Hydrochemical Characterisation and Assessment of Groundwater Suitability for Drinking and Irrigation Purposes in Sângeorz-Băi Area, Bistrița-Năsăud County (Romania)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Decision: major revisions

First, I congratulate the authors for their effort

Before definitively adopting this article, I would like the final text to take into account the following remarks and suggestions:

• Reword and rewrite the Abstract section
• Add recent and relevant references to the Introduction section
• Add the figure containing the map of the study area and the sampling points
• Correct Figure 2
• Correct Figure 3
• Comply with the journal template: line 247, line 312, ...
• Reread and correct the texts in paragraph (3.2. Major ions content) and consider Figures 2 and 3
• Reread and correct the Conclusion section

Comments for author File: Comments.pdf

Author Response

Reviewer 1

Before definitively adopting this article, I would like the final text to take into account the following remarks and suggestions:

• Reword and rewrite the Abstract section

Thank you very much for your observation. The abstract has been rewritten. Here is the new version of the Abstract:

" Groundwater quality is a key factor and a critical determinant of public health, agriculture, and socio-economic development, particularly in regions where private wells and mineral springs constitute the primary water sources. This study presents an integrated hydrochemical, radiological, and toxicological assessment of groundwater in the Sângeorz-Băi area, Romania, a spa region where mineral waters hold both therapeutic and economic significance. Samples from mineral springs, the municipal supply system, and private wells were analyzed to evaluate compliance with national and international standards and to assess their suitability for drinking, therapeutic, and agricultural purposes.

The results reveal distinct hydrochemical contrasts between sources. Mineral springs are characterized by elevated salinity, hardness, and Na–HCO₃ facies, whereas the municipal network and private wells are dominated by Ca–HCO₃ facies.  More than half of the private wells exceeded permissible limits for NO₃⁻, NO₂⁻, NH₄⁺, Pb, and Fe, with one well posing a significant nitrite-related health risk. Trace metal analysis indicated localized enrichment in Cu, Fe, and Pb. Radon and radium activities generally complied with regulations, although radium occasionally exceeded the more stringent WHO guidelines. Seasonal variation was minimal, reflecting stable groundwater chemistry. Health risk and irrigation assessments suggest that municipal supply water is largely safe for consumption, while private wells require targeted monitoring and mitigation. Despite elevated Na⁺ and Cl⁻, mineral springs retain therapeutic value under controlled use.

This study provides a replicable framework for groundwater quality assessment in spa regions and offers critical insights for public health protection, sustainable tourism, and agricultural resilience. "

 

• Add recent and relevant references to the Introduction section

The references cited in the Introduction have been updated with more recent and relevant sources

• Add the figure containing the map of the study area and the sampling points?

A map of the study area has been added to the manuscript, and a new co-author has been included. The newly added author contributed to the graphical components of the article.

• Correct Figure 2. Correct Figure 3 

We apologize for this mistake; according to the discussions in the text and the citation of former Figure 2 (now Figure 3) and former Figure 3 (now Figure 4) in the text, the figure titles are correct, but the images themselves should be reversed. We have made an appropriate change to the new version of the manuscript.

• Comply with the journal template: line 247, line 312,

The corrections have been applied throughout the manuscript: ‘Figure 1’ has been used instead of ‘Fig. 1,’ and reference [65] has replaced ‘(Barakat 2011).’

• Reread and correct the texts in paragraph (3.2. Major ions content) and consider Figures 2 and 3

Due to the inversion of former Figure 2 (now Figure 3) and former Figure 3 (now Figure 4), there was confusion in their interpretation. As mentioned above, we have made the necessary changes to former Figure 2 (now Figure 3) and former Figure 3 (now Figure 4). Please let us know if any additional changes are needed in the text in Section 3.2. Major ions content.

• Reread and correct the Conclusion section

Thank you very much for your observation. The conclusions have been rewritten.

Here is the new version of the Conclusions:

"This study provides a comprehensive, multidisciplinary assessment of groundwater quality in the Sângeorz-Băi area, an emblematic spa region of Romania. Private wells, the municipal supply, and mineral springs remain central to drinking water provision, therapeutic practices, and socio-economic development. By integrating hydrochemical, radiological, toxicological, and irrigation suitability analyses, the study yields conclusions of direct relevance to public health, water management, and sustainable regional development.

