Identification of Water Pollution Sources for Better Langat River Basin Management in Malaysia
Round 1
Reviewer 1 Report
The manuscript under the title "Identification of Water Pollution Sources for better Integrated Langat River Basin Management in Malaysia" concerncs important environmental problem. The manuscript is well written. Comments to the Authors, see below:
Page 2, Line 95 - "The" - Word repetition.
Page 3, Line 109-110 - The Authors wrote "These water samples were also collected once in three replicates during 2015". Does this method of sampling ensure representativeness? I think that one sampling, even in repetitions, is not enough. Please explain.
Page 6, Tab. 4 - In the case of the correlation matrix, the level of significance should be precisely given, i.e. correlation is significant at the 0.01 levelor 0.05, etc., while significant correlations should be appropriately marked. Just like in tab. 7.
Page 9, Fig. 3 - Fig. of poore quality.
Author Response
Responses to the comments of Reviewer 1
The manuscript under the title "Identification of Water Pollution Sources for better Integrated Langat River Basin Management in Malaysia" concerns important environmental problem. The manuscript is well written. Comments to the Authors, see below:
Comment: Page 2, Line 95 - "The" - Word repetition.
Response: Thanks. The sentence has been edited.
Comment: Page 3, Line 109-110 - The Authors wrote "These water samples were also collected once in three replicates during 2015". Does this method of sampling ensure representativeness? I think that one sampling, even in repetitions, is not enough. Please explain.
Response: This explanation has been included in the method section- Although the water samples were collected once, however, the analysis of water quality can give initial findings of water pollution sources specifically at the eight raw water intake points of the respective drinking water treatment plant (DWTP) in the Langat River Basin. Moreover, the findings can suggest further studies of water samplings at all the point sources of pollution in the entire Langat River Basin as well as total maximum daily load (TMDL) studies at the specific sites that are important for drinking water supplies.
Comment: Page 6, Tab. 4 - In the case of the correlation matrix, the level of significance should be precisely given, i.e. correlation is significant at the 0.01 level or 0.05, etc., while significant correlations should be appropriately marked. Just like in tab. 7.
Response: A note has been added below the Table 4.
Comment: Page 9, Fig. 3 - Fig. of poore quality.
Response: The Fig. 3 is generated by the SPSS software.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This work has presented a statistical analysis of the water quality parameters and the heavy metals in the Langat watershed in Malaysia. Overall the work is well presented. Methods are fairly well discussed and the results and discussion are also described in a scientific way. The authors have used PCA and cluster analysis to analyze the data which is often a common practice in such types of studies. I have some important suggestions that would help the authors to make this study useful for the end-users, particularly the policy and decision-makers of the region.
1. First the foremost, Try to depict the whole of your work through a conceptual diagram, similar to a graphical abstract, but much more than it, wherein the policy and decision suggestions are pretty well depicted.
2. A reader is often confused with a lot of PCA and dendrogram analysis, try to highlight their physical significance. Each component needs to be put into the context of its physical significance.
3. Overall the upper and mid areas of the Langat watershed are polluted, Ok, what about the management? Often the research which is sometimes obviously common sense is described at length, but the how-to solve is just dealt with in a few sentences. Kindly add a detailed section for the management of the watershed, using your results.
4. And this study is not an integrated watershed management study, as that also includes sediment and erosion analysis, along with similar other types of studies. So "Integrated" needs to taken off from the title.
5. It is very important to add a section on the limitations and future scope of this study in light of the results obtained from this study.
6. Figures need to be more illustrated.
Author Response
Responses to the comments of Reviewer 2
This work has presented a statistical analysis of the water quality parameters and the heavy metals in the Langat watershed in Malaysia. Overall the work is well presented. Methods are fairly well discussed and the results and discussion are also described in a scientific way. The authors have used PCA and cluster analysis to analyze the data which is often a common practice in such types of studies. I have some important suggestions that would help the authors to make this study useful for the end-users, particularly the policy and decision-makers of the region.
Comment: 1. First the foremost, Try to depict the whole of your work through a conceptual diagram, similar to a graphical abstract, but much more than it, wherein the policy and decision suggestions are pretty well depicted.
Response: Thanks for the comment. A new section has been included as sub-heading “4.1 Langat River Basin Management’ to address this comment.
Comment: 2. A reader is often confused with a lot of PCA and dendrogram analysis, try to highlight their physical significance. Each component needs to be put into the context of its physical significance.
Response: This comment has been address in line with the comments of other reviewers. The results and discussions parts have been separated and rearranged in the manuscript, and a figure has been move to supplementary material section according to the reviewers’ suggestion.
