Hydrogeochemical Characteristics and Formation Mechanisms of Groundwater Around Ji’an City, Southern China

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

A necessary and useful tool for water managers would be a map highlighting areas with high risk of anthropogenic pollution: areas affected by agricultural activities, livestock farming, mining, urban waste, industrial activities. The severity of anthropogenic impact could be illustrated by different colors, depending on the effect on groundwater. Please develop section 3.4 “Implications for sustainable groundwater management” accordingly.

Author Response

Comment 1: A necessary and useful tool for water managers would be a map highlighting areas with high risk of anthropogenic pollution: areas affected by agricultural activities, livestock farming, mining, urban waste, industrial activities. The severity of anthropogenic impact could be illustrated by different colors, depending on the effect on groundwater. Response 1: We sincerely appreciate the reviewer’s insightful comments. We fully agree that a map highlighting areas with a high risk of anthropogenic pollution would be an extremely valuable tool for water managers. In response to the comment, we have incorporated such a map into our study based on PCA results (Fig.10). The map clearly identifies areas impacted by anthropogenic activities, including agricultural operations, livestock farming, mining, urban waste disposal, and industrial activities. To effectively convey the severity of the anthropogenic impact on groundwater, we have employed a color-coding system. Different colors represent different levels of anthropogenic impact (Fig.10a), with darker shades indicating more severe effects on groundwater quality. This visual representation allows water managers to quickly and easily identify high-risk areas and prioritize their management and remediation efforts (lines: 568-587). Comment 2: Please develop section 3.4 “Implications for sustainable groundwater management” accordingly. Response 2: Thank you for pointing out the need to further develop section 3.4. We have taken this comment seriously and have significantly expanded and enhanced this section. In the revised section 3.4, we first summarize the implication of hydrochemical and multivariate statistical analyses in this study. These implications cover a wide range of aspects, such as aquifer-specific protection strategies, policy recommendations for regulating agricultural and industrial activities to minimize groundwater contamination, and strategies for improving the public awareness to protect groundwater resources. We have also discussed examples of groundwater sustainable management policies implemented in different regions worldwide including WFD in the European Union, SDWA in the United States, and integrated water management approach in the Singapore. We believe that this revised section now offers a more comprehensive and in-depth analysis of the implications for sustainable groundwater management, and would provide valuable guidance for policymakers, water managers, and other stakeholders (Lines: 591-652).

Reviewer 2 Report

Comments and Suggestions for Authors

The abstract should be more precise about the specific methods used and how the findings are novel or contribute to existing knowledge.

In introduction add clearer articulation of the research gap. For example, how does this study uniquely contribute to groundwater studies in the region or globally?

Tighten the first few paragraphs to avoid redundancy.

The methodology section should be improved by adding more detail about data quality checks or any limitations faced during sample collection.

Also, mention the specific statistical methods used to analyze the data (e.g., detailed description of PCA or Gibbs plot interpretation).

The results section should be more structured. For example, breaking down findings per aquifer type and discussing their implications separately may help readers follow the logic.

The discussion often gets bogged down in technical details (e.g., exact concentrations of ions). Condense the technicalities and focus on how these findings advance understanding or have practical implications.

Some results, like the contribution of PCA or the impact of anthropogenic activities, need clearer explanations and implications for groundwater management.

The Piper plot should have more explanatory context, particularly regarding the zones mentioned.

The conclusion is a bit weak. It should not only summarize the findings but also provide more actionable recommendations. For example, how should these results influence groundwater management practices? Are there specific policy implications?

Some sections, particularly the results and discussion, can be more concise. Avoid overloading with excessive data without linking them to the overall findings or implications.

Add more summary statistics or comparison charts that directly relate the findings to previous studies or expected trends.

Expand on the policy or management implications of the findings in the conclusion. Highlight how this research can guide future studies or inform groundwater resource management strategies.

Author Response

Comment 1. The abstract should be more precise about the specific methods used and how the findings are novel or contribute to existing knowledge.

Response 1: We must thank the reviewer for the constructive comments. We have revised the abstract to provide more precise details about the specific methods used and to highlight the novelty and contributions of our findings. In the revised abstract, we have explicitly mentioned the combination of methods employed, including multivariate statistical analysis (PCA), piper plot visualization, ion correlation analysis, Gibbs plots, and ion ratio coefficient methods. Additionally, we have clarified how our findings contribute to existing knowledge by emphasizing the distinct hydrogeochemical processes identified in different aquifer systems and the value of the data and methodologies for groundwater research and management in multi-aquifer systems (lines: 20-37).

Comment 2. In introduction add clearer articulation of the research gap. For example, how does this study uniquely contribute to groundwater studies in the region or globally?

Response 2: We much appreciate the reviewer’s valuable feedback. We have carefully revised the Introduction section to more clearly articulate the research gap and the unique contributions of our study.

Specifically, we have highlighted the lack of comprehensive studies on hydrogeochemical processes in multi-aquifer systems within complex geological regions like southern China. Previous research has often focused on single aquifer types or broad assessments, neglecting the differential impacts of natural and anthropogenic factors across diverse aquifer environments (lines: 774-78).

This study addresses the gap by providing a detailed analysis of groundwater chemistry across four major aquifer types in the Ji’an city region, and offering novel insights into spatial and aquifer-specific variations (lines: 89-94).

Comment 3. Tighten the first few paragraphs to avoid redundancy.