Groundwater from the municipal network generally complies with regulatory standards. In contrast, more than half of the private wells exceeded permissible limits for NO₃⁻, NO₂⁻, NH₄⁺, Pb, and Fe. One well showed acute nitrite contamination, representing an immediate health risk that requires discontinuation of use. Elevated Pb and Fe levels highlight the vulnerability of aquifers to diffuse agricultural inputs and infrastructure deficiencies. Mineral springs complied with regulatory limits for trace metals and radionuclides, but their high Na⁺ and Cl⁻ concentrations make them unsuitable for continuous consumption. They remain valuable for short-term therapeutic use under medical supervision and retain potential for economic exploitation through bottling. Radiological analyses indicated radon activities below international safety thresholds. Radium occasionally exceeded the stricter WHO guideline, requiring continued monitoring but not indicating immediate health risks.

The findings underscore the dual role of groundwater in the region: a critical source of safe drinking water under regulated conditions, but also a vector of contamination where private wells remain unmonitored. Effective protection requires systematic water quality monitoring, stricter regulation of agricultural practices, infrastructure improvements, and increased community-level risk awareness.

A key limitation of this study lies in the restricted temporal coverage of sampling, which was conducted only twice (autumn 2017 and spring 2018). Although these campaigns provide valuable insights under contrasting seasonal conditions, they do not capture the full extent of seasonal or inter-annual variability in groundwater quality. Long-term monitoring is therefore required to achieve a more comprehensive characterization of temporal dynamics.

In conclusion, this study advances the understanding of groundwater quality in a complex hydrogeological and socio-economic setting. It also provides a replicable framework for groundwater management in spa and rural regions facing similar challenges at the intersection of environment, public health, and sustainable development.”

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

General Assessment
The manuscript addresses the hydrochemical characteristics of groundwater in the Sângeorz Băi area and evaluates its suitability for drinking and irrigation. The topic is highly relevant to Sustainability, as it relates directly to sustainable water resource management, drinking water safety, and agricultural resilience. The dataset is comprehensive, and the methodology combines hydrochemical analysis with suitability indices, which are appropriate for the objectives. However, the manuscript requires substantial revisions to improve clarity, structure, and scientific rigor.
Major Issues
1. The English requires significant improvement. Some sentences are too long or grammatically incorrect. Professional language editing is recommended.
2. The Abstract and Conclusion sections should be more concise and focused on the main findings.
3. Sampling was conducted only twice (autumn 2017 and spring 2018). This is insufficient to capture seasonal or inter-annual variability. The limitation should be explicitly acknowledged.
4. Tables contain excessive information (e.g., Tables 1–4). Consider summarizing with averages and ranges, while moving detailed raw data to supplementary material.
5. The paper would benefit from additional statistical analysis (e.g., PCA, cluster analysis) to better explain controlling factors.
6. The discussion is largely descriptive. Comparative analysis with other European or Carpathian hydrogeological contexts would strengthen the conclusions.
7. The implications for policy and sustainable management should be elaborated. For example, how can authorities address wells exceeding Pb and NO₂⁻ limits?
8. More explicit reference to public health risks and recommendations is needed.
9. Figures (e.g., Piper, Gibbs diagrams) have low resolution. Please improve quality and ensure clarity also in black-and-white print.
10. Figure captions should be more explanatory, including sample numbers and symbols.

Minor Issues
1. Reference formatting does not fully follow Sustainability guidelines. Please check journal style and ensure DOIs are added where available.
2. Typographical errors (e.g., “therapeuthic” → “therapeutic”; “fro drinking” → “for drinking”) should be corrected.
3. The Abstract should be shortened to 200–250 words.

Author Response

 

Reviewer 2

The manuscript addresses the hydrochemical characteristics of groundwater in the Sângeorz Băi area and evaluates its suitability for drinking and irrigation. The topic is highly relevant to Sustainability, as it relates directly to sustainable water resource management, drinking water safety, and agricultural resilience. The dataset is comprehensive, and the methodology combines hydrochemical analysis with suitability indices, which are appropriate for the objectives. However, the manuscript requires substantial revisions to improve clarity, structure, and scientific rigor.

