Review Reports - High Content of Boron in Curative Water: From the Spa to Industrial Recovery of Borates? (Poland as a Case Study)

Round 1

Reviewer 1 Report

Review of the paper "High content of boron in curative water: From the spa to industrial recovery of borates? (Poland as a case study)"

The paper present a collection of historical and monitoring data of curative water plants to analyze boron concentration, species and distribution in Poland to infer the implications for human use and possible extraction of boron from this water.

However, while the issue can be of interest for the publication in minerals, there are serious flaws in this paper which need to be addressed before consider it for publication.

The main limit of the study, in my opinion, relies in the Results. While the authors collected a quite wide dataset on water chemistry, the results obtained are only very limitedly analyzed, and conclusions are drown in sections 3.1 and 3.2 without adding any relationship with data.

For example, the relationship between boron and total dissolved solids (which can be described only in the log-log plot in Figure 5) is an interesting result, but it is important to relate it also with other ions (were data are available), a notable example can be Cl (see for example Arnórsson & Andrésdóttir https://doi.org/10.1016/0016-7037(95)00278-8). Then, other more detailed approaches can be used to better interpret the data collected by the authors. Some examples can be the use of piper plots instead of the Szczukariew-Prikłoński classification of water samples, observing how the waters with different B load belong to different hydrochemical facies. As well, the map in figure 3 can better describe the spatial differences of B concentration. Authors should add a geological map as background and also indicate main tectonic forms (e.g. main faults).

I suggest to the authors to read other papers to find some analyses which can fit for a better interpretation of the collected data. See for example Farmer et al. 2019 (https://doi.org/10.1016/j.gca.2018.10.008) or Halim et al. 2010 (https://doi.org/10.1016/j.jhazmat.2010.01.008).

Then, the language need to be highly reviewed. Note that I am not only questioning the quality of the English. The paper generally needs a more accurate and professional formulation of statements in my opinion, and some sections need to be completely rearranged. For example, Discussion section is basically the Conclusion section, while sections 3.1 and 3.2 are reported as Results but do not present data, and should be included in Discussion. Moreover, the data expressed in the Material and Methods section (lines 122-127) seem to belong to the Results.

Then, the introduction section should more carefully indicate the main aim of the study. It is not clear which is the main aim of the study: is it the understanding of the factors affecting boron concentration? Is it the evalutaion of effects on human health? Or is it the evaluation of boron extraction techniques for industrial applications? As in the present form, in the paper these 3 possible aims result partly mixed and overlapped, and it is really hard to get through it.

Methods are not well defined: authors should immediately state that data are obtained from other studies, otherwise from the beginning of the sections it seems that water was directly analyzed by the authors. Moreover, a general description of the lithological and structural setting of the study area (which of course can affect the results on boron concentration in water) is completely missing.

Morover, there are some other minor issues which authors should consider.

An abundant revision of English language should be performed. For example, first sentences of introduction are not clear (lines 38-40) and lines 89-105 are extremely hard to follow. Moreover, some not scientific sentence are presented in the paper (e.g. in line 24 "as is the case today", or in line 231 "from several to several dozen").

Lines 58-72: I think this section whould be rephrased, considering the more important role of pH and reodx potential compared with B concntration in defining the species available in water. Authors should consider to add a Pourbaix diagram (i.e. a plot of pH vs Eh) to better illustrate the main species present in water.

The role fo discharge of springs is not clear in the paper (e.g. in lines 31-32 of the abstract or in lines 288-298). It is not understandable if the flow of water can affect toxicity of boron (or its extraction) and how it could affect. Maybe a correlation of B concentration vs water flow in springs can be more reasonable.

The use of table of tables is redundant in my opinion. Table 1 can be substituted with a graph, since these data are then already reported in supplementary material, and table 2 partly remarks the graph in figure 4.

Therefore, I recommend a complete re-writing of this paper, reviewing the interpretation of data and the whole structure, in order to make it suitable for publication.

Author Response

Dear Reviewer,

Thank you for your valuable comments from reviewers and we truly believe that this has improved the quality of our article. The text of the article has undergone major changes and would be completely unreadable in the form of track changes. Moreover, extra figures and tables have been added. In addition, some of the drawings have been improved.

