Geochemical Characteristics of Trace Elements of Hot Springs in the Xianshuihe–Xiaojiang Fault Zone

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript entitled “Geochemical characteristics of trace elements of hot springs in 2 the Xianshuihe-Xiaojiang Fault Zone” by B. Yao et al., presents a study of hot spring waters in the Xianshuihe-Xiaojiang Fault Zone. Geochemical characteristics of thermal waters from 74 springs are shown in the manuscript. Based on a detailed analysis of the geological structure of the territory, the authors draw conclusions about the depth of water circulation, sources of elements, and the water quality for drinking purposes.

The authors collected and analyzed a large number of water samples, conducted thorough statistical processing of the analyses, presented results on the relationship of elements with water-rock interactions or input with magmatic fluids.

The authors have done a great job, obtained significant results that will contribute to understanding the hydrochemistry of hot springs.

The article corresponds to the profile of the journal “Water”

Yet, the authors should address minor suggestions, listed below.

In all text, please place a space before references.

Fig. 1. Everything is mixed up in the legend: intrusive bodies, sedimentary strata, ages. It is necessary to bring it into correspondence (from ancient to Quaternary) and show at least the main formations with indices.

Line 152. Hereinafter. In cases where a sentence begins with an element, it is better to use a name rather than a symbol: Arsenic instead As.

Fig. 2. If I understood correctly from the figure, the content of barium, cobalt, nickel, lead, and thallium in surface waters is higher than in thermal waters. How is this possible?

Fig. 3. Very clear diagram!

Fig. 4. I don't see the white square in the diagram for surface water.

Fig. 12. Please, sign the size scale in English. Why does the model show arsenic in valency 3+, and not 5+? Have you determined the arsenic speciation? It is impossible to understand the different sources of elements from the model. For example, how can one understand that boron comes from a deep thermal reservoir, and iron and arsenic - from sedimentary rocks? The different circulation depths are also impossible to see.

In general, the manuscript is very interesting, a lot of information is presented about the composition of hot springs, many aspects of the genesis and relationships of elements are discussed.

Author Response

please refer to an attached file

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Major notes on the section 4.2. Water quality assessment.

 High concentrations of As, Mn, B, and Fe found in the hot spring waters in the XSHF-XJF, greatly exceeding the standard values are not hinting they are potentially polluting elements. In this case, we can talk about the natural enrichment of groundwater with these elements.

The same applies to the WQI values of spring water samples. High WQI values indicate not contamination, but natural enrichment. If the authors insist on the term pollution, it is necessary to provide an analysis of the sources of pollution.

Note on Figure 3. Heat map of risk assessment of trace elements in hot spring waters.

There are PI values, but not risk assessment.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

I inserted my detailed comments directly in the text. The paper has several major issues that could be taken into account, discussed (sometimes deepened), and corrected by AA.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

I am not a native speaker. Nevertheless, I tried to make a general English editing.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Dear authors,

it is an interesting paper and in attached file few suggestions are reported.

Please set higher quality for proposed figures. 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

Dear authors,

The manuscript titled "Geochemical Characteristics of Trace Elements of Hot Springs in the Xianshuihe-Xiaojiang Fault Zone" investigates the geochemical properties of trace elements in hot springs within the Xianshuihe-Xiaojiang Fault Zone. The study employs classic geochemical tools and multivariate statistical analysis on 74 hot springs, with a focus on the source, enrichment mechanisms, and water quality assessment of trace elements.

 

Overall Assessment:

The manuscript provides valuable insights into the geochemical characteristics of hot springs in a geologically significant area. The study's objectives are clear, and the methodology is sound. The following feedback is provided to enhance the clarity, structure, and completeness of the manuscript:

Abstract:

Clarify the abbreviation XSHF-XJF when first introduced in the abstract for readers unfamiliar with the terminology.

Introduction:

Expand on the global context of the study by briefly discussing how findings contribute to the existing knowledge on geochemical characteristics of hot springs.

Consider reorganizing the introduction to provide a more structured flow. For example, briefly introduce the study area and its geological significance before delving into the importance of trace elements in hot springs.

Geological Setting:

Provide a clearer transition from the introduction to the geological setting section. Briefly summarize why the geological setting is relevant to the study before detailing it.

Conclusions:

Ensure that the conclusions are a concise summary of the key findings. Consider rephrasing the conclusions for clarity.

