Structure of Late Pleistocene and Holocene Sediments in the Petrozavodsk Bay, Lake Onego (NW Russia)
, Alexandr Rybalko 2,3,4, Vera Strakhovenko 2,5, Natalia Belkina 2, Mikhail Tokarev 6,7, Maksim Potakhin 2, Mikhail Aleshin 6, Pavel Belyaev 2,8, Nathalie Dubois 9,10, Vladislav Kuznetzov 1,3, Dmitry Korost 6,7, Andrei Loktev 7, Natalia Shalaeva 6, Alexandra Kiskina 2,3, Natalia Kostromina 3, Yuriy Kublitskiy 1,2 and Alexander Orlov 1,2
Round 1
Reviewer 1 Report
Manuscript “Structure of the Late Pleistocene and Holocene Sediments in the Petrozavodsk Bay, Lake Onego (NW Russia)” by Subetto et al. presents some interesting data about glacial and interglacial lake sediment features using multi-proxy and multi-core geological studies. The material is appropriate for the MDPI-Minerals Journal. However, the paper needs thorough proof reading, extended literature review, clear statement about the issues (problematic) the manuscript addresses and restructuring certain parts of the manuscript (materials and methods, results and discussion) before it can be considered for publication. The authors should bear in mind that the manuscript should have a form of a research study intended to further the progress of science and not that of a technical rapport. This manuscript could be a very interesting contribution to further investigate gas accumulation in lake sediments and their contribution to global greenhouse-gas-budget.
Abstract
Please elaborate and put more details about your results in the abstract. How many cores were studied? Sediment age? Explain methods used and for what. Where and how did you observe pockmarks? What kinds of gases? Ideas for future research….
Introduction
It is not clear why you did this study. Is it because of the limited knowledge of the lake sediment features or because of the discovered gas sediment accumulation or is it the both? Explain here why your study is important and what it brings for the future studies in the region. You should use extended literature review here (ex. Lajeunesse et al., Normandeau et al., etc.) Please state at the beginning the problematic and at the end the objectives how you aim to address it.
(1) line 37-38: Provide references for these geological explorations
(2) line 37: …research was then…
(3) line 38: 1-1.5 m is not that short when studying lake sediments.
(4) line 41: These studies have determined the lake basin formation about 15,000 years ago.
(5) line 41: Is this age in BP? Indicate in the manuscript.
(6) line 43-45: As no seismoacoustic study existed for this area, paleogeographic development of the lakebed in the Late Pleistocene–Holocene was based on well-investigated sections of Quaternary deposits on the lake bluffs and peripheries,…
(7) line 45: What small lake?
(8) line 45: Delete I.
(9) line 45: You mean data and no dates?
(10) line 51: Given the limited knowledge….
(11) line 56: Reformulate the sentence, because it is not clear what you want to say here. It was…..
(12) line 58-59: Why is this sentence at the end of the introduction? It should be placed together with other issues (ex., lack of knowledge of bottom sediment structures) you want to address.
Regional setting
(13) Indicate GPS coordinates of the study site.
(14) line 65-66: …by overlying Quaternary deposits.
(15) Describe the climate, precipitation and the duration of the lake-ice.
(16) Describe the vegetation of the lake basin.
(17) Are there any anthropogenic disturbances, like dredging?
Materials and methods
This section is poorly done. Restructure methods such as that each method is described in a separate subsection (3.1.1. Seismoacoustic; 3.1.2. Sediment sampling; 3.2.1. CT; 3.2.2. 14C, etc.). Organize it by putting first methods for sediment analyses and then gas analyses. Be precise when you describe methods and how many cores, how long were the cores and how many samples were used for each method. Recheck the number of tables and figure you refer to in the text there are not in order!!!!!
(18) line 109: It’s not station No 2 and 3 it’s ONG2 and 3
(19) line 111: idem
Results and discussion
I have a hard time following this section. The seismic profiles were discussed from bottom to top and lithology from top to bottom. Normally in sedimentary studies we use one direction starting with bottom sediments and work ourselves up towards more recent surface sediment. This section needs to be rearranged. Start explaining lithological unit 5 first. Indicate the names of the cores you are presenting in the figure captions and in the text.
(20) line 170: …profiling allowed to characterize…
(21) line 172: Decide how to write NW, Northwest or North-west Russia and be consistent throughout the manuscript
(22) line 195-196: Provide the references for the stratigraphic scheme.
