Unveiling Heavy Metal Links: Correlating Dust and Topsoil Contamination in Vilnius Schools

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Line 33 Some HM are present in the natural environment as a geochemical background.

Lines 52-54 All soils are characterised by a greater susceptibility to environmental influences in the upper layers, which decreases with depth. 

Section 1 - in the paper the author refers to contamination, but does not specify the metal contamination thresholds.

Subsection 2.2 Please provide a more detailed methodology. How were the samples taken, how much material was taken, in how many replicates, how was it stored, how was it prepared for analysis. Please provide references for the methodology. Please delete the sentence on lines 81 and 84-85. 

The methodology is poorly described and needs to be thoroughly supplemented. The paper refers to soil contamination, which is not mentioned in the methodology. 

2.3.1. If samples were taken from "behind 77 radiators, above bookcases, in corners, above window sills", how can surface soil samples be described?

2.3.2-2.3.4 There is no need to describe individual statistical measures. Please abbreviate them and put them in one paragraph. 

Table 1 in soil or in dust?

 

In this paper, the authors attempt to link soil contamination from open areas with dust contamination from indoor school buildings. According to the methodology described, the metal content of dust was tested in 2022, and the data on soil contamination with metals are from the years 1999-2023. How can correlating such results provide reliable information?

No reference was made to the structure of the profiles, the nature of the soil and the terrain. The poorly described methodology gives the impression that random values were subjected to statistical analysis and some conclusions were drawn (especially since correlations were sometimes observed and sometimes not). On this basis, I suggest that the work should be (significantly) improved and revise once again.

Author Response

Response: The authors would like to thank the Reviewer-1 for their comments. Care has been taken to improve the work and address their concerns as per the specific comments below.

Reviewer Comments	Reply
Introduction Line 33 Some HM are present in the natural environment as a geochemical background.   Lines 52-54 All soils are characterised by a greater susceptibility to environmental influences in the upper layers, which decreases with depth.   Section 1 - in the paper the author refers to contamination, but does not specify the metal contamination thresholds.	Thank you for the suggestions, sentences fixed accordingly, and specified metal contamination threshold explained.
Materials and Methods The methodology is poorly described and needs to be thoroughly supplemented. The paper refers to soil contamination, which is not mentioned in the methodology.   2.3.1. If samples were taken from "behind 77 radiators, above bookcases, in corners, above window sills", how can surface soil samples be described?	Thank you for your feedback; we've now detailed methodologies and improved it. Especially sample collection.       Surface soil samples collected from other studies from different locations as well as nearby schools. We cited them in the article.
Discussions and Results 2.3.2-2.3.4 There is no need to describe individual statistical measures. Please abbreviate them and put them in one paragraph.   Table 1 in soil or in dust?         In this paper, the authors attempt to link soil contamination from open areas with dust contamination from indoor school buildings. According to the methodology described, the metal content of dust was tested in 2022, and the data on soil contamination with metals are from the years 1999-2023. How can correlating such results provide reliable information?	Thank you for your valuable feedback on the descriptive analysis section of our manuscript. We have revised this part to provide a clearer overview of individual statistics.     Table 1 is in soil as from different studies made between 2017 and 2023.                       Thank you for your question regarding the temporal differences in our data collection. We acknowledge the concern about correlating soil data from 1999-2023 with dust data from 2022 and would like to provide the following clarifications:   Historical Context: The extensive time frame of soil data allows us to identify long-term contamination trends, offering a historical perspective that is crucial for understanding current dust contamination levels.   Comprehensive Dust Sampling: When compared to historical soil data, the 2022 dust data, which was collected from a variety of schools, offers a current and representative view of indoor contamination that can be informative. Indoor-Outdoor Interaction: The continuous movement of soil particles into indoor environments suggests a link between outdoor soil and indoor dust contamination, justifying the comparison of these two datasets. By correlating these datasets, our intention is to explore general patterns and associations that shed light on the contamination dynamics in urban educational settings, rather than establishing direct, time-specific causal relationships. We believe this approach, despite its limitations, contributes valuable insights to the field.

