Use of Genus Cistus in Phytotechnologies: Application in a Closed Mercury Mine

Round 1

Reviewer 1 Report (New Reviewer)

Dear authors,

The resubmitted article needs improvements in the following points:

1      To indicate that the values obtained in Table 2 & Table 3 are statistically significant along a column, you must do a statistical analysis and input the proper letters.

2.       Lines 256-264: The authors should point out that the 3rd soil sample has half the Cation Exchange Capacity compared to the others. What are the consequences in terms of Hg sorption capacity on it? Is the uptake of Hg by the plant affected? Is the distribution of Hg in the soil-plant system altered?

3.       The reader gets a first impression of the manuscript through the summary. It is also known that some readers might merely scan the abstract before deciding whether to read the rest of the article in search of information and facts. It is advised that the abstract be self-contained for this reason. As a result, the abstract must include percentage information from the study's findings.

The revisions are minor and after their incorporation in the text, the manuscript will meet the requirements for publication.

Author Response

Dear reviewer, thank you for your time. We appreciate the interesting comments and suggestions provided by your review. We have been able to incorporate changes to reflect most of them. We hope that our comments are to your liking.

Here is a point-by-point response to your comments and observations.

Comments from Reviewer 1

1. To indicate that the values obtained in Table 2 & Table 3 are statistically significant along a column, you must do a statistical analysis and input the proper letters.

Statistical analysis has been properly described in lines 214-218 and proper letters have been included in Table 2 and Table 3.

2. Lines 256-264: The authors should point out that the 3rd soil sample has half the Cation Exchange Capacity compared to the others. What are the consequences in terms of Hg sorption capacity on it? Is the uptake of Hg by the plant affected? Is the distribution of Hg in the soil-plant system altered?

According to GLM followed by a Duncan test described in lines 214-218, there are no statistical differences for CEC (9.73 ± 1.17^a; 10.08 ± 2.01^a; 5.94 ± 1.12^a). Furthermore, the values are within the range for loam soils at pH > 6.0. (5-10 cmol +/kg). This parameter is homogeneous throughout the plot used in the field trial, so no differences in Hg sorption capacity are expected. Consequently, the absorption of Hg by the plant will not be affected, nor will the distribution of Hg in the soil-plant system be altered.

In any case, a mini conclusion has been introduced in lines 271-274, to clarify this point:

“The statistical study confirms that the CEC remained homogeneous in the entire plot used in the field trial (Duncan's test, Table 2) and the values are within the range for loam soils at pH > 6.0. (5-10 cmol +/kg). This parameter is homogeneous throughout the plot used in the field trial, so no differences in Hg sorption capacity are expected. Consequently, the absorption of Hg by the plant will not be affected, nor will the distribution of Hg in the soil-plant system be altered”.

3. The reader gets a first impression of the manuscript through the summary. It is also known that some readers might merely scan the abstract before deciding whether to read the rest of the article in search of information and facts. It is advised that the abstract be self-contained for this reason. As a result, the abstract must include percentage information from the study's findings.

The abstract has been thoroughly modified.

 

Reviewer 2 Report (New Reviewer)

The manuscript entitled:  “Use of genus Cistus in phytotechnologies: application in a closed mercury mine” is novel and well written. In the present form of the ms, the previous recommendations as well as other additional data from the authors have been incorporated. This work would deserve to be published as it is, but I think it would be better for the readers of the journal to incorporate the two recomendations I have, especially the one with the information on  the analytical techniques for determining Hg.

There are a few points that need to be reviewed and some improvements need to be introduced.

1.      Lines 176-186: In the chapter on Hg quantification, mention should be made of the model and the manufacturing house/country of the spectrophotometer. The specific conditions for the determination of Hg should also be detailed (temperature, pressure, etc). Finally, the detection limits of Hg and the recovery rates of the methods used, regarding the certified materials.

2.      Lines 234-245: We know that there are two determinants that control the availability of Hg in soils: the soil pH value and the organic matter value.  In my opinion, a more extensive analysis and discussion of the effect of soil pH on the chemical behavior of Hg in specific soil samples is needed.

