Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

thank you for submitting your manuscript. 

This is an interesting paper dealing with Hydrogeochemical characterization of mineral springs in the Peruvian Tropical Highlands. It is suitable for publication in the Water journal, after major revision addressing the following issues.

In the Introduction, the authors wrote that the objective of this study is to characterize physico-chemical parameters and microbiology of the mineral water sources of the Amazon region. Indeed, this is an ambitious project as the area of study is very wide. Also, to interpret the physico-chemical data obtained it is of paramount importance to consider some geological features of the study area, such as the depth of the water source and the mineralogical composition of all the rocks the water passes through in its path to the surface. To this end, it is important to report the stratigraphic sections in addition to the geological maps for the mineral springs studied. This aspects must be better deepened in the manuscript. The geology is definitely the weak point of this manuscript.

The manuscript contains several errors in form and minor inaccuracies that need to be corrected. The English form can also be improved. The bibliography cited is not always updated, relevant or exhaustive: authors should add references of recent literature more closely related to the area of study. The text and its division into different sections should be better reorganised.

Additional issues to be addressed are detailed in the following:
Abstract
Line 18: the authors should explicit which kind of rocks constitute the Pulluicana Group and the Sarayaquillo Formation, as the reader may not know them
Line 21: which are the source of Arsenic and aluminium?
Line 24: which are the possible biotechnological applications?

Introduction:
Lines 31-32: “Mineral waters are understood as all those waters whose dissolved element content is greater than 1,000 mg/l.”: this definition of “mineral water” is not universally accepted. The authors should better revised it and add also other proper references. They should also specify what they intend for “element content”.
Lines 46, 59, and elsewhere in the text: “Mg+2”, “SO4-2” should be replaced by “Mg2+”, “SO42-” 

Study area:
Line 89: what is the “physiography”?
All this section contain only information of the surface of the study area. A description of the geology of the area is completely absent and must be added here. The only reference regarding the geology quoted here is very outdated: 26. Bellido, E. (1969) Sinopsis de la geología del Perú.

2.3. Sampling and determination of physicochemical and microbiological parameters:
Line 119: “Samples were collected from 21 hydrothermal vents “: the figure with the location of the sampled hydrothermal vents should be quoted here

2.4. Classification of natural sources of mineral waters:
Lines 156-157: the classification the authors made into thermal, saline, and sulfur springs, based on “how the communities that lived and used the natural mineral water sources perceived these springs”, it’s not scientifically sound. They should better use proper scientific criteria to make such classification.

2.6. Data analysis:
Lines 183-184: “graphs of the geology and geomorphology of each zone were made to infer the relationship of the geological formation of its location with the nature of the water in these sources.”: on which data are based these graphs, are they literature data or field original data collected for this study?

Line 192: The section “3. Results and Discussion” and its contents should be divided into two distinct sections (3.Results, 4. Discussion), because, as it is, it is not quite clear which are the results of the present study.
Lines194-196 and Fig1: Not all 21 mineral springs studied are shown in fig 1.
Lines 209-210 and Fig.2: it is not quite clear the correspondence between the notation (eg, Me, Mf) and colors used in Fig.2 with the reference [49] quoted. The proper use of the formation’s notation and standard colors should be checked.

3.3. Geology of the location of mineral water springs:
Lines 230-289: The information contained in the section “3.3. Geology of the location of mineral water springs” does not pertain to the results section, as here the authors do not report any results of their own, but only (mainly outdated) literature on the geology of the study area. Part of this section should be moved to the “2.1. Study area” section, where, to complete the information on the geological framework of mineral springs, it is advisable to add also stratigraphic sections that provide information on the rocks that the water passes through on its journey from depth to the surface. Some sentences in this 3.3 section should be moved to the introduction and discussion sections.
Lines 276-287: In Figure 3 “Map of geology and location of identified mineral water sources.”, where the Geological map of Peru [56] is mentioned as reference source, the colors used by the authors are definitely wrong. The authors must use the standard color notation used worldwide to denote specific rock types. Also several mistakes are made in the figure caption, such as considering “Ji-280 c: Jurassic (conglomerate); Jms-c: Jurassic (sandstone-conglomerate); Js-s: Jurassic (siltstone-sandstone);” etc., as part of the igneous units (lines 280-282).
Lines 234-236; “composed of micritic limestones, marly limestones, and quartz sandstones, which allow the filtration and heating of groundwater [32].” It is not quite clear how this should be possible.
Lines 236-240: “Contrast with other high enthalpy hydrothermal systems such as the Borateras Geothermal Zone allows understanding that the permeability of the sedimentary rocks and the regional geothermal gradient is the main reason for the origin of the hydrothermal source in our study area, while Borateras, located in Peru in the Western Cordillera of the Andes in southern Peru, is associated with volcanic activity and more intense interaction between water and rocks at high temperatures [57].” This sentences are not reporting results, but rather a comparison with other areas of study. As such, all these sentences should be moved to the discussion section.
Lines 244-246: the sentence “Sulfurous springs worldwide have been recognized for their beneficial effects in treating skin and respiratory system conditions due to the action of hydrogen sulfide and other compounds [59].” Does not pertain to the results section but rather to the introduction.
Lines 247-251: “Saline springs are linked to sedimentary formations containing limestones and sandstones, such as the Sarayaquillo Formation and the Pulluicana Group, which allow the concentration of minerals, thus enriching the waters in salts. These rocks allow the concentration of minerals such as sodium and calcium in the water, generating highly saline waters [60]. “ The reference cited here do not pertain to the study area.
Lines 300-405: The content of section “3.4. Physicochemical, microbiological, and trace element characterization of natural mineral water sources” should be split into separate “results” and “Discussion” sections, because, as it is, it is not quite clear which are the results of the present study.
Lines 406-492: the content of the section “3.6. Spatio-temporal dynamics of physicochemical and microbiological parameters of mineral springs” should be moved to the discussion section, where it must be indicated whether the data discussed come from the results of this study or from other previous studies.
References
Lines 693-694 and elsewhere: Some references should be amended by adding the authors/editors names, as, for example, in reference [49] “INGEMMET. Boletín No. 55A: Geología del Perú; INGEMMET: Lima, Perú, 1995. Available online: https://hdl.han-693 dle.net/20.500.12544/176 (accessed on 15 January 2024).”

