Potential of Attapulgite/Humic Acid Composites for Remediation of Cd-Contaminated Soil
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this study, attapulgite and humic acid were used as raw materials to prepare stable materials for the remediation of cadmium-contaminated soil. There are several problems in the following aspects:
1. The SEM resolution of Figure 1 is too low to see the scale clearly.
2. It is recommended that the figures in each grouping be numbered so that, for example, when analyzing changes in morphology, they can be followed by which figure has changed.
3. In the morphological analysis, the author introduced the minerals on the surface of the material, but did not see the relevant characterization in Fig.1.
4. The material prepared in this study is a composite material of attapulgite and humic acid, but only humic acid is mentioned in the text. What role does attapulgite play?
5. This study should not only describe the experimental results, but also discuss in detail the reasons for this result and analyze the mechanism of action of the material on Cd.
6. What are the advantages of the materials prepared in this study compared to other studies and is it possible to make a list of comparisons?
7. In this paper, the physical and chemical properties of contaminated soil, such as pH and water content, are not seen. How do these physical and chemical properties affect the stabilization of Cd by composite materials?
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors(1) More experiments about attapulgite/humic acid composites for remediation of Cd-contaminated soil need to be added, and more analysis should be provided.
(2) The innovation and highlight in this paper should be further emphasized in abstract. Clarify the specific objectives of the research work in the abstract.
(3) Provide a brief overview of the relevant background information. This will help readers understand the context and significance of the study.
(4) The existing problems and limitations in previous researches should be further explained in introduction, and the authors should clearly state the motivation for the research and highlight the gap in current knowledge that their study aims to address.
(5) The conclusions should be more comprehensive. The authors should provide a summary of their main findings, the limitations of the study, and recommendations for future research. There are several grammar mistakes in the paper, please double-check throughout the whole manuscript.
Comments on the Quality of English LanguageThere are several grammar mistakes in the paper, please double-check throughout the whole manuscript.
Author Response
please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsI think that is recommendable improve Figures 2 and 5. Axes are not clear.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe manuscript "Potential of Attapulgite/Humic Acid Composites for Remediation of Cd-Contaminated Soil" by Hanru Ren and others presents the results of a lab test of attapulgite mixed with humic acid applied to soil in order to reduce the bioavalability of toxic Cd. The general idea is not new and similar field tests have been conducted by references 3, 27, 30 and 33 although the design of the test and several modifications such as the addition of humic acid are new. According to the authors "The humic acid and treated attapulgite were mixed according to the mass ratio of 1:3, 1:4, 1:5, 1:6 and 1:7, water was added to stir well, dried and ground to 100 mesh and got 5 kinds of composites which were denoted as HAA13, HAA14, HAA15, HAA16 and 100 HAA17." The authors results indicate that "The effectiveness of heavy metal immobilizing of curing is ranked according to the following order: HAA15>HAA16>HAA17>HAA14>HAA13. They conclude that "The attapulgite/humic acid composites can be used as stabilizing agent to remediated farmland soil polluted by heavy metal". One problem is the over-use of acronyms, some of which are not defined. "CK" is never defined although it used 35 times and is presumably the name of their control.
Another problem is that the study ignores all of the considerable literature pertaining to the potentially carcinogenic properties of attapulgite. The mineral is fibrous and is used as a substitute for asbestos. Although there is no general consensus on attapulgite there is enough data to treat it with caution. It would be counterproductive to spread a carcinogen on Cd contaminated soil even if it reduced the bioavalability of the Cd. The potential of attapulgite to induce mesothelioma has been documented in animals (Pott et al., 1976). In addition attapulgite has been implicated in a case study of a mine engineer with lung fibrosis, a respiratory disease, following a 2-year exposure to attapulgite (Sors et al., 1979). Guthrie (1992) reviewed the environmental health literature on attapulgite and summarizes papers by Waxweiler et al., 1988); Wagner (1982); Bignon et al., (1980); Nadeau et al., (1983) and others. Several more recent papers by Guthrie should also be read by the authors.
A line-by-line list of questions and comments follow:
Line 13 – Define DTPA and TCLP.
Line 158 – The toxic coefficients for Zn, Cr, Cu, Ni, Pb, and Cd of 1, 2, 5, 6, 5 and 30 are not generally accepted. For example, I suspect that most epidemiologists would rank Pb much more toxic than Cu. However what is the source of the toxic coefficients?
Line 175 - Define claviculate
Figure 1 – Poor resolution.
Figure 2 – The XRD peaks are not readable.
Line 212 – substitute "relate" for "relating"; add "the" before bioavailable and "of" before heavy; and substitute "metals" for "mental"
Line 214 – Refer to Table 1.