Comment: 3. Overall the upper and mid areas of the Langat watershed are polluted, Ok, what about the management? Often the research which is sometimes obviously common sense is described at length, but the how-to solve is just dealt with in a few sentences. Kindly add a detailed section for the management of the watershed, using your results.
Response: This comment has been addressed in the section ‘Sub-heading 4.1 Langat River Basin Management.’
Comment 4: And this study is not an integrated watershed management study, as that also includes sediment and erosion analysis, along with similar other types of studies. So "Integrated" needs to taken off from the title.
Response: The word ‘integrated’ has been removed from the title.
Comment: 5. It is very important to add a section on the limitations and future scope of this study in light of the results obtained from this study.
Response: This comment has been address in line with the comment of reviewer 3. The ‘limitations and future scope of this study’ has been added in the method section.
Comment: 6. Figures need to be more illustrated.
Response: This comment has been addressed in line with the comments of reviewer 3 via separating the results and discussions sections.
Author Response File: Author Response.pdf
Reviewer 3 Report
In the manuscript "Identification of Water Pollution Sources for better Integrated Langat River Basin Management in Malaysia" the authors analyze the water quality and pollution in the Langat River. The manuscript falls within the scope of the journal and as a local / regional interest as applied research.
My main concern is related with the origin of some of the raw data and how they are used the following analysis. To my understanding the authors conductivity, salinity and TDS data was acquired with a YSI probe. Thus, conductivity was measured and salinity was calculated from it. This was probably also the case for TDS, but this needs to be clarified. If this is case, the authors should review the multiple linear regression, since they are using all the three variables in it.
I am attaching the commented version of the manuscript.
Comments for author File: Comments.pdf
Author Response
Responses to the Comments of Reviewer 4
In the manuscript "Identification of Water Pollution Sources for better Integrated Langat River Basin Management in Malaysia" the authors analyze the water quality and pollution in the Langat River. The manuscript falls within the scope of the journal and as a local/regional interest as applied research.
Comment: My main concern is related with the origin of some of the raw data and how they are used the following analysis. To my understanding the authors conductivity, salinity and TDS data was acquired with a YSI probe. Thus, conductivity was measured and salinity was calculated from it. This was probably also the case for TDS, but this needs to be clarified. If this is case, the authors should review the multiple linear regression, since they are using all the three variables in it.
Response: Thanks for your comment. The regression analysis has been run again by SPSS according to the suggestion and necessary editing in the text has been done.
Comment: I am attaching the commented version of the manuscript.
ï‚· This sentence needs to be rewritten for clarity.
Response: The sentence has been re-written.
Comment: Did you mean due to severe floods?
Response: Thanks. It has been edited.
Comment: Consider to delete the word.
Response: Thanks. The word has been deleted.
Comment: Review the format.
Response: It has been edited.
Comment: The date of the samplings needs to be clear.
Response: These water samples were collected once in three replicates during 6 to 14 August 2015.
Comment: Please rewrite for clarity.
Response: The sentence has been edited.
Comment: Please clarify which were the data used to do the PCA and HA - was only the data from
2015.
Response: It is based on the data from 2015.
Comment: Please consider to put this figure 2 as supplementary material.
Response: The Figure 2 has been moved to supplementary material section as Figure S1.
Comment: Were all these data acquired with the YSI probe? If this is the case, the probe measures conductivity and calculates salinity and TDS, which explains the main correlation.
Response: Thanks for the comment. The sentence has been edited.
Author Response File: Author Response.pdf
Reviewer 4 Report
Dear authors,
your manuscript (MS) "Identification of Water Pollution Sources for better Integrated Langat River Basin Management in Malaysia" is interesting, but needs some revision prior to publication in Water.
General remarks:
- Please make clear what types of treatment plants you are referring to - Drinking water treatment plants (DWTPs) or Wastewater treatment plants (WWTPs) and be consistent along the whole MS. I assume that DWTPs are described in the text, but...
- Please remove the measurement units from figures 3 and 4, as they are presented in numerous parts of the text and tables. They do not add important information.
- Please revise the MS according to the Water template - the "Results" and the "Discussion" should be in separate paragraphs. Large parts of the "Results" paragraph should be moved to the new section - "Discussion".
Specific comments:
- Introduction (L43): Please explain in more detail how and why the treatment plants shut down. Again if they are WWTPs is one thing, but if they are DWTPs - completely another. Maybe additional information on these incidents during the study period would be beneficial for your Introduction.
- Introduction (L48): Please rephrase, something is wrong with the sentence.
- Introduction (L78, 83, 168, 433): I believe the better term is "exceed" than "cross".
- Materials and Methods (L125): Please add the number of replicates in brackets.
