Effect of Pumping Speeds on the Fate of Aniline in Different Soil Layer

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors, 

I reviewed this article “Effect of different pumping speeds -induced soil settlement on the fate and vertical distribution of aniline in the 3 Heterogeneous soil” which is interesting research work which has wider implications. I number of comments suggestions which needs to be considered below the final acceptance of the article. My general comments and suggestions for each are:

Abstract: Needs a rewriting, authors can’t assume reader knows everything about the Helen Mountain, the summarise key findings in two to three sentences rather than 4-5 bullet points. When referring to the removal rate reduced by %, what was the base value. The abstract is ending with the suggestion rather than study implementation.

Introduction: Authors, simply referring to TMVOC model, where they should introduce to several such models, by providing a rationale why above used model is more robust.

 Material and Methods:

Mostly clear, but selected study site map is needed for the wider readers, and not very clear how someone can repeat this work. When referring to the TMVOC model, needs more who else used this model, what’s the difference between the different studies. Needs more supporting references. Needs to be more specific, which specific App in the Excel or other software was used for the statistical analysis.

Results:

Before referring to the model validation, authors need to describe the model calibration, if pre-calibrated refer to the model source. Figure 2 needs to be referred and described in the text. Make a connection between the figures 3, a-c.

Conclusion:

Broader implication of the study is missing.

Based on above, I would like to consider this article for the publication in the Sustainability Journal after the suggested changes.

 

Comments on the Quality of English Language

na

Author Response

Dear Reviewer:

Thank you very much for your time and effort to provide professional comments on the paper "The Fate of aniline in different soil layers at varying pumping rates", each of your review comments has brought me revisions of this paper and future scientific research work As you are concerned, there are several issues that need to be resolved. Based on your suggestions, we have made extensive corrections to the previous manuscript.

The main text of the manuscript has been revised in accordance with the comments of the reviewers, and the corrected parts have been highlighted in Red in the article, and the following explanations (in Blue) are made in response to the comments of the reviewers:

Dear authors,

I reviewed this article “Effect of different pumping speeds -induced soil settlement on the fate and vertical distribution of aniline in the 3 Heterogeneous soil” which is interesting research work which has wider implications. I number of comments suggestions which needs to be considered below the final acceptance of the article. My general comments and suggestions for each are:

Abstract: Needs a rewriting, authors can’t assume reader knows everything about the Helen Mountain, the summarise key findings in two to three sentences rather than 4-5 bullet points. When referring to the removal rate reduced by %, what was the base value. The abstract is ending with the suggestion rather than study implementation.

Reply: Thank you for your suggestion. The information of Helan Mountain has been added to the Abstract. Summarized key findings in two or three sentences; The basic value of the amount of reduction in removal rate is compared with that when soil settlement is not considered, and suggestions are written at the end, as follows.

Abstract: Helan Mountain is an important ecological safety barrier in northwest China. In this study, ...... the NAPL phase removal rate decreases by 33.75% and the distribution of aniline to the NAPL phase increases, compared with that without considering the soil settlement. The......e aquifer. The simulation results can provide a technical reference for the future application of P&T technology in the remediation of organically contaminated sites to facilitate the sustainable use of soil. It is suggested that more attention should be paid to the water level fluctuation zone during the remediation of contaminated sites.

 

Introduction: Authors, simply referring to TMVOC model, where they should introduce to several such models, by providing a rationale why above used model is more robust.

Reply: Thank you for your suggestion. The principle of TMVOC supplement has been added in the introduction, as well as the limitations of other models compared with it. What research others have done with this model is shown below.

1. Introduction

At present, most research on the effect of extraction treatment technology for aniline remediation is at the laboratory and field experiment stage, and its design and operation are mostly based on empirical formulas or limited site practice [32,33]. There are still many deficiencies in P&T numerical simulation research. The sub-module TMVOC of the TOUGH model has excellent performance in a multiphase flow simulation. YANG et al. used TMVOC to study the influence of SVE technology on the behavior of benzene series at a low temperature [34]. G et al. determined the dissolution characteristics of gasoline employing the TMVOC model [35]. It can simulate the three-phase flow of water, soil gases and volatile organic compounds (VOCs) in multi-dimensional heterogeneous media. It adopts a modular design and finite integral difference grid subdivision method to simulate the pollution problem of an organic solvent leakage in saturated and unsaturated regions, including soil adsorption, gas phase extraction, groundwater mining, etc. Additionally, it is a tool used to analyze the behavior of non-aqueous liquids (NAPLs) below the vadiferous zone and groundwater level, which can be used for site-level simulations [36,37].