(23) line 205: Why didn’t you date organic remains from the surface layer (unite 1)?
(24) line 206: …, there are microlayers…
(25) line 207: …in the cores vary.
(26) line 208: You start talking about surface sediments then you talk about 20 to 30 cm core depth and then you go back up to the top, use one direction (bottom to top) for all your sediments!!!!
(27) line 208: 1 cm
(28) line 209: ….depth of what, sediments?
(29) line 211: …deposits are increasing…towards surface or bottom of this section?
(30) line 211: This is conformed….
(31) line 216: …, as shown on topographic image. Where are these images???
(32) line 219: …. thickness… increases.
(33) line 222: How do you know that these laminae are varved?
(34) line 226: … are called…
(35) I suggest you put optical and X-ray image next to each other. It is difficult to see these microlayering using only optical image.
(36) Instead of talking about the coring location, indicate the name of the core you are presenting and refer to Figure 1-c.
(37) line 244: Lithological and seismo-stratigraphic units correlate well.
(38) seismostratigraphic or seismo-stratigraphic?
(39) But differences which were diagnosed in sediment cores, not shown on seismic profiles. Reformulate this sentence I do not know what you mean.
(40) I3H or I3H?;
(41) Fluvioglacial deposits are gIIIos or IgIIIos? It would be easier for the reader if you would add description of the sediment layers in addition to the codes on the figures.
(42) line 253: Cores ONG2 and 5 were radiocarbon dated.
(43) line 256: …dates…
(44) line 251: It would be nice if you could make a visible mark for Holocene-Pleistocene transition on the Figure 10
(45) line 264: Can you add a subtitle when you start talking about ONG5 core.
(46) line 266: When you talk about redox zone would be nice to be referred to a figure.
(47) laminae or laminas?
(48) line 281: Can you indicate this erosion on the Figure 13 and be more precise about horizon from which to which depth. I do not follow your description in this section.
(49) line 354: …directly on sediment cores, which was used in this study.
(50) line 355: Provide references in text.
(51) line 360: It is interesting…
(52) Physical and mechanical properties, this section needs further development with figures and detail explanations and/or merge this section with 4.2. Stratigraphic features.
(53) line 370-374: This classification can be put in the annex.
(54) Are you presenting in Table 4 and 3 data from some other cores? If so, remove them and focus on the one you already mention in the manuscript (ONG1, 2, 4, 5, 6 and 7). Delete 2016!
Conclusion
(55) You need to put more details about your results in this section, same as for the introduction.
(56) line 387: The last sentence comes as a surprise as you have nowhere mentioned the ecological assessment in your manuscript, thus, it cannot be part of your conclusion.
References
I am strongly recommending more exhaustive literature review outside of Russia. Be consistent with how you write references (e.g., p. or pp., bold or not years of publication, etc.)
Author Response
We would like to thank to the reviewer for the detailed and very useful analysis of our manuscript! According to the comments of three reviewers, we have significantly revised the text. We introduced a new subsections, corrected all the Figures and its captions, removed an entire paragraph Physical and mechanical properties, and expanded the conclusion. All these inaccuracies and errors have been corrected. Thank you again for your interest in our work and your careful and meticulous analysis!
Abstract
It was improved
Introduction
It was improved
(1) line 37-38: Provide references for these geological explorations
It was done. (Semenovich, 1973)
(2) line 37: …research was then…
It was improved
(3) line 38: 1-1.5 m is not that short when studying lake sediments.
It was changed: “The sediments cores obtained in these studies were no longer than 1-1.5 m, thus only reaching the Upper and the Middle Holocene”
(4) line 41: These studies have determined the lake basin formation about 15,000 years ago.
(5) line 41: Is this age in BP? Indicate in the manuscript.
Now “15,000 years before present (yr. BP)”
(6) line 43-45: As no seismoacoustic study existed for this area, paleogeographic development of the lakebed in the Late Pleistocene–Holocene was based on well-investigated sections of Quaternary deposits on the lake bluffs and peripheries,…
(7) line 45: What small lake?
Now “As no seismoacoustic and long-sediment core studies existed in this area, paleogeography of Lake Onego in the Late Pleistocene-Holocene drew upon well-investigated geological sections of Quaternary deposits around the lake basin, including sediment cores from small lakes located near Lake Onego.
