Spatial Heterogeneity of Heavy Metals in Arid Oasis Soils and Its Irrigation Input–Soil Nutrient Coupling Mechanism
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript assessed the levels of some elements that the authors (wrongly) called heavy metals in different soils of a region and in irrigation water. The topic is relevant and in line with the scope of the journal. However, the way it is presented contributes little to scientific advances on the topic. The authors basically present many results and few developments on these. I recommend that the authors rewrite the paper following some of the suggestions below.
The abstract is very long and not very explanatory. It does not follow a logical sequence of writing. Rewrite the abstract with a short introductory section, followed by the objectives (clear and well-defined). Then, indicate how you intend to achieve the proposed objectives and the main results of the work. End the abstract with the main scientific advance achieved through this work.
The introduction is poor, presenting a lot of information, but little associated with the work. There is no clear hypothesis or objectives proposed for this work. I suggest that the authors rewrite the introduction of the paper with a review that indicates what motivated them to do this work. Describe the hypothesis and objectives at the end of the introduction.
Table 1 is indescribable.
Figures 3 and 5 are extremely confusing and difficult to interpret. Redo it.
Line 163 – Are boron and arsenic heavy metals?
Line 182 – Use boron in the first mention and (B) for the others.
314 to 320 – This continues to be a result, there is no discussion.
321 to 330 – This conclusion is merely suggestive. The authors did not research the origin of the heavy metal levels in each soil, they only quantified them. If the entire discussion is based on speculation, the manuscript loses its scientific character.
In general, item 4.1 is poor and very speculative. The same applies to items 4.2 and 4.3. The authors attempt to discuss all the results found in a minimal manner, instead of seeking a common denominator. The way in which the authors discuss the results is also very vague. There are few bibliographical references for a widely studied topic. The discussion regarding correlations is merely descriptive.
Once again, the lack of a clear hypothesis and well-established objectives caused the authors to get lost in the work. This was reflected in the conclusion. To whom is it new to conclude that the concentration of heavy metals in the soil varies depending on the source material and human activity? What is new about this manuscript?
The title, objectives, MM and conclusion are not in harmony.
Author Response
Response to Reviewer 1 Comments
Dear reviewer:
Thanks for your letter and for reviewer's comments concern our manuscript entitled “Spatial heterogeneity of heavy metals in arid oasis soils and its irrigation input-soil nutrient coupling mechanism” (Manuscript ID: 3734397). We are very grateful to the reviewers for their valuable comments and suggestions on our article, which has been of great help in our manuscript revision. The reviewer comments are laid out below in italicized font and specific concerns have been numbered. Our response is given in normal font and changes/additions to the manuscript are given in the green text.
Point-by-point response to Comments and Suggestions for Authors:
Comment 1:
The manuscript assessed the levels of some elements that the authors (wrongly) called heavy metals in different soils of a region and in irrigation water. The topic is relevant and in line with the scope of the journal. However, the way it is presented contributes little to scientific advances on the topic. The authors basically present many results and few developments on these. I recommend that the authors rewrite the paper following some of the suggestions below.
The abstract is very long and not very explanatory. It does not follow a logical sequence of writing. Rewrite the abstract with a short introductory section, followed by the objectives (clear and well-defined). Then, indicate how you intend to achieve the proposed objectives and the main results of the work. End the abstract with the main scientific advance achieved through this work.
Response 1:
Thank you very much for your valuable comments. The problem you pointed out about the unclear logical sequence and redundant explanations of the abstract is very pertinent. We have comprehensively restructured the abstract based on your suggestions, specifically modifying 12-30 lines of the manuscript.
Comment 2:
The introduction is poor, presenting a lot of information, but little associated with the work. There is no clear hypothesis or objectives proposed for this work. I suggest that the authors rewrite the introduction of the paper with a review that indicates what motivated them to do this work. Describe the hypothesis and objectives at the end of the introduction.
Response 2:
Thank you very much for your valuable comments. The problem of information redundancy and the lack of clear assumptions and goals you pointed out hits the nail on the head. We have made the necessary revisions based on your suggestions. For details, please refer to line 82-92 of the revised draft.
Comment 3:
Table 1 is indescribable.
Response 3:
We sincerely appreciate your constructive feedback on Table 1 in our paper. We understand your concern that Table 1 may be difficult to comprehend. In the following sections, we will provide a detailed explanation of the design rationale and logical structure of Table 1, with the aim of helping you better grasp its underlying concepts.
The core purpose of Table 1 is to clearly and systematically present the analytical methods for each indicator in the samples. During the research process, accurately determining the various elements and parameters in the samples is crucial for drawing reliable conclusions. However, due to differences in their chemical properties, concentration levels, and testing requirements, different indicators require specific analytical methods.
From the table structure, we have divided it into four columns. The “Index” column clearly lists all the indicators to be measured, covering metal elements (such as Cu, Cr, Ni, etc.), cation exchange capacity (CEC), pH, nutrient elements (Total N, Total P, etc.), and organic matter. The “Assay method” column provides detailed explanations of the measurement methods used for each indicator.