 

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript provides valuable insights into the distribution and implications of heavy metal contamination in educational settings.

1.Abstract: The abstract provides a concise overview of the study's objectives, methods, key findings, and implications. It could be enhanced by briefly mentioning any significant limitations of the study or suggestions for future research.

2.Introduction: Consider expanding the literature review to include more recent studies, providing a broader context of the current understanding in this field.

3.Materials and Methods: Sample Collection: The methodology for dust sample collection is detailed and appropriate. However, it would be beneficial to clarify how representative these samples are of the wider school environment

4.Materials and Methods: Statistical Analysis: The use of descriptive analysis, Pearson correlation, and other statistical methods is well-justified. Ensure that the rationale behind the choice of these specific methods is clearly articulated in the text.
Results and Discussion:
5.Materials and Methods: Data Presentation: The findings are presented clearly with effective use of figures. Ensure that all figures are of high quality and clearly legible.
6. Discussion Depth: The discussion insightfully interprets the findings, particularly the distinct patterns of heavy metal distribution in dust versus soil. More discussion on the potential health implications of these findings would enhance the manuscript's impact.
7.Conclusions-Comprehensiveness: The conclusion effectively summarizes the study's main findings and their implications. However, it could be strengthened by including specific recommendations for policymakers or suggestions for mitigating the identified risks.
Future Research: The conclusion would benefit from suggestions for future research directions, such as studying the long-term health impacts on students or exploring remediation strategies.
8. Conclusions-Future Research: The conclusion would benefit from suggestions for future research directions, such as studying the long-term health impacts on students or exploring remediation strategies.

Comments on the Quality of English Language

The manuscript is well-written and follows a logical structure. Minor grammatical and typographical errors should be corrected.

Author Response

Response: The authors would like to thank the Reviewer-2 for their comments. Care has been taken to improve the work and address their concerns as per the specific comments below.

Reviewer Comments	Reply
Abstract The abstract provides a concise overview of the study's objectives, methods, key findings, and implications. It could be enhanced by briefly mentioning any significant limitations of the study or suggestions for future research.	We have improved the abstract and added limitations of the study as suggested.
Introduction Consider expanding the literature review to include more recent studies, providing a broader context of the current understanding in this field.	Thank you for your suggestion. We've enriched the introduction with additional Lithuania-based studies, reinforcing our focus on the region despite the limited recent research on dust contamination in this area.
Materials and Methods Sample Collection: The methodology for dust sample collection is detailed and appropriate. However, it would be beneficial to clarify how representative these samples are of the wider school environment.   Statistical Analysis: The use of descriptive analysis, Pearson correlation, and other statistical methods is well-justified. Ensure that the rationale behind the choice of these specific methods is clearly articulated in the text.   Data Presentation: The findings are presented clearly with effective use of figures. Ensure that all figures are of high quality and clearly legible.	Thank you for your review. Sample collections have been improved for better clarification and readability. References added.
Discussions and Results The discussion insightfully interprets the findings, particularly the distinct patterns of heavy metal distribution in dust versus soil. More discussion on the potential health implications of these findings would enhance the manuscript's impact.	Thank you, we have added new section as Potential Health Implications in the end of results and discussion.
Conclusion he conclusion effectively summarizes the study's main findings and their implications. However, it could be strengthened by including specific recommendations for policymakers or suggestions for mitigating the identified risks. Future Research: The conclusion would benefit from suggestions for future research directions, such as studying the long-term health impacts on students or exploring remediation strategies. Conclusions-Future Research: The conclusion would benefit from suggestions for future research directions, such as studying the long-term health impacts on students or exploring remediation strategies.	Thanks for the suggestion, now we have improved conclusion.           We appreciate your suggestion and have updated the conclusion to include future research directions, focusing on the long-term health impacts on students and potential remediation strategies.