 Guo Z ,Brusseau L M ,Fogg E G .Determining the long-term operational performance of pump and treat and the possibility of closure for a large TCE plume[J].Journal of Hazardous Materials,2018,365796-803.

 Min P ,Erhu D ,Chunmiao Z .A data-driven approach to exploring the causal relationships between distributed pumping activities and aquifer drawdown.[J].The Science of the total environment,2023,870161998-161998.

Lari S K ,Johnston D C ,Rayner L J , et al.Field-scale multi-phase LNAPL remediation: Validating a new computational framework against sequential field pilot trials[J].Journal of Hazardous Materials,2018,34587-96.

 Chao S ,Chao X ,Yao Z , et al.A numerical simulation of thermally-enhanced soil vapor extraction with a validation of an actual contaminated site.[J].Chemosphere,2023,338139413-139413.

 Yang Y ,Li J ,Xi B , et al.Modeling BTEX migration with soil vapor extraction remediation under low-temperature conditions[J].Journal of Environmental Management,2017,203(P1):114-122.

 Lekmine G ,Lari S K ,Johnston D C , et al.Evaluating the reliability of equilibrium dissolution assumption from residual gasoline in contact with water saturated sands[J].Journal of Contaminant Hydrology,2017,19630-42.

 

 Material and Methods:Mostly clear, but selected study site map is needed for the wider readers, and not very clear how someone can repeat this work. When referring to the TMVOC model, needs more who else used this model, what’s the difference between the different studies. Needs more supporting references. Needs to be more specific, which specific App in the Excel or other software was used for the statistical analysis.

Reply:Thank you for your suggestions: 1. For the repeatability of this study, I have added a map of the study area, see 2.1; 2. In the introduction, I listed more scholars who have done other studies using this model to support it. See the introduction. 3. Use the data statistical analysis tool in EXCEL, as shown in 2.4,all changes are shown below..

2. Materials and Methods

2.1Materials

 

Fig1 study area.

1. Introduction

At present, most research on the effect of extraction treatment technology for aniline remediation is at the laboratory and field experiment stage, and its design and operation are mostly based on empirical formulas or limited site practice [32,33]. There are still many deficiencies in P&T numerical simulation research. The sub-module TMVOC of the TOUGH model has excellent performance in a multiphase flow simulation. YANG et al. used TMVOC to study the influence of SVE technology on the behavior of benzene series at a low temperature [34]. G et al. determined the dissolution characteristics of gasoline employing the TMVOC model [35]. It can simulate the three-phase flow of water, soil gases and volatile organic compounds (VOCs) in multi-dimensional heterogeneous media. It adopts a modular design and finite integral difference grid subdivision method to simulate the pollution problem of an organic solvent leakage in saturated and unsaturated regions, including soil adsorption, gas phase extraction, groundwater mining, etc. Additionally, it is a tool used to analyze the behavior of non-aqueous liquids (NAPLs) below the vadiferous zone and groundwater level, which can be used for site-level simulations [36,37].

 Guo Z ,Brusseau L M ,Fogg E G .Determining the long-term operational performance of pump and treat and the possibility of closure for a large TCE plume[J].Journal of Hazardous Materials,2018,365796-803.

 Min P ,Erhu D ,Chunmiao Z .A data-driven approach to exploring the causal relationships between distributed pumping activities and aquifer drawdown.[J].The Science of the total environment,2023,870161998-161998.

Lari S K ,Johnston D C ,Rayner L J , et al.Field-scale multi-phase LNAPL remediation: Validating a new computational framework against sequential field pilot trials[J].Journal of Hazardous Materials,2018,34587-96.

 Chao S ,Chao X ,Yao Z , et al.A numerical simulation of thermally-enhanced soil vapor extraction with a validation of an actual contaminated site.[J].Chemosphere,2023,338139413-139413.

 Yang Y ,Li J ,Xi B , et al.Modeling BTEX migration with soil vapor extraction remediation under low-temperature conditions[J].Journal of Environmental Management,2017,203(P1):114-122.

 Lekmine G ,Lari S K ,Johnston D C , et al.Evaluating the reliability of equilibrium dissolution assumption from residual gasoline in contact with water saturated sands[J].Journal of Contaminant Hydrology,2017,19630-42.

 

2.4 Sample testing and data statistical analysis

Excel's statistical analysis tool (Office 2003, Redmond, WA, USA); ......

