The Suitability of Selected Naturally Growing Plant Species for the Phytostabilization of Heavy Metals at Different Locations on the Slopes of a Zinc Smelting Waste Landfill: The Second Case Study
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis paper made an investigation on the potential of some plant species to phytostabilize heavy metals in an industrial landfill. I have the following suggestions or comments.
1) the paper is more like a report. The scientific merit should be clearly described.
2) The graphs should be re-made. Please refer to similar scientific papers for the formats of graphs and tables.
3) I think that the phenomenon is quite interesting. The authors should try to dig out the reasons behind. The aim is not necessarily be to phytostabilize metals. It is interesting enough to observe the different transfer ability of metals, and their difference among different slopes. The authors should try to analyze the reasons and confirm if it is a reasonable assumption.
4) Detailed background information should be provided. The soil properties? The latitude? The precipitation?
5) Other than BCF, the concentration of some metals should also be provided.
6) Discussion should be provided, with comparisons with other similar studies.
Comments on the Quality of English LanguageI am not a native speaker of English.
Author Response
Sir or Madam, please see the attachment.
Yours sincerely Paweł J. Mundała
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript focuses on a very interesting topic, phytoremediation, a clean remediation technology. The manuscript in question analyzes the bioconcentration factors of various metals in plants growing at different locations of a landfill in Poland. It suggests that the location is a significant factor influencing phytostabilization. However, the manuscript also contains serious inconsistencies and flaws.
The article title, “ The suitability of selected plant species for phytostabilization of heavy metals in the slopes of a zinc smelting waste landfill: the second case study”, does not reflect the content of the paper, as it does not propose a selection of suitable plants for phytostabilization but rather presents a characterization of the existing plants at the landfill in question. Also, it is indicated to be a “second case study,” but there is no reference to a first study or how these are related.
The abstract states that “phytostabilization is a measure of decreasing xenobiotic metals bioavailability,” which is not the correct definition of the phytoremediation method. The authors indicate that the results are statistically different but are unclear about what these results are. The conclusions presented in the abstract are also vague.
The introduction lacks a presentation of the state of the art, and the objectives are not coherent with those presented in the abstract.
The methods section should be more detailed; the sampling method is not clearly described, and almost all the details of the procedures are given in a referenced paper (which also refers to others for methodological detail). This section should also include a description of the statistical analysis.
The results and discussion are divided into two sections, a “Results and overall assessment” and “Detailed assessment”, it should be made clear why the authors opted for this approach. A characterization of the soil in the different locations studied is not presented, and the indication that the concentrations can be classified “in a range from natural content to severe contamination.” (line 137) appears too vague. The soil properties, metal concentrations, and bioavailable portions should be presented for all locations studied, and the bioconcentration factors must be analyzed in their light. In the second part of the results and discussion section, the authors present hypotheses; this should be done at the beginning of the paper. The statistical analysis is described in this section, and it should have been included in the Methods section. In this section, the authors argue that location is an important factor for bioaccumulation, and that it is an unclear concept and should be defined. However, the authors do not provide this definition other than indicate that it is a set of many factors (lines 201-209). Further on (lines 228-243) the authors discuss the influence of bioavailability, again, it would have been useful to have determined the bioavailable fraction. In this regard, the relationship between the bioaccumulation factors for the different metals and the organic content of soil at the different locations could be further discussed. In this section, rather than indicating which plants are most suitable for phytostabilization, the authors choose to indicate which are least suitable (lines 311-320). It is also unclear how the interaction of location and plant species/organ was determined (section 3.2.3). Figure 2 is somewhat confusing; on one hand, the data for each metal is separated into two graphs; on the other, the names of the series are not indicated in the figure caption. Graph 2I is entitled “Moss”; this and other graphs should not have titles, and in the caption it is indicated that “Due to the scale, mosses were excluded from Fig. 2I”. Further on, there is reference to a landfill in Krze (line 338); it is unclear what this refers to. The description of the bioconcentration pattern at the bottom, middle, and top of the slope needs further analysis and discussion. The last section of the results and discussion (lines 374 to 399) does not contribute to analyzing factors 4 and 5, as indicated in line 374.
The conclusions should be improved and do not answer directly to the objectives of the work.
Overall, the manuscript needs to be improved in coherence, content, experimental design, methodology description, data presentation, conclusions, and references.
