Updating Water Quality Standards Criteria Considering Chemical Mixtures in the Context of Climate Change

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Updating Water Quality Standards Criteria Considering Chemical Mixtures in the Context of Climate Change

Comments and Suggestions for Authors:

Decision: major revisions

The paper entitled “Updating Water Quality Standards Criteria Considering Chemical Mixtures in the Context of Climate Change” discusses the chemical pollution and climate change as criteria for water quality regulation updating; and on global north- south relations through a literature review of procedures and ways forward.

First, I congratulate the authors for their efforts.

Before publishing this work, it is necessary to take into consideration the following remarks:

The idea of ​​the article is relevant, but the way in which the work is presented requires further improvement to convince the reader and decision-makers in water management.

• For the ABSTRACT section: it is important to clearly state the methods used and the results obtained.
• For the INTRODUCTION section, it is necessary to rewrite following the solid writing method with more recent and relevant references on water standards and also references on the impact of climate change on water quality. The authors did not focus their research on water types such as drinking water, industrial water, bathing water, irrigation water, etc.
• The authors did not present detailed results of the chemical parameters to be updated (summary table of parameters for each water type: drinking water, irrigation water, etc.)
• In most paragraphs, the authors did not cite or provide references to support their ideas, such as: "2.1.2. Actions toward updating WQS : As stated in Table 1, most of the main organizations in the cited countries do not have an advanced discussion regarding updating WQS based on climate change and/or chemical mixtures." References to confirm this are required.
• In " Discussion," (the authors should discuss the results and how they can be interpreted from the perspective of previous studies and the working hypotheses. The findings and their implications should be discussed in the broadest possible context. Future research directions may also be highlighted). What is the purpose of this section?

Author Response

Dear reviewer, thank you for your input and time reviewing our work. We also want to thank you for investing your knowledge into the process and giving us insights that will increase the quality of the work. The responses to your comments are as follows:

The English was revised by an English native speaker.

Comments 1: For the ABSTRACT section, it is important to clearly state the methods used and the results obtained.

Response 1: Thank you for your suggestions. We agree with you and the abstract is now clearer as it has changes in the third sentence on L14 to "This paper explores chemical pollution and climate change as criteria for water quality regulation updating; and on global north-south relations using a thorough literature review including papers and all relevant regulations at the national level that rule over surface water regulations in different countries and proposes ways forward for the field of water quality". The abstract results have changed evidencing the main results of the research on L22 - "The research provided evidence that discussions on updating WQS to account for chemical mixtures are advanced in some countries such as The Netherlands but their implementation is needed. Furthermore, updates in WQS regarding climate change focus mostly on avoiding the climate crisis by reducing emissions. 

Comments 2: For the INTRODUCTION section, it is necessary to rewrite following the solid writing method with more recent and relevant references on water standards, and also references on the impact of climate change on water quality. The authors did not focus their research on water types such as drinking water, industrial water, bathing water, irrigation water, etc.

Response 2: Thank you for your suggestion. We agree that there needs to be a clearer definition of what kinds of water are being analysed in this study, so we changed two places in the text to make it clearer.

1. L103 - Last paragraphs of the introduction. Aiming an evaluation that would be present in all evaluated countries and a more concise evaluation, the scope of this work was defined as to use only surface water and drinking water The text changed as follows: "Surface water and potable water quality were selected as the primary focus of this study due to their widespread presence across all analyzed countries and the ongoing discourse regarding the integration of mixture effects and climate change considerations into their regulatory frameworks and criteria updates. Other water quality standards, including those for irrigation, industrial, or recreational (bathing) purposes, fall outside the scope of the present work".
2. L132 - The last sentence of the topic "2.1. Main actors": "Therefore, it is difficult to find a single organization responsible for the regulation of all chemicals; thus, this work will focus on the analysis of the regulatory bodies in charge of surface and drinking water, since they are the most advanced water quality areas in terms of discussing updating WQS".

Comments 3: The authors did not present detailed results of the chemical parameters to be updated (summary table of parameters for each water type: drinking water, irrigation water, etc.)

Response 3: Thank you for your input. The purpose of this work is to discuss the method of updating water quality regulation, thus it applies to any water quality threshold (for surface or drinking water). In order to make it clearer for you and for the reader, we changed the introduction section on L105 to "The primary focus of this discussion is therefore the procedures employed for updating these parameters, rather than the specific parameter values themselves".

