Estimation of Carbon Stocks and Stabilization Rates of Organic Matter in Soils of the «Ladoga» Carbon Monitoring Site

Round 1

Reviewer 1 Report

The manuscript brings an evaluation of two soils that encompass “carbon polygon” region/program of Russia. They provide a characterization of soil in terms of microbial activity and humic acid characteristics along soil profile, comparing the regions. However, they have 8 different samples, and the labels of samples are not consistent throughout the text. Sometimes just part of labels is shown (Fig 5 and 6) and sometimes they are changed to a number (Fig 7 and 9), making very difficult to follow the results and discussion; even when they make comparison among other soils and works. Further, the labels are not self-explicative, which is hard to the reader make associations to the areas of study and samples. This way, the reading is not so fluid. The motivation of the paper is good, aiming soil characterization, especially for Russia, improving soils dataset; and also considered carbon sequestration and climate change. But there is a lack of information regarding the novelty to improve the reach of manuscript. It is not a monitoring paper that followed the change of organic matter over the years, it deals more of a soil characterization where the significance of study area is not so clear.

Page 2, introduction – The authors mention the climate change, the worry about carbon sequestration, the huge territory area of Russia, and the carbon polygons of Russia program. However, the importance of the study area should be highlighted. Why was the Ladoga area chosen?

Page 2, introduction – The novelty of the paper is not so clear. The author should claim attention to the new information that this paper brings compared with already is available on literature. This should be a link with the previous question, once the importance to evaluate Ladoga area should be pointed out.

Page 2, line 91 – “by fluvioglacial eskers relief orm”.. please, check this statement and clarify the information. Further, the location of Ladoga near eskers is an important information to highlight the study area on Introduction section, where this information can be more explored.

Page 3, line 101 – The number of days recorded raining and precipitation are always so precisely? Please, think about to add this information as an average among the years.

Page 3, figure 1 – “Soil ID..” What is ID? Identification? Please add the complete information of this abbreviation once it is the first time it shows up in the document.

Page 4, line 120 – Check the parentheses in ..”CaCl2 extract”

Page 4, section “2.2.2” – Where is the description for humic acid extraction method? It is described on section 2.2.3 but HA is firstly mentioned at 2.2.2.

Page 4, table 2 – Please check the table description and add more information about its content, as well as check the line 153 were table 2 is mentioned to have “parameters of studied HA” and not area or yield percentage (please also correct the word “yield” on table.

Page 8, table 3 – What about ash content? At section 2.2.2 the authors mentioned that O content was determined by difference considering C, N, H, and ash. However, the sum of C, N,H, and O in table are 100. Further, the information of percentage as unit of measurement is missing. Please check the calculations and review the Van Krevelen diagram.

Page 10, line 260 – The percentage, how was it calculated? Please add this information in the 2.2.3 section.

Author Response

Response to a review of the manuscript “Estimation of carbon stocks and stabilization rates of organic matter in soils of the «Ladoga» monitoring site”.

Dear reviewer!

Thank you for your comments, they were completely taken into account, which improved the quality of the article for publication in Journal.

Text that has been changed is marked by yellow color.

General comments:

1. The manuscript brings an evaluation of two soils that encompass “carbon polygon” region/program of Russia. They provide a characterization of soil in terms of microbial activity and humic acid characteristics along soil profile, comparing the regions. However, they have 8 different samples, and the labels of samples are not consistent throughout the text. Sometimes just part of labels is shown (Fig 5 and 6) and sometimes they are changed to a number (Fig 7 and 9), making very difficult to follow the results and discussion; even when they make comparison among other soils and works. Further, the labels are not self-explicative, which is hard to the reader make associations to the areas of study and samples. This way, the reading is not so fluid. The motivation of the paper is good, aiming soil characterization, especially for Russia, improving soils dataset; and also considered carbon sequestration and climate change. But there is a lack of information regarding the novelty to improve the reach of manuscript. It is not a monitoring paper that followed the change of organic matter over the years, it deals more of a soil characterization where the significance of study area is not so clear.

Response: Thank you! We have provided uniform labeling of soil labels throughout the text, which has improved the perception of this paper.