Major Issues

1. The English requires significant improvement. Some sentences are too long or grammatically incorrect. Professional language editing is recommended.

Professional linguistic editing was performed to improve the English.

2. The Abstract and Conclusion sections should be more concise and focused on the main findings.

The abstract and conclusions have been rewritten.

Here is the new version of the Abstract:

" Groundwater quality is a key factor and a critical determinant of public health, agriculture, and socio-economic development, particularly in regions where private wells and mineral springs constitute the primary water sources. This study presents an integrated hydrochemical, radiological, and toxicological assessment of groundwater in the Sângeorz-Băi area, Romania, a spa region where mineral waters hold both therapeutic and economic significance. Samples from mineral springs, the municipal supply system, and private wells were analyzed to evaluate compliance with national and international standards and to assess their suitability for drinking, therapeutic, and agricultural purposes.

The results reveal distinct hydrochemical contrasts between sources. Mineral springs are characterized by elevated salinity, hardness, and Na–HCO₃ facies, whereas the municipal network and private wells are dominated by Ca–HCO₃ facies.  More than half of the private wells exceeded permissible limits for NO₃⁻, NO₂⁻, NH₄⁺, Pb, and Fe, with one well posing a significant nitrite-related health risk. Trace metal analysis indicated localized enrichment in Cu, Fe, and Pb. Radon and radium activities generally complied with regulations, although radium occasionally exceeded the more stringent WHO guidelines. Seasonal variation was minimal, reflecting stable groundwater chemistry. Health risk and irrigation assessments suggest that municipal supply water is largely safe for consumption, while private wells require targeted monitoring and mitigation. Despite elevated Na⁺ and Cl⁻, mineral springs retain therapeutic value under controlled use.

This study provides a replicable framework for groundwater quality assessment in spa regions and offers critical insights for public health protection, sustainable tourism, and agricultural resilience. "

 

Here is the new version of the Conclusions:

"This study provides a comprehensive, multidisciplinary assessment of groundwater quality in the Sângeorz-Băi area, an emblematic spa region of Romania. Private wells, the municipal supply, and mineral springs remain central to drinking water provision, therapeutic practices, and socio-economic development. By integrating hydrochemical, radiological, toxicological, and irrigation suitability analyses, the study yields conclusions of direct relevance to public health, water management, and sustainable regional development.

Groundwater from the municipal network generally complies with regulatory standards. In contrast, more than half of the private wells exceeded permissible limits for NO₃⁻, NO₂⁻, NH₄⁺, Pb, and Fe. One well showed acute nitrite contamination, representing an immediate health risk that requires discontinuation of use. Elevated Pb and Fe levels highlight the vulnerability of aquifers to diffuse agricultural inputs and infrastructure deficiencies. Mineral springs complied with regulatory limits for trace metals and radionuclides, but their high Na⁺ and Cl⁻ concentrations make them unsuitable for continuous consumption. They remain valuable for short-term therapeutic use under medical supervision and retain potential for economic exploitation through bottling. Radiological analyses indicated radon activities below international safety thresholds. Radium occasionally exceeded the stricter WHO guideline, requiring continued monitoring but not indicating immediate health risks.

The findings underscore the dual role of groundwater in the region: a critical source of safe drinking water under regulated conditions, but also a vector of contamination where private wells remain unmonitored. Effective protection requires systematic water quality monitoring, stricter regulation of agricultural practices, infrastructure improvements, and increased community-level risk awareness.

A key limitation of this study lies in the restricted temporal coverage of sampling, which was conducted only twice (autumn 2017 and spring 2018). Although these campaigns provide valuable insights under contrasting seasonal conditions, they do not capture the full extent of seasonal or inter-annual variability in groundwater quality. Long-term monitoring is therefore required to achieve a more comprehensive characterization of temporal dynamics.

In conclusion, this study advances the understanding of groundwater quality in a complex hydrogeological and socio-economic setting. It also provides a replicable framework for groundwater management in spa and rural regions facing similar challenges at the intersection of environment, public health, and sustainable development.”

3. Sampling was conducted only twice (autumn 2017 and spring 2018). This is insufficient to capture seasonal or inter-annual variability. The limitation should be explicitly acknowledged.

