Multimethod Analysis of Heavy Metal Pollution and Source Apportionment in a Southeastern Chinese Region

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

All comments and suggestions are included in the word file

Comments for author File: Comments.pdf

Comments on the Quality of English Language

     There are some grammatical mistakes. Please check the manuscript for grammar and English carefully.

Author Response

Comments 1: There are some grammatical mistakes. Please check the manuscript for grammar and English carefully.

Response: Thank you for your suggestion. We have thoroughly reviewed the entire manuscript and made all the necessary grammatical and language improvements. Please refer to the changes highlighted in yellow.

 

Comments 2: Abstract:is well presented.

Response: Thank you very much for your positive feedback on the abstract. We appreciate your valuable comments on the manuscript as a whole. We have carefully considered each of your suggestions and made the necessary revisions. We sincerely hope that our responses and modifications meet your expectations.

 

Comments 3:The literature survey in the introduction section can be enriched by adding more recentstudies as Chemosphere 307,135898.10.1016/j.chemosphere.2022.135898D

Response: Thank you for your suggestion. I have added the following reference to the manuscript at Line 256:

Hanfi, M.Y.; Seleznev, A.A.; Yarmoshenko, I.V.; Malinovsky, G.; Konstantinova, E.Y.; Alsafi, K.G.; Sakr, A.K. Potentially harmful elements in urban surface deposited sediment of Ekaterinburg, Russia: Occurrence, source appointment and risk assessment. Chemosphere, 2022, 307, 135898.

 

Comments 4:The novelty of study is not presented clearly.

Response: Thank you for your question. To address your concern, we have included an evaluation of the risks to human health in Lines 119-121 and Lines 126-128. We hope these additions help to clarify and enhance the novelty of our study.

 

Comments 5:L 59: remove zinc as you did not mention the names of other elements.

Response: Thank you for pointing this out. We apologize for the oversight. We have now corrected the text by adding the name of zinc in Line 61.

 

Comments 6:It is strongly recommended to assess the noncarcinogenic and carcinogenic risks for the humans.

Response: Thank you for your valuable suggestion. In response, we have incorporated an assessment of both carcinogenic and non-carcinogenic risks associated with soil heavy metals to human health within the study area. This evaluation is based on the equations and methods outlined in the study published in Chemosphere 307, 135898. We have included these details in Section 2.3.4 of the manuscript and compared our findings with the source apportionment of heavy metals in Jiangsu Province.

 

Comments 7:The average daily doses (ADD) through the three primaries routes of human exposure including inhalation (inh), ingestion (ing), and dermal contact (derm) are also strongly recommended to study. Authors can use the equations and methods presented from the study Chemosphere 307,135898.10.1016/j.chemosphere.2022.13589.

Response: Thank you for your insightful suggestion. We have now addressed this by studying the average daily doses (ADD) of heavy metals through the primary human exposure routes: inhalation, ingestion, and dermal contact. We utilized the equations and methods from the study published in Chemosphere 307, 135898. These assessments have been incorporated into Section 2.3.4 of the manuscript. Additionally, we compared our findings to the source apportionment of heavy metals in Jiangsu Province. The manuscript has been updated accordingly.

 

Comments 8:Authors should compare the results to other cities in China or worldwide.

Response: Thank you for your valuable suggestion. We have now expanded our analysis to include a comparison of our results with those from other cities in China and around the world. This broader perspective is intended to provide a more comprehensive understanding of the context and significance of our findings. We utilized the equations and methods from the study published in Chemosphere 307, 135898 and focused on the carcinogenic and non-carcinogenic risks of soil heavy metals to human health. These additions have been incorporated into Section 2.3.4 of the manuscript, and the necessary modifications have been made.

 

Comments 9:The Pb and Fe are very important elements to be included in the evaluation study. Have you tried to study any of these elements?

Response: Thank you for your question. We have not yet included lead (Pb) and iron (Fe) in our current study; however, we recognize their importance and plan to analyze and assess these elements in future research. Please refer to the revised manuscript for more details.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

In this manuscript the authors presented the results of soil heavy metal (Cd, Cr, Pb, Cu, Zn, Ni, Mn, Co, V, and As, and Hg) analysis in a southeastern region of China. The analysis included calculation of standard indicators the geoaccumulation index and potential ecological risk index to assess level of soil contamination followed by application of widely used PMF receptor model for source apportionment study. In addition, the spatial distribution of the concentrations of heavy metals are presented based on 282 sampling locations.