 

2. Page 2, introduction – The authors mention the climate change, the worry about carbon sequestration, the huge territory area of Russia, and the carbon polygons of Russia program. However, the importance of the study area should be highlighted. Why was the Ladoga area chosen? Page 2, introduction – The novelty of the paper is not so clear. The author should claim attention to the new information that this paper brings compared with already is available on literature. This should be a link with the previous question, once the importance to evaluate Ladoga area should be pointed Page 2, line 91 – “by fluvioglacial eskers relief orm”.. please, check this statement and clarify the information. Further, the location of Ladoga near eskers is an important information to highlight the study area on Introduction section, where this information can be more explored.

Response: Thank you! We reworked Introduction, the MM and Discussion section to highlight the importance of the study area and novelty of the paper.

 

3. Page 3, line 101 – The number of days recorded raining and precipitation are always so precisely? Please, think about to add this information as an average among the years.

Response: Thank you! We improve the data about weather.

 

4. Page 3, figure 1 – “Soil ID..” What is ID? Identification? Please add the complete information of this abbreviation once it is the first time it shows up in the document.

Response: Thank you! We remove soil ID from the article.

 

5. Page 4, line 120 – Check the parentheses in ..”CaCl2 extract”

Response: It was corrected.

 

6. Page 4, section “2.2.2” – Where is the description for humic acid extraction method? It is described on section 2.2.3 but HA is firstly mentioned at 2.2.2.

Response: Thank you! It was corrected.

 

7. Page 4, table 2 – Please check the table description and add more information about its content, as well as check the line 153 were table 2 is mentioned to have “parameters of studied HA” and not area or yield percentage (please also correct the word “yield” on table.

Response: Thank you! The table 2 was reworked.

 

8. Page 8, table 3 – What about ash content? At section 2.2.2 the authors mentioned that O content was determined by difference considering C, N, H, and ash. However, the sum of C, N,H, and O in table are 100. Further, the information of percentage as unit of measurement is missing. Please check the calculations and review the Van Krevelen diagram.

Response: Thank you! C,H,N content was obtained by the element analyzer, the oxygen content was calculated taking into account the ash.

 

9. Page 10, line 260 – The percentage, how was it calculated? Please add this information in the 2.2.3 section.

Response: Thank you! The spectra was calculated in Mnova software. We added the information in MM section.

 

Thank you for work of our article.

Sincerely,

Junior researcher of Saint-Petersburg State University, Vyacheslav I. Polyakov,

Professor of Saint-Petersburg State University, Evgeny V. Abakumov.

Reviewer 2 Report

Review

1.     The title of the manuscript “Estimation of carbon stocks and stabilization rates of organic matter in soils of the «Ladoga» carbon polygon”must be changed, since one of the meanings of the word "polygon" has a military meaning. Please, change.

2.     The word "Russia" is used at least 29 times in the manuscript in the text. It is understandable that this word can be used where it is absolutely necessary: to the contacts, to the reference list, but not so many times... This suggests that the topics of the article are not at the international level, but, on the contrary, at the local level. Which indicates the inconsistency of the article with the international level and scope of the journal.

3.     In Keywords: instead of "carbon polygon:", please,, include "soil", or soil type name.

4.     It's unclear if there's a thick black winding line in Figure 2. shows what height is above sea level?if so, it should be visible on the "y" axis, in m.

5.     Extraction ?yelds?, %, in Table 2? Please, correct the mistake.

6.     The sentence „Nitrogen carbon enrichment is very low throughout the profile“ is incomprehensible, like some others in the manuscript. English should be edited.

7.     In the conclusions, it should be considered in more detail what properties of soil genesis determine the carbon sequestration potential.

Author Response

Response to a review of the manuscript “Estimation of carbon stocks and stabilization rates of organic matter in soils of the «Ladoga» monitoring site”.

Dear reviewer!

Thank you for your comments, they were completely taken into account, which improved the quality of the article for publication in Journal.

Text that has been changed is marked by yellow color.

General comments:

1. The title of the manuscript “Estimation of carbon stocks and stabilization rates of organic matter in soils of the «Ladoga» carbon polygon”must be changed, since one of the meanings of the word "polygon" has a military meaning. Please, change.

Response: Thank you! It was corrected.

 

2. The word "Russia" is used at least 29 times in the manuscript in the text. It is understandable that this word can be used where it is absolutely necessary: to the contacts, to the reference list, but not so many times... This suggests that the topics of the article are not at the international level, but, on the contrary, at the local level. Which indicates the inconsistency of the article with the international level and scope of the journal.

Response: Thank you! We reworked the Introduction, Results and Discussion section, and increase the scope of work.