 

Reviewer 3 Report

Comments and Suggestions for Authors

Unveiling Heavy Metal Links: Correlating Dust and Topsoil 2 Contamination in Vilnius Schools

 

Please review and fix the referencing style. Please add the name of the software used to perform these data analyses. I'm still confused about how the authors got the topsoil data from 2011 to 2023 since I cannot find any references in the paper. Are figs 1 and 2 supposed to have a unit for the Y-axis?

 

Abstract:

 

1.        Please confirm whether the topsoil was taken from the school or nearby zones of the school.

2.        Did the authors test the heavy metal concentrations from 2011 to 2023? Please provide a rationale as to why 2022 was given more focus.

3.        Please add information as to what heavy metal was found to be higher.

4.        Please add significant findings from PCA.

 

Introduction:

The aims and objectives are unclear; please review it.

 

Materials and Methods:

 

Lines 79-80: What does extended duration mean? Please elaborate.

Lines 80-81: Please mention the details of XRF, such as brand, model, and limitations.

Lines 81-83. Please add references.

Lines 82-84: Please explain how they were broken into smaller samples. What was the size limit? Were they broken onsite or in a lab? How many samples were collected from each school? Were the samples collected in triplicates?

Lines 76-85: Please add detailed information about these schools, such as where they are in the city. What is their proximity to each other? Are they exposed to construction or any other anthropogenic activities? How many students attend these schools? Were the samples collected all year round?

 

Results and Discussion:

 

Why is there a dataset from 1999 in Fig.2? Please provide a rationale.

Line 205-230. Please add a reference, as this is not your data.

 

The results and discussion are all over the place. Please rewrite them. Some of my comments are provided below,

 

1)     Why do the authors suddenly focus on data from 2017 to 2023?

2)     Why are only selective datasets used for Pearson correlation?

3)     Moreover, why was the Pearson correlation not performed for 2022?

4)     How did you get the school data for 2011, 2017, 2018? Does this school data represent all 24 schools?

5)     No comparison was performed with WHO standards.

6)     What do these heavy metal values mean concerning toxicity for students attending these schools?

7)     Why haven't the authors compared their 2022 data with Table 1.? Table 1 is not referenced in the entire document to make a discussion.

 

 

Comments on the Quality of English Language

Please fix preposition errors.

Author Response

Response: The authors would like to thank the Reviewer-3 for their comments. Care has been taken to improve the work and address their concerns as per the specific comments below.