Results:Before referring to the model validation, authors need to describe the model calibration, if pre-calibrated refer to the model source. Figure 2 needs to be referred and described in the text. Make a connection between the figures 3, a-c.

Reply: The model has been calibrated before validation. The method is to see the convergence of the model, which is described in 2.3; Because a study area map is added at the front of the article, Figure 2 becomes Figure 3, which is quoted and described in 3.2. Figure 3, a-c is Figure 4, where b and c are similar in expression. For brevity and clarity, c has been deleted, Figure a shows the total mass removal rate of aniline, and Figure b shows the removal rate of gas, liquid and NAPL，all changes are shown below.

2.3. Numerical model

......The model assumed that the three phase states of aniline were always in chemical and thermal equilibrium. ...... In order to meet the capillary effect, the initial operation was carried out before the injection of pollutants, and the simulation was carried out until the convergence reached the static equilibrium and was then imported as the initial condition.

 

3.2 Migration mechanisms of aniline caused by pump rate

...... Figure 3 (a, c, e) shows that when the pumping rate...... As shown in Figure 3(b, d , e) the higher the pumping speed was, the deeper the high concentration area of aniline was, and the more obvious the obstruction phenomenon of aniline migration caused by the sedimentation effect was, the smaller the range of aniline contamination plume was, resulting in the phenomenon that a large amount of aniline accumulates near the source area......

 

3.3 Effect of pumping rate on aniline fate and interphase partition

 

1. Total mass removal rate.

 

b.Gas、Aq and NAPL mass removal rate

Fig 4.Effect of aniline removal rate at different pumping speeds

 

Conclusion:

Broader implication of the study is missing.

Reply: Thank you for your suggestions on the conclusion. I have rewritten the conclusion from the perspective of sustainability, as follows.

4 Conclusion

Employing the column experiment and model simulation, the behavior law of aniline in the extraction and treatment technology of a pesticide site in Helan Mountain area was studied as follows:

1) Considering the sedimentation effect, the pumping speed should be designed at 3.24×106 m3/month, and the settlement effect had a lag. It should therefore be repaired within 10 months after the repair to reduce the negative impact of settlement effect.

2) The larger the pumping speed was, the more obvious the settlement effect was. When the restoration was carried out at 5.18×106 m3/month, the removal rate reduced by 29.59% considering the settlement effect. The removal rate of the NAPL phase reduced by 33.75%, and the distribution of the NAPL phase by aniline increased by 26.68% due to the sedimentation effect. Because the NAPL phase was hydrophobic and difficult to remove, it was not appropriate to design a too-high pumping speed in the process of site restoration, otherwise a large amount of NAPL aniline would have reduced the sustainable use of the site.

3) The removal rate of aniline in the vadose zone of soil was most affected by sedimentation, which increased by 36.55%. Among them, the phase redistribution in the water-level fluctuation zone was the most obvious, and aniline in the NAPL phase escaped into the gas phase and disposed into the liquid phase. Therefore, efficient control methods should be selected according to the existence of the aniline phase in different strata. With the increase in formation depth, the concentration of aniline decreased, and the concentration of aniline in the NAPL phase was two orders of magnitude higher in the water-level fluctuation zone than 0.2 m below the water surface. Therefore, when using the extraction treatment technology for restoration, wells should be set near the water surface with a high concentration.

In this study, the behavior of aniline under pump-induced subsidence was only considered below the surface. Because the subsidence caused the difficulty of the downward migration of aniline, it was blocked near the source area. Therefore, we suggest performing additional research on the volatilization flux of aniline on the surface.

Based on above, I would like to consider this article for the publication in the Sustainability Journal after the suggested changes.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript sustainability-2843669 entitled "Effect of different pumping speeds -induced soil settlement on the fate and vertical distribution of aniline in the Heterogeneous soi" submitted by Gao et al. presents an interesting laboratory experiment were the effect of pumping recovery of an aniline polluted soil was tested. The experimental activity comprises both a lab experiment and a computational analysis of the problem. The experimental activity seems to be carried out in appropriate way useful to achieve reliable results while the manuscript is of good quality easy to read and follow.

Abstract: should be rewritten. The english of this part is poor and it is difficult to understand.

Keywords: avoid to repeat words already mentioned in the title.

Introduction: give a good presentation of the state of the art.

Materials and methods: quite good. Some other minor details regarding the soil are needed.

Results and discussion: clear and easy to read and understand.

Conclusions: based on the achived results; well written.

My specific comments are enclosed in the attached pdf file.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The language quality is sufficient.