Based on PMF receptor modeling, the four major sources were identified as natural sources, coal combustion and atmospheric pollution sources, industrial and traffic emission sources. The obtained results indicate spatial variations in ecological risk with moderate risk in the central and northwestern areas.

Generally, this is interesting paper since the soil contamination is important issue worldwide. The manuscript is well structured, in the introduction part most important previous studies and challenges have been analyzed.  The methodology part is reasonably described and the obtained conclusions are rationally supported by the results.

From my point of view, there is no scientific novelty presented in the study, it is rather systematic analysis of the existing database, but still the results could be interesting to the wider community.

Please find below several comments which can be addressed to improve the overall paper:

Materials and methods

Line 168: “The sampling methodology was systematic and followed a regular interval pattern.” Please explain what does it mean regular interval pattern and add information about time period when sampling was conducted.

Line 172: “A total of 282 sampling points were collected…”  Please precise what is the total number of samples analyzed? If there were 282 sampling points how many samples were used per sampling point? This is important to clarify to readers and discuss the reliability of the samples per sampling point (if only one sample was used per sampling point, please discuss this issue).

 Results:

Line 231: ”.. analyzed against the background values of study area..” I suggest to authors to add information about provided background values  – when background values (samples) were analyzed and did they perform sampling at all 282 sampling points or the methodology for obtaining background values was different?. Also, did they use average background value for all region, or there is background value for each sampling point?

 Table 2. The last column “Mean value relative to background exceedance factor” . Please use term average instead of mean due to the consistency (if it is average value?).

Figure 10. “Factor contribution plot from…” I suppose this is not contribution but rather composition of the PMF factors, thus it should be factor loadings…please check the figure caption.

Conclusion:

“…average concentrations of Cd, Cr, As, Hg, Pb, Cu, Zn, Ni, Mn, V, and Co were found to be 480 0.13, 71.72, 9.98, 0.09, 28.88, 35.98, 69.99, 32.94, 543.81, 110.18, and 14.95 mg∙kg‐1, respectively. The average concentrations of heavy metals in the soil of the study area are as follows: Mn > V > Cr > Zn > Cu > Ni > Pb > Co > As > Cd > Hg.” Please combine and rephrase these sentences, no need to repeat it. For example Mn (543.81) > V(110.18) ….

The authors should add brief limitations of the study and suggest potential future research direction.

 Technical issue:

Please check all figures titles and axes names  (for example, Figs. 3,4 7, 8, 9, 10 – x-axis name is mental instead of metal)

3.2.2. Correlation and cluster analysis is the same as 3.2.1 subtitle. It should be different and related to the PMF analysis and source apportionment

 

Author Response

Comments 1:Line 168: “The sampling methodology was systematic and followed a regular interval pattern.” Please explain what does it mean regular interval pattern and add information about time period when sampling was conducted.

Response: Thank you very much for your insightful comments on this manuscript. We have carefully considered each of your suggestions and made the necessary revisions. We sincerely hope that our responses and modifications meet your expectations.

 

The data used in this study originate from the first national soil pollution survey, conducted between April 2005 and December 2013. The survey utilized a systematic sampling methodology based on a regularly spaced grid pattern, designed to accurately represent the national soil conditions across various regions. This approach ensured a comprehensive representation of diverse determinants. Sampling points were randomly distributed across major land use types, including arable land, forest land, grassland, construction land, and unused land, adhering to the standards outlined in the "HJ/T 166-2004 Technical Specifications for Soil Environmental Monitoring."

 

Comments 2:Line 172: “A total of 282 sampling points were collected…”  Please precise what is the total number of samples analyzed? If there were 282 sampling points how many samples were used per sampling point? This is important to clarify to readers and discuss the reliability of the samples per sampling point (if only one sample was used per sampling point, please discuss this issue).

Response: Thank you very much for your valuable comments on the manuscript. We have carefully considered each of your suggestions and made the necessary revisions. We sincerely hope that our responses and modifications meet your expectations.

 

In response to your query, a total of 282 soil samples were collected from the study area. Each sampling point provided one sample, specifically from the topsoil layer (0-20 cm). The samples were collected using either bamboo or stainless steel shovels, then sealed and packaged in kraft paper to prevent contamination in Lines 173-175. The preservation and transportation of the samples adhered strictly to the "HJ/T 166-2004 Technical Specifications for Soil Environmental Monitoring" issued by the State Environmental Protection Administration. Each sample underwent duplicate measurements to ensure reliability and accuracy of the data. We acknowledge that collecting a single sample per sampling point might limit the assessment of local variability; however, the comprehensive distribution of sampling sites across various land use types helps to ensure a broadly representative dataset.