We agree with the reviewer that sampling on only two occasions (autumn 2017 and spring 2018) does not capture the full seasonal or inter-annual variability of groundwater quality. This is indeed a limitation of our study, and we have now explicitly acknowledged it in the revised manuscript (Conclusions section). Nevertheless, the two sampling periods were chosen to represent contrasting hydrological conditions (wet vs. dry seasons), which provides valuable first insights into the variability of water quality in the study area. We therefore consider our findings useful as a baseline assessment, while recognizing that future studies with longer-term monitoring are needed to fully capture seasonal and inter-annual dynamics.

We added the following paragraph: "A key limitation of this study lies in the restricted temporal coverage of sampling, which was conducted only twice (autumn 2017 and spring 2018). Although these campaigns provide valuable insights under contrasting seasonal conditions, they do not capture the full extent of seasonal or inter-annual variability in groundwater quality. Long-term monitoring is therefore required to achieve a more comprehensive characterization of temporal dynamics."

4. Tables contain excessive information (e.g., Tables 1–4). Consider summarizing with averages and ranges, while moving detailed raw data to supplementary material.

Tables 1 - 3 were modified to summarize (as Table 4) the data with ranges and averages. For Table 3 supplementary table notes were inserted under the table. Please let us know if any additional changes are needed for Tables 1-4. In Tables 1 – 4, the comma separating the thousands has been deleted to eliminate possible confusion (in the original form of the manuscript both the comma and dot were used to separate the thousands in the value of the numbers in the table).

5. The paper would benefit from additional statistical analysis (e.g., PCA, cluster analysis) to better explain controlling factors.

A PCA statistical analysis was inserted to highlight the correlation between the hydrochemical data. The fallowing text was inserted in the manuscript:

“To emphasize the trends and the relationships between the general physico-chemical parameters and the specific parameters (dissolved ions, heavy metals) and to identify the directions (principal components) along which the data variation is maximal, principal component analysis (PCA) was used (soft Past14.5) (Figure 5). Principal component analysis samples used in this study separated the samples into three distinct clusters (Figure 5), which explained 68.3% of total variance by the first two principal components (PCs): PC1 represents 59.4 % of the total variance in the water quality datasets and the PC2 represents 8.9%. The three clusters separated by the PCA consist in: (1) I1 – I8; (2) F1, F2, F4, F5, F8 – F11; (3) F3, F6, F7, F12 – F15, R1 – R7. Based on their distribution on PCA, the hydrochemical characteristics of cluster 1 are quite different from those of the other two clusters. The principal components did not indicate significant loadings between the analysed parameters, the loading coefficients being lower than 0.6. In the present study, the higher loadings for PC2 had positive values for Cd (0.58), NO₂^- (0.37), NO₃^- (0.34), SO₄^2- (0.33), Ni (0.3) and negative for F^- (-0.33). For PC1 the higher loadings were positive in the case of CE, TDS, salinity, alkalinity, hardness, K⁺, Mg^2+, HCO₃^-, Fe (0.26), Ca²⁺ (0.24), ORP (0.23) and a negative correlation for pH (-0.23). As it is shown in Figure 5, these variables are very closed to each other’s, reflecting a strong corelation among them and a greater contribution to PC1, comparing to other variables. In the case of PC2, the parameters had a higher dispersion, which represents a weaker correlation among them. The PCA indicated that dissolved ions had a higher contribution to the hydrochemical characteristics of the analysed water sources comparing to heavy metals (with the exception of Cd). “

 

Figure 5. Biplot of the first two principal components (PC1 and PC2, explaining 59.4% and 8.9% of the variance, respectively) extracted by the correlation matrix. ”

6. The discussion is largely descriptive. Comparative analysis with other European or Carpathian hydrogeological contexts would strengthen the conclusions.

In the Results and discussion section more details related to Comparative analysis with other European or Carpathian hydrogeological contexts, have been inserted, as follows:

’’The pH values we observed (6.5–7.6 across all water types) are consistent with the typical range for Carpathian springs and shallow wells, which usually vary between slightly acidic and slightly alkaline, depending on carbonate buffering capacity and local lithology (Hoaghia et al., 2021; Moldovan et al., 2021). Recent studies in Apuseni Mountains (Romania) and Low Tatra (Slovakia) reported groundwater pH mostly between 6.7 and 7.5, supporting the view that our samples fit well into the regional pattern (Backman et al., 1997; Hoaghia et al., 2021; Petruța et al., 2025).

