Assessment of the Hydrochemical Characteristics of the Carbon Observational Site ‘Carbon-Sakhalin’ (Aniva Bay, Sea of Okhotsk)

Round 1

Reviewer 1 Report

Comments 

1.What about specific surface area.?? the authors missed to provide any logical expectations for the improved surface area before carrying out experiments, making such standing point a bit weak.

2. The abbreviation in this article is confused; such abbreviations should be defined when they appear for the first time in the article.

3. The text is not well-organized including many typo and grammatical errors. The English level is very poor. Some main arguments are not supported by results.

4. The authors needs to add more explanation by comparison some latest work as as Graphitic Carbon Nitride Composites with Gold and ZIF-67 Nanoparticles as Visible-Light-Promoted Catalysts for CO₂ Conversion and Bisphenol A Degradation and and Efficient CO2 conversion and organic pollutants degradation over Sm3+ doped and rutile TiO2 nanorods decorated-GdFeO3 nanorods

5.Abstract should be refined

The text is not well-organized including many typo and grammatical errors. The English level is very poor. Some main arguments are not supported by results.

Author Response

We are very grateful to the reviewer for his valuable comments.

Here our poit to point answers:

1. Russia is still at the very beginning of the way to assess carbon emissions in the coastal zone of our seas. The observational site ‘Carbon-Sakhalin’ is one of the first marine poligon in Russia. In 2022, the first All-Russian experiment to limit greenhouse gas emissions was launched in accordance with Federal Law No. 34-FZ dated 03/06/2022 "On conducting an experiment to limit greenhouse gas emissions in certain subjects of the Russian Federation". To solve the problem of estimating and reducing CO2 emissions, as well as possible ways of sequestering carbon, the most studied water area of the Sea of Okhotsk, was selected. Aniva.  Aniva bay is located close to the scientific centers, has a developed infrastructure that provides convenient access to experimental sites. 

We add this comments to the introduction section.

2. All abbreviations in the text are checked and deciphered after the first mention.

3. After making edits to the article, the grammar will be corrected by a native speaker. We have significantly revised the conclusion and added more specific results there.

4. Thanks a lot for the comment. We cited these articles in the discussion section.

5. We have significantly revised absract. You can see it in the ne version of manuscript.

Reviewer 2 Report

The article delves into the establishment of a carbon polygon in Sakhalin Oblast, focusing on evaluating oceanic greenhouse gas emissions and the potential implementation of carbon farms for CO2 absorption. It explores the analysis of hydrochemical parameters in Aniva Bay to understand the marine ecosystem's carbon balance. Covering data from 1948 to 1994, the study reveals spatial and seasonal fluctuations in oxygen levels, pH, and biogenic matter, including inorganic phosphorus, nitrogen, and silicon. Overall, the paper is both fascinating and well-written. Here are some comments:

1-The abstract should be enhanced to include specific numerical outcomes reflecting the research findings.

2-Strengthening the literature review is imperative to ensure comprehensive coverage of prior research on the topic. This would help situate the study within the existing body of knowledge and identify potential gaps or areas for further exploration.

3-Why is the creation of a carbon polygon in Sakhalin Oblast necessary, and how does it align with the global shift towards carbon neutrality?

4-How do hydrochemical parameters in Aniva Bay serve as indicators of the marine ecosystem's carbon balance?

5-What notable spatial and temporal patterns emerged in the distribution of oxygen, pH, and biogenic matter?

6-What insights do the findings offer into seasonal variability in hydrochemical processes?

7-How can the data collected contribute to the potential deployment of carbon farms for CO2 absorption in the region?

8-The conclusion should be reworked to highlight key observations and insights gleaned from the research, emphasizing its significance and potential implications for future studies or practical applications.

Moderate editing of English language required

Author Response

We are very grateful to the reviewer for his valuable comments.

Here our poit to point answers:

1. We add to the abstract more detailed results with specific numerical outcomes.

2. Thank you so much for your comment. We have checked the references to recent works once again and significantly expanded the list of references.

3. The network of Carbon Polygons in Russia is created on a competitive basis and is funded by the Ministry of Science and Higher Education of the Russian Federation and business.

Financing is possible only after assessment the regional legislation in limiting greenhouse gas emissions, a regional system of carbon regulation, an inventory of all types of emissions and integral estimates of greenhouse gas emissions and absorption, the capabilities of scientific organizations, the complexity of the approach, the presence of a variety of non-urbanized ecosystems.

