Definition of Circulation Conditions and Groundwater Genesis of the Complex Krupaja Hydrogeological Karst System (Eastern Serbia)

Round 1

Reviewer 1 Report

Manuscript mentions the presence of three different karst waters with varying temperatures in close proximity, indicating that they belong to the same karst aquifer but circulate through different levels of karst channels at different depths. The paper also mentions the use of stable isotopes and hydrochemical analyses to determine groundwater ages and understand the genesis and circulation conditions of the karst waters. Overall, the paper focuses on studying the geometry and connections of karst conduits, analyzing groundwater circulation patterns, and investigating the genesis of karst waters in the Krupaja karst system. It utilizes field research, spatial modeling, hydrochemical analyses, and isotopic techniques to gather data and draw conclusions about the karst aquifer and its groundwater resources. However, after incorporating following comments, manuscript may consider for publication:

 

1.         The introduction provides a clear overview of the importance of karst groundwater and the goals of groundwater research. However, it lacks a concise statement of the specific objectives of the study conducted in the Krupaja karst system.

2.         The paper presents a comprehensive analysis of the Krupaja karst system, including stable isotopes, hydrochemical analysis, and spatial modeling. The combination of different research methods strengthens the credibility of the findings.

3.         The identification of three occurrences of karst waters with different temperatures within a short distance is intriguing and raises questions about the factors contributing to this phenomenon. However, the paper does not delve into a detailed discussion of the possible causes or mechanisms behind it.

4.         The paper mentions the development of 3D models for analyzing the distribution and position of karst channels. It would have been beneficial to provide more information about the methodology and techniques used for constructing these models, as well as their limitations and potential applications.

5.         The characterization of the Krupaja groundwater system in terms of circulation, temperature, and age provides valuable insights into the hydrogeological dynamics of the karst aquifer. However, additional discussion on the implications of these findings for water resource management or environmental protection would enhance the practical significance of the research.

6.         The conclusion and discussion section provides a concise summary of the key findings. However, it would benefit from a more detailed interpretation and analysis of the results, including comparisons with existing literature and potential implications for broader karst hydrogeology studies.

7.         The paper acknowledges the influence of various factors on groundwater genesis, such as precipitation, water-rock interactions, and human activities. It would be beneficial to explore these factors in greater depth and discuss their potential implications for water quality and sustainability in the Krupaja karst system.

8.         The inclusion of a schematic overview of the groundwater genesis and circulation in the Krupaja system is useful for visualizing the complex hydrogeological processes. However, more detailed explanations of the different circulation types and their relationships would enhance the understanding of the conceptual model.

9.         The paper mentions the high capacity of the Krupaja Spring to conduct water, but it does not discuss the potential implications of this flow rate for water supply or ecological considerations. Further exploration of the hydrological significance and ecological impacts of such a large discharge would be valuable.

10.      While the paper provides important insights into the Krupaja karst system, it would benefit from a clearer delineation of the study's limitations and uncertainties. Including a discussion of potential sources of error or areas for future research would enhance the scientific rigor of the study.

Overall, the research presented in the paper contributes to the understanding of the Krupaja karst system's hydrogeology. However, further development of some sections, such as the discussion of factors influencing groundwater genesis and the practical implications of the findings, would strengthen the paper's impact and applicability in the field of karst hydrogeology.

 

 

Quality of English Language is OK

Author Response

We would like to thank the Reviewer for his time and pointed out shortcomings and errors, with the aim of improving the quality of paper. We hope that we have been able to answer most of the suggestions. We also revised the English language once again, so that the quality of the paper would be even higher. Below are responses to comments and our corrections

 

1. The introduction provides a clear overview of the importance of karst groundwater and the goals of groundwater research. However, it lacks a concise statement of the specific objectives of the study conducted in the Krupaja karst system.

Thanks to the reviewer for the sent comment. The abstract has been revised and the main specific objectives of the study presented in the paper have been added.

 

2. The paper presents a comprehensive analysis of the Krupaja karst system, including stable isotopes, hydrochemical analysis, and spatial modeling. The combination of different research methods strengthens the credibility of the findings.

Thanks for the positive comment and general analysis of the work.