For example, for elements such as Cu, Ni, Cd, Se, and As, we use ICP-MS (inductively coupled plasma mass spectrometry) because ICP-MS offers extremely high sensitivity, a wide dynamic linear range, and the ability to simultaneously measure multiple elements, making it highly suitable for the precise determination of trace metal elements. For Cr and Zn, ICP-OES (inductively coupled plasma optical emission spectroscopy) is employed. This method demonstrates good accuracy and precision when determining major, minor, and trace elements, and it is relatively cost-effective. For Hg, due to its extremely low concentration in environmental samples and unique chemical behavior, CVAAS (cold vapor atomic absorption spectroscopy) provides high selectivity and sensitivity for detection.
For non-metallic elements and parameters, CEC is determined using the ammonium acetate exchange method (pH 7.0), a classic method for measuring soil cation exchange capacity, which accurately determines soil adsorption capacity for cations through ion exchange reactions under specific pH conditions; pH is measured using the glass electrode method (soil-water ratio 1:2.5), a simple, rapid method that accurately reflects soil acidity or alkalinity; Total nitrogen is determined using the Kjeldahl method, the standard method for measuring total organic and inorganic nitrogen, ensuring accuracy through steps such as digestion, distillation, and titration; total phosphorus is determined using the molybdenum-antimony spectrophotometric method, which utilizes the formation of complexes between phosphorus and ammonium molybdate under specific conditions for colorimetric determination, offering high sensitivity and accuracy.
We hope that this tabular presentation will enable readers to quickly understand the specific measurement methods for each indicator, facilitating replication of experiments or method comparisons by other researchers.
Once again, we appreciate your attention to and feedback on our paper. We hope our explanation has provided you with a clearer understanding of Table 1. If you have any further questions or suggestions, we will actively incorporate them and continue to improve our work.
Comment 4:
Figures 3 and 5 are extremely confusing and difficult to interpret. Redo it.
Response 4:
We sincerely thank you for your careful review of our paper and valuable feedback. We have taken your questions seriously and conducted a comprehensive review and revision. The specific revisions are as follows: Figures 3 and 5 were originally intended to enhance the credibility of the data in the article by including data distribution sets and adding normal distribution lines to present the data distribution. However, due to the large amount of data, the charts appeared too crowded. Following your suggestion, we have removed the data distribution sets and retained only the box plots, making corresponding revisions and corrections in the original text.
Comment 5:
Line 163 – Are boron and arsenic heavy metals?
Response 5:
Thank you for your insightful question. You are correct in pointing out the need to clarify the classification of boron (B) and arsenic (As).
From a strictly chemical perspective, heavy metals are typically defined as metals with a density greater than 5 g/cm³, such as cadmium (Cd), copper (Cu), and lead (Pb). Boron is a non-metallic element, while arsenic, although it exhibits metallic properties in certain compounds, is typically classified as a metalloid rather than a heavy metal.
In our study, we listed all the elements analyzed in the irrigation water samples from the ecological geological survey of the region. The inclusion of boron and arsenic aims to provide a comprehensive overview of the elemental composition of irrigation water. Although they are not strictly heavy metals, they may interact with heavy metals in the environment or influence the soil-plant system, which is relevant to our research on the coupling mechanism between irrigation inputs and soil nutrients in arid oasis soils.
As indicated by the title “Spatial heterogeneity of heavy metals in arid oasis soils and their coupling mechanisms with irrigation inputs and soil nutrients,” our research primarily focuses on the spatial distribution characteristics of typical heavy metals in soil and their coupling relationships with irrigation and soil nutrients. The analysis of other elements such as boron and arsenic in irrigation water aims to provide a more comprehensive picture of water quality and potential influencing factors.
Comment 6:
Line 182 – Use boron in the first mention and (B) for the others.
Response 6:
Thank you for your careful review and valuable suggestion. You are absolutely right. We have carefully checked the relevant part in Line 182 and the whole manuscript. We will revise it so that for boron, we will use "boron" at the first occurrence and then use "(B)" for all the following mentions. This will improve the readability and professionalism of our paper.
Comment 7:
314 to 320 – This continues to be a result, there is no discussion. 321 to 330 – This conclusion is merely suggestive. The authors did not research the origin of the heavy metal levels in each soil, they only quantified them. If the entire discussion is based on speculation, the manuscript loses its scientific character. In general, item 4.1 is poor and very speculative. The same applies to items 4.2 and 4.3. The authors attempt to discuss all the results found in a minimal manner, instead of seeking a common denominator. The way in which the authors discuss the results is also very vague. There are few bibliographical references for a widely studied topic. The discussion regarding correlations is merely descriptive.
Response 7:
We sincerely appreciate the time and effort you have dedicatead to reviewing our manuscript and for providing such insightaful comments regarding the sections from line 314 to 320 and 321 to 330.
Regarding the issue you raised about lines 314 - 320, where you felt it continued to be a result presentation without discussion. We would like to explain that our intention in this part was to use the results as a springboard to lead into the subsequent discussion. We presented the key findings on the distribution range of heavy metal content in different land - use types first, aiming to give readers a clear and direct understanding of the basic results before delving into a more in - depth analysis. However, we acknowledge that this approach might have given the impression of merely listing results. We have now revised this section to better integrate the results with the discussion, ensuring a smoother transition and a more logical flow of ideas.