Kind Regards

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The water quality of natural mineral springs is of great significance for the sustainable utilization and protection of regional water resources. The manuscript describes the hydrogeochemical characteristics of 21 springs in the tropical highlands of Peru, but the depth is insufficient and further modifications are needed.

1. In the introduction, the author needs to further emphasize the purpose and significance of this study at the end.
2. The section on materials and methods needs to be supplemented with relevant content on water sample quality control.
3. In addition to geological conditions, information on regional hydrogeological conditions is crucial for understanding the hydrogeochemical characteristics of spring water. Further strengthening and supplementation are needed.
4. Figure 3 is unclear and the legend is too small, it needs to be modified.
5. Is the spring water data suitable for applying PCA? What is the KMO value?
6. The biggest flaw of this paper is the lack of depth, as most of the conclusions are qualitative statistical analysis and lack quantitative analysis. In addition, the author needs to strengthen the hydrochemical genesis of the spring water.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper presents original data about the hydrogeochemical and microbiological fuature of 21 springs in the Peruvian Tropical Highlands (Peru).  A significant part of the article is related to the principal component analysis (PCA) between 14 parameters and the evaluation of water quality using the Ica-PE index. The authors also attempt to clarify the relationship between the physicochemical parameters of studied mineral springs with the geomorphology and geology of the area location. The manuscript subject is interesting, the presented data is original and valid, and inscribe in the Journal profile. Unfortunately, in this version the article cannot be accepted for publication according to several reasons. The main one – there is not table 6 with dataset in the text file, although the article refers to Table 6 (page 10, Lines 302-303). Without this table, it is difficult to evaluate the article because of not any actual data.

Unfortunately, I am unable to understand the significance (idea??) of Tables 2, 3, 4 and 5. It is unclear why the authors present a range of values for various parameters (pH, EC, t, chemical parammeters and i.e.) without any reference to real springs. In order to understand the differences between three different types of springs , it is important to consider their individual characteristics. What is  sulfur springs? H2S-bearing springs? And what are the constituents of the dissolved gas from other sources? And are these springs thermal? In general, the article needs to be revised to include information about the geochemical characteristics of each type, highlighting their differences in terms of their micro-component composition. In this paper version the presentation of the material is lacking clarity.

When discussing the composition of the mineral springs, it is essential to consider their connection to the geological and hydrogeological settings of the area. It is crucial to provide a concise overview of the hydrogeological conditions of the region, along with a geological cross-section of the study area.

You have to specify the purpose of the article! In this version it is unclear that you are actually studying. Currently, it is not enough to simply provide data on the chemical and microbiological composition of mineral springs, it is necessary to explain how these springs genesis.

Figures 2, 3 (maps), 4, 5 (Principal Component Analysis) are completely unreadable (they difficult to interpret) and need deeply correction.

Please, check terminology in the whole manuscript, in many cases inadequate professional terminology is used.

In the current version, the conclusions are not clear and do not result from the text of the article.

Unfortunately, in this version the article cannot be accepted for publication. Also, I would like to encourage the authors to resubmit the manuscript after full rewriting, revision and extension.

Comments on the Quality of English Language

The manuscript must be controlled in language by a native speaker. In some parts of the text, the author's ideas are difficult to interpret. 

Author Response

 "Please see the attachment."

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Accept in present form

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This version of the article has undergone significant revision, and there has been notable progress in terms of the logic of the argument. However, there are still some major comments. You'll find them in the article text.

The most significant problem, I believe, is the absence of a consolidated table that displays the actual data derived from testing 21 different sources. You collected 21 water samples (in August and September 2023) which were subsequently analyzed in a laboratory to determine the chemical composition of the water. However, for some reason, the data on the macro- and micro-component composition has not been presented. These data are fundamental and all further arguments and conclusions are based on them.

The text is missing table 4.

Tables 3 and 5 need to be reorganized according to the notes in the file.

Comments for author File: Comments.pdf

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf