Effects of Oil Contamination on Range of Soil Types in Middle Taiga of Western Siberia

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

To Sustainability

Title: Effects of Oil Contamination on Range of Soil Types in Middle Taiga of Western Siberia

Ref.: sustainability-3267816

 Dear Editor,

 Sutormin et al. report a paper where they studied effect of oil spillage or oil contamination on Wstern Siberia soil specifically podzolic, sod-gley and alluvial soil. In the control experiment author has introduced oil in different concentration and non ionic surfactant was applied to check their influence on degradation. Author has studied pH, CEC, capillary water capacity and so on. Author found oil contaminants were remain in the soil for longer time as natural decomposition rate is 0.02 to 0.4%. in addition, author found no impact of surfactant aster 35 days of applicability. I see that the author has not emphasis on surfactant chemistry and soil chemistry. The paper has no interesting results and scientific evidence lack the data. I believe that the work described is sufficient for this journal. Therefore, this article is strongly rejected with some recommendation.

 

1. Author has named the soil but what is basic difference in soil need to analyze, their pore, surface area, hydrophobicity and X-ray.

2. Where is the structure of the surfactant? You have provided the general tag name of the surfactant. You must provide the scientific structure and name of the surfactant.

3. If no structure can be provided, you must analyze the surfactant using elemental analysis. As your claim some time not match with other surfactant so you have to be specific.

4. What is the reason for selecting non-ionic surfactant? Have you try other surfactants?

5. Any surfactant coating on the soil changes the soil's tendency towards a more hydrophobic surface, thus preventing water from being adsorbed, and the coating also reduces the CEC of the soil.

Author Response

Dear Reviewer 1,

We appreciate your time and effort in reviewing our manuscript and thank you for your constructive feedback. We value the opportunity to address your concerns and further clarify the contributions of our research on oil contamination effects in Western Siberian soils.

1. While we acknowledge the importance of surfactant chemistry in remediation studies, our research focused primarily on the environmental and practical impacts of oil contamination across different soil types (podzolic, sod-gley, and alluvial soils), rather than on surfactant interactions at a chemical level. Our choice of a widely used industrial surfactant, Modified Syntherol (MS), and our subsequent observation of its limited effectiveness were intended to highlight the need for alternative or additional remediation approaches tailored specifically to these soil types. We feel this aligns well with the objectives of Sustainability in promoting effective, scalable environmental solutions.
2. Our study provides novel insights into the differential impacts of oil contamination on three distinct soil types in a sensitive taiga ecosystem, illustrating varying degrees of soil degradation and recovery limitations. These findings contribute valuable information for future remediation efforts in cold, remote regions similar to Western Siberia. By demonstrating that podzolic soils, with their lower organic content and acidity, are more severely impacted than sod-gley and alluvial soils, we offer new data that can guide soil-specific remediation approaches. Moreover, our study presents evidence that natural degradation rates in these soils are minimal, underscoring the need for enhanced remediation strategies in cold climates where microbial degradation is less effective. Furthermore, the findings of this study provide a foundation for the development of specialized software for the analysis of soil pollution. The data presented in Figures 2–5 could be used to construct mathematical models for calculating and predicting changes in soil properties due to oil contamination. The integration of such models into analytical software would facilitate the real-time assessment and forecasting of soil pollution impacts, thereby supporting informed decision-making in the context of pollution management and remediation planning. These tools could prove invaluable to environmental professionals engaged in the design of adaptive, data-driven responses to soil contamination challenges across a range of taiga ecosystems.
3. The study’s quantitative results on soil parameter changes—pH, CEC, and water retention—offer clear, data-backed evidence of oil’s impact on soil health and functionality. These findings emphasize the persistence of oil pollutants and the limited effectiveness of a standalone non-ionic surfactant, data points which are integral to our overall conclusions about sustainable remediation practices. We believe these results provide an essential contribution to the field, as they suggest the need for more integrated or enhanced bioremediation strategies in such ecologically vulnerable regions.
4. Our study addresses critical issues of sustainable soil management in oil-impacted ecosystems, providing foundational data to support the development of soil-specific remediation methods. These insights are highly relevant to the readership of Sustainability, as they advocate for tailored approaches to pollution management and emphasize the limitations of certain remediation agents in harsh environmental conditions. We hope that this research supports efforts to build effective, ecologically mindful responses to soil contamination in remote regions.