Comments on the Quality of English Language
I do not wish to provide feedback on the Quality of English language
Author Response
Sir or Madam, please see the attachment,
yours sincerely Paweł J. Mundała
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors of the article attempted to answer the question of whether the location (growth, development, species) of plants on anthropogenic heaps (enriched in post-smelter zinc) affects the accumulation of potentially toxic metals. This issue has not been the subject of wider scientific interest to date. Works on old dumps or zinc-contaminated areas are not numerous. Recently, a few articles on the failure of zinc plants in Poland and the contamination of soils with this element appeared in 2023 Sustainability, for example.
Typically, mixed samples were taken, indicating the ability of some species to accumulate metals, which could be used in the remediation of toxic waste sites. The authors noted that old dumps (that had been accumulated since 1820) are not homogeneous in terms of habitat. Plants growing at the base of old heaps accumulate potentially toxic metals differently from those plant groups that grow at the top. This observation seems particularly valuable to me. We counted BCF values depending on species/body vs. location on the landfill. Reclamation of landfills that have accumulated over the years, is a difficult and costly process. The evaluated work shows that in addition to the overall heavy metal content of plants, attention should also be paid to the site of plant growth, affecting the phytostabilization of metals.
For the study to be complete it seems expedient to conduct sequestration analysis. The overall content informs us about the process but only the bioavailable forms show the proper ability of plants to accumulate. As a result of the plants' interaction with the soil environment, bioavailable forms of metals can transform into forms that are more difficult to access. I suggest conducting research in this direction. Above-ground parts have been studied, and these accumulate statistically lower values than plant roots, as reported by numerous studies.
Ongoing research confirms the known facts that bryophytes accumulate metals well (they are difficult to use in reclamation due to their size ), as are the bearded birch and rowan considered to be pioneer species, perfectly able to cope with industrial stress.
Please answer in more detail what factors determined that the plants of the peak batches accumulated more metals (Pb, Cu, Zn), while Cd ( very mobile and soluble) took higher values at the foot of the heap?
Why, since the authors believe that “organic matter reduces the mobility of metals in the soil and thus affects the uptake of metals by plants” (237), did the increase in organic matter at the top of the heap (26% C org.), result in higher metal accumulation in plants?
Can soil additives (what kind?) be used on old heaps to lower the mobility and bioavailability of heavy metals?
Comments for author File: Comments.pdf
Author Response
Sir or Madam, please see the attachment,
yours sincerely Paweł J. Mundała
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsDear Authors,
The manuscript is significant, the research topic is relevant. The results and discussion are presented clearly and completely. There are some minor remarks.
The purpose of the study in the abstract and in the introduction are different, it is necessary to decide which purpose to keep.
If you decide to keep the aim from the abstract, namely “The aim of the study was to assess the impact of location i.e. the place of growing on the landfill for phytostabilization of cadmium, lead, zinc and copper”, please correct the title of the manuscript.
It seems to me that it is necessary to write another conclusion in which you will answer more clearly the questions posed in the introduction.
The current conclusion looks like a discussion of the results obtained, but not the conclusions of the article.
Author Response
Sir or Madam,
please see the attachment,
Yours sincerely Paweł J. Mundała
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have addressed my concerns. I suggest accept.
Author Response
Dear Sir or Madam,
Thank you very much for you opinion. Thank you very much for supporting us with the manuscript.
yours sincerely
Paweł J. Mundała
Reviewer 2 Report
Comments and Suggestions for AuthorsAfter reviewing a revised version, I regret to say that my opinion has not changed. The concerns I previously raised have not been adequately addressed by the authors, and the modifications made are lacking in quality.
Author Response
To the Reviewer 2.
After reviewing a revised version, I regret to say that my opinion has not changed. The concerns I previously raised have not been adequately addressed by the authors, and the modifications made are lacking in quality.
Dear Sir or Madam,
I do apologise for my unsuccessful delivery of our response to you.
I assume this scenario due to following facts:
- This was the most detailed revision we have received from four Reviewers. I notice and appreciate the time and work put in by you to figure out the manuscript and how to improve it. Sir or Madam thank you very much for your support.
- The very short, the second opinion.
Arthur and I have never allowed ourselves to be rude or disrespectful towards anyone. It including you the Person who supported us. So here we are submitting the answers for your questions, the discussions if we disagree with you and the explanations. Our response is in three files:
- A file, named by submitting system sustainability-3513557-coverletter.pdf hidden under link
‘In Author's Notes File Report Notes’, Here we wrote our answers.
