Spatial Distribution, Contamination Levels, and Health Risks of Trace Elements in Topsoil along an Urbanization Gradient in the City of Urumqi, China
Round 1
Reviewer 1 Report
This paper proposes research in the area of trace element concentrations analysis. The topic of this paper is relevant to the journal. The research is interesting and the conclusion is convincing. I have some comments I hope will improve the paper.
1. The authors directly used the term urbanization gradient. The definition is missing.
2. The motivation for analyzing concentrations of trace elements in the urbanization gradient is not clear. why is this problem important, why should the reader care?
3. Research reviews should not just give examples, but classifications and summaries of existing research.
4. Topsoil may contain more than seven elements, why did the authors analyze only seven elements?
Author Response
Point 1: The authors directly used the term urbanization gradient. The definition is missing.
Response 1: Special thanks to you for your good comments. We have added the definition of the term urbanization gradient from Line 68 to Line 70, and from Line 152 to Line 158 of the revised manuscript.
Point 2: The motivation for analyzing concentrations of trace elements in the urbanization gradient is not clear. Why is this problem important, why should the reader care?
Response 2: According to your advice, we have improved the Introduction section. (from Line 70 to Line 71, and from Line 102 to Line 108 of the revised manuscript)
Point 3: Research reviews should not just give examples, but classifications and summaries of existing research.
Response 3: Thanks for your favorable suggestions, we have made corrections on that. (from Line 102 to Line 108 of the revised manuscript)
Point 4: Topsoil may contain more than seven elements, why did the authors analyze only seven elements?
Response 4: Special thanks to you for your good comments. These seven elements have been listed as the priority control pollutants by the “Soil environmental quality - Risk control standard for soil contamination of development land (GB36600—2018)”. Therefore, our study focused on contamination risk assessments of these elements. According to your advice, we have added the reason why we analyzed these elements. (from Line 179 to Line 183 of the revised manuscript)
Special thanks to your dedicated work. Your comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We hope that the correction will meet with approval.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The effects of urbanization on contamination of urban soils in arid region oasis is a very meaningful topic. The authors analyzed the concentrations and health risks of seven trace elements of topsoil samples from urban, suburban, and rural gradients in the Urumqi city , but there are a lot of problems.
(1) The scale of the study area is too small, studies were carried out in multiple profiles would render this study even more meaningful.
(2) The authors did not extensively explain the novelty of the present work with respect to the current literature.
(3) The analysis should be combined with land-use types.
(4) Discussion on sources of trace elements must be in the framework of the geology, lithology, human activities ,etc. This information must be included to adequately sustain the proposed sources of trace elements due to the urbanization impact and human disturbance. A soil type map should also be provided.
(5) Conclusions: Do not simply repeat and/or summarize the results. What are your highlights?
(6) The scientific contribution of the present manuscript is very limited, results discussion should be strengthened to improve the scientific level.
Author Response
Response to Reviewer 2 Comments
Point 1: The scale of the study area is too small, studies were carried out in multiple profiles would render this study even more meaningful.
Response 1: Special thanks to you for your good comments. In our study, a typical and continuous urban-suburban-rural gradient zone is selected, and each gradient extended over a distance of approximately 8 km. We believe that the selected typical area meets the purpose and requirements of this study. According to your advice, we have added related text from Line 148 to Line 158 of the revised manuscript.
Point 2: The authors did not extensively explain the novelty of the present work with respect to the current literature.
Response 2: We have improved the Introduction section according to the your suggestion. (from Line 151 to Line 157, from Line 166 to Line 169, from Line 380 to Line 383, and from Line 429 to Line 436 of the revised manuscript)
Point 3: The analysis should be combined with land-use types.
Response 3: We have made corrections on that. (from Line 102 to Line 108, and from Line 125 to Line 129 of the revised manuscript)
Point 4: Discussion on sources of trace elements must be in the framework of the geology, lithology, human activities, etc. This information must be included to adequately sustain the proposed sources of trace elements due to the urbanization impact and human disturbance. A soil type map should also be provided.
