Spatial and Temporal Distribution and Source Analysis of Heavy Metals in Agricultural Soils of Ningxia, Northwest of China
Round 1
Reviewer 1 Report
I read the manuscript Spatial and temporal distribution and source analysis of heavy metals in agricultural soils of Ningxia, Northwest of China by Lin Chen , Kun Ma with a great interest!
Authors' R programming and analysing skills are impressive!
I think the manuscript ahould be accepted after some minor revisions (misprints, adding details, cheking text).
I think it is better to separate results fro discussion section.
line 114 delete phrase in brackets
Figure 1 please , clarify what does N-I, M-A, S-L stands for. provide this figure with legend and description, so that it self explanatory.
line 214 , 254,262, 301, 324, 361, 390, 430 Error! Reference source not found.. again, delete it or find the source.
Author Response
Replies to Reviewer #1 1. I think it is better to separate results from discussion section. Re: Thank you for the reviewer’s comments. It is a good suggestion to write the results separately from the discussion, but after discussion and comparison with the published papers on SUSTAINBILITY, we have concluded that the current writing style is OK, and we have gotten used to it and feel it is more targeted and readable, especially in section 3.5 Quantify sources of soil heavy metals, which of course is our reading and writing habit. Please reviewer agree with our writing style. Thank you. 2. line 114 delete phrase in brackets Re: Thank you for the reviewer’s comments. "Error! Reference source not found. " The place is that we have adopted the cross-reference format in Word, but we do not know why the correct reference cannot be made, and we have revised the full text for similar problems. 3. Figure 1 please , clarify what does N-I, M-A, S-L stands for. provide this figure with legend and description, so that it self explanatory. Re: Thank s to the suggestions of the reviewer, we have modified the annotation of the legend to enhance the readability of the Figure 1. Please see the revised manuscript for details. 4. line 214 , 254,262, 301, 324, 361, 390, 430 Error! Reference source not found.. again, delete it or find the source. Re: Thank you for the reviewer’s comments. "Error! Reference source not found. " The place is that we have adopted the cross-reference format in Word, and we have revised the full text for similar problems. Looking forward to hearing from you soon. With kindest regards, Yours Sincerely, Lin CHEN
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript entitled "Spatial and temporal distribution and source analysis of heavy metals in agricultural soils of Ningxia, Northwest of China” is interesting and of a board concern. The concentration of metals is important to be observed and evaluated along the way. More importantly, it is also affected by numerous factors and can affect many interests.
This manuscript elaborates the observations data in a way that can be easily followed and understandable. However, several key points shall be addressed before it can be accepted to publish.
1. Ln. 80. “Fewer studies have been conducted in agricultural fields in northwest China, where heavy metal pollution is less prevalent.” This statement is interesting and can be elaborated further. It is essential to state that the state of less prevalent areas may be highly polluted area after several years of development and change in land-use. The author shall clearly state the importance of this area in the introduction related with the agricultural function and any other possible function.
2. Is there any heavy metal with excess level detected in the agricultural products from the farmland in other region from the country? If so, the statement would be beneficial to strengthen the introduction.
3. Ln. 116. “has long enjoyed the fame of ‘An Oasis in the Hinterland’” How this name helps describing the area in terms of heavy metal pollution risk.
4. A note of figure 1 shall mention the full name of N-I, M-A, and S-L. although it has been mentioned in the earlier paragraph, to express the full name can ease the reader to note the name easily. It is also suggested that the characteristics of the areas such as arid, nearby the high flowrate river, etc. may be provided in the maps or the following paragraphs as it can help the description later.
5. The sampling method shall have reference. Why did the authors decide to measure from 0-20 cm? Ln. 134. “the principle of sampling in equal proportion to the scale and the distribution area of farmland” What is the principle? How many points of sampling did the authors have?
6. Ln. 159. Table S1 or Table 1? How did the authors obtain the background data?
7. How to calculate the coefficients of variables?
8. All the figures shall be mentioned in the text.
9. Why did the authors choose to show the box plot of 2021 (Figure 2)? How about the previous years?
10. Figure 3 and 4. It is interesting that the area nearby the river and in the mountains with high rainfall throughout the years showed higher accumulation of heavy metals. How does the irrigation affect the heavy metals occurrence in the least contaminated area?
11. Clear line between industrial activities and transportation (factor 2 and 4) shall be drawn to clearly state the boundaries and thus it can better explain the cause of Hg to be 100% from factor 4 not from factor 2 or any other factors.
