Biogeochemical Migration of Some Rare Elements in the “Leaf Debris–Soil” System of the Catenary Landscapes in Tropical Mountainous Forests in Southern Vietnam

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

Dear Authors,

I have reviewed the manuscript entitled: Biogeochemical Migration of Some Rare Elements in the "Leaf Debris - Soil" System of the Catenary Landscapes in Tropical Mountainous Forests in Southern Vietnam.

It is a classic study of chemical element analysis in different environmental matrices in order to clarify the biogeochemical migrations of the material composition of soils in the "leaf debris - soil" system.

 

The work has some flaws in terms of the methodology used; no analyte recovery study has been performed on the matrices tested (QA/QC), nor has a robust statistical study been carried out, which compromises the interpretation of the results.

 

Some issues to be reviewed

 

Figure 1. should list each of the 4 subfigures with letters (A), (B), (C) and (D). The coordinates (GPS) of the sampling points should be indicated. If the image is not their property, they should indicate the source or owner of the image.

 

Line 111. Indicate the laboratory conditions. Describe the type of preparation performed on the samples.

 

The results of all tests are expressed as mg/kg but it is not indicated whether it is dry weight (d.w.) or wet weight (w.w). In order to be able to compare analyte levels between different sampling points it is imperative that values are expressed in dry weight (d.w.).

 

Figs 2 to 12. The values analyzed are shown but the scatter bars are not shown. Does the value indicated correspond to a single sample analyzed? Were no replicates of each test performed?

 

L115. The procedure followed for the determination of the composition of the material is not indicated, please, if you have followed your own analytical procedure describe it, in case it is a procedure developed by other authors include the bibliographic citation.

 

From the point of view of quality control (QA/QC) of the analytical procedures, please indicate what they have been: i.e. use of reference material, recovery studies, etc.

 

L148.  It is indicated: A comparative analysis of the distribution of rare elements indicates that the content 149 of Se, Pd, Ag, Cd, Sn, and Bi in all the studied soils significantly exceeds their clarke con-150 centration (in bulk form). However, a statistical study (ANOVA) showing significant differences between the different sampling points including the reference values has not been performed.

Author Response

Comments 1: Figure 1. should list each of the 4 subfigures with letters (A), (B), (C) and (D). The coordinates (GPS) of the sampling points should be indicated. If the image is not their property, they should indicate the source or owner of the image.

Response 1: Thank you for your comment. The figure was corrected.

 Comments 2: Line 111. Indicate the laboratory conditions. Describe the type of preparation performed on the samples.

Response 2: Thank you for your comment. Under laboratory conditions complied with GOST ISO/IEC 17025-2019) [25], and soil and plant samples were dried in an oven to constant weight, sample preparation was carried out in accordance with GOST 17.4.4.02-2017 (Methods of sampling and preparation of samples for chemical, bacteriological, helminthological analysis) [26] and according to GOST R 58588-2019 for the selection and preparation of plant samples for agrochemical research and agroecological research [27], respectively. Plant samples were further prepared using the “dry ashing” method.

Comments 3: The results of all tests are expressed as mg/kg but it is not indicated whether it is dry weight (d.w.) or wet weight (w.w). In order to be able to compare analyte levels between different sampling points it is imperative that values are expressed in dry weight (d.w.).

Response 3: Thank you for your comment. The results of all tests are expressed as mg/kg. All test results are expressed in mg/kg. It is stated that this is dry weight (d. w.). The word “dry weight (d.w.)” was added in the manuscript    

Comments 4: Figs 2 to 12. The values analyzed are shown but the scatter bars are not shown. Does the value indicated correspond to a single sample analyzed? Were no replicates of each test performed?

Response 4: For each test, two repetitions were conducted. The indicated value is the average of the two repetitions. 

 Comments 5: L115. The procedure followed for the determination of the composition of the material is not indicated, please, if you have followed your own analytical procedure describe it, in case it is a procedure developed by other authors include the bibliographic citation.

