A New View on the Global Redox-Cycle of Biosphere Carbon

Round 1

Reviewer 1 Report

In the manuscript “A new view on the global redox-cycle of biosphere carbon”, the author presents original ideas on the organization of the global carbon cycle and suggests the model, which is based on the interaction between the geological and the biospheric constituents within the self-regulating cycle.  Although some details of the concept require further clarification, the model provides a plausible explanation of the evolution of biosphere and of the changes in the concentrations of oxygen and carbon dioxide over geological eras and periods.

There are few issues that need to be addressed. The reduced sulfur that is oxidized by the atmospheric oxygen assumes that this reaction can proceed with high intensity over long geological periods to explain lower concentrations of oxygen, e.g. during the whole Mesozoic. Is the production of reduced sulfur in orogenic times sufficient to maintain lower (15-17%) concentration of oxygen over tens and more millions years as compared to 30-35% oxygen during Permo-Carboniferous? Some estimation of the fluxes of release of sulfur and its reaction with oxygen would help. The estimations of oxygen concentrations are given with the reference to Lenton; they are rather moderate and not fully consistent with the estimations given by other researchers, this can be commented. In addition, the orogenic periods are characterized by the increased rate of weathering, which results in binding of atmospheric CO2 and reducing its concentration, which is shown, e.g., in the works of Berner. Some comments on this could be useful for clarification of the ideas of the manuscript.

More information about the supercontinental cycles and the timing of orogenic periods can be provided. In Figure 4, the scale is absent. It could help in estimating major processes occurring during the evolution of biosphere. In Figure 4, the spelling of “geosynclinal” should be corrected. Figure 3 is absent, and there are two figures 8 in the manuscript.  In the first Figure 8, the text inside the figure is in Russian.

There are several other stylistic and technical issues throughout the paper that need to be fixed. In the title, redox cycle should be without hyphen. In the abstract, the word “machine” could be replaced by “structure” or “system” which is more relevant. What is “minimumCCc” (line 20 in the Abstract)? References in the abstract, in general, should be avoided, but in this particular case one reference can be kept and its format should include the journal name, year and volume: Ivlev, A.A. Biosystems 2015, 137, 1–11.

The style can be improved throughout the manuscript. It is better to write the first name of the author in full, this also refers to the names of researchers in the text, e.g. to write Vladimir Vernadsky instead of V.I. Vernadsky.     

In conclusion, an attempt of the author to develop the global concept of the carbon cycle is challenging and can be supported. The ideas presented in the paper outline the whole unfoldment of the carbon cycle and have a great potential for further development and clarification of particular aspects of the process.           

Author Response

I am grateful to the reviewer 1 for the careful reading of the article and the critical comments made. Some of them turned out to be very useful and were used by the author to improve the article

1. The reviewer 1

The reduced sulfur that is oxidized by the atmospheric oxygen assumes that this reaction can proceed with high intensity over long geological periods to explain lower concentrations of oxygen, e.g. during the whole Mesozoic. Is the production of reduced sulfur in orogenic times sufficient to maintain lower (15-17%) concentration of oxygen over tens and more millions years as compared to 30-35% oxygen during Permo-Carboniferous? Some estimation of the fluxes of release of sulfur and its reaction with oxygen would help.  ... Some comments on this point could be useful for clarification of the ideas of the manuscript. ...

Reply:

If I understood the reviewer correctly, he believes that the oxygen content in the atmosphere during evolution is mainly determined by the amount of reduced sulfur, produced in the reaction of thermochemical sulfate reduction occurring in the subduction zone. In fact, it also strongly depends  on the binding of oxygen by the reduced forms of metals from igneous rocks that come to the Earth's surface with volcanic exhalations. Now it is not possible to quantify their separate effect. But it doesn't matter, since both reasons act simultaneously and in the same time interval (orogenic period). According to the above reason, it is not possible to estimate, the duration time of cycles which also demands quantitative parameters. I underline that the model is qualitative one aimed at explanations of the regular sequence of qualitative phenomena. In particular, the objectives were  to explain the chemical and isotopic changes of key substrates and products of photosynthesis observed in the course of evolution, since they compose the main factual material based on the well known laws  carbon isotope fractionation in photosynthesis.  This material was used to restore the related climatic changes and the biotic turnover in repetitive orogenic cycles (in the course of evolution) .