- Materials and Methods (L133): Please indicate which SRM (CRM) was used.
- Materials and Methods (L138): Please provide reference to the WQI, e.g. https://doi.org/10.1016/j.ecolind.2020.106872.
- Materials and Methods (L139): Please explain abbreviations when first used in the text. BOD would be replaced with "BOD5" (also in eq.1). Also, add SPC and SAL, which are included in table 4. Make sure that the units are expressed following the SI (e.g. "ppt" for salinity).
- Materials and Methods (Eq. 1): Please add a description to eq. 1 (e.g. SIDO).
- Results and discussions (L189, 195 and table 5): Please explain abbreviations when first used in the text (KMO).
- Results and discussions (L224): I believe the correct term is "electrical conductivity".
- Results and discussions (L230-238): There is a well-established relationship between Al and precipitation (rainfall, L95 in your MS) and turbidity (check https://doi.org/10.1007/s11270-020-04819-0), which may further explain the observed high concentrations of Al in the river. And this is also supported by your data.
Author Response
Responses to the comments of Reviewer 3
Dear authors,
Your manuscript (MS) "Identification of Water Pollution Sources for better Integrated Langat River Basin Management in Malaysia" is interesting, but needs some revision prior to publication in Water.
General remarks:
Comment: Please make clear what types of treatment plants you are referring to - Drinking water treatment plants (DWTPs) or Wastewater treatment plants (WWTPs) and be consistent along the whole MS. I assume that DWTPs are described in the text, but...
Response: Thanks for the comment. It has been edited as drinking water treatment plants (DWTPs).
Comment: Please remove the measurement units from figures 3 and 4, as they are presented in numerous parts of the text and tables. They do not add important information.
Response: The measurement units from figures 3 and 4 have been removed.
Comment: Please revise the MS according to the Water template - the "Results" and the "Discussion" should be in separate paragraphs. Large parts of the "Results" paragraph should be moved to the new section - "Discussion".
Response: The suggestion to separate “Results” and the “Discussion” sections have been followed.
Specific comments:
Comment: Introduction (L43): Please explain in more detail how and why the treatment plants shut down. Again if they are WWTPs is one thing, but if they are DWTPs - completely another. Maybe additional information on these incidents during the study period would be beneficial for your Introduction.
Response: Thanks. A new paragraph has been added in the introduction section to address this comment.
Comment: Introduction (L48): Please rephrase, something is wrong with the sentence.
Response: Thanks, the sentence has been edited.
Comment: Introduction (L78, 83, 168, 433): I believe the better term is "exceed" than "cross".
Response: Thanks, it has been edit.
Comment: Materials and Methods (L125): Please add the number of replicates in brackets.
Response: Thanks the number of replicate (i.e., 120) has been added in brackets.
Comment: Materials and Methods (L133): Please indicate which SRM (CRM) was used.
Response: Thanks, the SRM has been added in brackets (i.e., Multi-Element Calibration Standard III (PerkinElmer, Lot # CL7-173YPY1, PE # N9300233, Waltham, MA, USA).
Comment: Materials and Methods (L138): Please provide reference to the WQI, e.g. https://doi.org/10.1016/j.ecolind.2020.106872.
Response: The references have been added i.e. [9,33,34].
Comment: Materials and Methods (L139): Please explain abbreviations when first used in the text. BOD would be replaced with "BOD5" (also in eq.1). Also, add SPC and SAL, which are included in table 4. Make sure that the units are expressed following the SI (e.g. "ppt" for salinity).
Response: Thanks, the comments have been addressed in the text.
Comment: Materials and Methods (Eq. 1): Please add a description to eq. 1 (e.g. SIDO).
Response: A description has been added in the text under the Sub heading 2.3. Time series water quality data.
Comment: Results and discussions (L189, 195 and table 5): Please explain abbreviations when first used in the text (KMO).
Response: Thanks, the abbreviation has been added.
Comment: Results and discussions (L224): I believe the correct term is "electrical conductivity".
Response: Thanks, electrical conductivity has been edited in the text.
Comment: Results and discussions (L230-238): There is a well-established relationship between Al and precipitation (rainfall, L95 in your MS) and turbidity (check https://doi.org/10.1007/s11270-020-04819-0), which may further explain the observed high concentrations of Al in the river. And this is also supported by your data.
Response: This comment has been addressed in the introduction section of the revised version of this manuscript (line 52-69) as well as in discussion (line 510).
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Thanks for incorporating all the suggested corrections.
Best,
Reviewer 4 Report
Dear authors,
you have successfully implemented all the responses of the reviewers and your paper has been substantially revised to meet the high standard of Water.
