Assessment of Soil Heavy Metal Pollution and the Ecological Risk in an Agricultural Area from Sánchez Ramírez Province, Dominican Republic
and Lizaira Bello 1,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe submitted manuscript entitled: «Assessment of Soil Heavy Metal Pollution and the Ecological Risk in an Agricultural Area from Sánchez Ramírez Province, Dominican Republic» is scientifically interesting.
It is well written with a proper structure, coherent experiments, and interesting conclusions. However, there are some points that need to be modified and improved.
1) Line 20: Authors should refer to the chemical elements either by their position in the Periodic Table of the Elements or alphabetically and follow the same order in the rest of the manuscript and in the tables.
2) Line 25: The authors are recommended to replace «mg.kg-1» with mg kg-1.
3) The keywords should not repeat the words in the title. Any common words should be removed.
4) Lines 34-35: «Heavy metals are a common type of soil contaminant that can induce negative impacts on human and environmental health [1–3].». Please rewrite it in a more understandable way.
5) Line 94: The authors are recommended to replace «Km2» with Km2.
6) Figure 1: The authors should improve its resolution and clarity. Perhaps they could show the reader where the Yuna River is in relation to the sampling points.
7) Line 118: The authors are recommended to replace «105 o C» with 105 o C.
8) Lines 127-129: The ratios used to determine the soil pH in a distilled water ratio are 1:1, 1:2,5, 1:5 or 1:10. The 1:2 ratio is not mentioned in the literature. What literature reference or protocol was the 1:2 ratio used in the manuscript based on?
9) Lines 129-130: The authors should add the ratio of distilled water soil with which the electrical conductivity was determined.
10) Line 133: The authors are recommended to replace «NH4-acetate» with NH4-acetate.
11) Line 140: The authors are recommended to replace «r2» with R2.
12) Line 159: The authors are recommended to replace «Igeo» with Igeo and follow the same abbreviation in the rest of the manuscript.
13) Lines 201-203: «This section may be divided by subheadings. It should provide a concise and precise description of the experimental results, their interpretation, as well as the experimental conclusions that can be drawn.». The authors should remove this sentence from the manuscript because it is not considered necessary.
14) Line 133: The authors are recommended to replace «mS/cm» with mS cm-1.
15) Line 211: The authors are recommended to replace «meq/100g» with meq 100g-1 soil.
16) Lines 211-214: «In summary, the pH, EC, OM, CEC, sand, silt, and clay contents were relatively low. In general, the results obtained in this soil are very similar to those reported by Alberto Then et al. [27], in Bonao, Dominican Republic. The physicochemical properties for all sampling points can be found in Table S3.» The sentence is quite vague. Please rewrite it in a more understandable way.
17) Line 226: The authors are recommended to replace «mg.kg-1» with mg kg-1.
18) Line 265: Arsenic (As) is not considered as a heavy metal, but a metalloid and it is proposed to the authors to replace the expression «eight heavy metals» with «seven heavy metals and As» and follow the same expression in the rest of the manuscript.
19) In the Conclusion’s chapter, it is imperative for the authors to refer to a proposal for future work to be done as a follow-up to this research.
Author Response
"Please see the attachment."
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsDear authors,
The paper deals with assessment of soil heavy metal pollution and ecological risk in an agricultural area of Sánchez Ramírez Province in Dominican Republic. The aim of the manuscript is focused on the heavy metal contamination in paddy soil-rice systems and its potential threat to humans and ecosystems. This issue is of special interest for population's diet.
The structure of the paper is good and follows the journal requirements. The paper is well written, arranged in a systematic manner and data are correctly presented through many tables and graphs.
I have some suggestion for correction:
Line 25: Correct units.
Lines 46-48: This sentence should be removed to the end of Introduction, because it gives the aim of the study.
Line 94: Correct units.
Line 104: A better resolution of Figure 1 should be provided.
Lines 272-273: This conclusion should be if fertilizers were applied. Were fertilizers used in the study area? Clarify.
Lines 274-278: Spatial distribution maps should be clearer and more legible.
Generally, all figures are blurred.
Lines 329-330: Correct the sentence according to the above.
Good luck!
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper presents very interesting results on the content of heavy metals in agricultural soils, of a selected region of the Dominican Republic. The object of the study is very specific soils, namely rice paddy soils, and the authors should focus more on their properties. They also should complete, in the Introduction chapter how such strong reducing conditions in the soil affect the mobilization/retention of heavy metals.
Improvement, change is also required:
- line 20, Heavy metals understood here, after an environmental concept, not technology, why Mn and especially Fe were included. After all, the content of Fe in the studied soils is more than 7%! And does it have an impact on the environment? The same applies to the text, for example in line 225,
- line 94, not the weather but the climate,
-lines 98-100, first of all clayey is not a soil type, the type is for example Fluvisol, you would need to provide the soil classification of whether it is according to WRB or Soil Taxonomy. Secondly what does the presence of Fe, Ni, Co mean? What does it affect? Is the soil contaminated with them?
- line 109, it is impossible that the soil was taken at a depth of exactly 50 cm. Was it also a layer of some kind?