The higher electrical conductivity (EC), total dissolved solids (TDS), and salinity in mineral spring waters compared to private wells and supply networks reflect intense water–rock interaction and longer residence times, a common feature of mineralized waters in Carpathian and Central European contexts (Bodor et al., 2023). Classification of mineral springs as saline (TDS > 3,000 mg/L) aligns with European mineral-water surveys (Bodor et al., 2023), which frequently categorize commercialized springs in this range (Chau and Tomaszewska, 2019), while private wells and network waters fit the “freshwater” class (TDS < 1,000 mg/L).

Total hardness (TH) patterns also correspond to published values: Carpathian mineral springs are often “very hard” (>180 mg CaCO₃/L) owing to carbonate lithologies, whereas community supplies and wells in rural areas typically fall into “moderately hard to hard” categories, depending on aquifer depth and limestone/dolomite contributions (Hoaghia et al., 2021; Moldovan et al., 2021). Our results therefore mirror the broader regional hydrogeochemical trends and confirm the strong lithological control on hardness in the Carpathians.

The lack of strong seasonal variation in EC and TDS is also in agreement with hydrogeochemical monitoring in aquifers of the Carpathians, where buffering by carbonate reservoirs stabilizes ionic composition across seasons, with only minor springtime dilution effects observed in pH and hardness (Hoaghia et al., 2021).

Our findings that 7–27% of private wells exceeded national limits for NH₄⁺, NO₂⁻, and NO₃⁻ are consistent with European-scale evidence that agricultural diffuse pollution and inadequate sanitation are leading sources of nitrogenous compounds in groundwater. The European Environment Agency (EEA, 2023) reports that roughly 14% of monitoring stations across the EU exceed the 50 mg/L nitrate threshold, with rural wells in Eastern and Central Europe disproportionately affected.

Calcium concentrations exceeding WHO guidance in one well highlight localized geogenic influences. Elevated Ca²⁺ has also been documented in Apuseni karst aquifers (Hoaghia et al., 2021) and in bottled European mineral waters (Bodor et al., 2023), indicating that such anomalies are not uncommon in carbonate-dominated settings.

The major ion composition of our local supply and private wells (Ca–Na–HCO₃ type) reflects typical shallow aquifers in the Carpathians, where carbonate dissolution governs the dominance of Ca²⁺ and HCO₃⁻, with secondary inputs from Na⁺ and SO₄²⁻ (Hoaghia et al., 2021). In contrast, the Na–HCO₃ and Na–HCO₃–Cl facies observed in our mineral springs correspond to hydrochemical signatures reported in highly mineralized or saline Carpathian springs, particularly in Transylvania and northern Romania, where evaporitic or deep-seated sources contribute to enrichment in Na⁺ and Cl⁻ (Bodor et al., 2023).

The results are relatively similar with other studies focused on hydrochemistry of mineral springs in EU (Bodor et al., 2023). The study performed on a total of 692 mineral waters from 13 countries, showed that in terms of the ionic content, the dominant water type was bicarbonate, followed by fluoride, magnesium and calcium, and then sulphate and acidic had a lower prevalence (Bodor et al., 2023).

7. The implications for policy and sustainable management should be elaborated. For example, how can authorities address wells exceeding Pb and NO₂⁻ limits?

Thank you for this valuable suggestion. We have revised the discussion to elaborate on the implications for policy and sustainable management. Specifically, we now highlight how authorities could address wells with Pb and NO₂⁻ concentrations exceeding guideline limits. It were inserted supplementary bibliographic references related to public health risk.