Response 5: Thank you for your comment. A technique was used to measure the metal content in solid objects using inductively coupled plasma spectrometry in accordance with PND F 16.1:2.3:3.11-98. It was added into the references list

Comments 6: From the point of view of quality control (QA/QC) of the analytical procedures, please indicate what they have been: i.e. use of reference material, recovery studies, etc.

Response 6: Thank you for your comment. For the quality control (QA/QC) of the analytical procedures we used: GOST ISO/IEC 17025-2019), GOST 17.4.4.02-2017 (Methods of sampling and preparation of samples for chemical, bacteriological, helminthological analysis), GOST R 58588-2019 for the selection and preparation of plant samples for agrochemical research and agroecological research, and PND F 16.1:2.3:3.11-98.  They were added into the references list

Comments 7: L148.  It is indicated: A comparative analysis of the distribution of rare elements indicates that the content 149 of Se, Pd, Ag, Cd, Sn, and Bi in all the studied soils significantly exceeds their clarke con-150 centration (in bulk form). However, a statistical study (ANOVA) showing significant differences between the different sampling points including the reference values has not been performed.

Response 7: Thank you for your comment. Lateral migration in accordance with subordinate landscape settings, as well as the influence of plant litter and debris, as noted in this article, are the main reasons for the differences in concentrations of the studied elements in the horizons of the examined soils. The chemical composition of green plants and plant litter and debris we studied, as well as the ash content values for different landscape settings, indicate significant differences in the concentration of certain elements depending on their biological availability and selective (or non-selective) absorption by plants.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. What are the definitions of labile forms and mobile forms of trace elements and how to extract them for testing. 

2. Figure 4 : Why the content of Point 3 Labile Ag is higher than that of Total Ag 

3. Are the trace elements in soil and leaf debris and twigs tested by the same method, and why are the effective numbers of data inconsistent ? 

4. The parent materials of Point 4 and Point 5 may be affected by the transport and deposition of river runoff, which not only affects Pd and other elements, but also causes obstacles to the lateral migration of research elements, which needs to be paid attention to in the analysis.

Comments on the Quality of English Language

No Comments 

Author Response

Comment1. What are the definitions of labile forms and mobile forms of trace elements and how to extract them for testing. 

Response 1: Thank you for your comment. Under laboratory conditions complied with GOST ISO/IEC 17025-2019), and soil and plant samples were dried in an oven to constant weight, sample preparation was carried out in accordance with GOST 17.4.4.02-2017 (Methods of sampling and preparation of samples for chemical, bacteriological, helminthological analysis) and according to GOST R 58588-2019 for the selection and preparation of plant samples for agrochemical research and agroecological research, respectively. Plant samples were further prepared using the “dry ashing” method. Therefore, in the present study, the results of all tests are expressed in mg/kg dry weight (d.w.). A technique was used to measure the metal content in solid objects using inductively coupled plasma spectrometry in accordance with IPA F 16.1:2.3:3.11-98. They were added into the references list

Comment 2. Figure 4: Why the content of Point 3 Labile Ag is higher than that of Total Ag 

Response 2: Thank you for your comment. Indeed, there were typos in certain diagrams; therefore, we have corrected the (rightly pointed out by you) excesses of labile forms over bulk values and we separately thank you for your careful reading of our work! Figures were corrected

 

Comment 3. Are the trace elements in soil and leaf debris and twigs tested by the same method, and why are the effective numbers of data inconsistent? 

Response 3: Thank you for your comment. The trace elements in soil and leaf debris and twigs tested by the same method. The question regarding the actual values for soils and vegetation is not completely clear (why are the effective numbers of data inconsistent). It should be taken into account that there is a conversion per kg - both for soils and for plant ash. Naturally, for raw plant biomass, recalculation per kg of ash will show significant content values for some elements.

Comment 4. The parent materials of Point 4 and Point 5 may be affected by the transport and deposition of river runoff, which not only affects Pd and other elements, but also causes obstacles to the lateral migration of research elements, which needs to be paid attention to in the analysis.