Explanations of the comments are provided below:

“The main limit of the study, in my opinion, relies in the Results. While the authors collected a quite wide dataset on water chemistry, the results obtained are only very limitedly analyzed, and conclusions are drown in sections 3.1 and 3.2 without adding any relationship with data.”

After general changes of the text, we added a paragraph discussion in it.

Based on the collected data, according to reviewer comments, the more detailed examination of chemistry of these medicinal waters was done.

The earlier sections 3.1 and 3.2 have been moved to the discussion section. Next, the text of these paragraphs has been linked to the data collected during the our study.

2. “For example, the relationship between boron and total dissolved solids (which can be described only in the log-log plot in Figure 5) is an interesting result, but it is important to relate it also with other ions (were data are available), a notable example can be Cl (see for example Arnórsson & Andrésdóttir https://doi.org/10.1016/0016-7037(95)00278-8). Then, other more detailed approaches can be used to better interpret the data collected by the authors. Some examples can be the use of piper plots instead of the Szczukariew-Prikłoński classification of water samples, observing how the waters with different B load belong to different hydrochemical facies. As well, the map in figure 3 can better describe the spatial differences of B concentration. Authors should add a geological map as background and also indicate main tectonic forms (e.g. main faults).

The more detailed examination of chemistry of these medicinal waters was done. We provided correlation analysis of boron concentration versus major ions: Na⁺, Ca²⁺, Mg²⁺, Cl^-, SO₄^2-, CO₃^2- and HCO₃^- in the whole dataset as well as in each class of water. We described more preciously the methodology in the materials and methods section, and we added additional Figures and information to the text with new data.

According to reviewer suggestions, we counted ionic molar ratios (including boron) analyzed in others works (for example by Arnórsson & Andrésdóttir, Farmer et al. and Halim et al.). However, in the Polish waters analyzed by us, the Cl/B molar ratio ranges from less than 1 to 11090. The analyzed waters come from geologically diverse areas of Poland, and the obtained values of the Cl/B molar ratio are within a very wide range. Therefore, at the present stage of research, it is difficult to link the values of the Cl/B molar ratio with the processes determining the chemistry of these waters. (We wrote it in the text.)

Figure 3 indicate the main geological structures in Poland. The map with more geological details would make the drawing unreadable. An brief description of geological setting was added to the text. (Materials and Methods section), This article is the first stage of the work on boron concentration in curative waters. The aim of the article was not to analyze the factors influencing the boron concentration, but to point out of the problem of high content of boron in medicinal waters. Therefore, only a preliminary analysis of the concentration of boron in therapeutic water. Geochemical processes influencing boron concentration have not been analyzed. Due to the large amount of data (248 waters) coming from a large geologically and varied area (all of Poland), the impact of geological, chemical and hydrogeochemical processes on the concentration of boron was not considered. The boron concentration was presented versus mineralization and the types adopted in accordance with the classification used in balneology. Szczukariew-Prikłoński classification is widely used in categorization of curative water (balneology).

“Then, the language need to be highly reviewed. Note that I am not only questioning the quality of the English. The paper generally needs a more accurate and professional formulation of statements in my opinion, and some sections need to be completely rearranged. For example, Discussion section is basically the Conclusion section, while sections 3.1 and 3.2 are reported as Results but do not present data, and should be included in Discussion. Moreover, the data expressed in the Material and Methods section (lines 122-127) seem to belong to the Results”.

The text has undergone general changes, many sections were completely reangered. The earlier section -Discussion, was replaced with Conclusions. The earlier sections 3.1 and 3.2 have been moved to Discussion section. A linkage with the data collected by us in the work has been added to them. Text written in the Material and Methods section (lines 122-127) were moved from this section. The language corrections were done.

“Then, the introduction section should more carefully indicate the main aim of the study. It is not clear which is the main aim of the study: is it the understanding of the factors affecting boron concentration? Is it the evalutaion of effects on human health? Or is it the evaluation of boron extraction techniques for industrial applications? As in the present form, in the paper these 3 possible aims result partly mixed and overlapped, and it is really hard to get through it.”