We added the following information: "The exceedance of Pb and NO₂⁻ limits in several wells has significant implications for public health and groundwater management. According to national legislation, the authorities must ensure access to water sources of adequate quality, which does not pose a risk to consumers health, to constantly monitor these water sources, and to provide free access to data related to monitors quality parameters.  If locals want to use private wells as water sources, other than those monitored by the local authorities, they must be aware that they are assuming high risks. In this situation, the authorities have a major role, namely, to disseminate information on the water quality from the local distribution network and the negative impact on human health associated with the consumption of water of inadequate quality [77-81]. Academic community should also address this issue, by organizing different citizen science actions, together with local authorities. These actions could be focused on evaluating the water quality from private wells by performing specific analyses, disseminating the results, and raising awareness among locals related to the importance of water quality monitoring. Authorities can provide guidance related to possible solutions to improve water quality for private wells. Some of these solutions may require targeted interventions, such as point-of-use treatment (e.g., activated carbon filters for Pb, ion exchange or reverse osmosis for nitrate/nitrite) or may include stricter control of potential contamination sources (e.g. agricultural fertilizer usage).

8. More explicit reference to public health risks and recommendations is needed.

Additional references have been included in the manuscript. Please see the references: [77-81].

9. Figures (e.g., Piper, Gibbs diagrams) have low resolution. Please improve quality and ensure clarity also in black-and-white print.

We have improved the resolution of all figures.

10. Figure captions should be more explanatory, including sample numbers and symbols.

The figure captions show the symbols used. Figure 1, newly introduced in the manuscript, shows the number of samples in each category. Please let us know if further details are required.

Minor Issues

1. Reference formatting does not fully follow Sustainability guidelines. Please check journal style and ensure DOIs are added where available.

Thank you. We performed the required formatting changes.  

2. Typographical errors (e.g., “therapeuthic” → “therapeutic”; “fro drinking” → “for drinking”) should be corrected.

Thank you. The required changes have been made.

3. The Abstract should be shortened to 200–250 words.

The abstract has been shortened and now contains 233 words. Here is the new version of the Abstract:

" Groundwater quality is a key factor and a critical determinant of public health, agriculture, and socio-economic development, particularly in regions where private wells and mineral springs constitute the primary water sources. This study presents an integrated hydrochemical, radiological, and toxicological assessment of groundwater in the Sângeorz-Băi area, Romania, a spa region where mineral waters hold both therapeutic and economic significance. Samples from mineral springs, the municipal supply system, and private wells were analyzed to evaluate compliance with national and international standards and to assess their suitability for drinking, therapeutic, and agricultural purposes.

The results reveal distinct hydrochemical contrasts between sources. Mineral springs are characterized by elevated salinity, hardness, and Na–HCO₃ facies, whereas the municipal network and private wells are dominated by Ca–HCO₃ facies.  More than half of the private wells exceeded permissible limits for NO₃⁻, NO₂⁻, NH₄⁺, Pb, and Fe, with one well posing a significant nitrite-related health risk. Trace metal analysis indicated localized enrichment in Cu, Fe, and Pb. Radon and radium activities generally complied with regulations, although radium occasionally exceeded the more stringent WHO guidelines. Seasonal variation was minimal, reflecting stable groundwater chemistry. Health risk and irrigation assessments suggest that municipal supply water is largely safe for consumption, while private wells require targeted monitoring and mitigation. Despite elevated Na⁺ and Cl⁻, mineral springs retain therapeutic value under controlled use.

This study provides a replicable framework for groundwater quality assessment in spa regions and offers critical insights for public health protection, sustainable tourism, and agricultural resilience. "

 

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The research topic has clear practical significance and application potential. The data collection work of the paper is solid, covering rich physical and chemical parameters and the content of metals and radioactive elements. However, the paper has fundamental flaws in scientific depth, analytical methods and academic expression, and is currently more like a qualified "water quality monitoring report" than a "scientific research paper" with innovative and universal value. Its analysis is overly descriptive, lacking in-depth exploration of mechanisms and relevance to the broader academic context. Therefore, I recommend a major revision.

1. In the Introduction section, the references on groundwater resources research are too old and needs to be updated. The latest achievements in 2024 and 2025 will help better reflect the research background (10.1016/j.watres.2025.123648; 10.1016/j.watres.2025.123701).

2.The language requires some improvement; there are a lot of incorrect terminology and motherhood statements.

3.The number of references is huge and some of the citations are not relevant to the context, which seems to be piled up. It is recommended to streamline citations, keep the most relevant and up-to-date literature, and avoid over-citation.

