Soil Quality and Heavy Metal Pollution Assessment of Iron Ore Mines in Nizna Slana (Slovakia)

Round 1

Reviewer 1 Report

The manuscript "Soil quality and heavy metal pollution assessment of iron ore mines in Nizna Slana (Slovakia)" assesses the pollution with different heavy metals due to the influence of siderite mining activities. The authors considered chemical and biological indicators for evaluating the pollution load. I would recommend accepting the manuscript to be published in Sustainability Journal after considering the following comments:

• Please correct the use of the verb “used to” at lines 50, 62, and 141
• Authors used the acronym “Cox” to indicate “soil organic matter.” I would recommend “SOM,” which is commonly applied among soil scientists. Check lines 74,107, 218, 223, 225, Table 4, 231, 293, Table 5, and among other. Also, be consistent in using it to refer to soil organic matter or carbon (see lines 218, 231, 329).
• Many soil factors govern the sorption of heavy metals in soils such as soil texture, pH, OM,…; for example, see https://doi.org/10.1016/j.geoderma.2018.03.019; https://doi.org/10.1111/j.1365-2389.1992.tb00170.x). Particularly for the study area, “which consists of dolomitic stone,” soil contents of CaCO3 control the availability of heavy metals. I wonder if authors have CaCO3 measurements. Please consider discussing the rule of calcium carbonates on your heavy metal- results   
• I suggest changing the header of section “2.1. study area” to include soil sampling
• Check the format of “2nd and 17th” at lines 88 and 157, respectively.
• Table 1: please explain why the background values are precisely the same for NS 01, NS 02, and NS 03.

• Also, use one decimal number for As, Cu, Pb, Cr, and Zn
• Line 94: Use “study area” or “investigation area” instead of “problem area.”
• Line 110: please indicate the extraction methods for heavy metals (a type of acid digestion or extracting solution from the soil)
• In Table 2; I would recommend using units of “%” for Mn and Mg in a similar way to Fe
• Line 223: add “%” next to the values “1.4 and 9.8”

Conclusions; the sentence “The experimental results in the real….. the average value of 3.2” is not clear; please rephrase

Author Response

I thank the reviewers for a thorough review of our manuscript, their valuable advice, and the comments which we have tried to incorporate. We present our opinions chronologically.

Please correct the use of the verb “used to” at lines 50, 62, and 141

• Adjusted accepted

Authors used the acronym “Cox” to indicate “soil organic matter.” I would recommend “SOM,” which is commonly applied among soil scientists. Check lines 74,107, 218, 223, 225, Table 4, 231, 293, Table 5, and among other. Also, be consistent in using it to refer to soil organic matter or carbon (see lines 218, 231, 329).

• Adjusted accepted

Many soil factors govern the sorption of heavy metals in soils such as soil texture, pH, OM,…; for example, see https://doi.org/10.1016/j.geoderma.2018.03.019; https://doi.org/10.1111/j.1365-2389.1992.tb00170.x). Particularly for the study area, “which consists of dolomitic stone,” soil contents of CaCO3 control the availability of heavy metals. I wonder if authors have CaCO3 measurements. Please consider discussing the rule of calcium carbonates on your heavy metal- results   

• We have measurements available, but since we work from home due to the closure of Slovak universities for the corona virus, we cannot add detailed results, eg. maps, so we keep the discussion.

I suggest changing the header of section “2.1. study area” to include soil sampling

• - Adjusted accepted

Check the format of “2nd and 17th” at lines 88 and 157, respectively.

• Check – ok.

Table 1: please explain why the background values are precisely the same for NS 01, NS 02, and NS 03.

• Sampling of heavy metal background values for the territory of the Slovak Republic is not so detailed compared to our research. We used the nearest probe, ref. [37].

Also, use one decimal number for As, Cu, Pb, Cr, and Zn

• - Adjusted accepted

Line 94: Use “study area” or “investigation area” instead of “problem area.”

• Adjusted accepted

Line 110: please indicate the extraction methods for heavy metals (a type of acid digestion or extracting solution from the soil)

• We apologize for the inaccuracy,  modified in the text.

In Table 2; I would recommend using units of “%” for Mn and Mg in a similar way to Fe

• In Slovakia, we are using Mn and Mg mg kg^-1 , therefore we keep the use of this unit

Line 223: add “%” next to the values “1.4 and 9.8”

• Adjusted accepted

Conclusions; the sentence “The experimental results in the real….. the average value of 3.2” is not clear; please rephrase

• Adjusted accepted.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript seems to be interesting research material, but requires major correction. This paper contains too laconic presentation of the results, it does not contain an assessment of the quality of the analyses performed. These deficiencies should be corrected at the stage of preparing the manuscript for printing.

General remarks:

1. The authors raise an important and innovative scientific problem, however, the quality of the data presented has not been analysed, and the results are presented extremely laconic. It should be supplemented with information on: the accuracy of determinations, the limit of quantification of the research methods used and the results obtained for the reference materials used to assess the quality of the data presented.
2. Statistical analyses were performed for a sample set of n = 10, which may be insufficiently reliable and lead to erroneous conclusions. What I think is taking place.

Specific remarks:

The title of work: The title is a bit exaggerated in relation to the content of the manuscript.

Keywords: adequate.