The total greenhouse gas emissions in the Sakhalin Region were 12.333 million tons e-CO₂;  total net greenhouse gas absorption  were 11.068 million tons e-CO₂ (only  by forest lands) in the Sakhalin Region in 2019 [Report, 2021]. The total net greenhouse gas emissions in the Sakhalin Region amounted to 1.265 million tons of e-CO₂ in 2019. [Report, 2021].

Marine ecosystems and blue carbon were not included in the accounting. Therefore, the study of greenhouse gas fluxes in coastal marine ecosystems and the assessment of net absorption and emissions for subsequent inclusion in the national plan adaptation and mitigation of Russia is our strategic mission. The adaptation of the world's Ocean Carbon Dioxide Removal (CDR) technologies through the development of mariculture farms will help Sakhalin region quickly achieve carbon neutrality.

We add this comments to the introduction section

4. Aniva Bay is a part of the Sea of Okhotsk with the widest range of variability of natural conditions and difficult ice conditions. It is makes it impossible to conduct seasonal field observations of greenhouse gas absorption and constant monitoring of the carbon balance of the water area. The biological pump is the main part of the ocean's carbon pump [Pipko et al.,2021; Claustre et al., 2021; Ricour et al., 2023]. A many environmental factors needs for the of phytoplankton blooms as the main force of the biological carbon pump (sufficient illumination, nutrients content, acceptable temperature, a certain regime of salinity and hydrodynamics, and much more).  the range of environmental conditions is specific for each climatic zone.  And it determines the value of the primary productivity of the water area and carbon flux. Thus, the hydrological and hydrochemical conditions of the water area determine the net absorption of greenhouse gases by the marine ecosystem. Therefore, it is important to have a full-scale basis for modelling the annual cycle of carbon change in a particular ecosystem.

We add this comments to the introduction section

5. Unfortunately, the irregularity of field hydrochemical studies in Aniva Bay does not allow us to study the interannual variability of hydrochemical parameters. We have added the main features of seasonal and spatial variability Hch patameters to the Conclusions section.

6. Knowledge of seasonal and spatial variability of hydrochemical parameters in the water area of the Aniva bay, jointly with data on hydrological factors (water circulation, ice conditions, etc.), are a very important factor when choosing a location for the constructions of a carbon landfill, carbon farms and other marine facilities, as well as for calculating various risks associated with carbon emissions.

We add this comments to the Conclusions section

7. Our results showed that the availability of nutrients in  is sufficient for the mass placement of mariculture marine farms in the coastal zone of Aniva Bay. It is especially important we are shown the areas with the maximum nutrient run-off (mineral phosphorus and nitrogen) are  Salmon Bay and east coast. It is better sites for sanitary seaweed plantations for wastewater treatment or rapid absorption of CO₂ from the atmosphere [Spillias et al., 2023]. Our calculations show that when growing brown algae Saccharina japonica in of Aniva Bay for the purpose of decarbonization, it is possible to additionally sequesrate up to 49.5 thousand tons of C [Leonov et al., 2023]. Successful cultivation of algae, their timely removal from the environment (before the destruction of the thallus) and the production of biochar from them with further industrial use [Belmesov et al., 2023; Tsvetkov etal., 2023; 2024] will increase the absorption of CO₂ from the atmosphere and have a positive impact on the carbon balance of the entire region. Experimental measurements of CO₂ fluxes in the area of mariculture farms have shown a noticeable photosynthetic absorption of CO₂ from environment [Zhang et al., 2017; Han et al., 2021; Liu et al., 2022; Shi et al., 2023].

We add this comments to the Discussion

8. We have significantly expanded the Conclusion section, indicated the main seasonal and spatial features of Hch parameters, and added the practical significance of our results.

Reviewer 3 Report

The article is certainly interesting and useful both informationally and methodologically. All presented results are original and are of great importance for understanding the environmental situation in the basin of Sea of Okhotsk and coast of Sakhalin Island.  From this point of view, the results presented in the article are important for the countries bordering this region.

I think the manuscript could be accepted after some revision.

The main criticism concerns the absence or limitation of the some dates.

It will be more informative presentation of results if authors mention the following:

- The date of the creation of Carbon observational site ‘Carbon-Sakhalin’,

- The period of time in captures for each of figures, because it is not the same for all figures. For example, in Fig.5 there are results for period 2008-2023.

- Also in Abstract, it is useful to mention that presented results are not only databases for the period of 1948-1994, but engagement with sources as well as recent period. In any case, this will enhance the significance of the results.

Author Response

We are very grateful to the reviewer for his valuable comments.