4.The abstract is too long, abstract needs to be simplified and are usually limited to 250 words or less.

5.The hydrogeological conditions in the study area are insufficiently described, and the characteristics of aquifers, groundwater flow paths, and surface water-groundwater interactions are lacking. It is recommended to supplement regional hydrogeological maps and aquifer characteristics.

6.Section 3.1: Relying on the results of the literature, local precipitation isotope data (e.g., δ¹⁸O, δ²H) are not provided, and there is a lack of discussion on altitude effects and latitude effects. It is recommended to supplement local precipitation sampling and isotope analysis to enhance the local applicability of the study.

7.Section 3.2: The main ion content does not quantify the potential evaporation loss, and the literature only qualitatively describes "mineral springs are affected by evaporation", and does not use the Craig-Gordon model to calculate evaporation losses, nor does it quantify the evaporation of different seasons and groundwater burial depths in combination with local meteorological data

8.Conclusions are not really conclusions; it is a sort of summary of the study.

 

Author Response

 

Reviewer 3

The research topic has clear practical significance and application potential. The data collection work of the paper is solid, covering rich physical and chemical parameters and the content of metals and radioactive elements. However, the paper has fundamental flaws in scientific depth, analytical methods and academic expression, and is currently more like a qualified "water quality monitoring report" than a "scientific research paper" with innovative and universal value. Its analysis is overly descriptive, lacking in-depth exploration of mechanisms and relevance to the broader academic context. Therefore, I recommend a major revision.

1. In the Introduction section, the references on groundwater resources research are too old and needs to be updated. The latest achievements in 2024 and 2025 will help better reflect the research background (10.1016/j.watres.2025.123648; 10.1016/j.watres.2025.123701).

 Thank you. The required changes have been made.

2.The language requires some improvement; there are a lot of incorrect terminology and motherhood statements.

Professional linguistic editing was performed to improve the English.

 3.The number of references is huge and some of the citations are not relevant to the context, which seems to be piled up. It is recommended to streamline citations, keep the most relevant and up-to-date literature, and avoid over-citation.

We tried to eliminate some bibliographic references, but their number cannot be reduced more than it currently is, because many references represent legislative norms that are referred to in the Results and Discussion section, or are references in which different variables used in the calculation formulas are mentioned. In addition, the other two anonymous reviewers ask for more information in certain parts of the manuscript, as a consequence we added more citations and references at the end of the manuscript.

4.The abstract is too long, abstract needs to be simplified and are usually limited to 250 words or less.

The abstract has been shortened and now contains 233 words. Here is the new version of the Abstract:

" Groundwater quality is a key factor and a critical determinant of public health, agriculture, and socio-economic development, particularly in regions where private wells and mineral springs constitute the primary water sources. This study presents an integrated hydrochemical, radiological, and toxicological assessment of groundwater in the Sângeorz-Băi area, Romania, a spa region where mineral waters hold both therapeutic and economic significance. Samples from mineral springs, the municipal supply system, and private wells were analyzed to evaluate compliance with national and international standards and to assess their suitability for drinking, therapeutic, and agricultural purposes.

The results reveal distinct hydrochemical contrasts between sources. Mineral springs are characterized by elevated salinity, hardness, and Na–HCO₃ facies, whereas the municipal network and private wells are dominated by Ca–HCO₃ facies.  More than half of the private wells exceeded permissible limits for NO₃⁻, NO₂⁻, NH₄⁺, Pb, and Fe, with one well posing a significant nitrite-related health risk. Trace metal analysis indicated localized enrichment in Cu, Fe, and Pb. Radon and radium activities generally complied with regulations, although radium occasionally exceeded the more stringent WHO guidelines. Seasonal variation was minimal, reflecting stable groundwater chemistry. Health risk and irrigation assessments suggest that municipal supply water is largely safe for consumption, while private wells require targeted monitoring and mitigation. Despite elevated Na⁺ and Cl⁻, mineral springs retain therapeutic value under controlled use.

This study provides a replicable framework for groundwater quality assessment in spa regions and offers critical insights for public health protection, sustainable tourism, and agricultural resilience. "

5.The hydrogeological conditions in the study area are insufficiently described, and the characteristics of aquifers, groundwater flow paths, and surface water-groundwater interactions are lacking. It is recommended to supplement regional hydrogeological maps and aquifer characteristics. 