12. The discussion section shall be elaborated more on the impact of this result to the environment including land use or any other occasions during the observation period. The limitations and further suggestions based on the obtained data shall also be scrutinized to sum up the benefit of this study.
Author Response
Replies to Reviewer #2 1. Ln. 80. “Fewer studies have been conducted in agricultural fields in northwest China, where heavy metal pollution is less prevalent.” This statement is interesting and can be elaborated further. It is essential to state that the state of less prevalent areas may be highly polluted area after several years of development and change in land-use. The author shall clearly state the importance of this area in the introduction related with the agricultural function and any other possible function. Re: Thank you for the reviewer’s comments. We have revised the following content, please review it: “Fewer studies have been conducted on farmland in northwestern China, where heavy metal pollution is less prevalent, than in southern China. But changes in farming methods, irrigation conditions and climate change, the original heavy metal content of the area will also have the possibility of heavy metal pollution” 2. Is there any heavy metal with excess level detected in the agricultural products from the farmland in other region from the country? If so, the statement would be beneficial to strengthen the introduction. Re: Thanks to the reviewer helped us to improve the quality of the introduction, we cited the research results on excessive heavy metals in domestic agricultural products to strengthen the importance of this part. Thank you for your good advice. 3. Ln. 116. “has long enjoyed the fame of ‘An Oasis in the Hinterland’” How this name helps describing the area in terms of heavy metal pollution risk. Re: Thank you for the reviewer’s comments. Based on your comments, considering that the long history of irrigation and planting is a feature of the Northern Irrigation area, and the increase of irrigation and planting years has increased the risk of heavy metal pollution in farmland, we have supplemented and revised the relevant content, and please review it. 4. A note of figure 1 shall mention the full name of N-I, M-A, and S-L. although it has been mentioned in the earlier paragraph, to express the full name can ease the reader to note the name easily. It is also suggested that the characteristics of the areas such as arid, nearby the high flowrate river, etc. may be provided in the maps or the following paragraphs as it can help the description later. Re: Thank you for the reviewer’s comments, we have modified the annotation to express the full name of the legend to enhance the readability of the Figure 1. In addition, we strongly agree with the reviewer's suggestion to provide diagrams of features such as high flowrate river, in the northern area, only the Yellow River flows through, which we have marked, since there are no high-flow rivers (rivers with perennial water and used for agricultural irrigation) in the middle arid area and southern area of the study area, we have added a supplementary description to the overview of the study area to help readers understand. 5. The sampling method shall have reference. Why did the authors decide to measure from 0-20 cm? Ln. 134. “the principle of sampling in equal proportion to the scale and the distribution area of farmland” What is the principle? How many points of sampling did the authors have? Re: Thank you for the reviewer’s comments. Soil heavy metals of 0-20 cm are measured because the farmland layer in this study area is basically within this range, and this is the uniform depth of sampling of farmland heavy metal pollution in most domestic studies, so comparative analysis can be carried out (although the comparison with other regions was not made in this paper, it was mentioned in another manuscript we wrote). "the principle of sampling in equal proportion to the scale and the distribution area of farmland" refers to sampling according to the farmland area of each county, mainly considering the different land use types of each county. Although the area of some counties is large, the area of farmland is not necessarily large, that is, other land use types occupy a relatively high proportion. However, our research mainly focuses on the land use type of farmland. Therefore, we sampled the farmland area of each county in the study area. Those with large farmland area had more sampling points, while those with small farmland area had fewer sampling points. 6. Ln. 159. Table S1 or Table 1? How did the authors obtain the background data? Re: Thank you for the reviewer’s comments. We have neglected to cite the data, which may cause readers to be untrustworthy or even our academic misconduct. Thanks the reviewer for the timely reminder. The reference cited in Table 1 is: [48]State Environmental Protection Administration of China, China National Environmental Monitoring Centre. Background values of soil elements in China[M]. Beijing: China Environmental Science Press, 1990. 7. How to calculate the coefficients of variables? Re: Thank you for the reviewer’s comments. Linear correlations between different heavy metals in soils using scatter matrix analysi were plotted by R pro-graming language. The R code is as follows: install.packages("dplyr") library(dplyr) install.packages("PerformanceAnalytics") library(PerformanceAnalytics) setwd("F:/data") do
Author Response File: Author Response.pdf
Reviewer 3 Report
Materials and methods
Row 114, 157, 214, 238, 254, 262, 30, 324, 361, 390, 430 "(Error! Reference source not found.)" The authors should fix the error report. Does the error notice refer to the citation of tables and figures in the text?