 

Comments 3:Line 231: ”.. analyzed against the background values of study area..” I suggest to authors to add information about provided background values  – when background values (samples) were analyzed and did they perform sampling at all 282 sampling points or the methodology for obtaining background values was different?. Also, did they use average background value for all region, or there is background value for each sampling point?

Response: Thank you for your insightful comments. This study refers to the background value data provided by He and others in their work, "Research on the Soil Environmental Background Values of Jiangxi Province" (Beijing: China Environmental Science Press, 2006). The preparation for this research began in 1987, and the sampling process spanned one year, involving 14 organized sampling trips.

The background values referenced in our study are determined based on regional zoning characteristics. The method for representing the background value range differs depending on the distribution state of the elements: for elements with a normal distribution, the arithmetic mean is used, and for those with a log-normal distribution, the geometric mean is applied.

 

Specifically, the elements analyzed in this study were categorized as follows:

- Log-normally distributed elements include: As (37 sampling points), Cr (36 sampling points), Cu (37 sampling points), and Mn (37 sampling points).

- Normally distributed elements include: Co (37 sampling points), Cr (36 sampling points), Hg (37 sampling points), Ni (37 sampling points), Pb (37 sampling points), V (37 sampling points), and Zn (37 sampling points).

The background values were not obtained from all 282 sampling points. Instead, a representative method was used based on the regional zoning and distribution characteristics. For more detailed information, please refer to the original study, "Research on the Soil Environmental Background Values of Jiangxi Province."

 

Comments 4:Table 2. The last column “Mean value relative to background exceedance factor” . Please use term average instead of mean due to the consistency (if it is average value?).

Response: Thank you for your suggestion. We have updated the subtitle to "Average value relative to background exceedance factor" to ensure consistency.

 

Comments 5:Figure 10. “Factor contribution plot from…” I suppose this is not contribution but rather composition of the PMF factors, thus it should be factor loadings…please check the figure caption.

Response: Thank you for your comment. We have revised the title of Figure 10 to "Factor loadings plot from the PMF model using soil heavy metal concentration data." We appreciate your attention to detail.

 

Comments 6: “…average concentrations of Cd, Cr, As, Hg, Pb, Cu, Zn, Ni, Mn, V, and Co were found to be 480 0.13, 71.72, 9.98, 0.09, 28.88, 35.98, 69.99, 32.94, 543.81, 110.18, and 14.95 mg∙kg‐1, respectively. The average concentrations of heavy metals in the soil of the study area are as follows: Mn > V > Cr > Zn > Cu > Ni > Pb > Co > As > Cd > Hg.” Please combine and rephrase these sentences, no need to repeat it. For example Mn (543.81) > V(110.18) ….

Response: Thank you for highlighting this. We have revised the sentence in the manuscript to:

 

"The average concentrations of heavy metals in the soil are as follows: Mn (543.81 mg∙kg⁻¹) > V (110.18 mg∙kg⁻¹) > Cr (71.72 mg∙kg⁻¹) > Zn (69.99 mg∙kg⁻¹) > Cu (35.98 mg∙kg⁻¹) > Ni (32.94 mg∙kg⁻¹) > Pb (28.88 mg∙kg⁻¹) > Co (14.95 mg∙kg⁻¹) > As (9.98 mg∙kg⁻¹) > Cd (0.13 mg∙kg⁻¹) > Hg (0.09 mg∙kg⁻¹)."

 

Comments 7:The authors should add brief limitations of the study and suggest potential future research direction.

Response: Thank you for your suggestion. We have included a section discussing the limitations of our study, as well as potential directions for future research. Please refer to the revisions on lines 566-572.

 

Comments 8:Please check all figures titles and axes names  (for example, Figs. 3,4 7, 8, 9, 10 – x-axis name is mental instead of metal).

Response: Thank you for bringing this to our attention. We have thoroughly reviewed all figure titles and axis labels, and have corrected the inaccuracies, specifically changing "mental" to "metal" where necessary.

 

Comments 9:3.2.2. Correlation and cluster analysis is the same as 3.2.1 subtitle. It should be different and related to the PMF analysis and source apportionment.

Response: Thank you for pointing that out. The title has been updated to “3.2.2 PMF analysis and source apportionment” to better reflect the content and its relation to PMF analysis and source apportionment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Authors have addressed all the required comments, I recommend acceptance in present form.