 

3. In Keywords: instead of "carbon polygon:", please,, include "soil", or soil type name.

Response: Thank you! It was corrected.

 

4. It's unclear if there's a thick black winding line in Figure 2. shows what height is above sea level?if so, it should be visible on the "y" axis, in m.

Response: The figure 2 was reworked

 

5. Extraction ?yelds?, %, in Table 2? Please, correct the mistake.

Response: Thank you! The Table 2 was reworked.

 

6. The sentence „Nitrogen carbon enrichment is very low throughout the profile“ is incomprehensible, like some others in the manuscript. English should be edited.

Response: The sentence has been removed.

7. In the conclusions, it should be considered in more detail what properties of soil genesis determine the carbon sequestration potential.

Response: Thank you! We reworked discussion and conclusion sections.

 

Thank you for work of our article.

Sincerely,

Junior researcher of Saint-Petersburg State University, Vyacheslav I. Polyakov,

Professor of Saint-Petersburg State University, Evgeny V. Abakumov.

 

Reviewer 3 Report

Research of the monitoring climatic processes as well as emission and deposition of carbon compounds are timely and necessary due to climate and biosphere protection around the world. However, your study focuses only on two types of soils. In this paper, I could not find sufficiently convincing and statistically confirmed data that would confirm the justification of the proposed scientific hypotheses and conclusions. The purpose of the study is linked to one region of Russia and a specific climate, so the relevance of the described soil research is narrow. The number of experimental samples and the statistical reliability of the obtained data should be specified. Also, using standard deviation, which is a measure of how much the values are dispersed compared to the average value, which would also help a clearer understanding of the obtained results.

As a recommendation for presenting the results of this study, the authors must clarify and unify the names and terms in the entire description of the experiment, and it is also necessary to harmonize the results in the text and in the tables and figures.

Authors should provide sufficient detail tables and figures. Figure 1 is not to scale. The papers contains inconsistent and unclear markings. The Horizon boundaries of the profiles (Table 1) are presented very differently (OE, A/E, Bs, B/C, C and Hi_1-3, He_1-2). Master horizon characteristics and some subordinate horizon designations should be followed more consistently. In Table 4, AL and Al, as well as AR and Ar.

There are some very old literary sources (23, 28), or of marginal importance. References 20, 23 are from marginal journals, e. g. "Bulletin of the Leningrad state University„ and similar.

Soil organic carbon stocks are generally expressed in tones or Mg per hectare for a nominated depth. In this paper, carbon content is given without reference to depth. The depth of samples CP-1 and CP-2 is very different, 79 cm and 50 cm respectively.

The rearrangement of familiar names in "four ppm" (lines 50-52) makes reading difficult. Must be The international "4 per 1000" Initiative.

 

In the results section, analyzed data (in figures 5 and 6) carbon and nitrogen amounts are from the literature source WRB [26]. Other data were obtained by the authors themselves. The authors' ability to use and interpret these results needs to be clarified

Figure 7 shows the van Krevelen diagram. This diagram is based on an old paper [28] and its interpretation is questionable. Because with only 8 sample data, forming general regularities and describing trend lines is risky. There is a lack of data and evidence of statistical reliability that this is not a random point.

Methods of data statistical evaluation are not described. Authors should provide sufficient detail about statistical analysis.

 

 

Author Response

Response to a review of the manuscript “Estimation of carbon stocks and stabilization rates of organic matter in soils of the «Ladoga» monitoring site”.

Dear reviewer!

Thank you for your comments, they were completely taken into account, which improved the quality of the article for publication in Journal.

Text that has been changed is marked by yellow color.

1. Research of the monitoring climatic processes as well as emission and deposition of carbon compounds are timely and necessary due to climate and biosphere protection around the world. However, your study focuses only on two types of soils. In this paper, I could not find sufficiently convincing and statistically confirmed data that would confirm the justification of the proposed scientific hypotheses and conclusions. The purpose of the study is linked to one region of Russia and a specific climate, so the relevance of the described soil research is narrow. The number of experimental samples and the statistical reliability of the obtained data should be specified. Also, using standard deviation, which is a measure of how much the values are dispersed compared to the average value, which would also help a clearer understanding of the obtained results.

Response: Thank you! We added the statistical information in Tables 3 and 4 as well as in MM section.

 

2. As a recommendation for presenting the results of this study, the authors must clarify and unify the names and terms in the entire description of the experiment, and it is also necessary to harmonize the results in the text and in the tables and figures.