Row 138 “After removing the impurities, samples were sieved 138 through different apertures to prepare them for analyses” Too generic. Authors should include the size of sieve
Row 149 Since the analytical method followed is not detailed but there is a bibliographic reference, the authors should specify in what form they determined the concentration of heavy metals, total or bioavailable form?
Figures and tables
Almost all the figures and tables lack the corresponding citation in the text. Authors must add them in the text.
Authors should check that all tables and figures are cited in the text, including those in the supplementary files
Conclusion
In the introduction, the authors defined the objectives in the form of three questions. In the conclusions, they should follow the same pattern
Author Response
Replies to Reviewer #3
Materials and methods
Row 114, 157, 214, 238, 254, 262, 30, 324, 361, 390, 430 "(Error! Reference source not found.)" The authors should fix the error report. Does the error notice refer to the citation of tables and figures in the text?
Re: Thank you for the reviewer’s comments. "Error! Reference source not found. " The place is that we have adopted the cross-reference format for the figure or table in Word, but we do not know why the correct reference cannot be made, and we have revised the full text for similar problems. Please see the revised manuscript for details.
Row 138 “After removing the impurities, samples were sieved 138 through different apertures to prepare them for analyses” Too generic. Authors should include the size of sieve
Re: Based on the opinion of the reviewer, we have revised the description of the pretreatment of the soil sample, adding relevant details such as the aperture of the nylon screen. Thank you for the reviewer’s meticulous reminder.
Row 149 Since the analytical method followed is not detailed but there is a bibliographic reference, the authors should specify in what form they determined the concentration of heavy metals, total or bioavailable form?
Re: Thank you for the reviewer’s comments. The forms of heavy metals determined by us are all total form, which is consistent with the steps and methods cited in the references. In order to avoid repetition, we did not give detailed descriptions, and please reviewer and editor agree with our writing, thank you.
Figures and tables
Almost all the figures and tables lack the corresponding citation in the text. Authors must add them in the text. Authors should check that all tables and figures are cited in the text, including those in the supplementary files
Re: Thank you for the reviewer’s comments. "Error! Reference source not found. " The place is that we have adopted the cross-reference format in Word, but we do not know why the correct reference cannot be made, and we have revised the full text for similar problems, including those in the supplementary files (Table S1-S4, Figure S1). Please see the revised manuscript for details.
Conclusion
In the introduction, the authors defined the objectives in the form of three questions. In the conclusions, they should follow the same pattern
Re: Thanks to the good suggestions and opinions of the reviewer, we have revised the conclusion according to your suggestions, including deleting the content of the results and retaining and modifying the conclusions corresponding to the three questions in the introduction.
Looking forward to hearing from you soon.
With kindest regards,
Yours Sincerely,
Lin CHEN
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors have addressed the comments and suggestions accordingly and the manuscript has been well improved. It is understandable that the data were previously from observation and control measurements for the heavy metals in the soils in the concern area and the authors successfully formulated it into excellent manuscript with strong background. Prior to the manuscript acceptance several minor revisions can still be made to improve the manuscript quality, the comments are as follows;
1. Coefficient of variable mathematical formula can be shown in the text.
2. Figure 2 will be more informative by giving the data from 2017 as comparison for the reader.
3. Several typing error can be addressed, i.e. standard dviation.
4. Ln 446. similar results from other study can be incorporated to strengthen the assumption.
Author Response
Replies to Reviewer #2 (Round 2)
- Coefficient of variable mathematical formula can be shown in the text.
Re: Thank you for the reviewer’s comments. Linear correlations between different heavy metals in soils using scatter matrix analysi were plotted by R pro-graming language. Based on your suggestions, we have added the mathematical formula for the coefficient of variation to the text, please see the newly added section 2.5. Thank you for your good advice.
- Figure 2 will be more informative by giving the data from 2017 as comparison for the reader.
Re: Thank you for the reviewer’s comments. Based on the recommendations of the reviewer, we have supplemented the Igeo of 2017 (A) in Figure 2 and rewritten the results and analysis in this section.
- Several typing error can be addressed, i.e. standard dviation.
Re: We are very sorry for our writing mistakes, because English is not our mother tongue, so we have carefully reviewed the whole text and corrected the spelling mistakes we found, thank you.
- Ln 446. similar results from other study can be incorporated to strengthen the assumption.
Re: Thank you for the reviewer’s comments. According to the suggestions of reviewer, we have added and newly added references with similar research results, as detailed in the paper.
Looking forward to hearing from you soon.
With kindest regards,
Yours Sincerely,
Lin CHEN
Author Response File: Author Response.pdf