Abstract: it is not adequate to the content of the manuscript. Requires rework.

Materials and methods:

- Line 91-92: Please provide information on Fe and Mn content in the mined ores.

- Please complete the data with the assumptions for soil sampling.

- Please provide LOQ, LOD for the analyses performed, see papers: Kicińska A., 2019. Chemical and mineral composition of fly ashes from domestic furnaces, as well as health and environmental risk related to their presence in the environment. Chemosphere; 215, 574-585, doi: 10.1016 / j.chemosphere.2018.10.061 or Kicińska A., 2019. Environmental risk related to presence and mobility of As, Cd and Tl in soils in the vicinity of a metallurgical plant – Long-term observations. Chemosphere; vol. 236, art. no. 124308,

- Line 109: As (in paper “AS”) is not a heavy metal, it is a metalloid!

- Please complete this chapter with information on: the accuracy of determinations, limits of quantification of the methods used and the results obtained for the reference materials used to assess the quality of the data presented.

Results:

- Line 155-161: this entire paragraph should be moved to the description of the study area, not the results,

- Table 1: Please explain that there are large discrepancies in the background values ​​for Hg varied from 0.13 to 16.24? For As from 9.9 to 41.6? On so small area?

- Table 2: Based on this table, we are not able to verify the correctness of conclusions and analyses, the results presented are too general (Min. Max, Mean, SD) and require a more accurate presentation and discussion.

- why Contamination factor is so different for points NS01 and NS02 since they are located almost next to each other?

- line 199-202 - on the basis of what did the authors formulate such conclusions?

- line 240-241: "Currently ..." to the sentence is not true.

- The lack of correlation between distance and the tested parameters (Table 5) described by the authors is in complete contradiction with Fig. 2. Please compare the location of points.

Conclusion: A brief summary of the research results.

Author Response

I thank the reviewers for a thorough review of our manuscript, their valuable advice, and the comments which we have tried to incorporate. We present our opinions chronologically.

The title of work: The title is a bit exaggerated in relation to the content of the manuscript.

• In our opinion, the title is based on the content of the work.

Abstract: it is not adequate to the content of the manuscript. Requires rework.

• Adjusted accepted

Materials and methods:

- Line 91-92: Please provide information on Fe and Mn content in the mined ores.

-       Adjusted accepted

- Please complete the data with the assumptions for soil sampling.

- The procedures were in accordance with state standards, ref. [28,29].

- Please provide LOQ, LOD for the analyses performed, see papers: Kicińska A., 2019. Chemical and mineral composition of fly ashes from domestic furnaces, as well as health and environmental risk related to their presence in the environment. Chemosphere; 215, 574-585, doi: 10.1016 / j.chemosphere.2018.10.061 or Kicińska A., 2019. Environmental risk related to presence and mobility of As, Cd and Tl in soils in the vicinity of a metallurgical plant – Long-term observations. Chemosphere; vol. 236, art. no. 124308,

- analytical testing of heavy metals was carried out in cooperation with an accredited geoanalytical laboratory (material and methods are listed), LOQ and LOD cannot be completed as we work from home due to the closure of Slovak universities for the corona virus.

- Line 109: As (in paper “AS”) is not a heavy metal, it is a metalloid!

- Adjusted accepted

- Please complete this chapter with information on: the accuracy of determinations, limits of quantification of the methods used and the results obtained for the reference materials used to assess the quality of the data presented.

- It is problematic to add the required data as we work from home because of the closure of Slovak universities for corona virus, in the analyzes we proceeded according to the methodology presented in ref. [30].

Results:

- Line 155-161: this entire paragraph should be moved to the description of the study area, not the results,

- Adjusted accepted

- Table 1: Please explain that there are large discrepancies in the background values ​​for Hg varied from 0.13 to 16.24? For As from 9.9 to 41.6? On so small area?

- Accepted added: The results of background values of potentially toxic elements (Table 1) show considerable heterogeneity caused by geochemical anomalies, the sources of contamination are mainly minerals, their treatment and processing in the past, as well as hazardous waste materials on dumps [37].

- Table 2: Based on this table, we are not able to verify the correctness of conclusions and analyses, the results presented are too general (Min. Max, Mean, SD) and require a more accurate presentation and discussion.

- It is problematic to elaborate this chapter in detail, as I work from home because of the closure of Slovak universities for the corona virus and we do not have access to scientific databases.

- why Contamination factor is so different for points NS01 and NS02 since they are located almost next to each other?

- Contaminant factor values mainly affected elevated Hg values (5.39 mg kg^-1) at NS2 compared to NS1. This is justified in the work.

- line 199-202 - on the basis of what did the authors formulate such conclusions?

- The conclusions are formulated on the basis of the results obtained by the Hakanson methodology, ref. 36.37 / Table 3.

- line 240-241: "Currently ..." to the sentence is not true.

- Adjusted accepted

- The lack of correlation between distance and the tested parameters (Table 5) described by the authors is in complete contradiction with Fig. 2. Please compare the location of points.

- In this work we will not assess this factor in detail

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Please read the manuscript again and remove the typos.
The quality of the tests (precision, accuracy etc.) should be checked at the beginning of the research stage and not at the review stage.
It is not appropriate to explain the current situation with an epidemic.