2. The reviewer 1:

More information about the supercontinental cycles and the timing of orogenic periods can be provided.  In Figure 4, the scale is absent. It could help in estimating major processes occurring during the evolution of biosphere. More information about the supercontinental cycles and the timing of orogenic periods can be provided.

Reply:

Fig.4, this is not a graph, based on exact coordinates, but a diagram that shows qualitative changes that occur during geological time. For example,, in the early orogenic cycles, with a low oxygen content in the atmosphere, the influence of reduced forms of sulfur,  recovered in the subduction zone was manifested in the form of the prevalence of sulfur-oxidizing bacteria that spresd over the planet and provide a significant contribution to sedimentary organic matter.

3. The reviewer 1:

In Figure 4, the spelling of “geosynclinal” should be corrected. Figure 3 is absent, and there are two figures 8 in the manuscript.  In the first Figure 8, the text inside the figure is in Russian.

2. Reply :

The 3 reviewer's comments are justified.  The spelling of “geosynclinal”  is fixed .  Figure 3 is found and restored in the text. Figure 8 is corrected as well. The Russian  spelling on Fig.8 is removed .

4. The reviewer 1:

There are several other stylistic and technical issues throughout the paper that need to be fixed. In the title, redox cycle should be without hyphen. In the abstract, the word “system” could be replaced by “structure” or “system” which is more relevant. What is “minimumCCc” (line 20 in the Abstract)? References in the abstract, in general, should be avoided, but in this particular case one reference can be kept and its format should include the journal name, year and volume: Ivlev, A.A. Biosystems 2015, 137, 1–11.

Reply : All reviewer's recommendations are accepted and taken into account.

5. The reviewer 1:

There are several other stylistic and technical issues in the article that need to be addressed. The name of the redox cycle should be without a hyphen. In the abstract, the word “machine” could be replaced by “structure” or “system”, which is more appropriate. What is “minimumcc” (line 20 in the annotation)? References in the abstract, as a rule, should be avoided, but in this particular case, one link can be saved, and its format should include the name of the journal, year and volume: Ivlev A.A. Biosystems 2015, 137, 1-11.

Reply :

All minor mistakes, marked by reviewer are corrected. I decided to save the word "machine" otherwise there is a confusion with other  terms "systems"  that have another meaning.

Reference in the abstract is corrected.

6. Reviewer 1:

It is better to write the author's name in full, this also applies to the names of researchers in the text, for example, write Vladimir Vernadsky instead of V.I. Vernadsky.

Reply :

All reviewer's recommendations are accepted and corresponding corrections are inserted into the text.

Author Response File: Author Response.pdf

Reviewer 2 Report

The author of the paper “A new view on the global redox-cycle of biosphere carbon” presents a very interesting revisited interpretation of the earth carbon cycle that is worthy of publication on the Journal of Carbon Research.

However, the findings are presented in a form that is difficult to read and understandand. Besides, some concepts should present in deeper details, with a more recent terminology, and with updated citations.

For these reasons I think the paper should be published after a major revision of the text.

In particular:

Some concepts, such as the CO2/O2 ratio in relation to orogenic cycles, CO2 fluxes from the subduction zones, carbon isotopic variations in relation to predominant biological processes, photosynthetic pulsations, temperature variations with CO2 and orogenic cycles, sulfate reduction process in the subduction zone, changes of photosynthetic conditions in different stages of the orogenic cycles, are repeated many times in the text so that it becomes too long and discursive. I think that the reading of the text could be clearer if the author introduces all these concepts at the beginning of the text in an introduction and after presents the connections and the findings in a discussion section.

In the introduction the author could also give more details about the orogenic cycles that took place in the past (number, intensity, duration, etc.)

The various data are presented in different figures that refer roughly to the same time scale so I think the understandability of the text could improve with a single figure comprising  all the parameter discussed in the text and drown on the same time scale.

The author should clear distinguish what is the previous data and interpretations in a paragraph about the state of the art and what is the new interpretation and his contribution in the discussion section.

As regard the origin of the movement of the tectonic plates on the Earth it needs to write that the interaction between celestial bodies is one of the theories and not the only, in fact there is also the theory of the internal Earth processes. But in any case, this origin is not essential as regard the discussion and findings  developed in the text.