Reviewer Comments	Reply
Please review and fix the referencing style. Please add the name of the software used to perform these data analyses. I'm still confused about how the authors got the topsoil data from 2011 to 2023 since I cannot find any references in the paper.     Are figs 1 and 2 supposed to have a unit for the Y-axis?	Refencing reviewed and added software program has been used in the article.     We apologize for any confusion caused and appreciate your attention to this detail. The topsoil data from 2011 to 2023 were sourced from Kumpienė et al. 2011, Kadunas et al. 1999, DGE Baltic Soil, 2023 in Vilnius. We have now clarified this in the methodology section of our paper for better understanding.     Thank you for pointing out the missing units on the Y-axis in Figures 1 and 2. This was an oversight, and we have now updated both figures to include the appropriate units for clarity.
Abstract 1.        Please confirm whether the topsoil was taken from the school or nearby zones of the school.       2.        Did the authors test the heavy metal concentrations from 2011 to 2023? Please provide a rationale as to why 2022 was given more focus.     3.        Please add information as to what heavy metal was found to be higher.   4.        Please add significant findings from PCA.	The topsoil samples in our study were obtained from previous studies, sourced from areas near the schools as well as various locations across Vilnius, providing a comprehensive environmental context.     Topsoil samples as we previously mentioned belong to previous studies. We have edited the abstract for clarity.     Information has been added.     Additional information has been provided.
Introduction The aims and objectives are unclear; please review it.	Thank you for the suggestion, The aims and objectives have now been improved.
Materials and Methods Lines 79-80: What does extended duration mean? Please elaborate.           Lines 80-81: Please mention the details of XRF, such as brand, model, and limitations. Lines 81-83. Please add references. Lines 82-84: Please explain how they were broken into smaller samples. What was the size limit? Were they broken onsite or in a lab? How many samples were collected from each school? Were the samples collected in triplicates? Lines 76-85: Please add detailed information about these schools, such as where they are in the city. What is their proximity to each other? Are they exposed to construction or any other anthropogenic activities? How many students attend these schools? Were the samples collected all year round?	We have paraphrased the sentence as, Our focus was on the gradual accumulation of dust over a long period of time in samples places. Schools are built between 1930 to 2000s, therefore with renovations and other activities increased dust accumulation in certain places. That is the reason why we have used ‘extended duration’.       Thank you for your suggestions, method explained clearly in the revised article, references have been added. Also, clear explanation has been added.
Discussions and Results Why is there a dataset from 1999 in Fig.2? Please provide a rationale.   Line 205-230. Please add a reference, as this is not your data. 1)     Why do the authors suddenly focus on data from 2017 to 2023?       2)     Why are only selective datasets used for Pearson correlation? 3)     Moreover, why was the Pearson correlation not performed for 2022?   4)     How did you get the school data for 2011, 2017, 2018? Does this school data represent all 24 schools?     5)     No comparison was performed with WHO standards. 6)     What do these heavy metal values mean concerning toxicity for students attending these schools?   7)     Why haven't the authors compared their 2022 data with Table 1.? Table 1 is not referenced in the entire document to make a discussion.	The 1999 dataset comes from the 1999 publication of the Atlas by Kadunas et al. As a result of the lack of sufficient data to perform additional statistical analyses, we decided to present only descriptive analysis in order to offer an essential understanding.   Refences has been added.     The focus on data from 2017 to 2023 was due to the availability of more comprehensive and detailed datasets for these years, allowing for a robust analysis of recent trends in heavy metal contamination. Nevertheless, we have added small information between 1995-2011 as we don’t have datasets from these years we can’t do analysis.       As previously mentioned, due to insufficient datasets and a shortage of data to establish this correlation, we have chosen to proceed in this manner.       The data for 2011, 2017, and 2018 were sourced from Kumpienė et al. 2011 and DGE Baltic Soil, 2023. While these datasets encompass a broader range of locations, they include specific data points from areas in close proximity to the 24 schools, making them relevant for our analysis of heavy metal contamination in school environments.   Short Who comparison has been added for the soil data as for dust there are not limits.     The heavy metal values observed indicate a potential risk of toxicity for students, and further investigation is needed to assess the exact health implications in the context of long-term exposure in these school environments.     As mentioned earlier, because of the limited availability of datasets and insufficient data, we have opted to move forward in this way. Table 1 is mean values from DGE Baltic Soil, 2023 Also We have added 1999 and 2011 mean values too.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The work has undergone significant improvements in both its theoretical underpinnings and extensive methodology. 

In line 164 is Figure 2. Descripive analysis of soil datasets (figure missing), which is repeated in line 209. 

The paper can be published once the deficiencies have been corrected. 

Author Response

We sincerely appreciate your acknowledgment of the improvements made to our manuscript following your suggestions. 

We have identified the problem in Figure 2. We apologize for this error and have now corrected it

Reviewer 2 Report

Comments and Suggestions for Authors

1.Introduction: Although several new references have been added (lines 43-71), the articulation of the knowledge gap remains unclear. The current state of research on dust sourcing is inadequately presented, failing to fully showcase and highlight the significance of this study. The description of the primary reasons for pollution characteristic changes in Vilnius, as indicated by related studies, is vague, which significantly impacts the unfolding of subsequent analysis.

2.Materials and Methods: It would be preferable to graphically represent the sampling locations and indicate potential pollution sources in the vicinity on the map. The initial paragraph has added discussions on dust sampling methods from other literature; however, its significance and supportive role in this study are unclear. It needs to be explicitly stated whether the dust collection methods in this study are similar or identical to those in other literature. The paper does not collect topsoil samples but instead uses data reported from other sources, which is entirely acceptable. However, it would be better to clarify this at the beginning of the section rather than at the end.