 

3. The identification of three occurrences of karst waters with different temperatures within a short distance is intriguing and raises questions about the factors contributing to this phenomenon. However, the paper does not delve into a detailed discussion of the possible causes or mechanisms behind it.

We agree with the reviewer's remark and in the last chapter on conclusions and discussion we have added additional explanations related to the genesis and mechanisms.

 

4. The paper mentions the development of 3D models for analyzing the distribution and position of karst channels. It would have been beneficial to provide more information about the methodology and techniques used for constructing these models, as well as their limitations and potential applications.

We fully agree with the reviewer that the presentation of the formation and results of the 3D model, as well as the methodology of model creation, would contribute to the quality of the paper. However, the paper refers to several published journal papers as well as chapters in international monographs that are cited as literary sources, and their repetition would result in a high degree of self-repetition.

 

5. The characterization of the Krupaja groundwater system in terms of circulation, temperature, and age provides valuable insights into the hydrogeological dynamics of the karst aquifer. However, additional discussion on the implications of these findings for water resource management or environmental protection would enhance the practical significance of the research.

We are grateful for the reviewer suggestions and we fully agree that a very important part of the research and future management and use of this source as well as its protection. This is exactly one topic that new research is dealing with and that will probably be published in the near future. For now, this type of research is still in the phase of data collection and analysis.

 

6. The conclusion and discussion section provides a concise summary of the key findings. However, it would benefit from a more detailed interpretation and analysis of the results, including comparisons with existing literature and potential implications for broader karst hydrogeology studies.

Accepted and will be supplemented with reference to similar karst systems within the Beljanica karst massif.

 

7. The paper acknowledges the influence of various factors on groundwater genesis, such as precipitation, water-rock interactions, and human activities. It would be beneficial to explore these factors in greater depth and discuss their potential implications for water quality and sustainability in the Krupaja karst system.

In the conclusion, some ideas for future research and taping of groundwater of higher temperature within the Krupaj karst system are added.

 

 

8. The inclusion of a schematic overview of the groundwater genesis and circulation in the Krupaja system is useful for visualizing the complex hydrogeological processes. However, more detailed explanations of the different circulation types and their relationships would enhance the understanding of the conceptual model.

Accepted and will be supplemented with more detailed explanations.

 

 

9. The paper mentions the high capacity of the Krupaja Spring to conduct water, but it does not discuss the potential implications of this flow rate for water supply or ecological considerations. Further exploration of the hydrological significance and ecological impacts of such a large discharge would be valuable.

Like in comment 5. We are grateful for the reviewer suggestions and we fully agree that a very important part of the research and future management and use of this source as well as its protection. This is exactly one topic that new research is dealing with and that will probably be published in the near future. For now, this type of research is still in the phase of data collection and analysis.

 

 

10. While the paper provides important insights into the Krupaja karst system, it would benefit from a clearer delineation of the study's limitations and uncertainties. Including a discussion of potential sources of error or areas for future research would enhance the scientific rigor of the study.

Overall, the research presented in the paper contributes to the understanding of the Krupaja karst system's hydrogeology. However, further development of some sections, such as the discussion of factors influencing groundwater genesis and the practical implications of the findings, would strengthen the paper's impact and applicability in the field of karst hydrogeology.

Once again, we would like to thank the reviewer comments, which greatly helped to further and better explain the functioning of such a complex karst system through additional explanations in some sections. We hope that with additional clarifications the paper is now much better.

Reviewer 2 Report

This manuscript is acceptable but important revision and improvements are needed.

Please revise your manuscript according to the edits and comments included in the WORD version of the manuscript after my review using review tools.

Comments for author File: Comments.docx

English language needs more attention 

Please see the review as indicated using review tools in WORD version of the manuscript.

Author Response

We would like to thank the Reviewer for his time and pointed out shortcomings and errors, with the aim of improving the quality of paper. We hope that we have been able to answer most of the suggestions. We also revised the English language once again, so that the quality of the paper would be even higher. 

Author Response File: Author Response.docx

Reviewer 3 Report

The groundwater circulation is complex in karst system. The isotopes, hydro-chemistry and ages of groundwater were studied in karst system Krupaja (eastern Serbia). The results and conclusions provide the basis for better understanding the groundwater cycle in karst area. To enhance and improve the scientific and clarity of this manuscript, the comments are shown as follow.