- A file Manuscript.Suplemantary.docx Two tables with soil data
- A Manuscript file.
Paweł J. Mundała the corresponding author.
Comments and Suggestions for Authors
The manuscript focuses on a very interesting topic, phytoremediation, a clean remediation technology. The manuscript in question analyzes the bioconcentration factors of various metals in plants growing at different locations of a landfill in Poland. It suggests that the location is a significant factor influencing phytostabilization. However, the manuscript also contains serious inconsistencies and flaws.
The article title, “ The suitability of selected plant species for phytostabilization of heavy metals in the slopes of a zinc smelting waste landfill: the second case study”, does not reflect the content of the paper, as it does not propose a selection of suitable plants for phytostabilization but rather presents a characterization of the existing plants at the landfill in question. Sir or Madam, the tittle was changed. Now it is ‘The suitability of selected naturally growing plant species for phytostabilization of heavy metals at different locations on the slopes of a zinc smelting waste landfill: the second case study’
The tittle does not reflect the content of the paper, as it does not propose a selection of suitable plants for phytostabilization but rather presents a characterization of the existing plants at the landfill in question. Sir or Madam, we agree with you, we didn’t in plot or pot experiment test the most suitable plants for heavy metals stabilisation. We didn’t sow or plant any plants with the highest bioremediation abilities on the landfill. Finally the most important part of the manuscript (in our opinion) is dedicated to interactions of species. However we can’t agree with you. Please see our scientific questions. Line 127. Which species accumulate heavy metals, and in what amounts? Does the location on the landfill influence the content of metals? And in the conditions of this case study, did the above-mentioned factors interact? Two of them reflect to the stability of selected plant species. Please see the aim (lines 132 -134). ‘The aim of the study was to assess the suitability of selected natural and permanent plant species growing at various locations on a zinc smelting waste dump for phytostabilization of cadmium, lead, zinc and copper’. Please see the two way Anova, the hypothesis we tested for each metal separately. The species/organ influence on the phytostabilization (hypothesis II). Yes, the plants were naturally growing, they were only five species of them, we managed to increase this number up to eight (lines 283-290). However we wanted the plants dominating in the vegetation and growing on all parts of the landfill. Please see: table 1 (probabilities), table 3. BCF values for plant species/organs with determination of statistical significance of differences. Sir or Madam please see the supplementary materials (table 3S). Finally, please see the improved 3.2.2. Plant species or organ without location chapter. The discussion chapter order and plants the less suitable for bioremediation order we will explain with the next comments. Finally we pick up a problem reported by Domínguez et al. 2009 (Discussion chapter lines 408 -418). The most suitable for phytoremediation didn’t manage to survive and less suitable had to take over.
Also, it is indicated to be a “second case study,” but there is no reference to a first study or how these are related. Sir or Madam, thank you very much for the comments. We thought, that the link with ‘the first case study’ is clear, we were mistaken. Manuscript is improved.
Lines 10-12. Abstract: The case study is the second of three which we have been conducting on different industrial waste landfills. We are planning a fourth study comparing the three landfills.
Lines 158-159. General description of research methods. The site of this case study is the second of three landfills which we have already sampled. The first study was published as Szwalec at al. [5] in Sustainability.
Lines 189-191. General description of research methods. A detailed description of the research methods, experimental design, means of sample collection, and handling in the laboratory is given by Szwalec et al. [5], available at https://www.mdpi.com/2071-1050/14/12/7083
The abstract states that “phytostabilization is a measure of decreasing xenobiotic metals bioavailability,” which is not the correct definition of the phytoremediation method. Sir or Madam, we can see yours point of view and first of all our mistake!. The phytostabilization, phytoremediation in general requires high heavy metals bioavailability so that the ions could be taken up. Our way of thinking was following: the bioremediation decreases the contents of heavy metals in the soil. After many years of phytoremediation, the soil is no longer contaminated because was decontaminated. And this finally results in decreased heavy metal content including the bioavailable content. Sir or Madam, the Sustainability Journal limits the number of words in abstract up to 200. We didn’t want the Editor to finds us as people who don’t read the Instructions for the Authors. By deleting sentences or particular words, we managed to fit with 198 words and have one sentence from the introduction chapter in the abstract. Being glad on our own we managed to fit Instructions for authors requirements, we didn’t notice the mistake. Sir or Madam, the manuscript is improved. Please see the Abstract.