Response 4: Thank you for your comment. You have noted that the factors influencing the migration of elements at points 4 and 5 are more diverse. Indeed, for points 4 and 5, the possible influencing factors increase, and in particular, we have noted that it is not possible to assert definitively about the predominant influence of a specific factor. Nevertheless, we analyze the entry of these elements with plant litter and debris (actually, the content in plants), as well as the availability (presence) of these elements for plants in the soil. Indeed, there are more pathways of entry than for the higher-located landscape facies, which is particularly mentioned in the article.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

I find this study interesting and innovative. There are some corrections, suggestions, and improvements that I would like to suggest, including:

1. Knowledge gap and objective of studies are less emphasized. They need to be highlighted. 

2. The material and method section is very brief and needs some brief information about the methodology, e.g., sample preparation, etc. 

3. The captions of figures seems very lengthy. Give a more concise caption to each figure. 

4. The graphs in results need thorough overhauling. Bars should have error bars. Also the numbers written after decimal are too much. That values are not required. 

5. Proper statistical analysis are required. 

6. Make conclusion concise and only mention finding of this study. 

 

 

 

 

 

 

Comments on the Quality of English Language

Moderate editing is required. 

Author Response

Comment 1. Knowledge gap and objective of studies are less emphasized. They need to be highlighted. 

Response 1: Thank you for your comment. The introduction was rewritten. Knowledge gap and objective of studies were highlighted.

Comment 2. The material and method section is very brief and needs some brief information about the methodology, e.g., sample preparation, etc. 

Response 2: Thank you for your comment. More information about the methodology including sample preparation was added.

Comment 3. The captions of figures seems very lengthy. Give a more concise caption to each figure. 

Response 3: Thank you for your comment. The captions of figures were changed

Comment 4. The graphs in results need thorough overhauling. Bars should have error bars. Also the numbers written after decimal are too much. That values are not required. 

Response 4:  Thank you for your comment. We have taken into account your comment regarding the number of decimal places. However, when adding information about errors to the graphs, the graphs become overloaded, and therefore we did not add error values. The written numbers after decimal were written one decimal place. 

Сomment 5. Proper statistical analysis are required. 

Response 5: Thank you for your comment. The article constructed sequences of decreasing data, examined the behavior of elements in accordance with emerging geochemical traps, biosorption, and translocational migration pathways. Additionally, after the review, the relationship between metal concentrations in soils and leaf litter/debris was calculated based on Pearson's correlation coefficient.

Comment 6. Make conclusion concise and only mention finding of this study. 

Response 6:  Thank you for your comment. The conclusion was rewritten.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

 

Thank you for your corrected and improved manuscript. I have reviewed it again and continue to detect methodological errors.

 

You have included an analysis of variance  (ANOVA) in the results section, however, this is not indicated in the material and methods section. Please include mention of this statistical procedure in the "Material and methods" section.

 

In your "Comment #4" you indicate that the values indicated are the means of 2 replicates. Standard deviations (SD) and %CV should be calculated. The dispersion of the mean should be indicated in the graphs by means of whiskers covering the %CV.  Similarly significant differences should have been indicated by (*) in the bar figures.

Author Response

Comment 1: You have included an analysis of variance (ANOVA) in the results section, however, this is not indicated in the material and methods section. Please include mention of this statistical procedure in the "Material and methods" section.

Response 1: Thank you for your comment. Statistical procedure in the "Material and methods" section was added.

Comment 2: In your "Comment #4" you indicate that the values indicated are the means of 2 replicates. Standard deviations (SD) and %CV should be calculated. The dispersion of the mean should be indicated in the graphs by means of whiskers covering the %CV.  Similarly significant differences should have been indicated by (*) in the bar figures.

Response 2: Thank you for your comment. Of course, standard deviations (SD) and %CV were calculated in working process. However, when adding information about errors to the graphs, the graphs become overloaded, and therefore we did not add error values. After your comment the dispersion of the mean was added in the graphs.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The author has answered all my questions and I have no further questions.

Author Response

Comment 1: The author has answered all my questions and I have no further questions.

Response 1: Thank you for your comment

Author Response File: Author Response.pdf