As for the comments on lines 321 - 330, you pointed out that the conclusion seemed merely suggestive and that we did not research the origin of the heavy metal levels in each soil but only quantified them, and that if the entire discussion was based on speculation, the manuscript would lose its scientific character. We completely understand your concern. In fact, our discussion was not purely speculative. When analyzing the reasons behind the heavy metal distribution patterns, we referred to and cited relevant previous research findings. For example, when discussing the high arsenic content in cropland, we considered the influence of the geochemical background of soil - forming materials, which is supported by studies on the regional geology. Also, the impact of agricultural activities, such as the use of arsenic - containing pesticides, is well - documented in existing literature. We have also revised the original expressions like "may be" in the manuscript to make the language more standardized and in line with scientific requirements, in the meantime, we have rewritten the discussion section in accordance with your and reviewer 2's comments, and marked it in yellow text.
At the same time, we sincerely thank you for your insightful and valuable criticism of Section 4 of this paper. The primary objective of the current stage of this study is to identify and describe the key associative patterns that exist between specific variables. As an exploratory study, we believe that accurately describing these patterns is of significant value in itself, laying the groundwork for proposing mechanistic hypotheses in future research. A deeper exploration of causal relationships or potential mechanisms requires more refined data, which is beyond the scope of this paper and the capabilities of our current dataset, as mentioned in the section on future research directions. For details, please refer to lines 505-520 of the revised draft.
Comment 8:
Once again, the lack of a clear hypothesis and well-established objectives caused the authors to get lost in the work. This was reflected in the conclusion. To whom is it new to conclude that the concentration of heavy metals in the soil varies depending on the source material and human activity? What is new about this manuscript?
The title, objectives, MM and conclusion are not in harmony.
Response 8:
We sincerely appreciate your insightful and critical comments on our manuscript, which have provided us with a valuable opportunity to further refine and enhance our work.
We fully acknowledge your concern regarding the initial lack of a clear hypothesis and well - defined objectives, which, as you rightly pointed out, might have led to a certain degree of disorganization in the earlier version of the manuscript. We deeply regret any confusion or inconvenience this may have caused.
In response to your feedback, we have made significant revisions to the introduction section. We have thoroughly re - written it to clearly outline a specific hypothesis that guides our research. This hypothesis is based on a comprehensive review of existing literature and a careful consideration of the research gap in the field. Additionally, we have precisely defined the objectives of our study, ensuring that they are not only well - established but also directly aligned with the hypothesis. Moreover, we have detailed the step - by - step process for addressing the research questions, providing a clear roadmap for our work.
Regarding the results and conclusion, we have taken great care to ensure that the findings presented in the results section are directly related to and support the hypothesis and objectives. In the conclusion, we have not only restated the obvious fact that the concentration of heavy metals in the soil varies depending on the source material and human activity, but we have also delved deeper into the unique contributions of our study. We have highlighted the novel aspects, such as the specific patterns of heavy metal distribution we observed in different land - use types within our study area, which may have implications for local soil management and environmental protection strategies. We have also discussed how our findings add to the existing body of knowledge in the field, providing new insights and perspectives.
We have also carefully reviewed and revised the title, objectives, methods (MM), and conclusion to ensure they are in perfect harmony. The title now accurately reflects the core focus of the study, the objectives are clearly stated and achievable, the methods are appropriate for addressing the objectives, and the conclusion effectively summarizes the key findings and their significance in relation to the hypothesis and objectives.
We understand that scientific research should strive for clarity, novelty, and coherence, and we believe that our revisions have significantly improved the manuscript in these aspects. We would be grateful if you could kindly review the revised version and provide us with your further feedback.
Thank you once again for your time and effort in reviewing our manuscript.
Other clarifications:
First of all, I am very sorry to explain this situation, although we have already sent a request email to the editor before that, and it is not clear whether the reviewer is aware of it. At the request of the issuing organization, it is necessary to replace the boundaries of Figure 1 as well as Figure 4 of the article, and we guarantee that all research content will remain unchanged. We look forward to your understanding and support, and we apologize for the inconvenience.
Again, thank you very much for your valuable comments and suggestions. We hope that the revisions in the manuscript and our accompanying responses will be sufficient to make our manuscript suitable for publication in Sustainability.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper investigates spatial heterogeneity of heavy metals in arid oasis soils. The article made a very good impression, due to the large number of samples and spatial coverage. However, there are some comments to the article.
1) The abstract to the article is too long and needs to be shortened; it is necessary to emphasize the main conclusions obtained as a result of the research. Table 1 is not readable; the text is duplicated, also it is necessary to increase the size of Figures 3, 5.
2) In Figure 2, the content of Cu, Hg, Pb, Cd does not change in the water samples, what could be the reason for this? Probably, the content of Cu, Hg, Pb, Cd was below the detection limit of the device and the sensitivity of this technique did not allow to determine their content with sufficient accuracy, which raises doubts about all the data obtained and requires clarification and verification.
3) At the same time, Figure 2 shows a sharp increase in the concentrations of Cr, B, As, Se, but this is not indicated in the text in which soil type.
3) The Methods section describes that the cation exchange (CEC) value was determined, which is also shown in Figure 5. However, the text describes the electrical conductivity ECE. There is no description of how the cation exchange (CEC) value was determined. Therefore, it is not clear what value the authors actually determined.
4) To form a more complete picture of the sources of heavy metals in soils, it is necessary to provide at least published data on the content of heavy metals in rocks in order to reliably talk about the influence of the anthropogenic factor.
5) The Discussion section contains virtually no references to published sources; this section needs to be revised.