Here our poit to point answers:

1. The Program of Carbon Polygon in the Sakhalin Region was approved on 09/23/2021 at Expert Council on Scientific Support for the Development of Carbon Balance Control Technologies of the Ministry of Education and Science of the Russian Federation. The observational site ‘Carbon-Sakhalin’ is one of the first marine polygon in Russia. In 2022, the first All-Russian experiment to limit greenhouse gas emissions was launched in accordance with Federal Law

We add this information to the Introduction section

2. Thanks for the comment, we have supplemented the captions to the figures with dates.

3. We have supplemented the abstract by specifying other data sources as well.

Reviewer 4 Report

Assessment of the hydrochemical characteristics of the carbon observational site ‘Carbon-Sakhalin’ (Aniva Bay, Sea of Okhotsk) is an interesting paper to read. I believe this article will be a good recent contribution to close the gap in the literature about the Aniva Bay ecosystem functioning conditions. I was pleased to see the authors conduct a thorough analysis of instrumental observations regarding hydrochemical parameters and employ numerical simulations to delve into various aspects of the marine ecosystem carbon cycle during the preceding climatic period. The author's methodology is sound, and conclusions are underpinned by results. However, the manuscript will need to undergo moderate English editing before consideration for publication in Sustainability.

 Dear authors:

Comments and Suggestions for Authors

1 . This manuscript was introduced as an assessment of the hydrochemical characteristics of the carbon observational site of the Aniva Bay which was well reported in the abstract and the introduction. However, the data is very scarce about the studies related to Aniva Bay but mostly about the Sea of Okhotsk.

2. Section 2, was expected to introduce the previously published research papers about hydrochemical parameters in the Sea of Okhotsk and Aniva Bay. However, most of the references were about the Sea of Okhotsk (Lines 210 -213, 245-249, 270-272, 283-284, and 288) and little about the Aniva Bay. Most of the hydrochemical parameters were partly found in references 39, 65-68 (line 288), and 69 (lines 292-294).

3. The authors mentioned that the research, most complete hydrochemical research of Aniva Bay, was based on available published sources and measurement databases for the period of 1948-1994 (Abstract and Lines 324-327). However,  the Aniva Bay reported data are published from 2000-2013 (lines:  301-303, references: 40-41, 43, 45, 69).

4. Assessment of the hydrochemical characteristics of the carbon observational site ‘Carbon-Sakhalin’ (Aniva Bay) was overlooked by early historical studies. Most of the data was reported from the Atlas database from 1975 to 1994. Is there any chance to support the hydrochemical parameters of Aniva Bay with recent publications? Neglecting recent publications may lead to less accurate models. Especially, the purpose of this research is to meticulously unify the data, to significantly reduce errors in subsequent numerical calculations, particularly in estimating baseline carbon absorption and emission levels in Aniva Bay.

Moderate editing of English language required.

Author Response

We are very grateful to the reviewer for his valuable comments.

Here our poit to point answers:

1. Unfortunately, there are quite a few articles directly on the Aniva Bay. An overview of the work on Aniva Bay is presented at the end of section 2. We tried to find all the mentions of Aniva bay based on the analysis of hydrochemical parameters. Since the bay belongs to the Sea of Okhotsk, we have also added an overview of the works that are dedicated to the close areas of the Sea of Okhotsk. Our main results is directly based on Aniva bay data

2. In the Section 2 we note that regular hydrochemical observations were carried out in the Aniva Bay only from 1975 to 1994. In the last 30 years, hydrochemical studies have been fragmentary and aimed at solving specific practical problems in a narrow coastal zone. Therefore, in order to understand the processes and obtain a reliable assessment of the carbon balance, information is needed in the adjacent waters of the Sea of Okhotsk.

We tried to find all the mentions of Aniva bay and it seems to us that this has been done. If you know any other articles that we forgot to mention, we would be very grateful if you would inform us in a subsequent review.

3. Indeed, the main regular studies were carried out until 1994, as indicated in the papers []. The datasets in Aniva Bay 2000-2013 is fragmentary. Complex research of hydrochemical parameters in Aniva Bay was carried out on standard cross-sections in 2001-2013 (five sets of measurements a year in 2001, 2002, 2009, and three sets in 2013). 

4. Yes, there are good chances to clarify assessments of the hydrochemical characteristics. As part of our carbon project, we plan to carry out several complex surveys in 2024 and continue monitoring in the future. This will allow us to compare and contrast new results with historical datasets.
We added this comment in conclusion section.