Point 1. Author has named the soil but what is basic difference in soil need to analyze, their pore, surface area, hydrophobicity and X-ray.

Response 1: Thank you for your valuable feedback. In this study, we focused on key physicochemical properties, including pH levels, cation exchange capacity, and water retention capacity across podzolic, sod-gley, and alluvial soils, aiming to understand how oil contamination impacts soil health and functionality. However, we acknowledge that further characterization of these soils (pore, surface area, hydrophobicity and X-ray) would enhance our understanding of their structural and surface properties in response to contamination

Point 2. Where is the structure of the surfactant? You have provided the general tag name of the surfactant. You must provide the scientific structure and name of the surfactant.

Response 2: We are grateful for your feedback. The structure of the surfactant was incorporated into the text in lines 164–165. 

Point 3.  If no structure can be provided, you must analyze the surfactant using elemental analysis. As your claim some time not match with other surfactant so you have to be specific.

Response 3: We are grateful for your feedback. The structure of the surfactant was incorporated into the text in lines 164–165. 

Point 4.  What is the reason for selecting non-ionic surfactant? Have you try other surfactants?

Response 4:  Thank you for your question about choosing a non-ionic surfactant. We chose the non-ionic surfactant Modified Syntherol (MS) for our study because: Non-ionic surfactants are used in the oil industry because they are stable and effective in different environments, including different soil types and temperatures. MS is used in Russian oil fields, including the Western Siberian region, to recover oil. This makes it a good choice to test how well it works in the real world for cleaning up oil spills. We haven't tried other surfactants in this study. 

Point 5. Any surfactant coating on the soil changes the soil's tendency towards a more hydrophobic surface, thus preventing water from being adsorbed, and the coating also reduces the CEC of the soil.

Response 5: Thank you for highlighting the effects that surfactants can have on soil properties. Our study focused on evaluating whether Modified Syntherol (MS), a non-ionic surfactant commonly used in regional oil remediation, could effectively enhance the degradation of oil contaminants in the specific soil types of the study area. Our findings indicate that MS did not significantly improve oil degradation in these contaminated soils. We did not measure changes in soil hydrophobicity or cation exchange capacity (CEC) in the presence of MS, as our primary objective was to examine the effects of oil contamination on three soil types—podzolic, sod-gley, and alluvial—in Western Siberia’s middle taiga, assessing key physical and chemical properties.

Reviewer 2 Report

Comments and Suggestions for Authors

The article considers issues related to the study of the impact of oil pollution on a number of soils in the taiga of Western Siberia.

Oil pollution is considered one of the most severe and large-scale, global environmental problems due to its specificity. Soil intoxication, even in relatively small doses, leads to significant changes in almost all properties: chemical, physical, biological, morphological, disrupts the structure of the soil cover, inhibits the vital activity of soil organisms and plants. The idea of studying the consequences of oil and oil product pollution of natural environments is not new, however, it is still of interest to scientists in various fields of natural sciences.

Nevertheless, most of the studies are quite narrowly focused. As a rule, Russian soil scientists study either the soils of the north and Western Siberia, where a significant number of used deposits are located (for example, the soils of the Komi Republic), or chernozems, as the most valuable soils. The rest are given comparatively less attention. Of the pollutants, as a rule, the effect of crude oil is studied, less often - directly oil products. Also, the main interest is in changes in chemical and biological indicators as components of aspects of environmental assessment and soil fertility assessment. Physical properties become independent objects of study to a lesser extent and are usually considered only as additional characteristics.

Physical properties of soils are a set of characteristics that have a direct impact on the processes occurring in the soil, including soil fertility. The negative impact of oil pollution leads to a significant change in indicators important for mechanical processing, various agrotechnical measures and the normal life and functioning of soil organisms and plants.

Based on this, it is important to study changes in the physical properties of soils of different granulometric composition under the influence of pollution by oil products.

The results obtained in the article are of interest to readers in the field under consideration.

 

However, there are the following issues that should be clarified:

1. In the introduction, it is necessary to expand the literature review by considering the issues of oil pollution not only of soils in the Russian Federation, but also in other regions of the world (Saudi Arabia, USA, Nigeria, etc.), and also to cite the most well-known disasters associated with the consequences of oil pollution. Along with this, it is necessary to dwell on the methods of ensuring the normal ecological system of various natural and technical systems during the activities of enterprises in the oil and gas, mining industries, etc.