- lines 111-113, for what purpose is this information, if the localization of the points is not given. If anything, state briefly that the localization of the study points was determined using GPS,
- lines 120-121, were cementing substances used in the preparation of the pastille, which ones?
- line 127, better soil texture. This really done according to the original Bouyoucos method without any rare modifications?
- applies to the whole chapter 2.6 My concern is the use of WAS as a reference background, this is data from more than 60 years ago. I do not negate this, but please explain why exactly this geochemical background was used. I recommend following publication, where more recent data on the value of the reference geochemical background (GB) is given and the advantages and disadvantages of the various pollution indices are explained in detail: Kowalska et al. Pollution indices as useful tools for the comprehensive evaluation of the degree of soil contamination–A review. Environ Geochem Health 40, 2395–2420 (2018). https://doi.org/10.1007/s10653-018-0106-z
- lines 211-212, the sentence: "In summary, the pH, EC, OM, CEC sand, silt, and clay contents were relatively low" is completely ill-conceived. Can there be low sand, silt and clay content in the soil at the same time?!!! Even 16% minimum clay content is not low. Please also provide the size of the individual granulometric fractions.
- refers to chapter 3.3. Is the calculation of all correlation coefficients reasonable, such as between sand, silt or CE and heavy metal content? Please clarify,
- refers to chapter 3.5 Please consider whether counting Igeo and especially PI for Fe makes any sense? What does it mean based on Table 5 that there is moderate contamination of Fe. Maybe there is enrichment in Fe and so what? After all, its total form was determined. This is just a mathematical calculation, but it must have an environmental connection. Please note that Fe is used in the EF calculation,
- lines 327-328. Trivial sentence. These elements occur if not in all then in most of the world's soils.
- lines 329-330. This is not a conclusion. Please reflect carefully on this chapter.
Technical comments:
Technical notes:
- Figures 1 and 2 are unreadable. E.g., figure 1 shows only green spots where soils were taken,
- please check and correct the notation of units, e.g., line 25 as well as formulas of chemical compounds, e.g., line 133.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 4 Report
Comments and Suggestions for AuthorsDear authors, please consider the following comments:
Please superscript -1 in line 25
From lines 46 to 48 you wrote "Therefore, this study focused on the heavy … and wrote some references why you wrote reference and you spoke about your study.
In line 60 change tons/year to tons yr-1 , and in line 63 change kg/ha into kg ha-1, as well through the whole manuscript, tables and figures use the IS Units
In line 94, please superscript 2 in km2
The resolution of fig. 1 should be higher
Describe the positions LB01 to LB04
Please explain why you used 50 cm to determine the heavy metals background, most references used samples deeper than 1 m and sometimes 3 m, please explain and if possible write a reference
In Table S1, sometimes you wrote mg.kg-1 and sometimes you wrote mg/kg, please unify both to mg kg-1
Please write the manufacturing country of EC meter in line 130 and subscript 4 in NH4 in line 133
In line 140, superscript 2 in r2
Please write more details about ordinary Kriging in section 2.5. as well as more information about the software used such as company and country. As well, although you referred to the spatial distribution in the abstract, you didn’t write anything about it in the objectives
The data in Table S2 must be supported by references, please add one more column and write a reference for each index values
Change mS/cm into mS cm-1 and please don't forget to go through the whole manuscript and all tables and figures and forget sand, silt, and clay from % into g kg-1, and don't capitalize the units as in Table 1 (put the units in the suitable form)
I think you may forget to modify the letters or the numbers that should be subscripted or superscripted when you put the manuscript in the journal form, so please go through the manuscript and consider this
In Table 2, please revise the STD values because most of them are very high
All figures should be in a higher resolution
You just presented the results without any discussion, the results should be discussed in the light of previous studies based on the conditions of your study.
Author Response
"Please see the attachment."
Author Response File: Author Response.docx
Reviewer 5 Report
Comments and Suggestions for AuthorsThe manuscript deals with the detection, spatial distribution and ecological risk assessment of seven metals and one metalloid (As) in agricultural soils in an area of Dominican Republic. The manuscript is interesting, in the context of the widely use of fertilizers containing metals. The topic is interesting, even if the study is punctual (the covered area is 5.2 km2). The experiments seem properly performed and the results correctly interpreted.
The following comments should be taken into consideration:
Please translate in English the authors’ affiliations.
In the Figure 1, the names of the sampling points are a little unclear. If it is possible, please increase its accuracy.
How were the detection and quantification limits determined?
Page 5, lines 201-203: please delete the lines.
Author Response
"Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAccept in present form
Author Response
Thank you very much.
Reviewer 3 Report
Comments and Suggestions for AuthorsThanks for taking on board most of the comments and improving the paper. However, please make the following changes:
- line 97, km2
- Dear Authors you write "According to the Word Reference Base (WRB) classification, the soil in the study belongs to inceptisol types. The presence of Fe, Ni, and Co in soil does not necessarily indicate contamination. These metals may be of natural origin from the parent material" This is not true, there is no such group in the WRB classification. Inceptisols are a soil order in USDA soil taxonomy! Please consult a soil scientist and state absolutely (also in the References) what classification was used. Also, Insepitols are written with a capital letter.