We agree that additional data related to aquifers characteristics, groundwater flow paths, and surface water-groundwater interactions, would be of great interest, but unfortunately, for the investigated area we have not identified more data (free access) in this regard. Under these circumstances, we cannot provide additional details.

6.Section 3.1: Relying on the results of the literature, local precipitation isotope data (e.g., δ¹⁸O, δ²H) are not provided, and there is a lack of discussion on altitude effects and latitude effects. It is recommended to supplement local precipitation sampling and isotope analysis to enhance the local applicability of the study.

We sincerely thank the reviewer for this valuable suggestion regarding local precipitation isotope data and discussion of altitude and latitude effects. While we acknowledge that such information could provide additional insight into groundwater recharge and geochemical evolution, the primary focus of our study was on the health risks associated with groundwater quality, including chemical and radiological hazards, as well as irrigation suitability. Conducting local precipitation sampling and isotope analyses was unfortunately beyond the scope of the current study due to financial and infrastructural constraints.

We agree that future research incorporating local isotope measurements would further enhance the understanding of recharge dynamics and spatial variability.

7.Section 3.2: The main ion content does not quantify the potential evaporation loss, and the literature only qualitatively describes "mineral springs are affected by evaporation", and does not use the Craig-Gordon model to calculate evaporation losses, nor does it quantify the evaporation of different seasons and groundwater burial depths in combination with local meteorological data

We acknowledge that such information could provide valuable additional insight into the present study, but such investigations were unfortunately beyond the scope of the current study due to financial and infrastructural constraints.

8.Conclusions are not really conclusions; it is a sort of summary of the study.

Here is the new version of the Conclusions:

"This study provides a comprehensive, multidisciplinary assessment of groundwater quality in the Sângeorz-Băi area, an emblematic spa region of Romania. Private wells, the municipal supply, and mineral springs remain central to drinking water provision, therapeutic practices, and socio-economic development. By integrating hydrochemical, radiological, toxicological, and irrigation suitability analyses, the study yields conclusions of direct relevance to public health, water management, and sustainable regional development.

Groundwater from the municipal network generally complies with regulatory standards. In contrast, more than half of the private wells exceeded permissible limits for NO₃⁻, NO₂⁻, NH₄⁺, Pb, and Fe. One well showed acute nitrite contamination, representing an immediate health risk that requires discontinuation of use. Elevated Pb and Fe levels highlight the vulnerability of aquifers to diffuse agricultural inputs and infrastructure deficiencies. Mineral springs complied with regulatory limits for trace metals and radionuclides, but their high Na⁺ and Cl⁻ concentrations make them unsuitable for continuous consumption. They remain valuable for short-term therapeutic use under medical supervision and retain potential for economic exploitation through bottling. Radiological analyses indicated radon activities below international safety thresholds. Radium occasionally exceeded the stricter WHO guideline, requiring continued monitoring but not indicating immediate health risks.

The findings underscore the dual role of groundwater in the region: a critical source of safe drinking water under regulated conditions, but also a vector of contamination where private wells remain unmonitored. Effective protection requires systematic water quality monitoring, stricter regulation of agricultural practices, infrastructure improvements, and increased community-level risk awareness.

A key limitation of this study lies in the restricted temporal coverage of sampling, which was conducted only twice (autumn 2017 and spring 2018). Although these campaigns provide valuable insights under contrasting seasonal conditions, they do not capture the full extent of seasonal or inter-annual variability in groundwater quality. Long-term monitoring is therefore required to achieve a more comprehensive characterization of temporal dynamics.

In conclusion, this study advances the understanding of groundwater quality in a complex hydrogeological and socio-economic setting. It also provides a replicable framework for groundwater management in spa and rural regions facing similar challenges at the intersection of environment, public health, and sustainable development.”

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The revised manuscript has addressed all my questions.

Reviewer 3 Report

Comments and Suggestions for Authors

I have reviewed the revised manuscript, all the previous comments and suggestions were concerned and incorporated. On this basis, the manuscript is recommended to be accepted.