Author Response
Response to Reviewer 2 Comments
Dear reviewer:
Thanks for your letter and for reviewer's comments concern our manuscript entitled “Spatial heterogeneity of heavy metals in arid oasis soils and its irrigation input-soil nutrient coupling mechanism” (Manuscript ID: 3734397). We are very grateful to the reviewers for their valuable comments and suggestions on our article, which has been of great help in our manuscript revision. The reviewer comments are laid out below in italicized font and specific concerns have been numbered. Our response is given in normal font and changes/additions to the manuscript are given in the yellow text.
Point-by-point response to Comments and Suggestions for Authors:
Comment 1: The abstract to the article is too long and needs to be shortened; it is necessary to emphasize the main conclusions obtained as a result of the research. Table 1 is not readable; the text is duplicated, also it is necessary to increase the size of Figures 3, 5.
Response 1:
We sincerely appreciate your constructive feedback on Table 1, the abstract, Figure 3, and Figure 5 in the paper. Based on your feedback, we have streamlined the abstract in the manuscript. Figures 3 and 5 have been revised to remove the dataset distribution and normal distribution lines to enhance clarity. We also understand your concerns regarding the potential complexity of Table 1. In the following sections, we will provide a detailed explanation of the design rationale and logical structure of Table 1, aiming to help you better understand its core concepts.
The core purpose of Table 1 is to clearly and systematically present the analytical methods for each indicator in the samples. During the research process, accurately determining the various elements and parameters in the samples is crucial for drawing reliable conclusions. However, due to differences in their chemical properties, concentration levels, and testing requirements, different indicators require specific analytical methods.
From the table structure, we have divided it into four columns. The “Index” column clearly lists all the indicators to be measured, covering metal elements (such as Cu, Cr, Ni, etc.), cation exchange capacity (CEC), pH, nutrient elements (Total N, Total P, etc.), and organic matter. The “Assay method” column provides detailed explanations of the measurement methods used for each indicator.
For example, for elements such as Cu, Ni, Cd, Se, and As, we use ICP-MS (inductively coupled plasma mass spectrometry) because ICP-MS offers extremely high sensitivity, a wide dynamic linear range, and the ability to simultaneously measure multiple elements, making it highly suitable for the precise determination of trace metal elements. For Cr and Zn, ICP-OES (inductively coupled plasma optical emission spectroscopy) is employed. This method demonstrates good accuracy and precision when determining major, minor, and trace elements, and it is relatively cost-effective. For Hg, due to its extremely low concentration in environmental samples and unique chemical behavior, CVAAS (cold vapor atomic absorption spectroscopy) provides high selectivity and sensitivity for detection.
For non-metallic elements and parameters, CEC is determined using the ammonium acetate exchange method (pH 7.0), a classic method for measuring soil cation exchange capacity, which accurately determines soil adsorption capacity for cations through ion exchange reactions under specific pH conditions; pH is measured using the glass electrode method (soil-water ratio 1:2.5), a simple, rapid method that accurately reflects soil acidity or alkalinity; Total nitrogen is determined using the Kjeldahl method, the standard method for measuring total organic and inorganic nitrogen, ensuring accuracy through steps such as digestion, distillation, and titration; total phosphorus is determined using the molybdenum-antimony spectrophotometric method, which utilizes the formation of complexes between phosphorus and ammonium molybdate under specific conditions for colorimetric determination, offering high sensitivity and accuracy.
We hope that this tabular presentation will enable readers to quickly understand the specific measurement methods for each indicator, facilitating replication of experiments or method comparisons by other researchers.
Once again, we appreciate your attention to and feedback on our paper. We hope our explanation has provided you with a clearer understanding of Table 1. If you have any further questions or suggestions, we will actively incorporate them and continue to improve our work.
Comment 2: In Figure 2, the content of Cu, Hg, Pb, Cd does not change in the water samples, what could be the reason for this? Probably, the content of Cu, Hg, Pb, Cd was below the detection limit of the device and the sensitivity of this technique did not allow to determine their content with sufficient accuracy, which raises doubts about all the data obtained and requires clarification and verification.
Response 2:
Thank you for your insightful comments regarding the analytical results of trace metals in our study. We appreciate the opportunity to clarify the observations related to mercury (Hg), copper (Cu), lead (Pb), and cadmium (Cd) concentrations in water samples.
For mercury (Hg), we acknowledge that the reported value of 0.0001 mg/L approaches the detection limit of our analytical equipment. This limit represents the optimized sensitivity of our institutional instrumentation, which has been validated for ecological monitoring purposes. While we recognize that this precision may not meet ultra-trace analysis requirements, it aligns with the data resolution necessary for our ecological investigation objectives. Unfortunately, the original water samples have been exhausted in previous analyses, preventing retrospective re-measurement with alternative methods. Regarding copper (Cu), lead (Pb), and cadmium (Cd), we wish to emphasize that the consistent values of 0.05 mg/L (Cu), 0.01 mg/L (Pb), and 0.05 mg/L (Cd) across samples reflect actual environmental conditions rather than instrumental limitations.
We hope this clarification addresses your concerns. Should you require additional technical details or supplementary data, we would be pleased to provide them.
Comment 3：At the same time, Figure 2 shows a sharp increase in the concentrations of Cr, B, As, Se, but this is not indicated in the text in which soil type.
Response 3:
Thank you for pointing out the important observation of elevated concentrations of chromium (Cr), boron (B), arsenic (As), and selenium (Se) in Figure 2. We appreciate your careful attention to the consistency between the data and the text.