In Introduction, we clarified the main purpose of the work more precisely. In the text, especially in Discussion section, the three aspects of the work (subsections: Boron and chemical composition of water, The influence of boron on the human body and legal acts regarding the content of boron in water and The prospect of boron recovery from water with high boron content) were spread and discussed separately.

“Methods are not well defined: authors should immediately state that data are obtained from other studies, otherwise from the beginning of the sections it seems that water was directly analyzed by the authors. Moreover, a general description of the lithological and structural setting of the study area (which of course can affect the results on boron concentration in water) is completely missing”.

We improved and expanded the Materials and Methods section. In addition, in the Introduction, we highlighted the origin of the data discussed in the article.

The information on geological aspects has been written in the text in the sections (materials and Methods and Results)

“An abundant revision of English language should be performed. For example, first sentences of introduction are not clear (lines 38-40) and lines 89-105 are extremely hard to follow. Moreover, some not scientific sentence are presented in the paper (e.g. in line 24 "as is the case today", or in line 231 "from several to several dozen")”.

The text has been corrected in line with the comments.

“Lines 58-72: I think this section whould be rephrased, considering the more important role of pH and reodx potential compared with B concntration in defining the species available in water. Authors should consider to add a Pourbaix diagram (i.e. a plot of pH vs Eh) to better illustrate the main species present in water”.

In introduction we have added explanations and Figure 1a, showing the main forms of boron in waters depending on pH. In the article, we did not discuss the dependence of the forms of boron occurrence on the value of the redox potential, because we do not have such data for the discussed waters.

“The role fo discharge of springs is not clear in the paper (e.g. in lines 31-32 of the abstract or in lines 288-298). It is not understandable if the flow of water can affect toxicity of boron (or its extraction) and how it could affect. Maybe a correlation of B concentration vs water flow in springs can be more reasonable.”

The sentence: Unfortunately, most therapeutic water intakes with a high concentration of boron 31(above 100 mg/L) are characterized by low discharge. (previously line 31-32 and 288-298) was changed. Now it is: Unfortunately, most of water intakes with a high concentration of boron (above 100 mg/L) are low- yielding wells. We hope it is more understandable now. Additionally, for better explanation, we have included a Table S2 (in the supplement) with additional characteristics of water intakes with more than 100 mg/L of boron.

“The use of table of tables is redundant in my opinion. Table 1 can be substituted with a graph, since these data are then already reported in supplementary material, and table 2 partly remarks the graph in figure 4.”

The authors believe that the presence of Table 1 in the main text is necessary. Literature data indicate that waters with high boron content (above 25 mg/L) should not be freely available for drinking in pump rooms and other places in health resorts. These waters are gathered in Table 1. The authors also believe that Table 2 contains information that is not included in the figure 4.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript minerals-1010616 is a general review of boron content in Polish curative waters. The Authors collected the data regarding boron-bearing waters from different places located in Poland. The date was also analysed ,e.g in the context of location as well as mineralisation. It is an interesting article, however there are some questions that need to be raised during the review.

The title of manuscript is “High content of boron in curative water: From the spa to industrial recovery of borates? (Poland as a case study)”. However, the paper is mainly focused on analysis of boron concentration in Polish curative waters. The topic of “industrial recovery” was analysed.

Introduction – There is no information about global boron production. Share of the respective countries in the world market also in not provided.

Discussion – Which methods of boron recovery might be applied for Polish curative waters? What amount of the boron might be recovered from the sources?

Page 3 lines 95-97 – “Water with HBO2 content above 5 mg/L was referred to as boron water because metaboric acid has antiseptic effects only at a concentration off at least 5g/L” – meaning is not clear

Page 1 lines 42-44 – In some chemical formulas “zero” instead of letter “O” for oxygen was used

Author Response

Dear Reviewer,

Explanations of the comments are provided below:

“Introduction – There is no information about global boron production. Share of the respective countries in the world market also in not provided”

Information about global boron production has been added in Introduction.

Discussion – Which methods of boron recovery might be applied for Polish curative waters? What amount of the boron might be recovered from the sources?

Currently, simple, economical methods of global boron production from water on an industrial scale have not yet been developed. (Methods for extracting boron from water were tested on a laboratory and field scale.) Therefore, it is difficult to indicate specific methods with the present state of knowledge.