2. Based on the materials of sections "2.1. Soil Collection and Characterization", "2.2. Surfactant and petroleum investigations", it is necessary to present the methodology for conducting experimental studies in a block diagram.

3. Was the use of other oil concentrations considered? How was the water-to-oil ratio determined for uniform distribution of oil in the soil?

4. The weight method used should be explained.

5. What software was used to process the data and how was the statistical analysis performed, including the Student's t-test?

6. How were the nine soil subtypes determined? What methods were used?

7. Based on the data in Figures 1-4, it is necessary to present mathematical models that allow calculation and forecasting of output parameters, based on the results of the regression analysis.

8. The work should more clearly emphasize the scientific novelty of the results obtained.

9. The conclusions should be significantly expanded, and prospects for further research on the topic under consideration should be presented.

Author Response

Dear Reviewer 2,

We are grateful for your meticulous remarks about our manuscript. We found them highly instructive during the revision process. 

Point 1. In the introduction, it is necessary to expand the literature review by considering the issues of oil pollution not only of soils in the Russian Federation, but also in other regions of the world (Saudi Arabia, USA, Nigeria, etc.), and also to cite the most well-known disasters associated with the consequences of oil pollution. Along with this, it is necessary to dwell on the methods of ensuring the normal ecological system of various natural and technical systems during the activities of enterprises in the oil and gas, mining industries, etc.

Response 1: We are grateful for your recommendation. We have revised the introduction section in line with your feedback and hope it meets your expectations. 

Point 2. Based on the materials of sections "2.1. Soil Collection and Characterization", "2.2. Surfactant and petroleum investigations", it is necessary to present the methodology for conducting experimental studies in a block diagram

Response 2: Thank you for your proposal. Following the section entitled "2.2", the block diagram was updated. 

Point 3. (a) Was the use of other oil concentrations considered? (b) How was the water-to-oil ratio determined for uniform distribution of oil in the soil?

Response 3: (a) The oil concentration levels ranging from 50 g/kg to 150 g/kg were chosen because a concentration of 50 g/kg can be considered moderate contamination compared to the regional standard of 20 mg/kg. The higher concentrations are considered high oil contamination. Concentrations above 150 g/kg were not included in the study, as the results indicated that soils experienced significant changes at the initial 50 g/kg concentration, and further increases did not notably exacerbate these effects, suggesting a threshold for soil response to oil contamination in this experimental context. (b) Thank you for bringing this to our attention. There was a typo. This has been corrected in the revised version of the manuscript, lines 201-202. 

Point 4. The weight method used should be explained. 

Response 4: Thank you for the comment. We have corrected lines 145-146. 

In this study, the weight method was used to determine soil moisture content by drying a moist soil sample to a constant weight. This was achieved by first weighing the fresh sample and then drying it in an oven at a consistent temperature until no further weight loss was observed. The moisture content was then calculated as a percentage of the weight lost during drying relative to the oven-dried soil weight, as per the formula:  Soil Moisture Percentage (%) = [(Wet Soil Weight – Dry Soil Weight) / Dry Soil Weight] × 100.  

Point 5. What software was used to process the data and how was the statistical analysis performed, including the Student's t-test?

Response 5: Thank you for your feedback. We have revised the text in accordance with your comments in section 2.3. 

Point 6. How were the nine soil subtypes determined? What methods were used?

Response 6: The soil classification process involved an assessment of the content of different forms of iron in the selected soils. This was done to identify elementary soil-forming processes, which will then be used to classify soils in a more precise manner. This approach is based on the substantive-genetic approach, which forms the basis of the 'Classification and Diagnostics of Soils of Russia' (The source in Russian language http://infosoil.ru/index.php?pageID=clas04mode).

Point 7. Based on the data in Figures 1-4, it is necessary to present mathematical models that allow calculation and forecasting of output parameters, based on the results of the regression analysis.

Response 7:  Thank you for the suggestion to incorporate mathematical models for predicting output parameters. However, the primary aim of this study was to provide an experimental analysis of how various soil types (podzolic, sod-gley, and alluvial) respond to oil contamination, specifically focusing on changes in pH, cation exchange capacity, and water retention properties. The experimental data generated offers valuable insights but lacks the range and variability necessary for developing a robust predictive model at this stage. Additionally, given the specificity of the study region and conditions (Western Siberia’s middle taiga), developing generalized models would require further studies across various environmental conditions and contamination levels to enhance the applicability and accuracy of any forecasting models.