Author Response

Dear reviewer, thank you for your time. We appreciate the interesting comments and suggestions provided by your review. We have been able to incorporate changes to reflect most of them. We hope that our comments are to your liking.

Here is a point-by-point response to your comments and observations.

Comments from Reviewer 2

1. Lines 176-186: In the chapter on Hg quantification, mention should be made of the model and the manufacturing house/country of the spectrophotometer. The specific conditions for the determination of Hg should also be detailed (temperature, pressure, etc). Finally, the detection limits of Hg and the recovery rates of the methods used, regarding the certified materials.

Model, the manufacturing house/country of the spectrophotometer and detection limit are included in lines 181-183.

The Advanced Mercury Analyzer 254 LECO is an atomic absorption spectrometer designed for the determination of mercury in solid and liquid samples without the need for chemical pretreatment or sample preconcentration. The operation of the equipment is based on the combustion of the sample at a fixed temperature and pressure in an oven so that the mercury generated in the gas phase is amalgamated in a gold trap. The temperature and pressure are fixed in the equipment used and are predetermined.

Finally, the recovery rates of the methods used, regarding the certified materials are included in lines 189-193.

2. Lines 234-245: We know that there are two determinants that control the availability of Hg in soils: the soil pH value and the organic matter value. In my opinion, a more extensive analysis and discussion of the effect of soil pH on the chemical behavior of Hg in specific soil samples is needed.

We agree with your concerns because both parameters are determinants to control the availability of Hg in the soil. For this reason, the homogeneity of the soil was important to avoid biases in the absorption of different Hg from the plant. If one of these parameters were different throughout the field trial, it could alter the Hg distribution in the soil and affect Hg uptake by the plant. The objective of this work was to test if there were differences between species for Hg uptake, that is, if plants showed different Hg uptake strategies despite growing in the same soil conditions. For that reason, the pH must be constant. Statistical analysis showed this parameter constant in the soil and Hg mobility and Hg speciation at this pH were discussed at length in lines 234-245. At this pH, most of the mercury is found as mineral mercury in the form of cinnabar (HgS) which is not bioavailable to plant species. The data agree with the concentration of Hg available in the soil, which is also constant within the plot.

We are not sure to which specific samples other than ours the reviewer refers, but we believe that the role of pH is fully explained in this manuscript (see introduction lines 53-76). It may be, other pH conditions would be interested in discussing when this parameter will show more variety, but that is not the objective of this work.   

Reviewer 3 Report (New Reviewer)

I have gone through the manuscript and have a few suggestions for authors:

 

-Location coordinates required in material and methods

-Use points in the graph instead of commas.

-Figure 1 should be replaced with a high-resolution image.

Author Response

Dear reviewer, thank you for your time. We appreciate the interesting comments and suggestions provided by your review. We have been able to incorporate changes to reflect most of them. We hope that our comments are to your liking.

Here is a point-by-point response to your comments and observations.

Comments from Reviewer 3

1. Location coordinates required in material and methods.

Location coordinates have been included in lines 123-124.

2. Use points in the graph instead of commas.

Commas have been replaced in the graphs.

3. Figure 1 should be replaced with a high-resolution image.

Figure 1 has been updated with a high-resolution image.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Please see the attached file. 

 

Comments for author File: Comments.pdf

I believe that there are no serious issues with the English language, just a check on the syntax and grammar is needed to minimize any possible mistakes. 

 

 

Reviewer 2 Report

Comments for author File: Comments.pdf

Reviewer 3 Report

L 26 - lowercase keywords.

L 140 - The sampling protocol and analysis are detailed and described by mane  [6] - the name of the author.

L180 ...pH, Cation Exchange Capacity (C.E.C.) and Electrical Conductivity (E.C.).-  correction... pH, cation exchange capacity (CEC) and electrical conductivity (EC).

L334 - Figures 3 and 4 show... must be corrected Figures 1 and 2.

Figures must be numbered correctly. The reference from the text, to the figures, must be corrected.