t marked the location of the monitoring wells; we have modified the geographical map. The city and county to which the study area belongs to is added. Besides, the names of the surrounding city and the river are added as shown in Figure 1 (Line 132).

 

Figure 1. Geographical map of the study area.

 

Comment 9: Lines 101-102. “Samples were collected from private wells with sampling depths below 0.5 m.” Sampling depth from the water level or from the ground? Please also provide information about the groundwater level in the study area. Did you measure it?

Response: The expression is not accurate. The sampling depth is from the water table. According to the geological survey data in November 2021, the shallow groundwater level is buried at a depth of 10-35m, and the groundwater flow generally moves from northwest to southeast. We have added the relevant information in the current manuscript as shown in Lines 138-140.

Lines 138-140: “Samples were collected from private wells with sampling depths below 0.5 m from the water table. The shallow groundwater table is buried at a depth of 10-35 m.”

 

Comment 10: Why did you not measure Ammonium? This is key parameter in water quality assessment. Also phosphate is very important, but this is also not included, why?

Response: The ammonia nitrogen in all the groundwater samples was not detected in our testing, hence we did not pay much attention on the ammonia in this study. We are sorry for the missing monitoring data for phosphorus, we will pay attention to phosphorus in future research.

Comment 11: Results. Table 1. You could add the upper and lower quartile values to each parameter.

Response: We have added the upper and lower quartile values of each parameter in Table 1.

Table 1. Statics of chemical parameters of groundwater (unit: mg/L, except pH).

Parameters	Max	Min		Mean		SD	CV	Low quartile	upper quartile	Allowable Limitsa	Percentage exceeding the standard
pH	8.20	6.92	7.49		0.17		0.02	7.39	7.59	6.5-8.5	0.00
TH	1668.00	204.00	551.48		200.72		0.36	427.00	629.00	450.00	71.25
TDS	2371.00	271.00	747.29		284.70		0.38	574.00	872.00	1000.00	13.75
Fe2+	0.33	0.00	0.01		0.03		6.57	0.00	0.00	0.30	0.63
Na+	154.00	8.87	39.50		19.65		0.50	28.40	45.20	200.00	0.00
Al3+	0.05	0.00	0.01		0.01		1.09	0.00	0.01	0.20	0.00
Mn2+	0.07	0.00	0.00		0.01		2.56	0.01	0.00	0.10	0.00
Zn2+	2.44	0.00	0.05		0.21		3.80	0.04	0.03	1.00	0.63
As3+	0.00	0.00	0.00		0.00		1.38	0.00	0.00	0.01	0.00
F-	0.62	0.05	0.26		0.10		0.37	0.20	0.32	1.00	0.00
SO42-	552.00	11.00	191.84		93.03		0.48	141.00	238.00	250.00	20.00
Cl-	404.00	8.98	72.54		50.75		0.70	43.90	82.90	250.00	2.50
NO3--N	104.00	1.79	17.23		13.27		0.77	7.65	22.40	20.00	30.63
NO2--N	1.55	0.00	0.01		0.12		8.58	0.00	0.01	1.00	0.63
Ca2+	528.00	64.60	161.41		62.26		0.39	122.00	183.00	-	0.00
Mg2+	97.00	9.68	36.59		14.32		0.39	28.60	42.30	-	0.00
K+	23.60	0.36	2.15		2.19		1.02	0.97	2.60	-	0.00
CO32-	6.00	0.00	0.04		0.47		0.08	0.00	0.00	-	0.00
HCO3-	578.00	186.00	315.86		68.88		4.59	258.00	360.00	-	0.00

 

^a Allowable Limits represent the values of grade III standards in the groundwater quality standard limits of the People’s Republic of China.

 

Comment 12: The authors present the results of the Spearman correlation, but it is not mentioned in the materials and methods, please add information to the relevant subchapter.

Response: We haven’t conveyed the methods of the Pearson correlation in the original version of Materials and Methods, the information about the Pearson correlation is added in Lines 176-177.

