Mercury Accumulation in Food Crops and Phytoremediation Potential of Wild Plants Thriving in Artisanal and Small-Scale Gold Mining Areas in Uganda

Round 1

Reviewer 1 Report

The work presented offers good food for thought on the level of Hg contamination in areas where the environmental quality and thus its relationship to human health is still at a neonatal stage. For this reason, the effort made to produce this research is significant. The work is clear in form and content. It lacks lightness in the materials and methods where the strategies used for plant selection, plant and soil sampling, and some other information regarding sampling sites, such as their distance from sources, are not at all clear. Furthermore, the materials and methods are not informative for understanding how the experimental design was performed, its criteria, etc. The reader must also wait until the following paragraphs to understand which types of plants were used for the analyses and which of their portions (including roots, stem and leaves) were considered. Here are a few pointers for improving the work. 

Line 69-70: add chemical identifications.

Add in the Introduction some additional information about global regulation of mercury emissions and current global Hg emissions, as indicated by https://0-doi-org.brum.beds.ac.uk/10.3390/biology10111198

Line 103: please check 999.9 m.

Line 109. Please add additional information to the sampling protocol: How far were the sample collection sites from the industries? On the basis of which criteria were the areas to be sampled selected? How large were the collection plots? How many replications for each site? Were the plots taken where the plants were also collected? On the basis of which criteria were the plants selected? Only herbaceous plants? Also cultivated plants? Shrubby plants? Please specify. At the end of this paragraph, add the list of determined and therefore used for analysis.

Line 132: What does pulverized mean? Soil samples are first dried, then sieved, then homogenized and then pulverized with an agate mortar. 

Line 136: What portions of the plants were used? Leaves? Stem and leaves? Stem, leaves and roots? Please specify. I assume that the samples were broken up and not homogenized and then sieved. Thus, only the fraction below 2 mm was taken into account. Why was this procedure followed? What was the purpose of sieving?

Line 119-122: Is the procedure you followed for collecting the soil a standardized procedure? If yes, please add the reference 

Line 145: Please give the reference of the method used. Is it possible that through evaporation of the sample, some Hg may have been lost during the procedure? Have the authors evaluated the recovery of this methodology? I believe it is crucial for the validation of measurements made later.  

Line 169: Both for contaminated and non-contaminated suspected soils (with reference to the latter, please also cite https://0-doi-org.brum.beds.ac.uk/10.3390/app11157023).

Line 224-225: please specify this aspect in "Sampling".

Line 259-260: please specify this aspect in "Sampling".

Line 347: substitute "ignorance" with "failure to inform"

Author Response

Please see the attachment.

Emmanuel Tebandeke

Author Response File: Author Response.doc

Reviewer 2 Report

The study is devoted to a very interesting question - namely, the accumulation of mercury in the soils of the plants of the plots. contaminated by artisanal gold mining in the Republic of Uganda. As far as I can tell, the authors have conducted comprehensive studies that include not only the analysis of mercury content, but also studied the parameters of the environment - namely pH, Eh and the content of organic carbon in soils. Such studies make a significant contribution to the knowledge of the behavior and levels of mercury.

In general, I think that the article can be published in this form, however, there are several comments and additions that are designed to improve the structure and clarity of understanding of the text of the article.

1. I think that in the abstract and in the introduction it is necessary to add information about the complexity of research - namely, that the parameters of the soil environment (pH, Eh, organic carbon content) were also studied. This will make the presentation of the article more advantageous, since such studies are quite rare.

2. I didn't see a link to Figure 1 in the text. it needs to be added.

3. Perhaps the conclusions should reflect whether the goals have been achieved and whether the objectives of the study have been solved. And also to concretize the results obtained by the authors - that is, the new results in scientific circulation.

Author Response

Please, see the attachment.

Emmanuel Tebandeke

Author Response File: Author Response.doc

Round 2

Reviewer 1 Report

The work has been significantly improved. There is only a few small points to be clarified but overall it now clearly presents its scientific novelty. A few more small suggestions below:

Line 134-135: "parked" is a nice but inappropriate word.

Line 174: facts regarding the quality of measurements taken are missing.

Author Response

Please, see the attachment.

Emmanuel Tebandeke

Author Response File: Author Response.doc