Lines 214-437 – The remainder of the paper compares the bioavailability, ecological risk, BCR speciation (including EXC, RES, RED and OX speciation); Environmental Risk Assessment (ERF); and Ecotoxicity Assessment (bioconcentration factor (BCF) and transfer factor (TF)) of the 5 numbered HAA treatments and the ATP treatment to the undefined CK treatment. The resulting abundance of data is difficult for the reader to evaluate. It would be very helpful if the authors prioritized the results and chose two or three of the more important factors for emphasis. Some of the factors are of marginal interest and could be deleted. This would greatly enhance readability.
Comments on the Quality of English LanguageThe English needs considerable work.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for Authors(1) What is the thoretical principle of remediation of Cd-contaminated Soil?
(2) More information about the microscopic morphology of attapulgite/humic acid composites should be added.
(3) Date Analysis should be provided systamatically.
(4) The discussion should be added in the manuscript. The conclusion should be verified.
(5) Clarify the specific objectives of the research work in the abstract. Clearly state the research questions in this paper.
(6) There are several grammar mistakes in the paper, please revise and double-check throughout the whole manuscript. The language could benefit from further editing and polishing.
Comments on the Quality of English LanguageThere are several grammar mistakes in the paper, please revise and double-check throughout the whole manuscript. The language could benefit from further editing and polishing.
Author Response
The grammar of this article has been corrected
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsRe-review
The revised manuscript "Potential of Attapulgite/Humic Acid Composites for Remediation of Cd-Contaminated Soil" by Hanru Ren and others includes a few minor clarifications but is largely unchanged from the previous version. The text is still unnecessarily complex and filled with acronyms. The research design is quite simple. According to the authors, humic acid and attapulgite were mixed according to five different mass ratios (1:3, 1:4, 1:5, 1:6 and 1:7). The authors applied each mixture to soil in order to reduce the bioavalability of toxic Cd. Several variables including bioavailability, ecological risk, BCR speciation and others were statistically compared through experiments. The authors conclude that the 1:5 mixture had the best results. However, the described response of each mixture to each of the variables is tedious and difficult to follow. I suggested that if the long list of variables was reduced to only a few of the more important ones the readability would be increased. This suggestion was ignored and the manuscript remains very difficult to follow. Nevertheless, the subject of the manuscript (attapulgite remediation of cadmium) has been a very popular line of published research for several years and there seems to be considerable interest in the subject. Therefore, my best advice as to how the manuscript could easily become much more interesting and useful would be to compare the Cd remediation results of the 1:5 treatment with the results of attapulgite treatments proposed by Yang et al. (2022); Liang et al. (2019); Zhao et al. (2023); Jia et al. (2023); and Xia et al. (2021) or any of the rapidly growing list of attapulgite mixtures that also claim to be effective Cd remediation treatments. How does the proposed 1:5 mixture compare to the long list of published alternatives?
Another suggestion that was ignored pertains to the large body of research claiming that attapulgite may be carcinogenic due to its fibrous resemblance to asbestos. It would be tragic if large areas of soil were irreversibly treated with attapulgite if evidence is revealed that the treatment was carcinogenic. If the authors have good, published evidence that attapulgite fibers are unlike any asbestos and are safe, then such evidence should be cited.
Comments on the Quality of English LanguageThe English is a serious problem and is quite distracting.
Author Response
The syntax of the article has been corrected
Author Response File: Author Response.pdf
Round 3
Reviewer 4 Report
Comments and Suggestions for Authors
I carefully read the brief reply by the authors to my review of the revised manuscript "Potential of Attapulgite/Humic Acid Composites for Remediation of Cd-Contaminated Soil" by Hanru Ren and others. I was surprised by the authors refusal to make any of the changes that I suggested. I have conducted considerable research on asbestos including a paper on Attapulgite and am very familiar with the subject. The subject of the manuscript (attapulgite remediation of cadmium) has been a popular line of published research for several years. Therefore, my best advice as to how the manuscript could easily become much more interesting and useful would be to compare the results of their proposed treatment with the results of attapulgite treatments proposed by any of the rapidly growing list that also claim to be effective Cd remediation treatments. Another suggestion that was ignored pertains to the large body of research claiming that attapulgite may be carcinogenic due to its fibrous resemblance to asbestos. If the authors have good, published evidence that attapulgite fibers are unlike any asbestos and are safe, then such evidence should be cited. Otherwise the manuscript may comply with the minimum criteria for publication; I just can't bring myself to recommend it.
Comments on the Quality of English LanguageThe English is still quite poor.
Author Response
Please see the attachment.
Thank you for your time.
Author Response File: Author Response.pdf