Response 4: We have improved the Discussion section, and added the sources analysis of trace elements. (from Line 412 to Line 417, and from Line 424 to Line 436 of the revised manuscript). We have also provided the soil type map of the study area, according to your suggestions. (Page 14, revised Figure 1)
Point 5: Conclusions: Do not simply repeat and/or summarize the results. What are your highlights?
Response 5: We are so sorry for our incorrect writing. We have checked the manuscript carefully, and rewrote the Conclusions section. (from Line 590 to Line 634 of the revised manuscript)
Point 6: The scientific contribution of the present manuscript is very limited, results discussion should be strengthened to improve the scientific level.
Response 6: Many thanks for your suggestion. We have improved the Results and Discussion parts of our manuscript to improve the scientific level. (from Line 347 to Line 350, from Line 380 to Line 383, from Line 412 to Line 417, from Line 424 to Line 436, and from Line 575 to Line 588 of the revised manuscript)
We have tried our best to revise the manuscript according to your construction comments and suggestions. We sincerely hope that this revised manuscript has addressed all your comments and suggestions.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Thank you to the authors for addressing all suggested revisions.
Author Response
Response to Reviewer 1 Comments
Thank you very much for your support and guidance on the article.
Author Response File: Author Response.docx
Reviewer 2 Report
Regrettably, the author did not give satisfactory answers to the questions raised in the revised draft. For example, Response 1，the Line 148 to Line 158 of the revised manuscript has nothing to do with the question raised. The same problems occur in Response 3 and Response 4. This makes me suspect that the author does not have a serious and rigorous attitude towards scientific research.
Author Response
Response to Reviewer 2 Comments
Point 1: Regrettably, the author did not give satisfactory answers to the questions raised in the revised draft. For example, Response 1, the Line 148 to Line 158 of the revised manuscript has nothing to do with the question raised. The same problems occur in Response 3 and Response 4. This makes me suspect that the author does not have a serious and rigorous attitude towards scientific research.
Response 1: Many thanks for your suggestions, and we apologize for not satisfying you with the response to the previous manuscript.
As to point 1: We agree with the reviewer that multiple profiles would render this study even more meaningful. However, we believe that expanding our profiles is neither feasible, given the costs involved, nor would significantly support our argument. For this reason, we chose not to make this change. Nevertheless, we recognize this limitation should be mentioned in the paper, so we added the following sentence in the discussion: “We also suggest that multiple profiles of the urbanization gradient of the study area would render this study even more meaningful.”(from Line 593 to Line 595 of the revised manuscript)
As to Point 3: The reviewer suggested that the analysis should be combined with land-use types. Nevertheless, The urbanization gradient zones in our study is divided according to land-use types of the studied area. Therefore, we believe that discussions of the effects of different urbanization gradients on trace elements can represent the effects of different land use types. We added land use types for different urbanization gradients to the revised manuscript. (from Line 153 to Line 155 of the revised manuscript). Moreover, according to the land use type and the spatial distribution of trace elements in the study area, we simply analyzed the pollution sources of Hg, Cd, Ni, Pb, Zn, and Cu elements, including soil parent material sources, industrial sources, transportation sources, and agricultural sources (see lines 415 to 441 of the revised manuscript).
As to Point 4: The reviewer suggested that discussion on sources of trace elements must be in the framework of the geology, lithology, human activities, etc. According to our results, As was the major non-carcinogenic and carcinogenic element in the topsoil of all urbanized gradients in Urumqi city. Therefore, we only discussed, in the original manuscript, the main sources of As element in topsoil (please see from Line 560 to Line 575 of the revised manuscript). We don’t think it’s necessary to discuss the sources of other elements, considering the scope of our paper. However, based on the reviewer's suggestion, we have supplemented and improved the source analysis of trace elements again (from Line 409 to Line 415 of the revised manuscript). We also provided the soil type maps of the study area according to the reviewer’s suggestions.
Once again, we thank you for the time you put into reviewing our paper and sincerely hope that this revised manuscript has addressed all your comments and suggestions.
Author Response File: Author Response.docx
Round 3
Reviewer 2 Report
Article corrections approved.