 

Lines 176-177: “The PCA and Pearson correlation are conducted through IBM SPSS Statistics 24.”

 

Comment 13: Moreover in Figure 5. you write about Pearson correlation. Pleas clarify which did you use. Also add the results of the normality tests, and the chosen correlation method according to this. In Figure 5.b. The correlation values are not readably, please modify. You can divide it into two figures, so you will be able the enlarge it.

Response: The details about the Pearson correlation and the normality tests are added in Lines 356-358. We apologized for the definition of the original figure 6. In the current, we have enlarged the figures as shown below.

 

Figure 6. The Pearson correlation coefficient of major geochemical parameters. The correlations with p-values <0.05, and 0.01 are shown with * and **, respectively. r= . Except for HCO₃^-, all the parameters have passed the normality tests.

 

Comment 14: Figure 6. Important diagram, please provide references in the text for the interpration and to the design of the chart. The discussion is missing. The own results should be evaluated and compared with the international literature.

Response: The interpretation and the discussion about this chart are insufficient. We have added the relevant discussion as shown in Lines 377-385:

 

Lines 377-385: “The correlation between NO₃^-/Na⁺ and Cl^-/Na⁺ makes a distinction of nitrate sources between agricultural activities and urban sewage, different NO₃^- sources have different NO₃^-/ Cl^- ratios(Amiri et al., 2022). As shown in Figure 67, the values of NO₃^-/ Cl^- vary from 0.002 to 0.38, the relatively low NO₃^-/ Cl^- and elevated Cl^- suggest shows that  NO₃^- in groundwater is are significantly affected by the combination of both, but aAgricultural activities play the dominant role in exert a controlling position on the hydrochemistry formation process of groundwater(Huang et al., 2022). A combination of agricultural components and communal effluent is in accordance with the dense population and farmland in the study area.”

Comment 15: 3.4. Groundwater Quality Assessment part is very weak, and does not support the study very well.

Even the authors stat in line 356 “These results demonstrate that only using limited parameters cannot estimate the real groundwater quality comprehensively”

The problem may arise also because you did not included important parameters. And did not consider Ammonium and phosphate for example. This is the researchers responsibility to include the proper parameters, and may not the fault of the index method. Also can be an addition the your country use sometimes higher limits than the international standars. Like Nitrite, international standard is 0.5, your standard is 1 mg/L.

So I suggest to modify, or remove, or see other studies and compare. You can try other more easy water quality indicators.

Response: Thank you for your suggestion. Based on previous research, we have selected important water quality parameters from the groundwater quality standards. It is not realistic to consider all parameters comprehensively, so we can only consider as many parameters as possible for evaluation. In order to assist in the management of groundwater in the Hutuo River water source area, we have selected Class III standards from China's groundwater quality standards in this study, the contribution can provide a basis for the establishment or optimization of groundwater quality/quantity monitoring and management. There is a lack of introduction about the entropy water quality index, which makes it difficult to demonstrate its rationality and importance. Therefore, we have added the corresponding introduction are added in Lines 63-69.

“Numerous index are developed to evaluate water pollution. Among them, the water quality index (WQI) is one of the most widely used index to determine the overall groundwater quality(Fadel et al., 2021). The combination of entropy weights and the conventional WQI called the entropy water quality index (EWQI) are proposed, it can improve the reliability of the assessment results(Egbueri et al., 2020). EWQI has been used by numerous studies for water quality assessment(Masood et al., 2022; Naik et al., 2022).”

 

Comment 15: Conclusion. Need to be modified according the modifications suggested before, especially after reconsidering the result of the EWQI.

