Phytoremediation Properties of Sweet Potato for Soils Contaminated by Heavy Metals in South Kazakhstan

Round 1

Reviewer 1 Report

Dear authors,

I have read the manuscript with interest and some questions raised.

Section: Materials and Methods. 2.7. Atomic Absorption Spectrometry

Please add details concerning each standard solutions used (please add details about commercial name manufacturer, city and state).

Authors stated “ The quality control involved of blank samples and each calibrated standard solutions of heavy metals”. Please explain why certified reference material was not used. Please add the recovery figures and the precision values of the methods.

Author Response

Please add details concerning each standard solutions used (please add details about commercial name manufacturer, city and state). 

Answer: Comments accepted and added reference standard manufacturer information added.

Authors stated “ The quality control involved of blank samples and each calibrated standard solutions of heavy metals”. Please explain why certified reference material was not used. Please add the recovery figures and the precision values of the methods.

Answer: According to reference standard materials concentration were 1 mg/L, which was too higher concentration check. Therefore, calibration standards were used to validate the methodand was described.

Reviewer 2 Report

This study investigated the phytoremediation properties of sweet potato on adjacent to mine tailings solils contaminated with Pb, Zn, Cd and assessed the polluton class and potential risk of HM accumulation upon soils in South kazakhstan. The experimental methods sound like reasonable. The conclusions  have some significance. I recommend to publish this paper here after finishing the major revision below:

 

1. Some format inconsistency on the units, such as mg/kg or mg*kg-1. Please unify.

 

2. The cadmium, lead, zinc are abbreviate as Cd, Pb, Zn, respectively. Please use their abbreviation form in the text.

 

3. In Reference, the capital words should be unified. For example, Ref. 1 uses the capital form while Ref. 2 uses the lower-case format. These should be unified.

 

4. The SEM image is very blurry in Figure 4. Please provide the picture with high resolution ratio.

 

5. From the Table 3, it could be seen that Pb contents are clearly higher thant the Zn and Cd. However, in the soils, Zn contents are far higher than the Pb and Cd. At same time, Zn and Cd contents are highest in Field 3. Authors should give some explanation on these. 

Author Response

1. Some format inconsistency on the units, such as mg/kg or mg*kg-1. Please unify. 

Answer:  Comment accepted and units changed.

2. The cadmium, lead, zinc are abbreviate as Cd, Pb, Zn, respectively. Please use their abbreviation form in the text.

Answer: All heavy metals were abbreviated as Cd, Pb, Zn.

3. In Reference, the capital words should be unified. For example, Ref. 1 uses the capital form while Ref. 2 uses the lower-case format. These should be unified.

Answer:  Comments accepted and all references unified.

4. The SEM image is very blurry in Figure 4. Please provide the picture with high resolution ratio.

Answer:   SEM image changed with high resolution.

5. From the Table 3, it could be seen that Pb contents are clearly higher thant the Zn and Cd. However, in the soils, Zn contents are far higher than the Pb and Cd. At same time, Zn and Cd contents are highest in Field 3. Authors should give some explanation on these. 

Answer:  The effects of heavy metals on translocation have been described. Some metals are poorly absorbed in soils, but have high remediation properties.

Reviewer 3 Report

Dear authors,

I have read your paper "Phytoremediation properties of sweet potato for heavy metal 2 contaminated soils in South Kazakhstan" in detail and the very idea of using sweet potatoes to remove heavy metals from abandoned mine tailings is very interesting and represents a good solution to prevent the migration of this type of metal into the environment. You conceived the work very nicely, so when the work is viewed as a whole, in addition to the experimental and practical significance, it also has an interesting theoretical significance.

In order for the paper to gain importance, I would ask you to make small corrections related to

- the marking of decimal places (an example is the error on line 10, 262,90),

- rewriting the introduction specifying the advantages of your methodology compared to the used ones, and, most importantly,

- describe the metal collection mechanism in certain parts of the plant. Describe in more detail what is responsible for the selective isolation of certain metals both in the tuber part, as well as in the part of the leaf and stem.

Best regards,

Reviewer 

The English language in which the paper was written is very good and during the review of the paper, I did not come across any objections that affected the vagueness and grammatical incorrectness.

Author Response

- the marking of decimal places (an example is the error on line 10, 262,90).

Answer: All HM concentration's decimals changed.

 - rewriting the introduction specifying the advantages of your methodology compared to the used ones, and, most importantly.

Answer: There were added information about AAS advantages to determine single HM in Introduction section.

-describe the metal collection mechanism in certain parts of the plant. Describe in more detail what is responsible for the selective isolation of certain metals both in the tuber part, as well as in the part of the leaf and stem.

Answer: There were described HM translocation mechanism in plants. 

Reviewer 4 Report

A more in-depth discussion is needed to explain the reasons for the results obtained. Could you characterize Pb, Zn and Cd to account for bioconcentration?

Minor editing of English language required

Author Response

A more in-depth discussion is needed to explain the reasons for the results obtained. Could you characterize Pb, Zn and Cd to account for bioconcentration?

Answer: Comment accepted. We added more information to characterize HM concentrations to account for bioconcentration.

Minor editing of English language required.

English language has been improved, using MDPI language editing service.

 

Reviewer 5 Report

In the manuscript reference applsci-2551631, Toishimanov et al. examined the potential of sweet potato (Ipomoea batatas L.) for the phytoremediation of heavy metal residues around an abandoned lead factory in Shymkent, Kazakhstan. The ecological risk and geo-accumulation indexes as well as the bio-concentration and translocation factors were also determined. These aspects of the work are interesting and the obtained results looks in some sense positive, but the manuscript can be accepted for publication in Applied Sciences by elucidating and taking into consideration the following points.