The authors indicate that the results are statistically different but are unclear about what these results are. The conclusions presented in the abstract are also vague. Sir or Madam the limitation of the Journal. Please see the improved Abstract further Method chapter.
The introduction lacks a presentation of the state of the art, and the objectives are not coherent with those presented in the abstract. The introduction is improved, the details are added. Please see introduction chapter lines 80-119.
The objectives are not coherent, Sir or Madam you are absolutely right. However it is not random authors’ weakness. It was planned due to the following reasons:
- The size of abstract,
- The previous experience with Sustainability Journal Reviewers. We were advice to write scientific questions in the introduction instead of scientific hypothesis. We liked this advice, we found it as an improvement of our scientific skills. The hypothesis are written in short form (we do hope more friendly to the Reader). We know, and we can state hypothesis for two way Anova: the first pair of hypothesis
H0: The location doesn’t impact onto cadmium BCF level.
HA: The location impacts onto cadmium BCF level.
The second pair of hypothesis:
H0: The plant species/organ doesn’t impact onto cadmium BCF level.
HA: The plant species/organ impacts onto cadmium BCF level.
And the third pair of hypothesis:
H0: The location and plant species/organ at the same time and common don’t impact onto cadmium BCF level.
HA: The location and plant species/organ at the same time and common impact onto cadmium BCF level.
And the same for Cu, Pb and Zn.
Now the aims are improved, we do hope you will find them much more coherent, please see the improved manuscript.
The methods section should be more detailed; the sampling method is not clearly described, and almost all the details of the procedures are given in a referenced paper (which also refers to others for methodological detail). This section should also include a description of the statistical analysis.
Sir or Madam, this is not our random mistake but a planned result of our previous experience in this case with the Editors. The easiest and the most logical way is copy the right Material and method chapter paragraph from previous manuscript and paste in this: the sampling methods, mineralisation methods, sample handling in the laboratory. The Editors don’t want to publish any text which was already publish. This is due to the author’s low. We were advised to do what we done i.e. describe our methods in one publication and then cite it. We chose Sustainability also due the fact the Journal is an open access. Everybody who wants, from a computer with any ID may load the manuscript and read in our opinion very detailed methodology. This is also the reason why do we writhe in the tittle ‘the second case study’ instead of much easier ‘a case study’. referenced paper (which also refers to others for methodological detail). Sir or Madam, it also can be explain. We were told, and by the way we also think so that it is very good to cite the books for analytical chemists to proof the used method. This is to support what was done. Sir or Madam accepting your comment we decided to add a scheme of sampling areas and points. It will not be a repetition and we hope let clarify the and improve the Material and method chapter, please see the improved manuscript (figure 2).
The results and discussion are divided into two sections, a “Results and overall assessment” and “Detailed assessment”, it should be made clear why the authors opted for this approach. Sir or Madam there are two reasons for this. They are equal so they are written in random order:
- The way we understand writing a scientific manuscript. We confirm the common know hypothesis in our particular conditions. In this case it is the hypothesis ‘species influences the BCF’. This topic discussion was named ‘Results and overall assessment’. We are trying to research something new or at least not well researched. In this study it is the hypothesis ‘location and its influences on BCF’ and the interaction (the first and third hypothesis).
- The way we were able to discuss the results of our study. We mean the possible scientific publications we manage to find, read and cite.
The manuscript already has twenty one pages so we didn’t add this information to the main text of the manuscript.
A characterization of the soil in the different locations studied is not presented, and the indication that the concentrations can be classified “in a range from natural content to severe contamination.” (line 137) appears too vague. Sir or Madam, minor correction in the manuscript was done here, tables 1SA 1SB with soil data was added to the resubmitted version to the Supplementary Material. Sir or Madam, please let us stay vague here. We would like to stay with this subdivision the BCF in the manuscript, the heavy metal contents in the supplement. The soil properties, metal concentrations, and bioavailable portions should be presented for all locations studied, and the bioconcentration factors must be analyzed in their light. Sir or Madam, bioaccumulation factor is a quotient of metal concentration in a plant (the numeral) and in the soil (the denominator). So on this purpose we used BCF to study the phytostabilization. Every data in the main manuscript is in light of soil concentration. Metal concertation in plants and in soli are in the Supplementary materials (Table 1SA.). The heavy meatal content estimation according to Kabata-Pendias at al. [39] method is in Supplementary materials (Table 1SB). The second background (much less important) were the same plants overgrowing the landfill. Our study are including the potential source of misleading i.e. metal translocation factors. The best for BCF is always take the root samples however we were not able to. The third background is statistic, BCF data are less positively skewed, and are as good as the concentration useful in statistic.