Unfortunately, most of water intakes with a high concentration of boron (above 100 mg/L) are low- yielding wells. The amounts of the potential production of H₃BO₃ [kg/day] from these water is included in Table S2 (in the supplement).

Page 3 lines 95-97 – “Water with HBO2 content above 5 mg/Lwas referred to as boron water because metaboric acid has antiseptic effects only at a concentration off at least 5g/L” – meaning is not clear

The introduction has been changed and expanded. The problem of HBO2 content in therapeutic waters has been presented more preciously. We hope this is clarified enough

Page 1 lines 42-44 – In some chemical formulas “zero” instead of letter “O” for oxygen was used

It was corrected in the text.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors kindly addressed most of the comments and I think the manuscript clearly improved in term of quality. However, some minor issue still need to be considered in my opinion before publication.

Generally, introduction improved in clarity. I would also rephrase in lines 160-162: I suggest "The main aim of the study is to highlight the high content of boron in curative water and potentially consider it as a source of Boron for industrial applications".

I would add a short section in materials and methods, considering which data were collected from literature and which data were obtained from direct measures from the authors, since it seemed that all records were obtained from literature, but then in the section 4.2 authors state "tested by us" (line 392). Do the authors mean water analyzed in their dataset, or chemically analyzed in their laboratories?

In my opinion, discussion in lines 267-297 could be much clearer adding a piper plot (see for example Binda et al., 2020 https://doi.org/10.3390/min10121058 or Sekine et al, 2020 https://doi.org/10.3390/min10090792).

Moreover, while I still considered the log log graph more useful in Figure 6, I see the authors discussing also the linear graph of B concentration vs TDS. Nonetheless, both Figure 6a and 6b seem to me log-log graphs (they seem the same graph). Moreover, I think the numbering is wrong and it should be figure 5.

I think that after these suggestions the paper can worth publication.

Author Response

To Reviewer 1,

Thank you very much for any corrections improving the quality of our work. All changes made by us to the text of the article are visible in the pdf file.

An explanation below:

Generally, introduction improved in clarity. I would also rephrase in lines 160-162: I suggest "The main aim of the study is to highlight the high content of boron in curative water and potentially consider it as a source of Boron for industrial applications".

It was changed.

I would add a short section in materials and methods, considering which data were collected from literature and which data were obtained from direct measures from the authors, since it seemed that all records were obtained from literature, but then in the section 4.2 authors state "tested by us" (line 392). Do the authors mean water analyzed in their dataset, or chemically analyzed in their laboratories?

We added a short section 2.2. Physico-chemical parameters of curative waters. We removed the wording "tested by us" from the text of manuscript, because all pchysico-chemical parameters of curative water were collected by us, not done by us. In section 2.2. we have clarified where the water analysis comes from.

In my opinion, discussion in lines 267-297 could be much clearer adding a piper plot (see for example Binda et al., 2020 https://doi.org/10.3390/min10121058 or Sekine et al, 2020 https://doi.org/10.3390/min10090792).

We added Piper diagram with short description.

Moreover, while I still considered the log log graph more useful in Figure 6, I see the authors discussing also the linear graph of B concentration vs TDS. Nonetheless, both Figure 6a and 6b seem to me log-log graphs (they seem the same graph). Moreover, I think the numbering is wrong and it should be figure 5.

We corrected and merged figure 5.

We look forward to your favorable response.

Authors

Reviewer 2 Report

Most of the doubts addressed in the first review were answered. Therefore, I would recommend accepting it after minor revision.

The only minor issue is associated with the question of "industrial recovery" mentioned in the title. I understand that the article is devoted mainly to the question of curative waters as the potential boron source. However, even one paragraph in Introduction, shortly presenting current state-of-art in this field would justify why waters containing boron may be even considered as a potential source of this element.

Author Response

To Reviewer 2,

Thank you very much for any corrections that improve the quality of our work.

An explanation below:

Any changes made in the text of the article are visible in the pdf file.

In the intrusion, we have added a short paragraph about the possibility of obtaining boron from water (some text has been moved from Section 4.3).

I look forward to your favorable response.

Authors