·         The authors fail to elaborate in which details the present work exceeds current knowledge. Please see: Noviardi et al., 2023. Journal of Degraded & Mining Lands Management, 10(4); Cheng et al., 2015, Environmental Monitoring and Assessment, 187, 1-9; Nenman et al., 2022, Journal of Applied Chemistry, 10(4), 104-113.

·         The atomic absorption spectrometry (AAS) methodology that was used for heavy metal analysis was not validated. The following parameters should be definitively included: limit of detection (LOD), limit of quantification (LOQ), and linearity. Please also add the mean recovery for the methodology, the standard error and the coefficient variation value.

·         There is a lack of details in the experimental section, with the information provided interested scientists will not be able of duplicating the trial. For example, the energy dispersive X-ray fluorescence spectrometry (ED-XRFS) technique is not included. Provide more details about the conditions of the SEM methodology such as: magnification ×? backscattered electron or secondary electron imaging mode? accelerating voltage? effective working distance? were the samples sputter coated?

·         Statistical analysis. The experimental design should be addressed. Furthermore, means need to be separated by using a proper statistical procedure. In all tables, the metal content should be expressed as mg/kg ± SE/SD.

·         X-ray diffraction (line 239)? Did the authors refer to the XRFS technique?

·         In the R&D section, SEM description is missing!

·         For a better comparison, could the authors provide the heavy metal content in the soil and sweet potatoes (tuber and leaves) by means of the ED-XRFS technique?

·         In general, discussion of the results is descriptive and does not go beyond what was measured. Authors need to present and discuss their results concisely and compare them to those previously reported by others researchers as well as clearly indicate what new information is contributed by the present study.

·         Figures are very poor in quality. I strongly recommend the author embellish all figures.

·         Please, check the usage of the terms "concentration" vs "content". According to IUPAC terminology, concentration characterizes the composition of a mixture with respect to the volume; content, represents the amount of a component divided by the mass of the system.

·         I think you can end up the discussion section with more conclusions from your study.

 

·         There are many instances where the text is difficult to follow because of grammatical errors. I strongly recommend that the manuscript be read and corrected by a native English speaker.

 

I strongly recommend that the manuscript be read and corrected by a native English speaker.

Author Response

    The authors fail to elaborate in which details the present work exceeds current knowledge. Please see: Noviardi et al., 2023. Journal of Degraded & Mining Lands Management, 10(4); Cheng et al., 2015, Environmental Monitoring and Assessment, 187, 1-9; Nenman et al., 2022, Journal of Applied Chemistry, 10(4), 104-113.

Answer:  These studies were carried out under different conditions, but nevertheless, bioconcentration and translocation factors show the phytoremediation properties of sweet potatoes.

The atomic absorption spectrometry (AAS) methodology that was used for heavy metal analysis was not validated. The following parameters should be definitively included: limit of detection (LOD), limit of quantification (LOQ), and linearity. Please also add the mean recovery for the methodology, the standard error and the coefficient variation value.

Answer:  In the Materials and Methods section, and R&D section were described the method validation for the determination of HM by AAS.

  There is a lack of details in the experimental section, with the information provided interested scientists will not be able of duplicating the trial. For example, the energy dispersive X-ray fluorescence spectrometry (ED-XRFS) technique is not included. Provide more details about the conditions of the SEM methodology such as: magnification ×? backscattered electron or secondary electron imaging mode? accelerating voltage? effective working distance? were the samples sputter coated?

Answer:  In the section Materials and Methods, R&D section were described and the characteristics of the SEM were added.

  Statistical analysis. The experimental design should be addressed. Furthermore, means need to be separated by using a proper statistical procedure. In all tables, the metal content should be expressed as mg/kg ± SE/SD.

Answer:  All studied samples were analyzed in triplicate. Accordingly, in all tables, the HM concentrations were shown with SD.

 X-ray diffraction (line 239)? Did the authors refer to the XRFS technique?

Answer:  SEM-EDS conditions for structural analysis have been added.

 In the R&D section, SEM description is missing!

Answer: Comment accepted and SEM part described.

       For a better comparison, could the authors provide the heavy metal content in the soil and sweet potatoes (tuber and leaves) by means of the ED-XRFS technique?

Answer:  Since the studies were carried out last year, at that moment all samples were examined in an AAS.

 In general, discussion of the results is descriptive and does not go beyond what was measured. Authors need to present and discuss their results concisely and compare them to those previously reported by others researchers as well as clearly indicate what new information is contributed by the present study.

Answer: We added more information to discuss our results.

    Figures are very poor in quality. I strongly recommend the author embellish all figures.

Answer:  We changed figures with high resolution.

 Please, check the usage of the terms "concentration" vs "content". According to IUPAC terminology, concentration characterizes the composition of a mixture with respect to the volume; content, represents the amount of a component divided by the mass of the system.

Answer:  Comment accepted and changed. In our research we will use term “concentration” to describe quantity of HM.

I think you can end up the discussion section with more conclusions from your study.

Answer: We added more conclusions in the discussion sections.

There are many instances where the text is difficult to follow because of grammatical errors. I strongly recommend that the manuscript be read and corrected by a native English speaker.

Answer: English language has been improved, using MDPI language editing service.

Round 2

Reviewer 2 Report

Now, I recommend the ms. to publish here.

Reviewer 5 Report

The document has been corrected according to my previous comments. I have no further suggestions.