Response: Thank you! We have unified the names of the soils in the text of the article.

 

3. Authors should provide sufficient detail tables and figures. Figure 1 is not to scale. The papers contains inconsistent and unclear markings. The Horizon boundaries of the profiles (Table 1) are presented very differently (OE, A/E, Bs, B/C, C and Hi1-3, He1-2). Master horizon characteristics and some subordinate horizon designations should be followed more consistently. In Table 4, AL and Al, as well as AR and Ar.

Response: Thank you! It was corrected.

 

4. There are some very old literary sources (23, 28), or of marginal importance. References 20, 23 are from marginal journals, e. g. "Bulletin of the Leningrad state University„ and similar.

Response: Thank you! Yes, it’s classical literature in the studied topic. Most of the literature list has been published in the last 10 years.

 

5. Soil organic carbon stocks are generally expressed in tones or Mg per hectare for a nominated depth. In this paper, carbon content is given without reference to depth. The depth of samples CP-1 and CP-2 is very different, 79 cm and 50 cm respectively.

Response: Thank you! Figures 5 and 6 show the carbon and nitrogen content of the soil horizons at different depths. In our opinion, the kg*m^-2 dimension is the most suitable for this research, because the study area is concentrated on a small territory.

 

6. The rearrangement of familiar names in "four ppm" (lines 50-52) makes reading difficult. Must be The international "4 per 1000" Initiative.

Response: Thank you! It was corrected.

 

 

7. In the results section, analyzed data (in figures 5 and 6) carbon and nitrogen amounts are from the literature source WRB [26]. Other data were obtained by the authors themselves. The authors' ability to use and interpret these results needs to be clarified.

Response: Thank you! In figures 5 and 6 our own data from the investigated soil profiles, we corrected figures. The data obtained provide information about the processes occurring in molecular level in soil organic matter and provides information about the stocks and content of organic matter in the studied soils.

 

8. Figure 7 shows the van Krevelen diagram. This diagram is based on an old paper [28] and its interpretation is questionable. Because with only 8 sample data, forming general regularities and describing trend lines is risky. There is a lack of data and evidence of statistical reliability that this is not a random point.

Response: The diagram is a common and widespread study of the elemental composition of humic acids. We added the additional information about statistical data.

 

Thank you for work of our article.

Sincerely,

Junior researcher of Saint-Petersburg State University, Vyacheslav I. Polyakov,

Professor of Saint-Petersburg State University, Evgeny V. Abakumov.

Round 2

Reviewer 2 Report

 Please do not repeat the obsessively "carbon polygon" and "Russia"... Instead, it is more appropriate to use "study site", "carbon monitoring site", soil researched", as in the now revised name. The country in which the research was conducted is not "the center of the world", and there is no need to put accents on it. 

Author Response

Response to a review of the manuscript “Estimation of carbon stocks and stabilization rates of organic matter in soils of the «Ladoga» monitoring site”.

Dear reviewer!

Thank you for your comments, they were completely taken into account, which improved the quality of the article for publication in Journal.

Text that has been changed is marked by red color.

 

General comments:

1. Please do not repeat the obsessively "carbon polygon" and "Russia"... Instead, it is more appropriate to use "study site", "carbon monitoring site", soil researched", as in the now revised name. The country in which the research was conducted is not "the center of the world", and there is no need to put accents on it.

Response: Thank you! We removed the term “carbon polygon” and words “Russia”.

 

Thank you for work of our article.

Sincerely,

Junior researcher of Saint-Petersburg State University, Vyacheslav I. Polyakov,

Professor of Saint-Petersburg State University, Evgeny V. Abakumov.

Reviewer 3 Report

There are quite a few changes in the works, but this introduces even more noticeable inaccuracies.

Data on the extraction procedure are added in Table 2. Added data on the mass of the samples and the mass of the extracted HAs, but these data do not in any way give the exact result that the authors present in the column "extraction yields of HAs, %". It is necessary to clarify how this characteristic is calculated.

In Table 3, the data have also been changed, the ratio H/C has disappeared, and it were calculated in an unclear way the ratios O/C and H/C mod. It is necessary to clarify the data, as well as their presentation and labeling.