Response: We have improved the Conclusion as shown below:

Lines 456-480: “In this study, hydrogeological and multivariate analyses are used to characterize the distribution of groundwater hydrochemistry and associated controlling factors over the Hutuo River Drinking Water Source Area. The concentration of NO₃^- overpasses the permissible limit for grade III of national standards in the groundwater quality standard limits in 30.63% of the 160 samples. The NO₃^- concentration of the samples lower than grade III of national standards is 30.63%. The TH of 71.25% of the 71.25% groundwater samples exceeded the national limit. Piper diagram indicates that the groundwater types belong to Ca-HCO₃ (78.1%), mixed Ca-Mg-Cl (20%), and Ca-Cl (1.9%). In the majority of the samples, HCO₃ and alkaline earth metals (Ca²⁺ and Mg²⁺) are the main anions and cations, indicating the possibility of an ion exchange process, weathering of silicates, carbonates, and the dolomite in groundwater. Graphical and binary diagrams indicate that the water-rock interaction plays a crucial role that influences the formation of groundwater hydrochemistry, including the dissolution of halite, gypsum, and carbonated rocks, the weathering of silicate rocks, and ion exchange dissolution. The principal component (PC) analysis transforms the chemical components into five PCs, which represent the rock-water interaction and agricultural return, redox environment, geogenic sources, the utilization of agricultural fertilizer, and the weathering of aluminum silicates and dissolution of carbonates, respectively. The groundwater in the Hutuo River Drinking Water Source Area is classified into good suitable for drinking according to the EWQI method, but the relatively high concentration of salinity issues should be considered further discussed when used as irrigation water. Hence, the high concentrations of salinity and nitrate need to be monitored, and a groundwater pollution warning system is suggested to be established on this basis. The study may provide scientific support for sustainable groundwater management and pollution protection in Shijiazhuang City (North China Plain) and elsewhere other similar places.”

 

My overall evaluation is, that the manuscript needs major scientific revisions.

Comments on the Quality of English Language

Minor modifications are needed.

 

Response Thanks for your helpful advice. We have carefully checked the manuscript and corrected the errors accordingly. The typical modifications are as follows:

• Line 13: “in” has been revised to “of”
• Line 15: “is” has been revised to “are”
• Lines 18-21: “to characterize the distribution of groundwater hydrochemistry and associated controlling factors using the hydrogeological and multivariate analysis, and the quality assessment was conducted by the entropy-weighted water quality index (EWQI).” has been revised to “the spatial distribution of groundwater chemistry and related controlling factors are analyzed using the hydrological and multivariate analysis.”
• Lines 71-77: “Groundwater is not only an important source of drinking water for people in Shijiazhuang City but also the key resource for agricultural development (Lu et al., 2008). However, with the development of urbanization and industrialization, increasing pollution emissions take place, and the quantity and quality of groundwater are threatening (Gao et al., 2021).” has been revised to “Groundwater is the dominant source of drinking and irrigation water in Shijiazhuang (Lu et al., 2008). However, the quantity and quality of groundwater are threatened with the development of urbanization and industrialization (Gao et al., 2021).”
• Line 87: “transforming” has been revised to “transformed”
• Line 103: “and their comparison with” has been revised to “based on”
• Line 117: “rainfall” has been revised to “precipitation”
• Line 142: “analyses” has been revised to “analysis”
• Line 172: “were extracted” has been revised to “are calculated”
• Line 173: “were” has been revised to “are”
• Line 226: “revealed” has been revised to “reveal”
• Line 245: “diverged” has been revised to “diverges”
• Lines 255-256: “surpasses” has been revised to “surpass”
• Line 257: “is” has been revised to “are”
• Line 272: “were” has been revised to “are”
• Line 282: “insinuates” has been revised to “imply”
• Lines 295-296: “the groundwater all falls in the rock dominance area” has been revised to “most of the groundwater samples concentrate in the rock dominance area”
• Lines 298-299: “suggesting” has been revised to “indicating”
• Lines 315-316: “which indicates that Ca²⁺ and SO₄^2- do not mainly come from the dissolution gypsum” has been revised to “which indicates that dissolution gypsum is not the main origin of Ca²⁺ and SO₄^2-”
• Line 350: “Spearman correlation” has been revised to “The Pearson correlation coefficient”
• Line 398: “extensive” has been revised to “over-used”
• Line 405: “in” has been revised to “of”
• Line 415: “showed” has been revised to “shows”
• Line 421: “are above” has been revised to “exceed”
• Lines 446-447: “One groundwater sample was found PS value as high as 17” has been revised to “PS value of a groundwater sample reaches 17”

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have improved the manuscript, and the work can, in principle, eventually be published. There are further minor issues that the authors will need to address beforehand.

