Effect of Carbide Slag Combined with Biochar on Improving Acidic Soil of Copper Sulfide Mines
Round 1
Reviewer 1 Report
It is a common concern that heavy metal-rich acidic soils of copper sulfide mines continues to harm the ecological environment. The authors proposed a novel approach using biochar and carbide slag in combination to deal with this problem. Different condition experiments were conducted and good results on optimizing the pH and concentration of heavy metals of copper sulfide acid soil were obtained, which is excellent contribution to the field of mine rehabilitation. However, there are some problems with the content in the author's manuscript. The existence of these problems leads me to suggest minor revision.
(1) If possible, the characterization of macroscopic and microscopic morphological of raw materials should be added in the manuscript.
(2) The XRD results of carbide slag and biochar should be added in the manuscript.
(3) All table headings are missing periods.
(4) P7, line 227-228, please check that parentheses are used correctly.
(5) It seems the Figures 1-6 are missing the abscissa title.
(6) If possible, the role of free calcium ions formed from the reaction of carbide slag with acidic soil should also be analyzed.
Author Response
Dear Reviewer,
Thanks very much for taking your time to review this manuscript. I really appreciate all your comments and suggestions! Please find my itemized responses in below and my revisions/corrections in the re-submitted files. Thanks again!
Comment 1:If possible, the characterization of macroscopic and microscopic morphological of raw materials should be added in the manuscript.
Response 1:We are so grateful for your kind suggestion .The research we had done is more oriented towards engineering applications, and the characterization of macroscopic and microscopic morphological of raw materials will be the key point in our future work.
Comment 2:The XRD results of carbide slag and biochar should be added in the manuscript.
Response 2:Thank you for this valuable feedback.We would like to add the XRD results of the amendments,but now all the Labs are on vacation(Chinese Spring Festival).In addition,we had run XRF tests on the amendments,and the results were shown in Table 1.
Comment 3:All table headings are missing periods.
Response 3:Thank you for your careful review.The periods had been added.Please see in line 105,line 125.
Comment 4:P7, line 227-228, please check that parentheses are used correctly.
Response 4:Thank you for your careful review again! The parentheses had been corrected in that sentence.Please see in line 227-228.
Comment 5：It seems the Figures 1-6 are missing the abscissa title.
Response 5：We are very sorry for the puzzle caused to the reviewer.In order to make it easier for readers to understand the figures, we put the title below the figures along with the description of the picture.
Comment 6:If possible, the role of free calcium ions formed from the reaction of carbide slag with acidic soil should also be analyzed.
Response 6:We totally agree with the reviewer .However,we didn't conduct any experiments on free calcium ion in the beginning.This leads to the fact that we don't have enough data to analyze the free calcium ion.In the future ,we will pay more attentioan on the analysis of mechanism.
Special thanks to you for your good comments.
Reviewer 2 Report
The manuscript evaluated the effects of biochar and carbide slag application on physicochemical properties and ryegrass growth in acidic soil of copper sulfide mines. This research is useful for soil improvement in copper sulfide mines. I suggest revising the whole manuscript throughout the text not limited to the following comments.
Abstract:
1. Please add the central questions the problem or the main reason your research addresses. For example, why is that topic worth examining? are you filling a gap in previous research? etc.
2. Lines 18-24: results should include some important data.
Introduction
3. Line 32: There should be a space between "development" and "(". Please check other similar cases.
4. The research status of Carbide slag is not detailed and comprehensive enough and it is recommended to clarify the research gap.
5. The sentences in lines 89-91 and 14-16 are completely repeated, please revise them. In the introduction, the objectives of the research should be clarified. Lines 93-94 are also repeated with the abstract, needs to change the writing.
Materials and methods:
6. Line 98: For the snake sampling method, please give a reference or a specific description.
7. Line 102: What type of biochar, such as straw biochar or rice husk biochar?
8: Line 163: Please put the equation on a single line.
Results
9. For 3.1, the source of the figure or table on which the analysis is based needs to be clarified.
10. line 224: p should italicize.
11. For Fig. 1, why the soil pH of COB1 is lower than that of COB1, which added soil biochar?
Discussion
12. In the discussion, it is recommended to add some discussion on potential future research.
Reference:
13. Lines 489-491: Please modify the reference format.
Author Response
Dear reviewer:
Thank you for your decision and constructive comments on my manuscript. We have carefully considered the suggestion of Reviewer and make some changes. We have tried our best to improve and made some changes in the manuscript.
Abstract:
Comment 1: Please add the central questions the problem or the main reason your research addresses. For example, why is that topic worth examining? are you filling a gap in previous research? etc.
Resopnse 1: We have added the main reason that worth examining.Please see line 26～27.
Comment 2: Lines 18-24: results should include some important data.
Resopnse 2: Thanks for your suggestion.We have added sone important data in this part.Please see line 22～23.
Introduction:
Comment 3:Line 32: There should be a space between "development" and "(". Please check other similar cases.
Resopnse 3: We appreciate your careful review and we have corrected all errors of this type.
Comment 4:The research status of Carbide slag is not detailed and comprehensive enough and it is recommended to clarify the research gap.
Resopnse 4: A clarification of Carbide slag has added in this part.Please see line 89.
Comment 5:The sentences in lines 89-91 and 14-16 are completely repeated, please revise them. In the introduction, the objectives of the research should be clarified. Lines 93-94 are also repeated with the abstract, needs to change the writing.
Resopnse 5: We have revised the text to address your concerns and hope that it is now clearer. Please see line 90～92.
Materials and methods:
Comment 6:Line 98: For the snake sampling method, please give a reference or a specific description.
Resopnse 6: The snake sampling method is also called the S-type sampling method.This method is suitable for the plots with small area, uneven terrain, uneven soil and more sampling points. The depth depends on the purpose of sampling, generally 0-20cm surface layer.