I also disagree with the phrase "which are characterised by the presence of iron, nickel, and cobalt", but what does this add to the paper. Why are only these 3 elements mentioned. Is it that ores of these metals are present? Because I don't understand at all why this should be mentioned, And is there no Al, K or Ca in these soils, for example? In that case, why aren't they being written about.
- I accept the explanation regarding GB, but it is far more common to cite Kabata-Pendias or the UCC,
- Figure 2 is still very unreadable.
- There is no need to specify units in Table 3. Please change MO to OM! Again, please reflect on some of the correlations. What is the scientific relevance of calculating correlations between sand content and especially EC and heavy metals (note there is CE in this table).
Author Response
The authors appreciate the valuable recommendations of the reviewers to enrich the content of the manuscript.
Comment 1: line 97, km2
Response 1: This correction was made.
Comment 2: Dear Authors you write "According to the Word Reference Base (WRB) classification, the soil in the study belongs to inceptisol types. The presence of Fe, Ni, and Co in soil does not necessarily indicate contamination. These metals may be of natural origin from the parent material" This is not true, there is no such group in the WRB classification. Inceptisols are a soil order in USDA soil taxonomy! Please consult a soil scientist and state absolutely (also in the References) what classification was used. Also, Insepitols are written with a capital letter.
Response 2: The sentence was rewritten and a reference was added as follows:
Line 99 -The dominant soils in this region are Inceptisol and to a lesser extent vertisol [30].
Comment 3: I also disagree with the phrase "which are characterised by the presence of iron, nickel, and cobalt", but what does this add to the paper. Why are only these 3 elements mentioned. Is it that ores of these metals are present? Because I don't understand at all why this should be mentioned, And is there no Al, K or Ca in these soils, for example? In that case, why aren't they being written about.
Response 3: This sentence was deleted.
Comment 4: I accept the explanation regarding GB, but it is far more common to cite Kabata-Pendias or the UCC,
Response 2: The sentence was
Comment 5: Figure 2 is still very unreadable.
Response 5: The figures were sent in TIFF format.
Comment 6: There is no need to specify units in Table 3. Please change MO to OM! Again, please reflect on some of the correlations. What is the scientific relevance of calculating correlations between sand content and especially EC and heavy metals (note there is CE in this table).
Response 6: Table 3 was modified according to your suggestions.
Reviewer 4 Report
Comments and Suggestions for AuthorsPease consider these comments:
Please explain why you used 50 cm to determine the heavy metals background, most references used samples deeper than 1 m and sometimes 3 m, please explain and if possible write a reference
Response 6. In paddy soil-rice systems, the arable layer is typically 0-30 cm deep, while undisturbed soils are found at a depth of 50 cm. For this study, the local background value was established at this depth.
Reviewer: Please write this in M&M section supported by reference
Comment 8. Please write the manufacturing country of EC meter in line 130 and subscript 4 in NH4 in line 133
Response 8. The correction was made.
Reviewer: I didn't see this correction in the manuscript
Comment 16. You just presented the results without any discussion, the results should be discussed in the light of previous studies based on the conditions of your study.
Response 16. There are no previous studies carried out in this area, for that reason we compare our results with the Maximum heavy metals concentration values for healthy agricultural soil, according to the Food and Agriculture Organization (FAO), geochemical background (WAS), and local background (LB).
Reviewer: It is not important to be in this area, it may be in similar areas or areas have the same conditions. As well, your study has to be discussed well (i.e. you should interpret your results and add the indication and implication of these results ……)
Author Response
The authors appreciate the valuable recommendations of the reviewers to enrich the content of the manuscript.
Please explain why you used 50 cm to determine the heavy metals background, most references used samples deeper than 1 m and sometimes 3 m, please explain and if possible write a reference.
Reviewer: Please write this in M&M section supported by reference
Response 1: The sentence was rewritten and a reference was added as follows:
Four subsoil samples were collected at a depth of 40 - 50 cm, in positions F1 to F4 (Figure 1), to estimate local background [32].
Comment 8. Please write the manufacturing country of EC meter in line 130 and subscript 4 in NH4 in line 133
Response 8. The correction was made.
Reviewer: I didn't see this correction in the manuscript
Response 2: This correction is found in the manuscript highlighted in red on lines 129-133.
CHN: China.
Comment 16. You just presented the results without any discussion, the results should be discussed in the light of previous studies based on the conditions of your study.
Response 16. There are no previous studies carried out in this area, for that reason we compare our results with the Maximum heavy metals concentration values for healthy agricultural soil, according to the Food and Agriculture Organization (FAO), geochemical background (WAS), and local background (LB).
Reviewer: It is not important to be in this area, it may be in similar areas or areas have the same conditions. As well, your study has to be discussed well (i.e. you should interpret your results and add the indication and implication of these results ……)
Response 3: Section 3.2 was rewritten according to your suggestions and the results were compared with other studies carried out in the Dominican Republic.