Future work will aim to broaden the dataset and include regression analyses to support model development, potentially offering predictive tools for soil contamination impact across diverse taiga ecosystems. We appreciate your input as it guides the direction of our ongoing research. 

Point 8. The work should more clearly emphasize the scientific novelty of the results obtained.

Response 8:  Thank you very much for your feedback. We hope that the revised Introduction, Discussion and Conclusion sections make the scientific novelty of the results clearer. 

Point 9. The conclusions should be significantly expanded, and prospects for further research on the topic under consideration should be presented.

Response 9:  Thank you for the comment. The Conclusion section has been revised. 

Reviewer 3 Report

Comments and Suggestions for Authors

Review of the manuscript: sustainability-3267816

Effects of Oil Contamination on Range of Soil Types in Middle Taiga of Western Siberia

The topics of the manuscript are important for science and practice. The scope of the paper generally corresponds to the purpose of the journal ‘Sustainability’. The Authors set out to investigate the physical and chemical properties of the soil in West Siberian oilfields and to test its ability to self-remediate.

I am convinced that the authors have applied the correct research methodology, which they have presented graphically step by step for better understanding by the reader.

 

Comment 1

L175-176: The samples were taken layer by layer, with one sample from each genetic zone horizon (between 0 and 15 cm).

Why only one sample, why weren't 3 replicates done?

Comment 2

I suggest a statistical analysis of the results obtained.

 

Author Response

Dear Reviewer 3,

We appreciate your time and effort in reviewing our manuscript and thank you for your constructive feedback. 

 

Point 1. L175-176: The samples were taken layer by layer, with one sample from each genetic zone horizon (between 0 and 15 cm). Why only one sample, why weren't 3 replicates done?

Response 1: We are grateful for your insightful comments. It would appear that there has been a misunderstanding. The aforementioned lines reflect the methodology employed for the collection of genetic zone horizons during the process of soil sampling. The soil sampling was conducted in accordance with the specifications of the "Envelope" method. The "Envelope" method of soil sampling is a widely accepted approach for the collection of soil samples for the assessment of contamination or the analysis of soil properties within a specified area. This method entails the collection of samples from the four corners and the centre of a predefined area, forming a spatial arrangement that resembles an envelope or pentagon. Further details regarding this methodology can be found in the following article: 10.1016/j.heliyon.2019.e01377. Additionally, all data processing was conducted subsequent to the measurements, which were repeated on three occasions to ensure accuracy. To avoid similar misunderstandings, lines 229–233 have been modified accordingly.

 

Point 2. I suggest a statistical analysis of the results obtained.

Response 2: We would like to express our gratitude for your feedback. In order to address the discrepancy in the alteration of valuable soil characteristics between groups of soil samples in the absence and presence of oil contamination, a single-factor ANOVA was conducted. The figures 2-4 have been updated and the significance of the differences (p) relative to the value of the analysed soil samples has been marked. 

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Author has made significant improvement in the manuscript and improve the quality of manuscript.

Ln 234-235
The soil classification was conducted based on the assess ment of the content of different forms of iron in the selected soils (not presented). 
Remove word Not presented or remove this statement. 

 

Author Response

Dear Reviewer 1,

Thank you for your constructive feedback on the revised version of the manuscript. We are extremely grateful for your input. 

Point 1. Ln 234-235. The soil classification was conducted based on the assessment of the content of different forms of iron in the selected soils (not presented). Remove word Not presented or remove this statement.

Response 1: Thank you for your valuable feedback. In the revised version of the manuscript, the word "not presented" has been removed. In addition, these lines have been modified according to reviewer #2's comment.

Reviewer 2 Report

Comments and Suggestions for Authors

Add your answers to my previous questions number 3 and 6 to the text of the article in the appropriate sections.

Author Response

Dear Reviewer 2,

We are grateful for your careful comments on our manuscript. We found them very instructive during the revision process. 

Point 1. Add your answers to my previous questions number 3 and 6 to the text of the article in the appropriate sections.

Response 1: Thank you for your valuable suggestion. The answer to your question #3 has been added on lines 601-607 of the revised manuscript; the answer to your question #6 has been added on lines 663-667 of the revised manuscript.