The tables from the Supplementary Material, the soil data
Table 1SA. Soil close to total heavy metal contents and selected soil parameters
|
|
|
Cd |
Cu |
Pb |
Zn |
pH KCl |
ogranic matter |
|
Base |
|
mg*kg-1 DW |
no unit |
% |
|||
|
Mean |
9,98 |
51,92 |
589,22 |
1734,43 |
6,73 |
28,83 |
|
|
SD |
0,96 |
3,17 |
28,07 |
96,69 |
0,17 |
3,56 |
|
|
% |
|||||||
|
RSD |
9,6 |
6,1 |
4,8 |
5,6 |
2,5 |
12,4 |
|
|
Middle |
|
mg*kg-1 DW |
no unit |
% |
|||
|
Mean |
14,25 |
61,27 |
1680,64 |
3983,35 |
6,65 |
26,57 |
|
|
SD |
2,85 |
4,59 |
69,71 |
206,01 |
0,17 |
2,98 |
|
|
% |
|||||||
|
RSD |
20,0 |
7,5 |
4,1 |
5,2 |
2,6 |
11,2 |
|
|
Top |
|
mg*kg-1 DW |
no unit |
% |
|||
|
Mean |
19,38 |
32,07 |
510,68 |
1504,58 |
6,73 |
17,13 |
|
|
SD |
1,21 |
2,37 |
28,96 |
71,66 |
0,13 |
1,06 |
|
|
% |
|||||||
|
RSD |
6,3 |
7,4 |
5,7 |
4,8 |
1,9 |
6,2 |
|
Table 1SB. Heavy metal soil contents assessment with Kabata Pendias et al. method [39]
|
Percentage share |
||||||
|
Metal/location |
natural content |
increased content |
contamination |
|||
|
low |
medium |
high |
very high |
|||
|
Cd base |
0.0 |
0.0 |
0.0 |
43.7 |
56.3 |
0.0 |
|
Cd middle |
0.0 |
0.0 |
0.0 |
12.5 |
87.5 |
0.0 |
|
Cd top |
0.0 |
0.0 |
0.0 |
0.0 |
75.0 |
25.0 |
|
Cu base |
0.0 |
100.0 |
0.0 |
0.0 |
0.0 |
0.0 |
|
Cu middle |
0.0 |
100.0 |
0.0 |
0.0 |
0.0 |
0.0 |
|
Cu top |
100.0 |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
|
Pb base |
0.0 |
0.0 |
0.0 |
100.0 |
0.0 |
0.0 |
|
Pb middle |
0.0 |
0.0 |
0.0 |
100.0 |
0.0 |
0.0 |
|
Pb top |
0.0 |
0.0 |
37.5 |
62.5 |
0.0 |
0.0 |
|
Zn base |
0.0 |
0.0 |
0.0 |
100.0 |
0.0 |
0.0 |
|
Zn middle |
0.0 |
0.0 |
0.0 |
0.0 |
100.0 |
0.0 |
|
Zn top |
0.0 |
0.0 |
0.0 |
100.0 |
0.0 |
0.0 |
In the second part of the results and discussion section, the authors present hypotheses; this should be done at the beginning of the paper. Sir or Madam, the Reviewer one wrote us ‘The manuscript is more like a report than a scientific work’ To avoid this we were taught to write a scientific questions in the Introduction chapter instead of scientific hypothesis in normal (long) form and a particular hypothesis is the discussion chapter. The statistical analysis is described in this section, and it should have been included in the Methods section. No Sir or Madam, please let us disagree. What you suggest is a standard procedure, being used when a scientific method is approved, applied by different researcher at different Universities. When the method (here statistical analysis) has been used in many different scientific polygons. This is not our case. Starting our study we thought, we will have to use non parametric Kruskal Wallis test. It appeared we could use Anova, in our opinion much better tool in this problem. We would also like to discuss the statistical analysis in the manuscript with the other researchers we hope will read and discuss.