Comments 4: In most paragraphs, the authors did not cite or provide references to support their ideas, such as: "2.1.2. Actions toward updating WQS : As stated in Table 1, most of the main organizations in the cited countries do not have an advanced discussion regarding updating WQS based on climate change and/or chemical mixtures." References to confirm this are required.

Response 4: Thank you for your input. We agree that the sentence is strong and thus needs confirmation from a reference. Therefore, a new reference that endorses the sentence was used as citation number 43 on the first sentence of Topic 2.1.2 on L236. References were also updated.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors,

The presented review paper, "Updating Water Quality Standards Criteria Considering Chemical Mixtures in the Context of Climate Change", is a well-structured, thorough literature review of the need to update the Water Quality Standards in the context of climate change. It deals with a new approach that has to be followed by the regulatory bodies - instead of considering toxicological assays performed under laboratory conditions (not in the real environment with synergistic and/or antagonistic interactions with other contaminants) or literature research on new compounds, an approach to utilize the chemical pollution and climate change as criteria for water quality regulation updating should be undertaken.

The review focuses on whether there are current ongoing discussions among the main organisations worldwide in charge of updating WQS for drinking water and surface water in the view of climate change or chemical mixtures.

My recommendations are the following:

1. L413-414: Please replace the cited "(Altenburger et al., 2019; Kortenkamp 413
   & Faust, 2018)." with "[18,44]".
2. L417-421: Please remove the Discussion part (left from the template used), as the Results and the Discussion are already combined (L232-416)

Author Response

Dear reviewer, thank you for your input and time reviewing our work. We also want to thank you for investing your knowledge into the process and giving us insights that will increase the quality of the work. The responses to your comments are as follows: 

Comments 1: L413-414: Please replace the cited "(Altenburger et al., 2019; Kortenkamp 413
& Faust, 2018)." with "[18,44]".

Response 1: Thank you for the remark and thorough work review. I've corrected the reference, and now it is in the proposed formatting of the journal.

Comments 2: L417-421: Please remove the Discussion part (left from the template used), as the Results and the Discussion are already combined (L232-416)

Response 2: Thank you for the remark. We have deleted said section, and now results and discussion are combined.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Review of the article: “Updating Water Quality Standards Criteria Considering Chemical Mixtures in the Context of Climate Change”

The manuscript addresses a relevant and timely topic concerning the revision and update of water quality regulations. However, the discussion remains too general and lacks sufficient depth. In particular, the article does not provide concrete examples or case studies, such as specific regulatory changes implemented in individual countries. A comparative overview of selected national approaches would significantly enhance the value and applicability of the work.

Moreover, the paper does not describe the procedural framework or mechanisms through which water quality regulations are typically revised. Including such information would improve the clarity and practical relevance of the manuscript.

The article’s structure is rather limited, consisting of plain text and a single table. This minimal use of visual aids results in a presentation that is not particularly engaging and may hinder comprehension. To improve readability and accessibility, the manuscript should incorporate additional visual elements—such as block diagrams, flowcharts, or supplementary tables—which could help clarify key concepts and processes discussed in the text.

1. Introduction

Page 2, line 89-91:“Thus, a critical discussion on ways forward will be elaborated, and process-updating methodologies will be proposed, considering the feasibility and scientific relevance.”

A detailed explanation of the proposed methodology should be included in the later sections of the manuscript. Presenting it in the form of a schematic or diagram would significantly improve the clarity and understanding of the approach.

2. Review

All subsections within the Review section should be supplemented with more detailed and comprehensive information.

2.1.1.1. Literature research update

Page 4, line 129-130“All the studied countries have methodologies in place to update their WQS based on  literature research”

The manuscript should include a more in-depth discussion of the methodologies applied in each country.  

 

2.1.1.2. Climate change

This chapter should be expanded to address additional aspects of climate change. It would be most effective to first discuss individual components of climate change and subsequently present specific water quality parameters that are influenced by each of these components.

The content of this chapter is currently insufficient, and the number of references cited is too limited. A broader review of the relevant literature is strongly recommended. An example of pertinent literature is provided at the end of the review, but more comprehensive citation throughout the chapter is necessary.

2.1.1.3. Chemical mixtures

Please provide examples of chemical compounds that should be considered for inclusion in water quality regulations. A discussion on recent developments or updates in the analytical methods used to detect specific chemical compounds is missing from this chapter.

 

4. Discussion

It is difficult to determine what the authors intended to convey in this short chapter.

