Assessment of Heavy Metal Pollution of Agricultural Soil, Irrigation Water, and Vegetables in and Nearby the Cupriferous City of Lubumbashi, (Democratic Republic of the Congo)

Round 1

Reviewer 1 Report

The aim of the present study was interesting to quantify and evaluate the pollution levels and the potential sources of soil, irrigation water and vegetable contamination by the metals As, Cd, Cr, Cu, Pb, Co and Zn in the urban gardens of Lubumbashi (DR Congo).

The manuscript acceptable with following revisions:

Minor Comments:

There is need to format the manuscript according to Mdpi style especially references.

Major Comments

Table 1 and Table 4 needs statistical analysis to show significance.

Discussion section can be improved by comparing results with previous studies.

Author Response

Bonjour, cher examinateur

Veuillez vous référer à la pièce jointe conjointe pour les réponses données pour la révision de mon manuscrit.

Profitez de votre journée.

Félicien

Author Response File: Author Response.docx

Reviewer 2 Report

The main important failures are:

1- Recent, relevant and more references are needed, mostly in the introduction the discussion section seems more like a result and state of the art than a discussion of the findings

2-  the methods and results sections are incomplete and need clarification. The discussion should start addressing the main findings. Studies with conflicting results obtained are lacking. Discussions of strengths and weaknesses are absent.

4- Some equations are NOT clear, such as:

a- Cfi (L: 159)

b- ?? = (L: 181)

5- There are many typist errors, such as:

a- Font of Lycopersicon esculentum Mill, A (L: 101)

b- 2.4.1. (L: 155) is it 2.3.1 ?

c- There are some words in French such as: where Cn et Bn  (L: 182)

6- There are no statistical methods in the manuscript.

7- Why is the cobalt result in Table 1, even though it was not analyzed?

8 - The design of figures is very bad

9- I’m not native English speaker but I have noticed many phrasal constructions that I think are in a strange wording order and that could be improved.

 

Author Response

Hello, dear Reviewer

Please refer to the joint attachment for the answers given for the revision of my manuscript.

Enjoy your day.

Félicien

Author Response File: Author Response.docx

Reviewer 3 Report

Detailed comments below:

 

Title. I suggest changing the title with an emphasis on the assessment on a polluted region (copper mining).

 

Introduction section

The introduction section is properly described. The importance of this research for the health of the people of the region was emphasized. As the authors declare, this type of research has not been conducted in this area before, which adds value to this manuscript.

 

Materials and methods section

The sampling and analysis methodology was chosen correctly. However, the method of assessing the content of heavy metals in the soil is inappropriate. The XRF method allows for estimating the content of heavy metals, not with suitably high sensitivity determination. Typically, this method is used to evaluate the percentage of the main elements in matrix (steel, minerals, cement, concrete etc.) as oxides. In the future, I propose mineralization with acids and determination with reference methods, ICP or AAS.

 

Table 1. Please show in Table 1 the limits of quantification for the XRF method of determination of metals, instead of ND. The lack of results of heavy metal content in soils makes it impossible to calculate the pollution factors. What values were used for the calculations? The low content of Fe in the tested soils is surprising. Please check the units.

 

Page 6. Line 220-227. How was soil contamination assessed, e.g. for Cd, Pb, Co, since there were no results from the XRF method?

 

Table 2. Please explain in detail how factors and PLI was calculated. What data was used in the calculations?

 

Table 3. The unit of concentration is mg/L (mass to volume). Please check and correct the units.

 

Discussion

The Discussion section is described very precisely and appropriately.

 

Conclusions

According to the authors, phytoremediation is not a solution to the problem of environmental pollution with heavy metals in those area. I agree with this opinion. Only methods of alternative cultivation, additions of alkaline factors or biochar to soil may reduce the bioavailability of heavy metals. In my opinion the main aspect of pollution is the treatment of mine wastewater, e.g. by chemical precipitation and sedimentation in open tanks (mining sump), and only then using it for irrigation.

Author Response

Hello, dear Reviewer

Please refer to the joint attachment for the answers given for the revision of my manuscript.

Enjoy your day.

Félicien

Author Response File: Author Response.docx