In this section, the authors argue that location is an important factor for bioaccumulation, and that it is an unclear concept and should be defined. However, the authors do not provide this definition other than indicate that it is a set of many factors (lines 201-209). Sir or Madam, please let us disagree again. We wrote preciously: location ‘is a set of many factors, treated in phytoremediation studies as tertiary or quaternary, whose effect on bioaccumulation is not considered in practice’. We are unable to list the factors now, we also didn’t find in other researcher study the list of this factors. However we can see the results of their impact on BCF. In the Discussion chapter we are trying to list and discuss some of them. Now we can assume, some of the ‘location’ factors are: temporal for instance water deficiency of excess or microbes diversity deficiency. Apart diversity in one landfill we hypothesise the factors diversity between the landfills. This is the reason why do we try to study the second case (zinc smelting waste) while the first was the coal fly and bottom ash, we have been carry on the third landfill (case study) and then want to compere the BCF’s between them.
Further on (lines 228-243) the authors discuss the influence of bioavailability, again, it would have been useful to have determined the bioavailable fraction. No, Sir or Madam, we can’t agree. The soil is a substrate, or a technosoil, definitely it is not a soil ecosystem. We do not know:
- the water movement within the dump,
- the metal load leached out the landfill,
- the microbial activity of the soil including microbial heavy metals stabilisation,
- the oxidation-reduction conditions,
- mineral composition of the waste,
- the quality, capasity (cation exchange capacity) of organic matter,
- the influence of other factors on the phytostabilization process for instance drought or nitrogen lack.
By this reasons the bioavailable concentrations could be too temporal, too much variable during the year or at least vegetation period (i.e. 220 days in south of Poland). We didn’t want this variability to shadow the variability of location. Due to the above mentioned facts we decided to take close to total heavy metals mineralisation and extraction as much more representative to the study of phytostabilization.
In this regard, the relationship between the bioaccumulation factors for the different metals and the organic content of soil at the different locations could be further discussed. In this section, rather than indicating which plants are most suitable for phytostabilization, the authors choose to indicate which are least suitable (lines 311-320). Sir or Madam, in our scientific questions and aims we didn’t assume the order from the most suitable to the less suitable for the phytoremediation. Why do we apply such not obvious order? The vegetation on the landfill is rich (thick and lush). So we thought, some of the less sustainable for the phytostabilization plants may be cut down to create more space for the more sustainable plants.
It is also unclear how the interaction of location and plant species/organ was determined (section 3.2.3). Interaction is a tool given by two way Anova. Apart essaying the influence of the first factor (location) and the second factor (species/organ) Anova lets us essay the interaction of the first factor and the second factor simultaneous impact. Thanks Anova we can talk not only the BCFPb at the top statistically differ from BCFPb at the bottom. But also discuss the difference between BCFPb for oak leaves at the top and BCFPb for birch steam at the bottom.
Figure 2 is somewhat confusing; on one hand, the data for each metal is separated into two graphs; on the other, the names of the series are not indicated in the figure caption. Sir o Madam, the figures you writing was remade, please see the improved manuscript.
Graph 2I is entitled “Moss”; this and other graphs should not have titles, and in the caption it is indicated that “Due to the scale, mosses were excluded from Fig. 2I”. Sir or Madam manuscript is improved.
Further on, there is reference to a landfill in Krze (line 338); it is unclear what this refers to. Sir or Madam manuscript is improved. The description of the bioconcentration pattern at the bottom, middle, and top of the slope needs further analysis and discussion. Sir or Madam we absolutely agree, we would like to finish this manuscript. Write the third case study (the third landfill), finally we would like to in forth manuscript compare the results and carry further analysis and discussion.
The last section of the results and discussion (lines 374 to 399) does not contribute to analyzing factors 4 and 5, as indicated in line 374. Sir or Madam, the manuscript is improved.
The conclusions should be improved and do not answer directly to the objectives of the work. Sir or Madam, the manuscript is improved.
Overall, the manuscript needs to be improved in coherence, content, experimental design, methodology description, data presentation, conclusions, and references.
Sir or Madam, thank you very much for yours comments and questions, we improved: the tittle, abstract, introduction including the aims, the material and method, the discussion, the conclusions and the references. Sir or Madam, we do hope you will find our work better now.
yours sincerely Paweł J. Mundała
Author Response File: Author Response.pdf