Response 3: Done.

Comment  4. The methodology section should be improved by adding more detail about data quality checks or any limitations faced during sample collection. Also, mention the specific statistical methods used to analyze the data (e.g., detailed description of PCA or Gibbs plot interpretation).

Response 4: We agree with the reviewer’s comments. We have revised the Methodology section to provide more detailed information on data quality checks and the specific statistical methods employed (lines: 158-162).

Specifically, we have elaborated on the quality assurance measures implemented during sample collection, including field measurements, sample preservation techniques, and quality control analyses. A more detailed description of the statistical methods has been added, including the use of Piper plots for hydrochemical classification, Gibbs plots for interpreting water-rock interactions, and Principal Component Analysis (PCA) for identifying and quantifying the contributions of natural and anthropogenic factors. The PCA methodology, including varimax rotation and eigenvalue criteria, is now explicitly described (lines: 180-193).

Comment 5. The results section should be more structured. For example, breaking down findings per aquifer type and discussing their implications separately may help readers follow the logic.

Response 5: We thank the reviewer for the valuable suggestion to improve the structure of the Results section. We have carefully revised this section by organizing the findings according to aquifer type, as recommended by the reviewer, to enhance clarity and logical flow. Additionally, we have added a dedicated section on the implications of these variations, highlighting how different aquifer types exhibit distinct vulnerabilities to natural processes and human activities (lines: 204-222, 236-241, 410-420, 449-454, 495-500).

Comment 6. The discussion often gets bogged down in technical details (e.g., exact concentrations of ions). Condense the technicalities and focus on how these findings advance understanding or have practical implications.

Response 6: We must thank the reviewer’s insightful comments which greatly improve the manuscript. We have carefully revised the discussion section to address this concern (lines: 410-420, 449-454, 495-500, 529-534). 

Comment 7. Some results, like the contribution of PCA or the impact of anthropogenic activities, need clearer explanations and implications for groundwater management.

Response 7: We sincerely appreciate the reviewer’s constructive feedback, which has helped us enhance the clarity and practical relevance of our findings. We have thoroughly revised the relevant sections to provide more explicit explanations of the PCA results and their implications for groundwater management, particularly concerning natural processes and anthropogenic impacts (lines: 529-534, 542-547).

Comment 8. The Piper plot should have more explanatory context, particularly regarding the zones mentioned.

Response 8: We greatly appreciate the reviewer’s valuable suggestion, which has prompted us to enhance the clarity and interpretability of the Piper plot in our manuscript. We have provided a detailed explanation of the Piper plot, with a specific focus on the zones depicted and their geochemical significance (lines: 255-262).

Comment 9. The conclusion is a bit weak. It should not only summarize the findings but also provide more actionable recommendations. For example, how should these results influence groundwater management practices? Are there specific policy implications?

Response 9: We sincerely appreciate the reviewer’s insightful comments regarding the conclusions. We agree that the original conclusion lacked sufficient actionable recommendations and policy implications. In response to this feedback, we have significantly revised the conclusion to not only summarize the key findings but also provide detailed and practical suggestions for groundwater management practices and policy-making (See Conclusions).

Comment 10. Some sections, particularly the results and discussion, can be more concise. Avoid overloading with excessive data without linking them to the overall findings or implications.

Response 10: We must thank the reviewer for the comments. We have substantially revised the results and discussion part.

Comment 11. Add more summary statistics or comparison charts that directly relate the findings to previous studies or expected trends.

Response 11: We must thank the reviewer for the constructive comments. We have compared our results to previous ones in the text. Since the revised manuscript is relatively long and already contains 10 Figs. and 4 Tables, we did not add more charts.

Comment 12. Expand on the policy or management implications of the findings in the conclusion. Highlight how this research can guide future studies or inform groundwater resource management strategies.

Response 12: We agree with the reviewer’s comments. The conclusions have been revised according to the comments (See Conclusions).

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors,

 

Please, find  my comments for the manuscript sustainability-3951339 in the document attached, as comments.

Comments for author File: Comments.pdf

Author Response

Comment 1. The authors are suggested to give a more detailed explanation for the both figures (Fig. 2).

Response 1: We must thank the reviewer’s suggestion for a more detailed explanation of Figure 2. We have added more descriptions for Fig. 2 in the text (lines: 118-120, 142-149).

Comment 2. Please include additional details regarding the element determination procedure and the instruments used (model, manufacturer, and country).

Response 2: We sincerely appreciate the reviewer’s insightful comment. We have provided more details regarding the element determination procedures and the instruments used in our study (lines: 118-120, 142-149).

Comment 3. Moreover, a paragraph describing the Quality Assurance/Quality Control (QA/QC) procedures is mandatory to ensure the reliability and reproducibility of the analytical results.

Response 3: We agree with the reviewer. Descriptions on the QA/QC procedures have been added (lines: 163-175).

Comment 4. The authors should include examples of groundwater sustainable management policies implemented in different regions worldwide.

Response 4: We thank the reviewer for this valuable comments. We agree that including examples of groundwater sustainable management policies from different regions worldwide would enrich our discussion and provide a more global perspective on the topic. Therefore, we have introduced several representative examples of groundwater sustainable management policies implemented in different countries including in United States, Europe and Asian (lines: 624-643).

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

I have no further comments. Thank you very much for considering my suggestions.

Your reviewer no.

Reviewer 2 Report

Comments and Suggestions for Authors

Accept