A regard the subduction, this happens also between two oceanic plates and not only between oceanic and continental plates so the author should correct this in the text.

The term geosynclinals is very obsolete, I think the author should use a more appropriate term referring to periods of low tectonic activity of the Earth.

The sulfates that reduce in the subduction zones are present both in the gypsum and also in the anhydrite and in the dissolved form in the marine waters so the authors should be more general or specify all these components.

The author does not mention anyway the processes that regard the present CO2 extraction from the internal Earth by fossil fuel combustion. This is changing the CO2 geological cycle: a little notation about this new process that could affect the next orogenic cycle could be inserted in the discussion and conclusion.

Some minor revision:

The English of some sentences is difficult to understand, may be a revision of the language style could improve the understanding of the text.

I suggest to use the word ipoxic or low oxygen level instead of anoxic that means completely absence of oxygen.

Row 139: may be the author refers to equation 3 instead of 4

Figure 8: the legend inside the figure should be translated.

 

Author Response

I am grateful to the reviewer 2 for the comprehensive reading of the article and the critical comments done. Some of them turned out to be very useful and were used by the author to improve the article.

1. Reviewer 2

"....the results are presented in a form that is difficult to read and understand. In addition, some concepts should be presented in more detail, with more up-to-date terminology and updated citations.    ...For these reasons, I believe that the article should be published after a serious revision of the text.

Reply :

It would be strange if, after publishing a dozen articles and a monograph, I suddenly abruptly changed the terminology that I had largely adopted from my predecessors, in particular, from Rutten's monograph "The Origin of Life". However, I admit that not being a native English-speaking person, not all my  phrases that may encountered in the text are clear. Therefore,  I tried to make the essence of what I was saying to be accurate as possible. Nevertheless some expressions  could remain unsuccessful.  I reviewed once again the entire text to eliminate possible errors.

2. Reviewer 2

I think the paper should be published after a major revision of the text. In particular, some concepts, such as the CO2/O2 ratio in relation to orogenic cycles, CO2 fluxes from the subduction zones, carbon isotopic variations in relation to predominant biological processes, photosynthetic pulsations, temperature variations with CO2 and orogenic cycles, sulfate reduction process in the subduction zone, changes of photosynthetic conditions in different stages of the orogenic cycles, are repeated many times in the text so that it becomes too long and discursive. I think that the reading of the text could be clearer if the author introduces all these concepts at the beginning of the text in an introduction and after presents the connections and the findings in a discussion section.

Reply :

At the beginning of the review, the author listed many topics considered by the model: "Some concepts, such as the CO₂/O₂ ratio due to orogenic cycles, CO₂ fluxes from the subduction zones, changes in carbon isotopes due to prevailing biological processes, pulsations of photosynthesis, temperature fluctuations due to CO₂ and orogenic cycles, the process of reduction of sulfates in the subduction zone, changes in photosynthesis conditions at various stages of the subduction process. orogenic cycles. I think if I had followed the reviewer's advice, the introduction would have turned into a small monograph and the essence of the article would have drowned in it. On the contrary, I have deleted all the points that are not directly related to the topic, replacing them with the references to the previously published works. On the contrary,

I focused on two main points. One of them concerns the geological part of the article - the uneven movement of lithospheric plates, consisting of a short-term orogenic period and a long-term geosynclinal period. Thjis part of the article is based mainly on the materials of the predecessors. Another point concerns the biosphere topic, which includes the evolution of photosynthesis and its mechanism, and the fractionation of carbon isotopes in photosynthesis, including their relationship with evolution (with changes in environmental conditions in geological time). This part is based mainly on the results of my own researches.  Special attention was paid to the relationship between the geological and biospheric parts of the model , i.e. to sulfate reduction reaction, in which organic matter is oxidized and resultant CO2 necessary for photosynthesis is produced. I came to this presentation way after 8 years of publishing experience.

3. Reviewer 2

As for the origin of the movement of tectonic plates on Earth, it is necessary to write that the interaction between celestial bodies is one of the theories, and not the only one, in fact, there is also a theory of internal terrestrial processes. But in any case, this origin is not essential from the point of view of the discussion and conclusions set out in the text.

Reply:

I completely agree with this remark. The text is amended.

4. Reviewer 2

As for subduction, it also occurs between two oceanic plates, not just between oceanic and continental plates, so the author should correct this in the text.