Include a brief discussion of potential implications of the findings and suggest avenues for future research.

Language and Clarity:

Carefully proofread the manuscript for grammatical errors and ensure clarity in sentence structures.

Define any abbreviations upon first use for the benefit of readers who may not be familiar with them.

Figures and Tables:

Check the formatting and labeling of figures and tables for consistency.

Recommendation:

Considering the potential significance of the study and its contribution to the understanding of hot springs in the Xianshuihe-Xiaojiang Fault Zone, the manuscript is recommended for acceptance with minor revisions. Addressing the specific feedback provided will improve the overall quality and readability of the manuscript.

Comments on the Quality of English Language

Language and Clarity:

Carefully proofread the manuscript for grammatical errors and ensure clarity in sentence structures.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

AA should make the changes in the text they report in the cover letter but that they haven't done in the revised version or they have done incorrectly. They are:

 

- Page 4

Number 8: or Ca? (see at the end of the period)

Response 8: We apologize for this error. We have added the Ca²⁺ in Line 157.

Please, correct as follows: …and Ca²⁺ and Mg²⁺ are the dominant cations;

- Page 5

Number 1: What does it mean?

Response 1: We apologize for the lack of clarity. We have revised this sentence in Line 184.

What does it mean what you wrote in the revised text?: “in partial water samples”;

Page: 13

Number 1: how did you constrain it? On which basis? Tectonic setting, geothermometry, geothermal gradient?

Response 1: Thank you for your comment. Yan et al. (2022) has calculated the thermal storage temperature and circulation depth in the XSHF using cationic temperature scales and SiO2 temperature scales. Tian et al. (2023) estimated the thermal storage temperature and circulation depth in the AZF using the FixAl method, a multicomponent geothermometry. Li et al. (2021) estimated the thermal storage temperature and circulation depth in the XJF using the quartz geothermometers with no steam loss, the chalcedony. In the study, we cite their data to explore the relationship between trace elements and circulation depth. We have added the references in Line 464. Where is it?

The weak point that still remains is the relationship between EC values and TDS ones. EC values are probably wrong! AA should check carefully all reported values (one by one). Since values are taken from another paper, please, check their correspondence with your samples (W1 through W74). Table S1 can not be published as it is.

Response 6: Thank you for your comment. The values of EC (Electrical Conductivity) are measured in the field using portable equipment. TDS (Total Dissolved Solids) is calculated according to the following formula: TDS=Na⁺+K⁺+Mg²⁺+Ca²⁺+Cl^-+SO₄^2-+CO₃^2-+NO₃^-+0.5*HCO₃^- we have carefully checked the Table S1 to make sure it's correct. 

I am regretful but the problem in comparing TDS and EC values still persists! Two possibilities are valid: 1) EC values are not correct and 2) chemical analysis shows a mass balance outside the range ± 5%. From table S1 it seems that, apart from 6-7 samples out of 74, the mass balance is ok. Accordingly, the AA must consider the first hypothesis. As a thumb rule in water monitoring, the relationship between the two variables is; Conductivity ='k' x TDS. So in basic water chemistry, we take k=0.7. Thus, if you have a TDS value, just divide it by 0.7 and you will get conductivity in units of µS/cm. The factor value of 'k' can change at times (generally spans from 0.6 and 0.9) based on the aqueous nature of samples (i.e. with their saline content), but the above-reported statements give an idea about the general interplay between EC and TDS. In table S1, I inserted three columns: 1) the rough values of TDS obtained by multiplying EC by 0.7, 2) the differences between ECmeas and EC calc, and 3) the same difference expressed as a percentage. Despite the limitations in the relationship between EC and TDS (mainly for saline waters), it seems to me that most (if not all) EC values reported in table S1 are wrong! It is not possible that a water (for instance sample W42), with a TDS = 3228 mg/L has an EC = 539 mS/cm!! Again, water with a TDS = 2004 mg/L has an EC = 57600 mS/cm!! Finally, the third column reports a suspect result: the difference, in percentage, between ECmeas and ECcalc is always 30, irrespective of the salinity content of the waters. How is it possible? Referring to table S1, I trust in chemical analysis (even if I have not checked them all), not in EC values!

Comments for author File: Comments.zip

Comments on the Quality of English Language

AA improved the quality of English. Now it’s ok.

Author Response

Please see the attachment

Author Response File: Author Response.pdf