Organic Carbon in the Bottom Sediments of Lake Baikal: Geochemical Processes of Burial and Balance Values

Round 1

Reviewer 1 Report

To,

 

Editor

Journal of Water

 

Subject:-Title Organic Carbon in the Bottom Sediments of Lake Baikal:Geochemical Processes of Burial and Balance Values

 

Dear Sir,

 

I am submitting my points;

1. Appropriate keywords may provided with the journal instruction.
2. The date of collections, expedition with locations latitudes, longitudes, number of samples and number of replicates of analysis may indicated.
3. If this may appropriate the sections should indicate separately for pore water and pore water based sediments.
4. ORP methodology may explained well if the separate probe may attached for reliable results. 
5. The pre calibration standards may also indicated for the Eh-ORP.
6. The graph may indicated as discussion on dissolved oxygen was scarce.
7. The work presented is in short as most upto the results section 2.4, was of same concept was already published by the authors. The earlier published work by authors on inorganics of pore water may compared within present work.
8. The adsorption section was brief, it may explained with justification. How the minerals nature nanoparticles phase in lake environment.
9. What benefits of this study helpful for understanding climate change, if this may indicated in the manuscript. 
10. The present study may compared with other major lakes, as presently this was scarce in the manuscript.
11. Heading of subsections may carefully addressed.

Author Response

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Reviewer 2 Report

Disclaimer: I have only evaluated DOC dynamics in marine systems and am probably not up to date on that body of literature (no longer do these studies) and I have very little practical knowledge and background on lake DOC dynamics.

 

This manuscript reports on work in Lake Baikal basins with the main goal being a better understanding of DOC fluxes (sequestration, liberation, mobilization, vertical movement) under varying environmental conditions. Dissolved cations and anions were also measured in sediment profiles and linked to DOC and DIC concentrations to understand controlling factors on their flux(es). The introduction makes a compelling argument, from a <global> carbon cycling perspective, to justify this work. Unfortunately, I feel there is too little specifics given to previous work (one short paragraph with a reference list: lines 66-68). I think this paragraph should be expanded to better lay the groundwork for the present study. What specific information gaps necessitate the current work? They make the argument that the gap is DOC dynamics, but in some of the studies TOC was measured and used by proxy (the methods section uses the flux calculations presented in a previous paper (ref 28)). To me, this paragraph should be the prime focus for the introduction rather than a, “lots of studies have been done” with reference list. Because I am not familiar with past work on LB, I took a look over these papers and they are reasonably comprehensive, so the present work should really be justified by pointing out where the previous studies need further elucidation.

 

The methods seem reasonable to me. I have not used the exact instrumentation outlined in the methods section, but a quick web search leads me to believe they are appropriate and of adequate precision. In terms of DOC flux calculations, the authors chose a nominal DOC molecular weight (1000 Da, I presume). This isn’t a bad estimate but there was no justification given for this assignment. I am only familiar using Fick’s law with methane (which has a known MW). It would have been interesting to perform the calculation(s) with different MW ranges, compiled into a table, perhaps. While it is problematic to assume certain MW ranges infer lability (in marine systems, it was long assumed that high MW DOC was refractory, but later this fraction was shown to be labile in certain circumstances). In all instances (equations), it would be better to use a formula generator (I believe MS Word still has one) which makes the equations easier to see and understand (e.g. ()).

 

The discussion section(s) are well-reasoned and supported by the literature. The section(s) (4.1-4.6) offer considerable information on ratio(s) and correlations between different species. Most of the discussion focuses on Figs. 2-3 – which is appropriate. I think a figure showing DOC and DOC fractions plotted against Ca²⁺, Eh, FOC-FeR, etc would offer insight as these correlations are fairly robust (as reported goodness-of-fit statistics….). This would offer the reader a more condensed picture of the relationships than the profile figures (especially if both were presented). Not critical but a suggestion.

 

The final sections (including conclusions) are reasonable and I see no reason to refute the findings based on the data and interpretations.

 

I gave the manuscript a rapid read. Based on the authors’ affiliations, I assume they are not native English speakers. I always feel hypocritical – as there is no way I could write a MS in a foreign language. However, “Water” states that articles are published in English. While the prose is mostly correct grammatically, I think it would be very useful to have a full proofread by a native English writer to give better sentence flow.

 

Another systematic point – many units are in fractional notation. Standard notation is always preferred (I think) for English journals (e.g. C/m² should be C m^-2).

 

Overall, I would suggest publication with minor edits.

 

Some specifics noted during my read:

 

Ln 9; errant character (looks like a backwards capital N)?

Ln 17, it’s customary to represent units using power notation (e.g. mM C m^-2 yr^-1).

Ln 17, “i.e.” should be italicized (i.e.) 

Ln 50, missing “is”

Ln 67, missing “the”

Ln 242, “fastest” should be “faster”

Lns 259-260, “with its uneven distribution” – remove “its”

Ln 372, “drain” should probably be changed to “sink” – it is a more commonly-used term

Ln 472, “Character” misspelled

 

See above 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

 

Review of “Title Organic Carbon in the Bottom Sediments of Lake Baikal:  Geochemical Processes of Burial and Balance Values” by Pogodaeva et al. Submitted to Water.

This study explored the geo-chemical process of dissolved organic matter in the water-sediment interface of the Lake Bakikal.  They found that redox conditons were the main regulator of DOC exchange in the interface via pore water DOC and other elements analysis. This study could promote our understanding of the carbon cycling in the largest freshwater lake.

This study is well designed and conducted. The manuscript is clear and well organized. I think this paper is pretty much ready to be accepted  with some minor revisions.

 

Specific comments: 

1. In the title: The authors use “Title organic matter”, this should be “ Total organic matter”.

2. In the introduction part, “Climate change contributes to the increase in DOC in the surface waters around the world”. Please cite the original paper.

 3. In figure 2, add units of the components.

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

.

To,

 

Editor

Journal of Water

 

Subject:-Organic Carbon in the Bottom Sediments of Lake Baikal: Geo-

chemical Processes of Burial and Balance Values

 

Dear Sir,

 

I submit my comments as followings;

1. Still th title may rearranged with removal of balance values. 
2. The objectives may be defined more with citations as this work may be extension of those studies. Objectives may given with numbering and followed within manuscript.
3. The methodology needs more references for procedures, equations etc.
4. Reference pl. for identical scheme L-147.
5. The (3.5) southern basin may have organic characters for pore water in sediments, that may also discussed and figured. A reference attached for the convenience Klump, J. V., Edgington, D. N., Granina, L., & Remsen III, C. C. (2020). Estimates of the remineralization and burial of organic carbon in Lake Baikal sediments. Journal of Great Lakes Research, 46(1), 102-114. 
6. As earlier the point 3 raised for discuss pore water and pore water sediments but that did not explained appropriately. 
7. Why did not porewater assessed for OC, Fe and Mn and sediments for chemical analysis and redox potential. The sections 2.1 and 2.2 are lacking information and their correlation.
8. Ensure calibration (I.e Zobel solution) as in point raised 5.
9. It may still the discussions were deficient of dissolved oxygen as raised 6.
10. It may not explained appropriately as objectives were unclear.
11. Please present a short review in table to assign creditability of present work as requested in point 10.
12. The Mn and Fe accumulation may calculated per year
13. The errors may removed from manuscript abstract.
14.  

Author Response

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Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

.

Needs improvement

Author Response

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Author Response File: Author Response.pdf