(8) line 45: Delete I.
It was deleted
(9) line 45: You mean data and no dates?
Yes, Data
(10) line 51: Given the limited knowledge….
It was changed
(11) line 56: Reformulate the sentence, because it is not clear what you want to say here. It was….
It was reformulated
(12) line 58-59: Why is this sentence at the end of the introduction? It should be placed together with other issues (ex., lack of knowledge of bottom sediment structures) you want to address.
It was reformulated
Regional setting
(13) Indicate GPS coordinates of the study site.
It was done and there are coordinates on the Figure 1
(14) line 65-66: …by overlying Quaternary deposits.
It was done
(15) Describe the climate, precipitation and the duration of the lake-ice.
In our opinion, this information is not necessary
(16) Describe the vegetation of the lake basin.
In our opinion, this information is not necessary
(17) Are there any anthropogenic disturbances, like dredging?
No, you are not
Materials and methods
This section is poorly done. Restructure methods such as that each method is described in a separate subsection (3.1.1. Seismoacoustic; 3.1.2. Sediment sampling; 3.2.1. CT; 3.2.2. 14C, etc.). Organize it by putting first methods for sediment analyses and then gas analyses. Be precise when you describe methods and how many cores, how long were the cores and how many samples were used for each method. Recheck the number of tables and figure you refer to in the text there are not in order!!!!
It was done
(18) line 109: It’s not station No 2 and 3 it’s ONG2 and 3
Thank you, it was corrected!
(19) line 111: idem
Corrected
Results and discussion
I have a hard time following this section. The seismic profiles were discussed from bottom to top and lithology from top to bottom. Normally in sedimentary studies we use one direction starting with bottom sediments and work ourselves up towards more recent surface sediment. This section needs to be rearranged. Start explaining lithological unit 5 first. Indicate the names of the cores you are presenting in the figure captions and in the text.
(20) line 170: …profiling allowed to characterize…
It was improved
(21) line 172: Decide how to write NW, Northwest or North-west Russia and be consistent throughout the manuscript
NW
(22) line 195-196: Provide the references for the stratigraphic scheme.
It was provided
(23) line 205: Why didn’t you date organic remains from the surface layer (unite 1)?
Because the C14 Lab in Saint-Petersburg University does only by bulk analyses, no AMS
(24) line 206: …, there are microlayers…
…thin layers…
(25) line 207: …in the cores vary.
… in the cores are different.
(26) line 208: You start talking about surface sediments then you talk about 20 to 30 cm core depth and then you go back up to the top, use one direction (bottom to top) for all your sediments!!!!
Corrected
(27) line 208: 1 cm
Corrected
(28) line 209: ….depth of what, sediments?
Paraphrased
(29) line 211: …deposits are increasing…towards surface or bottom of this section?
Thank you, it was corrected “… towards bottom of this unit.”
(30) line 211: This is conformed….
Corrected
(31) line 216: …, as shown on topographic image. Where are these images???
The reference on the Figure 13 was added.
(32) line 219: …. thickness… increases.
…its thickness increases
(33) line 222: How do you know that these laminae are varved?
We know based on our previous studies of a large number of sections of bottom sediments of different types of lakes and on the research of colleagues (e.g.Subetto, 2009; Hang et al., 2019; Gromig et al., 2019)
(34) line 226: … are called…
Corrected
(35) I suggest you put optical and X-ray image next to each other. It is difficult to see these microlayering using only optical image.
(36) Instead of talking about the coring location, indicate the name of the core you are presenting and refer to Figure 1-c.
It was done
(37) line 244: Lithological and seismo-stratigraphic units correlate well.
Corrected
(38) seismostratigraphic or seismo-stratigraphic?
seismo-stratigraphic
(39) But differences which were diagnosed in sediment cores, not shown on seismic profiles. Reformulate this sentence I do not know what you mean.
“Lithological units 1 and 2 are not expressed on seismic profiles”
(40) I3H or I3H?;
I3H
(41) Fluvioglacial deposits are gIIIos or IgIIIos? It would be easier for the reader if you would add description of the sediment layers in addition to the codes on the figures.
We have simplified the nomenclature
(42) line 253: Cores ONG2 and 5 were radiocarbon dated.