Fig. 7 shows the Krevelen diagram, which is based on a very old source [28]. this work, "van Krevelen, D.W. Studies of gas absorption. VI. A graphical representation for the efficiency of physical absorption. Recueil 520 des Travaux Chimiques des Pays-Bas 1950, 69, 503-508, doi:10.1002/recl.19500690416. " is intended for gas adsorption analysis. This source cannot be found or is cited inaccurately. There are many more recent works that would be more appropriate sources of information and examples of how to perform analysis based on the author's chosen van Krevelen diagram.

van Krevelen diagrams are graphical plots of the elemental H:C versus O:C ratios of the molecular formulas, which assign the components into chemical classes in the van Krevelen space. There are quite a lot of descriptions in the literature where stoichiometric ranges are used to establish boundaries of the classification spacefor the components found in natural organic matter. For example:

Nicole DiDonato, Hongmei Chen, Derek Waggoner, Patrick G. Hatcher. Potential origin and formation for molecular components of humic acids in soils. Geochimica et Cosmochimica Acta, Volume 178, 2016, Pages 210-222, ISSN 0016-7037, https://doi.org/10.1016/j.gca.2016.01.013. (https://www.sciencedirect.com/science/article/pii/S0016703716000387)

Sleighter, R. L.; Hatcher, P. G. The application of electrospray ionization coupled to ultrahigh resolution mass spectrometry for the molecular characterization of natural organic matter. J. Mass Spectrom. 2007, 42 (5), 559–574.

TSUTOMU OHNO,* , † ZHONGQI HE, ‡ RACHEL L. SLEIGHTER, § C. WAYNE HONEYCUTT, ‡ AND PATRICK G. HATCHER.  Ultrahigh Resolution Mass Spectrometry and Indicator Species Analysis to Identify Marker Components of Soil- and Plant Biomass-Derived Organic Matter Fractions. ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 44, NO. 22, 2010.  2010 American Chemical Society Published on Web 10/19/2010. https://pubs.acs.org/doi/pdf/10.1021/es101089

 

Fig. 9 is different in the original and revised versions of the article. The data in Table 4 and the names of the axes in Figure 9 of the graph match, but the graph in the current version ( C,H -AL/ O,N – AL and AL h,r+AR h,r and the graph points do not correspond to those given in Table 4.. In the initial version the points on the graph coincided with the values in the table

There should not be such ambiguities and inaccuracies in the work.

In Table 3, numbers are separated by commas, and there must be a dot.

I recommend that the authors carefully review the data presentation again.

Author Response

Response to a review of the manuscript “Estimation of carbon stocks and stabilization rates of organic matter in soils of the «Ladoga» monitoring site”.

Dear reviewer!

Thank you for your comments, they were completely taken into account, which improved the quality of the article for publication in Journal.

Text that has been changed is marked by red color.

 

General comments:

1. Data on the extraction procedure are added in Table 2. Added data on the mass of the samples and the mass of the extracted HAs, but these data do not in any way give the exact result that the authors present in the column "extraction yields of HAs, %". It is necessary to clarify how this characteristic is calculated.

Response: Thank you! We added the formula in MM section.

 

2. In Table 3, the data have also been changed, the ratio H/C has disappeared, and it were calculated in an unclear way the ratios O/C and H/C mod. It is necessary to clarify the data, as well as their presentation and labeling.

Response: Thank you! We corrected the data.

 

3. 7 shows the Krevelen diagram, which is based on a very old source [28]. this work, "van Krevelen, D.W. Studies of gas absorption. VI. A graphical representation for the efficiency of physical absorption. Recueil 520 des Travaux Chimiques des Pays-Bas 1950, 69, 503-508, doi:10.1002/recl.19500690416. " is intended for gas adsorption analysis. This source cannot be found or is cited inaccurately. There are many more recent works that would be more appropriate sources of information and examples of how to perform analysis based on the author's chosen van Krevelen diagram.

Response: Thank you! We changed the reference.

 

4. 9 is different in the original and revised versions of the article. The data in Table 4 and the names of the axes in Figure 9 of the graph match, but the graph in the current version ( C,H -AL/ O,N – AL and AL h,r+AR h,r and the graph points do not correspond to those given in Table 4.. In the initial version the points on the graph coincided with the values in the table

Response: Thank you! We corrected the data.

5. In Table 3, numbers are separated by commas, and there must be a dot.

Response: Thank you! It’s done.

 

Thank you for work of our article.

Sincerely,

Junior researcher of Saint-Petersburg State University, Vyacheslav I. Polyakov,

Professor of Saint-Petersburg State University, Evgeny V. Abakumov.