Reply:

 I completely agree with this remark. The text has also been amended accordingly. A small addition is that I have considered the subduction only between the oceanic and continental plates, since only on the continental plates  the sedimentary organic matter is accumulated  which is oxidized further.

5. Reviewer 2

The term "geosyncline" is very outdated, I think the author should use a more appropriate term referring to periods of low tectonic activity of the Earth.

Reply :

I used only the terms "geosynclinal and orogenic periods, which I borrowed from Rutten's monograph and used in all previously published works. I explained their meaning in my very first work (Ivlev, BioSystems, 2015). I didn't use the term "geosyncline".

6. Reviewer 2

Sulfates that are reduced in the subduction zones are present in both gypsum and anhydrite, as well as in dissolved form in marine waters, so the authors should be more general or specify all these components.

Reply:

I agree with the remark partly, since as oxidizer acts the oxygen of sulfate-ions taken from gypsum and anhydrate. Clarifications in the text have been made. The dissolved sulfates do not get in the subduction zone.

7. Reviewer 2

In any case, the author does not mention the processes that relate to the current extraction of CO2 from the bowels of the Earth by burning fossil fuels. This changes the geological cycle of CO2: a small note about this new process, which may affect the next orogenic cycle, could be included in the discussion and conclusion.

Reply:

The reviewer is right.  I did not consider modern orogenic cycles (oscillations), as they are out of the scope of the article.

8. Reviewer 2

The English language of some sentences is difficult to understand, perhaps a revision of the language style could improve the understanding of the text.

I suggest using the word ipoxic or low oxygen level instead of oxygen-free, which means no oxygen at all.

Reply : I took into account this remark. I tried to improve the language style and used word ipoxic instead of oxygen-free.

Reviewer 2

Minor corrections:

Line 139: Perhaps the author refers to equation 3 instead of 4

Figure 8: The symbols inside the figure should be translated.

Reply :

I took into account all the minor comments. Appropriate corrections have been made in the text of the article.

Author Response File: Author Response.pdf

Reviewer 3 Report

This article discusses on the new view on the global redox-cycle of biosphere carbon. The viewpoint of this article is very novel. However, it was obscure and difficult to understand. I suggest that the author reorganize their viewpoints and present them to the readers in a more concise manner. Therefore, I recommend Reconsider after major revision. 

Author Response

Reviewer 3                                           

This article discusses a new perspective on the global redox cycle of carbon in the biosphere. The point of view presented in this article is very new. However, it was unclear and difficult to understand. I suggest that the author reorganize his points of view and present them to readers in a more concise form. Therefore, I recommend reviewing it after serious revision.  

Reply :

Since the reviewer 3 didn't make any specific comments, I couldn't understand what seemed unclear and difficult to understand the article. However, since his conclusions coincided with the conclusions of the reviewer 2, I can only refer to the answers of reviewer 2.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The author accepted almst (but not all) my suggestion so I suggest to publish the paper with only some little corrections indicatedin the attacched document.

Best regards.

Comments for author File: Comments.pdf

Author Response

Replies to corrections of Reviewer 2: 

I am very grateful to Reviewer 2 for  help in editing the English translation. All proposed minor revisions were accepted and included into the text (highlighted in red). Failed expressions are fixed.

Reviewer 3 Report

The work is novel. Therefore, the author should try best to make it easier for the potential readers to understand. I strongly recommend that the author could rephrase the manuscript according to the instructions suggested by the Carbon journal. For example, the Introduction section is missing. This section is very important for readers as it could  tell us he importance and innovation of this work. In addition, the other sections of the revised manuscript should add the number to make them more organized. The conclusion section is tediously long, and should be written in a more concise way.

Author Response

Replies to notes of Reviewer 3

Reviewer 3:

The work is novel. Therefore, the author should try best to make it easier for the potential readers to understand. I strongly recommend that the author could rephrase the manuscript according to the instructions suggested by the Carbon journal. For example, the Introduction section is missing. This section is very important for readers as it could  tell us he importance and innovation of this work. In addition, the other sections of the revised manuscript should add the number to make them more organized. The conclusion section is tediously long, and should be written in a more concise way.

Reply:

The Introduction section is inserted into the text. The numbering of all sections is introduced. The conclusion is as shortened as possible.