It was corrected
(43) line 256: …dates…
It was corrected. This paragraph (“The Table 2 represents… . ”) has been moved to methods
(44) line 251: It would be nice if you could make a visible mark for Holocene-Pleistocene transition on the Figure 10
The Pleistocene-Holocene boundary was visualized with a thick line
(45) line 264: Can you add a subtitle when you start talking about ONG5 core.
Highlighted with a new paragraph
(46) line 266: When you talk about redox zone would be nice to be referred to a figure.
There is a reference (Strakhovenko et al., 2020 J. Great Lake Research)
(47) laminae or laminas?
layers
(48) line 281: Can you indicate this erosion on the Figure 13 and be more precise about horizon from which to which depth. I do not follow your description in this section.
(49) line 354: …directly on sediment cores, which was used in this study.
It was corrected (lines 375-376)
(50) line 355: Provide references in text.
It was done ([16]) Line 380
(51) line 360: It is interesting…
It was corrected (line 383)
(52) Physical and mechanical properties, this section needs further development with figures and detail explanations and/or merge this section with 4.2. Stratigraphic features.
We decided to remove this section from the article
(53) line 370-374: This classification can be put in the annex.
This section was removed from the article
(54) Are you presenting in Table 4 and 3 data from some other cores? If so, remove them and focus on the one you already mention in the manuscript (ONG1, 2, 4, 5, 6 and 7). Delete 2016!
The section Physical and mechanical properties was deleted from the article
Conclusion
(55) You need to put more details about your results in this section, same as for the introduction.
(56) line 387: The last sentence comes as a surprise as you have nowhere mentioned the ecological assessment in your manuscript, thus, it cannot be part of your conclusion.
The conclusion was rewritten
References
It was corrected
Author Response File: 
Author Response.doc
Reviewer 2 Report
Section Regional setting
Figure 1 lacks a linear scale (scale bar). Without this, it is difficult to assess the situation.
Section Materials and Methods
- There is probably an error in estimating the total length of the profiles. The total length of the profiles is indicated as 19 km (line 84). But 8 profiles at a distance of 250 meters plus 10 profiles at a distance of 50 meters will add up to a greater length. 2. Macro and trace elements analyzed by AAC method. After the acid attack procedure? What and in what proportion acids? At what temperature regime? Among the listed elements, Hg is present. Was the Hg assay special in AAC mode with pre-amalgamation? In addition to AAC the ICP-MS method was used. What elements were identified by ICP-MS? Standards were used for quality control (“rock reference materials”, line 166). What standards? 42 samples of AAC and ICP-MS were analyzed, but further there are no data on the content macro and microelements and the results are not presented either in the form of tables or in the form of diagrams.
Section Results and Discussion
- On the left side of Figure 2 and 3 advisable indicate the scale. 2. Figure 10 requires better quality. 3. In Table 3, it is sufficient to indicate methane concentrations in integer unit. 4. One difficult questions about the regime of gases in sediments. Good and high-quality presentation of results, but at the same time a complete lack of comparative analysis with the regime of gases in other freshwater lakes in the world. For example, in the sediments of the Great Lakes, methane concentrations are higher or lower? It is advisable to make a short(!) comparison of gas concentrations for other lakes in the world.
Author Response
Reviewer 2
We would like to thank to the reviewer for the detailed and very useful analysis of our manuscript! According to the comments of three reviewers, we have significantly revised the text. We introduced a new subsections, corrected all the Figures and its captions, removed an entire paragraph Physical and mechanical properties, and expanded the conclusion. All these inaccuracies and errors have been corrected. Thank you again for your interest in our work and your careful and meticulous analysis!
Section Regional setting
Figure 1 lacks a linear scale (scale bar). Without this, it is difficult to assess the situation.
It was corrected.
Section Materials and Methods
- There is probably an error in estimating the total length of the profiles. The total length of the profiles is indicated as 19 km (line 84). But 8 profiles at a distance of 250 meters plus 10 profiles at a distance of 50 meters will add up to a greater length.
Thank you! It was corrected (96 km, line 85)
- Macro and trace elements analyzed by AAC method. After the acid attack procedure? What and in what proportion acids? At what temperature regime? Among the listed elements, Hg is present. Was the Hg assay special in AAC mode with pre-amalgamation? In addition to AAC the ICP-MS method was used. What elements were identified by ICP-MS? Standards were used for quality control (“rock reference materials”, line 166). What standards? 42 samples of AAC and ICP-MS were analyzed, but further there are no data on the content macro and microelements and the results are not presented either in the form of tables or in the form of diagrams.