As you suggested, we have revised the manuscript to explicitly link these element trends to specific soil types. The updated text (lines 151–166) now includes: land use types corresponding to high-value sample concentrations.
We hope this revision enhances the coherence of the paper and thank you for your guidance in interpreting the data.
Comment 4：The Methods section describes that the cation exchange (CEC) value was determined, which is also shown in Figure 5. However, the text describes the electrical conductivity ECE. There is no description of how the cation exchange (CEC) value was determined. Therefore, it is not clear what value the authors actually determined.
Response 4:
We sincerely appreciate your careful review and valuable feedback on the cation exchange capacity (CEC) method. We apologize for the typographical error in the text where “ECE” (electrical conductivity) was inadvertently used instead of “CEC.” This error has been corrected throughout the text, particularly in Section 3.4. We sincerely apologize for this oversight and appreciate your rigorous attention to scientific rigor.
Once again, thank you for your constructive criticism.
Comment 5: To form a more complete picture of the sources of heavy metals in soils, it is necessary to provide at least published data on the content of heavy metals in rocks in order to reliably talk about the influence of the anthropogenic factor.
Response 5:
We appreciate your valuable suggestion regarding the need for geological background data to strengthen our discussion of anthropogenic impacts. You are absolutely correct that comparing soil heavy metal concentrations with bedrock data would provide a more robust framework for distinguishing between natural and anthropogenic sources.
While we acknowledge the value of such comparative analyses, it is important to note that there is currently a lack of regionally published data on heavy metal concentrations in local bedrock strata in the public domain. Our research team has indeed initiated a parallel geological survey as part of a broader regional environmental assessment program, which includes systematic sampling and analysis of bedrock materials. However, this comprehensive dataset is currently in the publication preparation stage and has not been included in the current manuscript due to space constraints.
We plan to incorporate these geological reference data in future studies, which will enable us to perform more quantitative source attribution through isotope tracing or enrichment factor calculations.
Thank you for pointing out this important methodological consideration. Your suggestion prompted us to articulate this limitation more clearly in the discussion section (revised lines 485–500) and guided our future research direction.Since Reviewer 1 also raised the same issue, we have marked it with a green text background in the original text.
Comment 6: The Discussion section contains virtually no references to published sources;
this section needs to be revised.
Response 6:
Thank you for your insightful feedback. We have thoroughly revised the Discussion section as suggested. Specifically, we have:
Restructured unclear literature citations to provide more detailed explanations of how existing studies support our key arguments. Added three new references (27-29) to strengthen the theoretical foundation of our analysis. Explicitly linked each revised paragraph to the corresponding literature sources. The updated Discussion now better integrates published evidence with our findings while maintaining the original focus on topic. We appreciate your guidance in improving the scholarly rigor of this section.
Other clarifications:
First of all, I am very sorry to explain this situation, although we have already sent a request email to the editor before that, and it is not clear whether the reviewer is aware of it. At the request of the issuing organization, it is necessary to replace the boundaries of Figure 1 as well as Figure 4 of the article, and we guarantee that all research content will remain unchanged. We look forward to your understanding and support, and we apologize for the inconvenience.
Again, thank you very much for your valuable comments and suggestions. We hope that the revisions in the manuscript and our accompanying responses will be sufficient to make our manuscript suitable for publication in Sustainability.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis is a very interesting topic regarding correlation (water and different soils), analysing heavy metals using ICP-MS, as well as pH, organic matter, available and total N and P, and conductivity.
The methodology is appropriate and the conclusions regarding the hypothetical origin of the heavy metals, according to the data, are accurate.
However, it would have been interesting, for the phenomena of leaching and soil porosity, to add the texture of the soils (sand, silt and clay) and the extent of permeability in different types of environments and the evolution of depositional materials.
We find the geographical description very accurate, which in other similar articles is usually more concise or non-existent.
In our opinion, the topic of textures is broadly missing. I do not know if you have the data, but if so, we believe it should be provided.
Author Response
Response to Reviewer 3 Comments
Dear reviewer :
We are very grateful to the reviewers for their valuable comments and suggestions on our article, which has been of great help in our manuscript revision. The reviewer comments are laid out below in italicized font and specific concerns have been numbered. Our response is given in normal font and changes/additions to the manuscript are given in the blue text.
Point-by-point response to Comments and Suggestions for Authors:
Comment 1:
This is a very interesting topic regarding correlation (water and different soils), analysing heavy metals using ICP-MS, as well as pH, organic matter, available and total N and P, and conductivity. The methodology is appropriate and the conclusions regarding the hypothetical origin of the heavy metals, according to the data, are accurate. However, it would have been interesting, for the phenomena of leaching and soil porosity, to add the texture of the soils (sand, silt and clay) and the extent of permeability in different types of environments and the evolution of depositional materials. We find the geographical description very accurate, which in other similar articles is usually more concise or non-existent. In our opinion, the topic of textures is broadly missing. I do not know if you have the data, but if so, we believe it should be provided.
Response 1:
Thank you for your thoughtful feedback and constructive suggestions. We sincerely appreciate your recognition of the study's merits and your valuable insights regarding soil texture analysis.
We fully acknowledge the importance of soil texture parameters (sand/silt/clay content) and permeability characteristics in understanding heavy metal migration and depositional processes. While our current experimental design focused on nutrient and heavy metal dynamics, your recommendation has highlighted an important gap in the geophysical characterization of the soils.