Comment 7:Line 102: What type of biochar, such as straw biochar or rice husk biochar?
Resopnse 7: The type of biochar is straw biochar.
Comment 8: Line 163: Please put the equation on a single line.
Resopnse 8: We are terribly sorry. We've corrected the mistake.Please see line 161.
Comment 9:For 3.1, the source of the figure or table on which the analysis is based needs to be clarified.
Resopnse 9: We have added a clarification in this part.Please see line 213.Thanks again for your advice
Comment 10:line 224: p should italicize.
Resopnse 10: We appreciate your careful review. All errors of this type have been corrected
Comment 11:For Fig. 1, why the soil pH of COB1 is lower than that of COB1, which added soil biochar?
Resopnse 11: Compared with the acidity of soil, the alkalinity of this type of straw biochar is weak and not enough to significantly improve the pH of soil. The reason why the pH of C0B1 is lower than that of C0B0 may be that the sulfide in the soil of C0B1 is further oxidized to produce more acid, or there may be an error in the measurement of pH. However, in our opinion, this error is relatively small and will not affect the whole experiment, which is acceptable.
Discussion:
Comment 12: In the discussion, it is recommended to add some discussion on potential future research.
Resopnse 12: We fully endorse your proposal and appreciate.Potential future research has been added in this part.Please see in line 395～397.
Reference:
Comment 13: Lines 489-491: Please modify the reference format.
Resopnse 13: We have modified the reference format.Please see in line 487～489.
Special thanks to you for your good comments.
Reviewer 3 Report
The manuscript provides insight into low cost and effective remediation mechanisms of biochar and carbide slag on acidic soils of copper sulfide mines. The outcomes of this research could be used to implement a low cost and efficient remediation technique in copper sulfide mines. The whole manuscript is very well written and presented to the reader. The introduction is based on recent findings and “Materials and Methods” are described with sufficient details. The results have been appropriately verified by statistical analysis. Tables and figures are very clear to the reader and understandable. Main results and ideas are generally well documented, justified and supported by relative references. Minor changes are recommended (please see attached file) regarding:
-units of soil properties in Table 1
-there should be a description about how and which rates of carbide Slag and Biochar are combined in section 2.2 and in accordance with Table 2
-the lack of significant values for the CxB interactions referred in section “Results”
-meaning of a few sentences throughout the text is not clear
Based on the above the manuscript could be considered for publication.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer:
Thank you for your decision and constructive comments on my manuscript. We have carefully considered the suggestion of Reviewer and make some changes. We have tried our best to improve and made some changes(Please check in red) in the manuscript.
Comment 1：units of soil properties in Table 1
Response 1：Thanks for your careful review.We have make some corrections follow your suggestion.Please see Table 1.In addition,Na2O,Al2O3,SO3，CaO，P2O5，K2O，SO3，Fe2O3 were tested by XRF,so that those compounds have no unit.
Comment 2：there should be a description about how and which rates of carbide Slag and Biochar are combined in section 2.2 and in accordance with Table 2.
Response 2：We deeply appreciate your suggestion and we have added a description in this part .Please see in line 111-113.
Comment 3：the lack of significant values for the CxB interactions referred in section “Results”
Response 3：The significant values for the CxB interactions referred in section “Results” were added.Thanks you for your careful review again!
Comment 4：meaning of a few sentences throughout the text is not clear.
Response 4：Those sentences have been corrected,Please see in line 58,line 65-66,line 86.
Special thanks to you for your good comments.
Round 2
Reviewer 2 Report
1. please add "straw biochar“ to line 100.
2. I know that the snake-shaped sampling method is a term commonly used in Chinese to describe it. But I searched google and found no references. I think you need to make it clearer for readers to understand the meaning, such as adding some references. Or, you can add some specific descriptions, e.g. the whole sampling area is ?? (hm2 ).
I found this literature for S-shaped sampling method, maybe it can be used as a reference. file:///C:/Users/46458/Downloads/applsci-12-06062-v2.pdf
3. What type of correlation analysis is in Fig. 7? Pearson correlation? It needs to be clarified in 2.4.
4. Where is the analysis for Fig. 7?
Author Response
Dear reviewer:
We deeply appreciate you for your advice on our manuscript and we have made relevant corrections according to your suggestion.
Round 2
Comment 1:please add "straw biochar“to line 100.
Response 1：“straw biochar“has been added.Please check in line 106.
Comment 2:I know that the snake-shaped sampling method is a term commonly used in Chinese to describe it. But I searched google and found no references. I think you need to make it clearer for readers to understand the meaning, such as adding some references. Or, you can add some specific descriptions, e.g. the whole sampling area is?? (hm2).
I found this literature for S-shaped sampling method, maybe it can be used as a reference. file:///C:/Users/46458/Downloads/applsci-12-06062-v2.pdf.
Response 2:Thank you again for your contribution to our manuscript.We fail to search this literature which you recommend online.However,we added some specific descriptions about snake-shaped sampling method.Please check in line 102-103 in red.
Comment 3: What type of correlation analysis is in Fig. 7? Pearson correlation? It needs to be clarified in 2.4.
Response 3:We are very sorry for our carelessness.It is Pearson correlation analysis heat map.Related descriptions have been added,please check in line 346.
Comment 4:Where is the analysis for Fig. 7?
Resopnse 4:Fig.7 is a supplement to Fig.1-3 and mainly expresses the correlation between the two factors in Fig.1-3. Therefore, there is no independent analysis of Fig.7 in this paper.The supplement can be found in line 253-254,line 276and line290-291.
Thank you again for your comments on our manuscript!
Author Response File: 
Author Response.docx