This paragraph was removed from the text
Section Results and Discussion
- On the left side of Figure 2 and 3 advisable indicate the scale.
It was done - Figure 10 requires better quality.
It was improved
- In Table 3, it is sufficient to indicate methane concentrations in integer unit.
The Table 3 was corrected
- One difficult questions about the regime of gases in sediments.
The answer to this question requires additional research - Good and high-quality presentation of results, but at the same time a complete lack of comparative analysis with the regime of gases in other freshwater lakes in the world. For example, in the sediments of the Great Lakes, methane concentrations are higher or lower? It is advisable to make a short(!) comparison of gas concentrations for other lakes in the world.
Thank you for this question! This work will be done in the next publication. In this paper, we wanted to present new seismostratigraphic results and data on the structure of bottom sediment cores.
Author Response File: Author Response.doc
Reviewer 3 Report
Please, correct minor mistakes in the text where indicated.
Information about the precise amount of sampled sediment cores, their coordinates, location on maps as well as figures and tables captions/legends needs to be corrected and/or reorganized.
Two sections in Materials and methods concerning sedimentological, geochemical, petrographical and mineralogical analyses are unnecessary, please remove.
Radiocarbon dating results need to be described and discussed in the text.
Sections 4.4 Mineralogy and 4.5. Physical and mechanical properties are included for no clearly stated reasons as this information neither discussed nor included in Conclusions.
Comments for author File: 
Comments.pdf
Author Response
Reviewer 3
We would like to thank to the reviewer for the detailed and very useful analysis of our manuscript! According to the comments of three reviewers, we have significantly revised the text. We introduced a new subsections, corrected all the Figures and its captions, removed an entire paragraph Physical and mechanical properties, and expanded the conclusion. All these inaccuracies and errors have been corrected. Thank you again for your interest in our work and your careful and meticulous analysis!
Please, correct minor mistakes in the text where indicated.
Thank you! We have corrected all the errors and inaccuracies you mentioned in the article (PDF file)
Information about the precise amount of sampled sediment cores, their coordinates, location on maps as well as figures and tables captions/legends needs to be corrected and/or reorganized.
It was done.
Two sections in Materials and methods concerning sedimentological, geochemical, petrographical and mineralogical analyses are unnecessary, please remove.
According to the comments of all reviewers, we have changed the structure of the Materials and methods section.
Radiocarbon dating results need to be described and discussed in the text.
The results of Dating are discussed in the article(lines 255-279)
Sections 4.4 Mineralogy and 4.5. Physical and mechanical properties are included for no clearly stated reasons as this information neither discussed nor included in Conclusions.
Section 4.6 Mineralogy was improved. The section Physical and mechanical properties was removed
Author Response File: Author Response.doc
Round 2
Reviewer 1 Report
Please see the attached file.
Comments for author File: Comments.pdf
Author Response
Please check the revised file with comments addressed.
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear authors, I appreciate you have changed the text according to my suggestions. However some editing ought to be done before publication.
Please, correct minor mistakes in the text where indicated. Check reference list.
Loads of symbols presented at Figures 10-13 are missing from the Legend to Fig.9. Please, correct.
Still I can not understand the reason behind including mineralogical data in this paper. You neither discuss the results (only summing up the already published materials) nor include it in Conclusions. Moreover, you get them by doing a research on different sediment cores and present no evidence for an assumption that methane really “contributes to the formation” of authigenic minerals. So this section better to be removed and corresponding part from Materials and methods. May be some part of it can be squeezed in the section 4.4 Lamination. At least it would look much more relevant there.
Section 4.3 Radiocarbon dating better be reorganized according to my suggestions. At least start with ages description and finish with sedimentation rates, not the other way around.
You really need to expand Conclusions by including the most important results of your research. If I’m not mistaken you present the first radiocarbon dating of Onego lake sediments. Why you did not even mention it in the Conclusions? Please, correct
The same concerns gaseous composition of sediments. You write on page 19 that “the study outcomes are of particular importance” so, why you did not include it in the Conclusions? Please, correct.
Comments for author File: Comments.pdf
Author Response
In this file we make ansvers for some reviewer’s comments.
Author Response File: Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
