The Impact of Induced Industrial and Urban Toxic Elements on Sediment Quality
, Mothepane Happy Mabowa 1, Luke Chimuka 2, James Tshilongo 1,2 and Mokgehle Refiloe Letsoalo 1,*Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsReview on the manuscript: “Assessment of sediment quality impacted by industrial and urban wastes”
In this manuscript the authors evaluated the quality of the sediment of Jukskei River, South Africa. The authors calculated the contaminated and enrichments factors for the elements: As, Pb, Cd, Hg, Th, and U.
This study is interesting and it is of potential ecological significance.
However, the following issues should be addressed by the authors before further consideration of this manuscript for publication.
Minor issues:
1. Section 3.1. I did not understand the unit mm/kg. Did the authors mean mg/kg? What is the measurement unit for Pb – (third rоw) mg/kg?
2. The equations for the calculation of enrichment and contamination factors are not clearly presented. The authors should improve the format of the manuscript. Both equations are between the tables 2 and 3. Please improve the presentation!
Major issues:
1. Please add references for Table 2.
2. The authors must include information about the physicochemical characteristics of the sediments. Were these characteristics the same for all samples?
3. The authors did not present the reference values for the elements. Were these values close to the background values? Please include these values in a Table!
4. The authors did not calculate the geo-accumulation index. Why? This index has been used to estimate the degree of pollution in aquatic sediments.
5. Pollution load index is also not presented. This index can provide information for the overall sediment toxicity. Why the authors did not calculate and discuss this index?
6. The physicochemical characteristics must also be included in Table 7. How did the authors calculate the significance of the Pearson’s correlation coefficients? Were the observed correlations between As and Fe; Cd and Pb; Pb and Fe significant. If yes, what is the level of the significance? (Please see reference 15 from the references).
Comments for author File: 
Comments.pdf
Author Response
Minor issues
Comment 1. Section 3.1. I did not understand the unit mm/kg. Did the authors mean mg/kg? What is the measurement unit for Pb – (third rоw) mg/kg?
Author’s Response:) We are thankful and accept the reviewer’s comment, the unit mm/kg was corrected to mg/kg. The measurement unit for Pb is mg/kg.
Comment 2. The equations for the calculation of enrichment and contamination factors are not clearly presented. The authors should improve the format of the manuscript. Both equations are between the tables 2 and;
Author’s Response:) We accept the reviewer’s comment, all the equations including enrichment and contamination factors are clearly presented and the format of the manuscript is greatly improved.
Comment 3. Please improve the presentation!
Author’s Response :) We appreciate the reviewer’s comments. The presentation is improved. There are some other sections added to improve the quality of the manuscript.
Major issues
Comment 1. Please add references for Table 2.
Author’s Response :) We accept the reviewer’s comments; reference is added on the Table 2.
Comment 2. The authors must include information about the physicochemical characteristics of the sediments. Were these characteristics the same for all samples?
Author’s Response :) Thank you for your suggestion and we accept the reviewer’s comments. We humbly would like to bring it to the attention of the reviewer that we didn’t have anymore sample left to perform additional experiments. Nonetheless, we have added the gross alpha and beta radioactivity results that were not yet received from the outsourced lab during the first submission of the manuscript.
Comment 3. The authors did not present the reference values for the elements. Were these values close to the background values? Please include these values in a Table!
Author’s Response :) We accept the kind comment from the reviewer, the table for the reference values for the elements is added. The concentration differs based on the sampling points. Only Pb has values close to the reference values.
Comment 4. The authors did not calculate the geo-accumulation index. Why? This index has been used to estimate the degree of pollution in aquatic sediments.
Author’s Response :) We accept the kind comment from the reviewer, geo-accumulation index is added to the manuscript.
Comment 5. Pollution load index is also not presented. This index can provide information for the overall sediment toxicity. Why the authors did not calculate and discuss this index?
Author’s Response :) We accept the kind comment from the reviewer, pollution index is added to the manuscript and discussed.
Comment 6. The significance of the Pearson’s correlation coefficients? Were the observed correlations between As and Fe; Cd and Pb; Pb and Fe significant. If yes, what is the level of the significance? (Please see reference 15 from the references).
Author’s Response :) Thank you for your suggestion and we accept the reviewer’s comments. The section 3.1.3 of the revised manuscript explains how the Pearson’s correlation was calculated. ANOVA was used to calculate p values to determine the level of significance.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper analyses the results of research covering a very important issue concerning the impact of humans on the natural environment, in this case the contamination of bottom sediments in the river with heavy metals.
Important methodological note: When locating environmental sampling sites (in this case bottom sediments), one should not only be guided by the accessibility of a given place, but also by the possibility of fully demonstrating the impact of the factors studied.
That is, their location should be representative and allow for the most accurate analysis of the obtained research material. In general, the research results make an important contribution and have great scientific value.
However, it would be worthwhile to:
- specify the title of the paper more precisely, the current one does not fully correspond to the content of the article,
- formulate and include a specific aim of the paper,
- write correctly the equations (1 and 2) concerning the discussed indicators,
- in the summary, supplement (list in order) the heavy metals that were characterized by the best values ​​of the discussed indicators.
Author Response
Comment 1. The paper analyses the results of research covering a very important issue concerning the impact of humans on the natural environment, in this case the contamination of bottom sediments in the river with heavy metals.
That is, their location should be representative and allow for the most accurate analysis of the obtained research material. In general, the research results make an important contribution and have great scientific value.
Important methodological note: When locating environmental sampling sites (in this case bottom sediments), one should not only be guided by the accessibility of a given place, but also by the possibility of fully demonstrating the impact of the factors studied.
Author’s Response :) Thank you for your suggestion and we accept the reviewer’s comments. The study area was fully investigated prior to sampling campaigning and all possible sources of pollutants were identified and samples were collected based on the river accessibility.
Comment 2. Specify the title of the paper more precisely, the current one does not fully correspond to the content of the article,
Author’s Response :) We thank the reviewer for this kind response, the title of the paper is revised.
Comment 3. Formulate and include a specific aim of the paper.
Author’s Response :) We thank the reviewer for this kind response, the introduction section was revised and the aim of the study was formulated.
Comment 3. Write correctly the equations (1 and 2) concerning the discussed indicators.
Author’s Response :) Thank you. All the equations were corrected and indicators were discussed fully.
Comment 4. In the summary, supplement (list in order) the heavy metals that were characterized by the best values of the discussed indicators.
Author’s Response :) We thank the reviewer for this kind response, the heavy metals were added on the summary.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors imrpoved the quality of the manuscript and responded to all questions. The manucript can be accepted in the present form.