 

References:

Khan, S. J., Deere, D., Leusch, F. D., Humpage, A., Jenkins, M., & Cunliffe, D. (2015). Extreme weather events: Should drinking water quality management systems adapt to changing risk profiles?. Water research, 85, 124-136.

Lipczynska-Kochany, E. (2018). Effect of climate change on humic substances and associated impacts on the quality of surface water and groundwater: A review. Sci. Total Environ 640, 1548-1565.

 

 

Comments for author File: Comments.pdf

Author Response

Dear reviewer, thank you for your input and time reviewing our work. We also want to thank you for investing your knowledge into the process and giving us insights that will increase the quality of the work. The responses to your comments are as follows:

Comments 1:

1. Introduction
Page 2, line 89-91:“Thus, a critical discussion on ways forward will be elaborated, and process-updating methodologies will be proposed, considering the feasibility and scientific relevance.”

A detailed explanation of the proposed methodology should be included in the later sections of the manuscript. Presenting it in the form of a schematic or diagram would significantly improve the clarity and understanding of the approach.

Response 1: For this clarification, we added information from L97 to L107, and we created a new figure for the paper to increase understanding of the work.
Text added: "First, the main responsible agencies will be listed, and their processes for establishing concentration thresholds will be described. The primary focus of this discussion is therefore the procedures employed for updating these parameters, rather than the specific parameter values themselves.

Surface water and potable water quality were selected as the primary focus of this study due to their widespread presence across all analyzed countries and the ongoing discourse regarding the integration of mixture effects and climate change considerations into their regulatory frameworks and criteria updates. Other water quality standards, including those for irrigation, industrial, or recreational (bathing) purposes, fall outside the scope of the present work. Thus, a critical discussion on ways forward will be elaborated, and process-updating methodologies will be proposed, considering the feasibility and scientific relevance."

Comments 2: 

2. Review

All subsections within the Review section should be supplemented with more detailed and comprehensive information.

2.1.1.1. Literature research update

Page 4, line 129-130“All the studied countries have methodologies in place to update their WQS based on  literature research”

The manuscript should include a more in-depth discussion of the methodologies applied in each country.  

Response 2:

We thank you for your input and agree that we could increase the information provided. However, for the cited countries and the EU the inclusion of chemical mixtures and climate change on the updating processes is not easily accessible and are frequently behind a procedural barrier. Thus, to obtain the data on the updating process in depth we face chalenges of data unavailability. To make this topic clearer the following information was added on L157: "The periodicity of updating is not clearly established, nor is the detailed methodology for those countries. Therefore, the discussion is in such early stages about including climate change and chemical mixture that there are few documents easily accessible for all the seven territories analyzed".

Comments 3:

2.1.1.2. Climate change

This chapter should be expanded to address additional aspects of climate change. It would be most effective to first discuss individual components of climate change and subsequently present specific water quality parameters that are influenced by each of these components.

The content of this chapter is currently insufficient, and the number of references cited is too limited. A broader review of the relevant literature is strongly recommended. An example of pertinent literature is provided at the end of the review, but more comprehensive citation throughout the chapter is necessary.

Response 3:

Thank you for your input on this topic. The intention with this topic is to talk about how the subject of climate change is being included on the discussions for the updating process. For the corrections, we added more information on the possible effects of climate change on water quality, at the begining of the section on L176. We have also changed the subtitle of the section to match the intention of the section "2.1.1.2. Including climate change on the updating process". 

The same correction was done to the title of the next section, L188 "2.1.1.3. Including chemical mixtures on the updating process". An extra paragraph was added to explain the topic while providing the solicited information about quantification methods and a brief description of the possible compounds that would be found.

While talking about climate change it is common to relate the temperature increase with the solubilization of compounds such as trace metals and polycyclic aromatic hydrocarbons that are in the sediment [39]. Furthermore, an increased erosivity is also expected with increased rainfall caused by climate change [39]. These processes could promote greater interaction between pollutants and thus greater effects on the biota [37,39]. It is important to highlight that the quantification of those compounds in the environment is related to the limit of detection of the available equipment for a given region, thus, protection could vary depending on the country [40].

Comments 4:

4. Discussion

It is difficult to determine what the authors intended to convey in this short chapter.

 

Response 4: Thank you for your input on the subject. The topic was removed because it was not intended to be placed in that manner on the paper.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

It is necessary to do a proofreading by the authors before putting the manuscript online, for example the title of figure 1

Reviewer 3 Report

Comments and Suggestions for Authors

The article has been corrected and can be published.