Although we did not collect texture data during this phase of research, your suggestion provides clear direction for future work. In subsequent studies, we plan to incorporate soil texture analysis alongside geochemical parameters to more comprehensively investigate the interactions between soil composition, porosity, and contaminant transport. This will enable a more nuanced understanding of how soil matrix properties influence heavy metal behavior across different environmental settings.
We are grateful for your expertise in identifying this opportunity for methodological enhancement. Your comments have significantly enriched our perspective and will undoubtedly strengthen the rigor of our ongoing research in this field.
Other clarifications:
First of all, I am very sorry to explain this situation, although we have already sent a request email to the editor before that, and it is not clear whether the reviewer is aware of it. At the request of the issuing organization, it is necessary to replace the boundaries of Figure 1 as well as Figure 4 of the article, and we guarantee that all research content will remain unchanged. We look forward to your understanding and support, and we apologize for the inconvenience.
Again, thank you very much for your valuable comments and suggestions. We hope that the revisions in the manuscript and our accompanying responses will be sufficient to make our manuscript suitable for publication in Sustainability.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsMost parts of this paper are suitable for publication. However, there are still some places for improvement.
1） What about heavy metals in Gezi River compared with other rivers/lakes in China, and rivers/lakes in other countries?
2) Selenium (Se) is a non-metallic, why it is also inclued in this study?
3) Why heavy metals (Bismuth (Bi) and Cobalt (Co)) are not included in this study?
4) What are national or international limits of heavy metals in the soil?
5）How did concentrations of heavy metals in soil change in last few decades, and what is its trend in the near future?
Author Response
Response to Reviewer 4 Comments
Dear reviewer :
We are very grateful to the reviewers for their valuable comments and suggestions on our article, which has been of great help in our manuscript revision. The reviewer comments are laid out below in italicized font and specific concerns have been numbered. Our response is given in normal font and changes/additions to the manuscript are given in the blue text.
Point-by-point response to Comments and Suggestions for Authors:
Comment 1: What about heavy metals in Gezi River compared with other rivers/lakes in China, and rivers/lakes in other countries?
Response 1:
Thank you for your valuable question regarding the comparison of heavy metal concentrations in the Gezi River with other rivers/lakes. Our study specifically focused on investigating the coupling mechanism between irrigation inputs (river water) and soil nutrient/heavy metal dynamics within the arid oasis ecosystem. The research design was intentionally localized to:
Regional Relevance: Prioritize understanding local soil-water interactions given the unique hydrogeological conditions of the study area Methodological Focus: Utilize spatial analysis techniques (geostatistics, spatial interpolation) to map soil-water relationships at a watershed scale. Practical Limitations: Resource constraints prevented expansion to cross-regional comparisons. While we acknowledge the scientific merit of comparative studies across different water systems, our current analysis was designed to establish baseline relationships within this specific agro-ecological zone. The referenced literature in our paper (Sections 2.3 & 3.2) supports our methodological choice to prioritize localized soil-water coupling over broad geographic comparisons.
We appreciate your suggestion for future research directions. In subsequent studies, we plan to incorporate comparative analyses with other river systems using the same analytical framework to enhance our understanding of regional heavy metal behavior patterns.
Comment 2: Selenium (Se) is a non-metallic, why it is also inclued in this study?
Response 2:
Thank you for your insightful question regarding the inclusion of selenium (Se) in our study. While Se is technically a non-metal, it is frequently classified as a metalloid or "quasi-metal" in environmental research due to its:
Chemical Behavior: Se exhibits intermediate properties between metals and non-metals, showing similar environmental mobility and speciation patterns to metal(loid)s like arsenic (As). Ecological Risk: At elevated concentrations, Se demonstrates toxic effects and bioaccumulation potential comparable to heavy metals. Analytical Synergy: Se is routinely measured using the same ICP-MS methodology employed for heavy metal analysis in our study (Section 2.2). Research Framework: Our study's scope (Section 1.3) intentionally adopted a broad geochemical perspective to investigate soil-water interactions, which logically encompasses elements with significant environmental impact regardless of metallic classification.
We appreciate your attention to this methodological detail. The classification of Se in environmental studies often depends on contextual research objectives, and our approach aligns with established practices in soil contamination research.
Comment 3: Why heavy metals (Bismuth (Bi) and Cobalt (Co)) are not included in this study?
Response 3:
Thank you for your valuable observation regarding the exclusion of bismuth (Bi) and cobalt (Co) from our study. We appreciate your attention to the completeness of our heavy metal analysis.
During the experimental design phase, we prioritized investigating elements with well-documented environmental impacts and analytical relevance to our specific research objectives (Section 2.1). While Bi and Co are recognized as metals of environmental concern, their omission was an oversight in fully aligning with comprehensive heavy metal research frameworks. We acknowledge this limitation and agree that expanding the scope to include these elements would enhance the study's completeness. In future investigations, we plan to incorporate Bi and Co analyses using the same rigorous methodology to provide a more comprehensive assessment of heavy metal dynamics in arid oasis ecosystems.
Your feedback has been instrumental in identifying this opportunity for methodological improvement, and we are grateful for your contribution to strengthening our research approach.
Comment 4: What are national or international limits of heavy metals in the soil?
