The Impact of Climate Change and Soil Classification on Benzene Concentration in Groundwater Due to Surface Spills of Hydraulic Fracturing Fluids
Round 1
Reviewer 1 Report
In this work, the risk of benzene contamination in groundwater was evaluated in one of the oil fields, California, US. The effect of different factors was investigated, including climate change, soil classification, and water table depth. The manuscript is properly organized and the writing is well tailored. Hence, the manuscript could be recommended for publication after a major revision considering the following comments:
Comment #1: In the title, ‘’To’’ shouldn’t be capitalized.
Comment #2: Abstract should be supported with more qualitative findings, instead of the general introductory sentences.
Comment #3: In the introduction section, the novelty of this work should be highlighted, in terms of briefly discussing the reported literature studying the same oil field (study area) or nearby sites, or even other oil contaminated sites in US. Moreover, the aim and main objectives of this study should be clearly stated at the end of the introduction section.
Comment #4: The main assumption, determinants and general considerations of the developed numerical model should be clearly stated (e.g., FEM, saturated-unsaturated flow, etc.).
Comment #5: It is not clear how the solute transport model parameters were estimated (Table 1).
Comment #6: How about the model calibration and validation?
Comment #7: All equations in the manuscript should be supported with appropriate references whenever possible.
Comment #8: Did the authors consider any real-time concentration data of benzene presence in groundwater of the study area.
Comment #9: It is significantly questionable to call the two considered temperature scenarios a climate change effect.
Comment #10: The topic of this work is really interesting. However, the inadequacy of creditability and validity is strongly affecting the quality of the manuscript.
Comment #11: Generally, the manuscript still needs some proofreading work, in terms of unnecessary spacings, and sub/superscripts formatting.
Author Response
Response to Reviewer 1 Comments
Point 1: In the title, ‘’To’’ shouldn’t be capitalized.
Response 1: Incorporated
Page 1; Line 3.
Point 2: Abstract should be supported with more qualitative findings, instead of the general introductory sentences.
Response 2: Incorporated
Page 1; Lines 24, 25, and 26.
Point 3: In the introduction section, the novelty of this work should be highlighted, in terms of briefly discussing the reported literature studying the same oil field (study area) or nearby sites, or even other oil-contaminated sites in the US. Moreover, the aim and main objectives of this study should be clearly stated at the end of the introduction section.
Response 3: Incorporated
Page 2, lines 70-80
Page 3; Lines from 119 to 137 (It is necessary to understand the role of climate change on Benzene transport in different types of soil and its impact on groundwater. Therefore, this study aims to assess the benzene concentration in shallow groundwater resulting from surface spills of hydraulic fracturing fluids, with special reference to the role of an expected rise in temperatures due to climate change and the role of soil properties such as the water content and the chemical substance characteristics such as diffusion)
Point 4: The main assumption, determinants, and general considerations of the developed numerical model should be clearly stated (e.g., FEM, saturated-unsaturated flow, etc.).
Response 4: Incorporated
Page 4; Lines from 175 to 180.
Point 5: It is not clear how the solute transport model parameters were estimated (Table 1).
Response 5: Incorporated
Page 6; Each parameter supported with reference, residual soil water content lines 198 to 199, the partitioning coefficient (Kd) calculated as presented in lines 222 to 232, Henry's Law Constants and diffusion coefficients was presente lines 224 to 225.
Point 6: How about the model calibration and validation?
Response 6: Thanks for the comment, Incorporated Page 6; Lines from 245 to 248.
Point 7: All equations in the manuscript should be supported with appropriate references whenever possible.
Response 7: supporting references have been added.
Point 8: Did the authors consider any real-time concentration data of benzene presence in groundwater of the study area.
Response 8: thanks for your significant comment, yes evidence shows the benzene present in the groundwater of the study area.
Page 2; Lines from 71 to 73.
Point 9: It is significantly questionable to call the two considered temperature scenarios a climate change effect.
Response 9: thanks for your significant comment, the reason behind the selection was discussed on page 5, lines 211-215.
Point 10: The topic of this work is really interesting. However, the inadequacy of creditability and validity is strongly affecting the quality of the manuscript.
Response 10: Thank you for your efforts and comments. As indicated earlier the justification for temperature has been addressed as per Q9. Validation has been addressed as per question 6. Furthermore, supporting references have been added for equations and methods.
Point 11: Generally, the manuscript still needs some proofreading work, in terms of unnecessary spacings, and sub/superscripts formatting.
Response 11: Thank you for your efforts and comments. The manuscript has been checked a by professional.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The article discusses about influence of the migration of pollutants from the earth's surface from the water phase through the soil on the example of the Benzene. Midway-Sunset oil field was selected as a starting issue for the proposed numerical methods. Virtually any type of chemical that could be present in surface waters could be selected and the penetration of these pollutants into subcutaneous waters could be determined by the chosen numerical method.
The problem was posed correctly.
Indication of the depth of penetration of pollutants - correct.
Indication of the risk of contamination of subcutaneous waters - also correct.
Some editorial shortcomings, e.g. line 153 - description of dependence no. 1
Should be noted, however, a slight dissonance between abstract and conclusions.
The abstract emphasizes the threats very strongly - especially with Earth warm increasing temperature.
But the conclusions indicate that there are no threats of contamination of underground waters. In my opinion, it was necessary to add conclusions regarding the risk of lowering level subcutaneous waters and much higher pollution of surface waters with toxic substances as the resulting from human activity in the process of processing petroleum substances and other sectors of the industry, including intensive agricultural production.
Another very negative phenomenon is the loss of oxygen in surface waters as a result of climate warming.
To sum up, the article is very interesting and should be published.
Author Response
Response to Reviewer 2 Comments
Point 1: Some editorial shortcomings, e.g. line 153 - description of dependence no. 1.
Response 1: Incorporated
Page 5; Line 179.
Point 2: Should be noted, however, a slight dissonance between abstract and conclusions.
Response 2: Incorporated
Page 11; Lines 326 t0 332.
Point 3: But the conclusions indicate that there are no threats of contamination of underground waters. In my opinion, it was necessary to add conclusions regarding the risk of lowering level subcutaneous waters and much higher pollution of surface waters with toxic substances as the result of human activity in the process of processing petroleum substances and other sectors of the industry, including intensive agricultural production.
Response 3: thanks for your significant comment, our study shows that there are threats of contamination of underground waters, especially show groundwater.
Page 11; Lines from 335 to 337.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The quality of the manuscript has been enhanced, so it could be published in the present form.