>>lines 159-183. The limits of detection and accuracy of the analysis on isotopes/ions is essential to understand the data and results.
>>Tables 1-6. Check the decimal places/digit of the data. Keep the decimal digit to coincide with the accuracy of the equipment or analysis.
>>Lines 249-268. The Local Isotope Meteoric Line (LIML) is not shown in Figure 5. What is the meaning of LWML KB in figure 5? Generally, LMWL stands for Local Meteoric Water Line.
>>What model was used to calculate the groundwater ages by 3H and 3H/3He? The groundwater recharge process is different since the recharge water flows more rapidly through connected karst openings to discharge at springs and streams than through other types of sedimentary aquifers.

 

Moderate editing of English language maybe required to enhance this manuscript.

Author Response

We would like to thank the Reviewer for his time and pointed out shortcomings and errors, with the aim of improving the quality of paper. We hope that we have been able to answer most of the suggestions. We also revised the English language once again, so that the quality of the paper would be even higher. Below are responses to comments and our corrections

>>lines 159-183. The limits of detection and accuracy of the analysis on isotopes/ions is essential to understand the data and results.

Thanx to reviewer on good perception, still since we are the users of the data that participated in their collection and processing, but not in the performance of laboratory analyzes (the institutes that performed the analyzes are listed in the paper), we are unable to list the technical data of the equipment. All the equipment on which the research was carried out is listed in the paper.

 

Some of limiThe sensitivity of the mass spectrometer is 1×10^-3 A/Torr and 2×10^-4 A/ Torr for argon and helium, respectively. It enables us to detect even 5000 ³He atoms. The resolution of more than 600 at 3 amu allows us to resolve a ³He⁺ peak and H₃⁺/HD⁺ double peak. The tritium concentration of environmental water samples are determined via the mass spectrometric analysis of its daughter, ³He. The pressure sensitivity and hence the systematic error of the measurement of low level helium abundances are eliminated by adding an ultrapure 4He spike to each tritiogenic ³He samples. The 10-20 % of systematic error could be reduced below 2 permil. Besides tritium analyses, noble gases dissolved in groundwater are determined by the mass spectrometer. ³H/³He apparent ages and recharge temperatures can be calculated from the noble gas concentrations and helium isotope ratios. 

>>Tables 1-6. Check the decimal places/digit of the data. Keep the decimal digit to coincide with the accuracy of the equipment or analysis.

Checked

>>Lines 249-268. The Local Isotope Meteoric Line (LIML) is not shown in Figure 5. What is the meaning of LWML KB in figure 5? Generally, LMWL stands for Local Meteoric Water Line.

We thank the reviewer for pointing out the error. Figure 5 is now fixed

 

>>What model was used to calculate the groundwater ages by 3H and 3H/3He? The groundwater recharge process is different since the recharge water flows more rapidly through connected karst openings to discharge at springs and streams than through other types of sedimentary aquifers.

Since it is about circulation through a karst aquifer, the same model was used for calculations within the complex karst system. The method and model used to calculate the groundwater ages by 3H and 3H/3He can be found in literature Palcsu et al. 2010; Papp et al. 2012

The sensitivity of the mass spectrometer used for calculate the groundwater ages is 1×10^-3 A/Torr and 2×10^-4 A/ Torr for argon and helium, respectively. It enables us to detect even 5000 ³He atoms. The resolution of more than 600 at 3 amu allows us to resolve a ³He⁺ peak and H₃⁺/HD⁺ double peak. The tritium concentration of environmental water samples are determined via the mass spectrometric analysis of its daughter, ³He. The pressure sensitivity and hence the systematic error of the measurement of low level helium abundances are eliminated by adding an ultrapure 4He spike to each tritiogenic ³He samples. The 10-20 % of systematic error could be reduced below 2 permil. Besides tritium analyses, noble gases dissolved in groundwater are determined by the mass spectrometer. ³H/³He apparent ages and recharge temperatures can be calculated from the noble gas concentrations and helium isotope ratios.