Response 4:
Thank you for raising the important issue of national and international heavy metal limits in soil. This study aims to explore the coupling mechanisms between heavy metals and soil nutrients under different land use types, rather than conducting an environmental risk assessment. Therefore, we did not include heavy metal thresholds in our analysis.
For reference, the Chinese national standard “Soil Environmental Quality—Risk Control Standards for Agricultural Land Soil Pollution” (GB 15618-2018) specifies risk screening values. The European Union's Eco-SSLs (Ecological Soil Screening Levels) and the World Health Organization's (WHO) Health-Based Guidelines provide similar frameworks, although there are differences in threshold values and protection objectives. We will attach national standards at the end of this document.
We fully recognize the value of integrating these standards in future research. In subsequent studies, we plan to:
Include national/international thresholds for comprehensive environmental risk assessment;
Conduct spatial comparative analysis in river systems as recommended;
Expand the scope of heavy metal elements studied;
Your feedback is crucial in shaping our future research direction. We appreciate your guidance in enhancing the practical applicability of our work.
Here is the translated English version of your soil pollution risk screening table, maintaining original data structure and units:
Chinese National Standard “Soil Environmental Quality Standards” (GB15618-2018)
Unit: mg/kg
|
No. |
Pollutant Itema |
Soil Type |
pH ≤ 5.5 |
5.5 < pH ≤ 6.5 |
6.5 < pH ≤ 7.5 |
pH > 7.5 |
|
1 |
Cadmium |
Paddy field |
0.3 |
0.4 |
0.6 |
0.8 |
|
Other |
0.3 |
0.3 |
0.3 |
0.6 |
||
|
2 |
Mercury |
Paddy field |
0.5 |
0.5 |
0.6 |
1.0 |
|
Other |
1.3 |
1.8 |
2.4 |
3.4 |
||
|
3 |
Arsenic |
Paddy field |
30 |
30 |
25 |
20 |
|
Other |
40 |
40 |
30 |
25 |
||
|
4 |
Lead |
Paddy field |
80 |
100 |
140 |
240 |
|
Other |
70 |
90 |
120 |
170 |
||
|
5 |
Chromium |
Paddy field |
250 |
250 |
300 |
350 |
|
Other |
150 |
150 |
200 |
250 |
||
|
6 |
Copper |
Orchard |
150 |
150 |
200 |
200 |
|
Other |
50 |
50 |
100 |
100 |
||
|
7 |
Nickel |
- |
60 |
70 |
100 |
190 |
|
8 |
Zinc |
- |
200 |
200 |
250 |
300 |
a Heavy metals and metalloid arsenic are calculated based on total element content. For paddy-upland rotation fields, the stricter risk screening value is adopted.
Comment 5: How did concentrations of heavy metals in soil change in last few decades, and what is its trend in the near future?
Response 5:
Thank you for your important question regarding temporal trends of soil heavy metal concentrations. Our research represents the first systematic investigation of heavy metal dynamics in this specific arid oasis ecosystem.
We acknowledge that:
Historical Data Gap: No published literature or public databases contain historical heavy metal concentration data for this region prior to our study.
Baseline Establishment: Our work establishes the first comprehensive baseline dataset for soil geochemistry in this area.
Long-term Monitoring: We have initiated a multi-year monitoring program to track temporal changes in heavy metal concentrations
While we cannot provide retrospective trends at this stage, our ongoing research includes:
Quarterly soil sampling across representative land use types;
Statistical modeling of potential accumulation patterns;
Correlation analysis with evolving agricultural practices.
We plan to publish temporal trend analyses once sufficient longitudinal data has been collected. Your question highlights the critical need for such long-term environmental monitoring, and we appreciate your guidance in shaping this important research direction.
Other clarifications:
First of all, I am very sorry to explain this situation, although we have already sent a request email to the editor before that, and it is not clear whether the reviewer is aware of it. At the request of the issuing organization, it is necessary to replace the boundaries of Figure 1 as well as Figure 4 of the article, and we guarantee that all research content will remain unchanged. We look forward to your understanding and support, and we apologize for the inconvenience.
Again, thank you very much for your valuable comments and suggestions. We hope that the revisions in the manuscript and our accompanying responses will be sufficient to make our manuscript suitable for publication in Sustainability.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsNow, I feel comfortable considering the manuscript for publication.
Author Response
Response to Reviewer 1 Comments ( Round 2 )
Dear reviewer:
Thanks for your letter and for reviewer's comments concern our manuscript entitled “Spatial heterogeneity of heavy metals in arid oasis soils and its irrigation input-soil nutrient coupling mechanism” (Manuscript ID: 3734397). We are very grateful to the reviewers for their valuable comments and suggestions on our article, which has been of great help in our manuscript revision. The reviewer comments are laid out below in italicized font and specific concerns have been numbered. Our response is given in normal font and changes/additions to the manuscript are given in the green text.
Point-by-point response to Comments and Suggestions for Authors:
Comment:
Now, I feel comfortable considering the manuscript for publication.
Response:
Thank you sincerely for your favorable assessment of our manuscript and for considering it for publication. We deeply appreciate the time and expertise you dedicated to reviewing our work, and we are truly honored by your positive feedback.
Your insights have provided valuable guidance for refining our research.
Once again, thank you for your support and encouragement. It is a privilege to have our research evaluated by such a distinguished expert in the field.
With our warmest regards !
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors have revised the article, but it still requires revision.