3.Results and Discussion: What are the possible reasons for the variations in concentrations of various pollutants in the soil over the years? The article employs multiple analysis methods, including Pearson Correlation Analysis, Principal Component Analysis, and Hierarchical Clustering Analysis. These methods are not innovative in themselves, as they are also found in other literature. The authors are encouraged to conduct more background research. Additionally, a detailed analysis of the potential sources of heavy metal pollution in the urban environment of Vilnius is warranted. While general pollution sources are mentioned, a more detailed investigation into specific local industrial activities, traffic patterns, or historical pollution events could provide a richer understanding of the findings.

4.Health Implication Discussion: Although the paper briefly mentions the potential health implications of heavy metal exposure, the significance of this study in that context is not well articulated. Suggestions based on the findings for public health policies or guidelines for educational institutions could be very impactful. It would be beneficial for the discussion to elaborate on the implications of heavy metal exposure and offer concrete recommendations for mitigating these risks.

 

Comments on the Quality of English Language

Overall, the language of the article is basically okay.

Author Response

Dear Reviewer,

Thank you for your valuable feedback on our manuscript. We have carefully considered your comments and have made several revisions to our manuscript to address your concerns more effectively. Below is a summary of the key changes we have implemented.

Introduction:

1. Knowledge Gap: We've highlighted the lack of research on heavy metal pollution in indoor dust, especially in educational environments, at the start of the introduction.
2. Current Research on Dust Sourcing: Recent studies have been referenced to establish the current understanding in this field, focusing on the neglected area of indoor dust pollution in schools.
3. Pollution in Vilnius: A detailed explanation of pollution changes in Vilnius, including factors like industrial activities and traffic patterns, is now included to set a clear context for our study.
4. Link to Study's Focus: The revised introduction directly links the pollution characteristics in Vilnius to the aims of our study, emphasizing its relevance and contribution to the field.
5. Regional Focus: A new paragraph underscores the scarcity of such studies in Lithuania and Eastern Europe, highlighting the regional importance of our study.

Material and method:

1. Graphical Representation Added: We included a map illustrating the sampling locations and nearby potential pollution sources, enhancing visual comprehension.
2. Clarification on Dust Sampling Methods: We explicitly stated the similarity of our dust sampling methods to those in referenced literature, focusing on our use of brush techniques.
3. Topsoil Sample Data: We now clearly mention at the outset our use of pre-existing datasets for topsoil samples and provide the rationale behind this approach.

Results and Discussion:

We acknowledge that the procedures used, namely Pearson Correlation Analysis, Principal Component Analysis, and Hierarchical Clustering Analysis, are well-established techniques in environmental science research. Nevertheless, we maintain that their implementation within the framework of our research provides innovative perspectives, especially in urban educational settings. We selected these strategies based on the characteristics and magnitude of our data. Although powerful machine learning techniques have the potential to provide various viewpoints, the magnitude of our dataset made these approaches less suitable for our specific research goals.

Moreover, we agree with your proposal to carry out a comprehensive examination of potential origins of heavy metal contamination in Vilnius. To address this, we have expanded the discussion section of our paper to include examinations of different studies that were made in Vilnius, to keep in mind that there are not a lot studies related to soil and especially dust in Lithuania and Vilnius to find this information. This thorough analysis offers a more complete comprehension of the environmental elements that contribute to the reported heavy metal concentrations in our study.

Health Implication Discussion:

1. Guidelines for Renovation of Older Buildings: Our study underscores the necessity for thorough cleaning and removal of accumulated dust, particularly in older Soviet-era school buildings, to mitigate exposure risks.
2. Public Health Policies: We suggest the implementation of routine environmental monitoring in schools, particularly those located in urban areas with historical pollution. This would aid in identifying and addressing pollution sources proactively.
3. Educational Institution Protocols: We recommend the establishment of regular dust cleaning protocols in schools and the use of air purifiers to reduce the concentration of indoor pollutants.

 

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for implementing the suggestions, the paper has improved in quality.

Author Response

We sincerely appreciate your acknowledgment of the improvements.