The geological background of the article is a little weak. If possible, could the authors add geological and hydrogeological conditions in the study area?

Groundwater quality evaluation is the focus of this paper, but in the “3.Results and Discussion” section, the EWQI only occupies a small part, and the connection between other parts and EWQI should be strengthened.

Please carefully check the text and picture layout of the entire manuscript to avoid some small errors. (1) Figure 4a lacks ion valence states; (2) The font color in Figure 7 is inconsistent.

Comments on the Quality of English Language

Non

Author Response

Responses to Reviewer1

Comments: The authors have improved the manuscript, and the work can, in principle, eventually be published. There are further minor issues that the authors will need to address beforehand.

Response: Thank you for your careful review and recognition, we’ve addressed the concerns you raised in the revision of our manuscript (presented in red color in the manuscript with changes), as explained below.

 

Comment 1: The geological background of the article is a little weak. If possible, could the authors add geological and hydrogeological conditions in the study area?

Response: We’ve added the geological and hydrogeological conditions of the study area as shown in Lines 115-121:

Lines 115-121: “The survey area belongs to the top and middle sections of the Hutuo River alluvial fan in the Ziya River system. It is divided into the hydrogeological structure zoning of fissure karst and the hydrogeological structure zoning of loose rock pore aquifer within a depth of 120 meters. Fissure karst water is distributed in the northwest of the survey area and is a hidden fissure karst water. Loose rock pore water is distributed throughout the region, and the main water source for the Hutuo River system groundwater type water source is the second water bearing rock group of loose rock pore water.”

 

Comment 2: Groundwater quality evaluation is the focus of this paper, but in the “3.Results and Discussion” section, the EWQI only occupies a small part, and the connection between other parts and EWQI should be strengthened.

Response: We have added the connection between EWQI and the above part as shown in Lines 378-381:

Lines 378-381: “The agricultural pollution sources may cause serious pollution to regional groundwater, and the exceeding of several water quality parameters indicates that the groundwater quality in the Hutuo River Drinking Water Source Area needs appropriate assessment.”

 

Comment 3: Please carefully check the text and picture layout of the entire manuscript to avoid some small errors. (1) Figure 4a lacks ion valence states; (2) The font color in Figure 7 is inconsistent.

Response: We have added the ion valence states in Figure 4a as shown below:

 

Figure 4. Relationship between the concentration of a Cl vs. Na⁺, b Ca²⁺ vs. SO₄^2-, c Ca²⁺ vs. HCO₃^-, d (Ca²⁺ + Mg²⁺) vs. (HCO₃^-+SO₄^2-), e (K⁺ + Na⁺ - Cl^-) vs. (Ca²⁺ + Mg²⁺ - HCO₃^- - SO₄^2-).

And the colors in Figure 7 are modified into consistent as shown below:

 

Figure 7. The binary diagram of NO₃^-/Na⁺ v.s. Cl^-/Na⁺ (as molar ratios).

Thanks again!

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

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. 

Figure 6. Do not use equation in the title.

I recommend the manuscript for publication.

 

Author Response

Responses to Reviewer2

Comments: 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. Figure 6. Do not use equation in the title. I recommend the manuscript for publication.

Response: Thank you for your careful review and recognition, we have deleted the equation listed in Lines 332-333, and the equation is moved to Lines 164-165:

Lines 164-165: “The Pearson correlation is calculated by:

r= .”

Thanks again!

Author Response File: Author Response.pdf