1) According to Figure 2, the content of Cu, Hg, Pb, Cd does not change in the water samples, probably the content in the water was below the detection limit of the device or the sensitivity of this method did not allow determining their content with sufficient accuracy, which raises doubts about all the data obtained and requires clarification and verification.
2) References to literature have been added to the text of the article, but the references are not formatted according to requirements (sometimes round brackets are used, sometimes in square brackets).
3) Table 1 and Figure 6 are duplicated in the text. Figure 6 is of poor quality, the designations are poorly visible.
Author Response
Response to Reviewer 2 Comments ( Round 2 )
Dear reviewer:
Thanks for your letter and for reviewer's comments concern our manuscript entitled “Spatial heterogeneity of heavy metals in arid oasis soils and its irrigation input-soil nutrient coupling mechanism” (Manuscript ID: 3734397). We are very grateful to the reviewers for their valuable comments and suggestions on our article, which has been of great help in our manuscript revision. The reviewer comments are laid out below in italicized font and specific concerns have been numbered. Our response is given in normal font and changes/additions to the manuscript are given in the yellow text.
Point-by-point response to Comments and Suggestions for Authors:
Comment 1: According to Figure 2, the content of Cu, Hg, Pb, Cd does not change in the water samples, probably the content in the water was below the detection limit of the device or the sensitivity of this method did not allow determining their content with sufficient accuracy, which raises doubts about all the data obtained and requires clarification and verification.
Response 1:
Thank you very much for your professional advice. You raised this issue in the first round of questions, and our response may not have been clear enough. We will provide a more detailed response here, offering further background information on the concentration reports for mercury (Hg), copper (Cu), lead (Pb), and cadmium (Cd) in the water samples. Your expertise is crucial to improving the presentation of these findings.
Regarding mercury (Hg), we need to clarify that the reported value of 0.0001 mg/L is close to the detection limit of our analytical instrument. This device has been rigorously validated for ecological monitoring and operates at optimized sensitivity. While we acknowledge that this threshold may approach the limits of ultra-trace analysis in certain cases, it meets the resolution requirements specified for our ecological survey objectives. Unfortunately, the original water samples have been entirely used for previous analyses, and it is currently impossible to conduct retrospective remeasurements using alternative methods.
Regarding copper (Cu), lead (Pb), and cadmium (Cd), we emphasize that the stable values of 0.05 mg/L (Cu), 0.01 mg/L (Pb), and 0.05 mg/L (Cd) reflect the environmental conditions observed at the sampling points. These measurements were obtained under standardized protocols and demonstrated reproducibility in repeated analyses, indicating that they accurately represent metal concentrations in the environment rather than instrument limitations.
We hope this additional explanation addresses your concerns. If you require further technical clarification or supplementary documentation, we would be happy to provide additional materials at your convenience. Your insights are crucial to enhancing the scientific rigor of this work.
With our highest regards and gratitude !
Comment 2: References to literature have been added to the text of the article, but the references are not formatted according to requirements (sometimes round brackets are used, sometimes in square brackets).
Response 2:
Thank you sincerely for your meticulous review and valuable feedback regarding the formatting consistency of our references. We deeply appreciate your guidance in ensuring adherence to scholarly standards, and we are grateful for the opportunity to strengthen the manuscript's compliance with academic conventions.
In response to your observation about mixed bracket styles (round vs. square brackets) in the references, we have conducted a comprehensive revision of all citations throughout the manuscript.
We recognize the importance of uniform citation practices for reader clarity and scholarly rigor, and we are confident that these revisions now align fully with the journal's formatting requirements. Should you identify any remaining inconsistencies or require additional adjustments, we stand ready to implement further refinements promptly.
Once again, we extend our deepest appreciation for your expertise in elevating the manuscript's quality. It is an honor to have our work evaluated by such a distinguished reviewer.
With our highest respect and gratitude!
Comment 3: Table 1 and Figure 6 are duplicated in the text. Figure 6 is of poor quality, the designations are poorly visible.
Response 3:
Thank you profoundly for your meticulous review and constructive feedback regarding the duplication of Table 1/Figure 6 and the resolution concerns with Figure 6. We sincerely appreciate your vigilance in maintaining manuscript quality and extend our deepest gratitude for bringing these matters to our attention.
Concerning Duplication of Table 1/Figure 6:
Upon thorough investigation, we confirm that this duplication arose from an unintended technical error during PDF conversion. While the original Word document maintained proper single instances of these elements, the formatting transition introduced redundancies. We have immediately implemented corrective measures by:
Removing duplicate instances from all manuscript versions;
Conducting cross-platform verification (Word/PDF) to prevent recurrence;
Establishing new quality control protocols for document conversion.
Regarding Figure 6 Clarity:
We sincerely apologize for the suboptimal image quality in the initial submission. This issue stemmed from multiple compression iterations during preliminary uploads. To resolve this:
We have replaced Figure 6 with a high-resolution version (300+ DPI);
Enhanced labeling contrast for improved visibility.
Should any residual concerns persist or require additional adjustments, we stand ready to address them promptly. Your expertise continues to be invaluable in refining this work, and we are truly grateful for your commitment to scholarly excellence.
Again, thank you very much for your valuable comments and suggestions. We hope that the revisions in the manuscript and our accompanying responses will be sufficient to make our manuscript suitable for publication in Sustainability.
Author Response File: Author Response.pdf