Author Response

Dear Reviewer:

Thank you very much for your time and effort to provide professional comments on the paper "The Fate of aniline in different soil layers at varying pumping rates", each of your review comments has brought me revisions of this paper and future scientific research work. As you are concerned, there are several issues that need to be resolved. Based on your suggestions, we have made extensive corrections to the previous manuscript.

The main text of the manuscript has been revised in accordance with the comments of the reviewers, and the corrected parts have been highlighted in Red in the article, and the following explanations (in Blue) are made in response to the comments of the reviewers:

The manuscript sustainability-2843669 entitled "Effect of different pumping speeds -induced soil settlement on the fate and vertical distribution of aniline in the Heterogeneous soi" submitted by Gao et al. presents an interesting laboratory experiment were the effect of pumping recovery of an aniline polluted soil was tested. The experimental activity comprises both a lab experiment and a computational analysis of the problem. The experimental activity seems to be carried out in appropriate way useful to achieve reliable results while the manuscript is of good quality easy to read and follow.

Abstract: should be rewritten. The english of this part is poor and it is difficult to understand.

Reply: Thank you for your suggestion. I have revised the abstract and translated it through MDPI company.

 

Keywords: avoid to repeat words already mentioned in the title.

Reply: Thank you for your comments, the title and keywords have been revised according to your suggestions, as shown below.

Title：The Fate of aniline in different soil layers in soil environment at different pumping rates

Keywords：settlement; aniline;soil layer; transport model

 

Introduction: give a good presentation of the state of the art.

Reply: Thank you for your recognition.

 

Materials and methods: quite good. Some other minor details regarding the soil are needed.

Reply: Thank you for your suggestion. According to your comments in the PDF manuscript, soil properties have been added to Table 1 in the text, as shown below.

 

(a) soil.

Soil type	D（kg/m3）	n	KXY（m）	KZ（m）	E（MPa）	PH	BET(m2·g-1)	SOC(g·kg-1)
Loam	1890	0.350	1.21×10-11	1.210×10-13	20	7.34	12.99	41.3
Sand	1600	0.420	6.06×10-11	6.060×10-13	60	7.65	2.82	13.8

 

Results and discussion: clear and easy to read and understand.

Reply: Thank you for your recognition.

 

Conclusions: based on the achived results; well written.

Reply: Thank you for your recognition.

 

My specific comments are enclosed in the attached pdf file.

Reply: Most of your comments in the PDF have been dealt with in the above questions, the remaining two questions: 1. This part of the introduction is too long, I have revised it to the following; 2. The abbreviations in Table 1 have been marked with full names below the table, as shown below.

 

 

Soil is a large reservoir and secondary source of environmental pollutants. Pores provide a preferential path for the movement of water, air and chemicals through soil, which is of great significance for the movement of solutes and pollutants in soil [15,16], the change of water level during pumping leads to sediment compaction, and soil settlement and pore rupture and reduction [17–20]. This eventually leads to soil compression, trapping pollutants in pores [21], changing the permeability of soil and blocking the movement of water[22].

 

Table1. Physical and chemical properties of materials

(a) soil.

Soil type	D（kg/m3）	n	KXY（m）	KZ（m）	E（MPa）	PH	SSA(m2·g-1)	SOC(g·kg-1)
Loam	1890	0.350	1.21×10-11	1.210×10-13	20	7.34	12.99	41.3
Sand	1600	0.420	6.06×10-11	6.060×10-13	60	7.65	2.82	13.8

（b）aninline.

S(mg·L-1)	MW(g·mol-1)	Kd(s-1)	Pvap(KPa)	B(K)	ρ(kg·m-3)	Tc(℃)	Pc(bar)	Koc(m3·kg-1)
3600	93.13	4.63×10-9	2.0	486.85	1000	525	53	0.06

D:soil density; n:void ratio; K:permeability coefficient; E:elasticity modulus; SSA:specific surface area; SOC:soil organic carbon; S: Solubility; MW:Molecular weight；Kd:Biological decay constant; Pvap:vapour pressure; B:boiling point；ρ:Compound density; Tc:Critical temperature; Pc:Critical temperature pressure; Koc:Partition coefficient of compounds in organic matter.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Comments and recommendations to the manuscript (MS) "Effect of different pumping speeds-induced soil settlement on the fate and vertical distribution of aniline in the Heterogeneous soil" (authors Rui Gao, Yue Wang, Beidou Xi, Ying Wang, Shunguo Bai , Jianchao Zhu) submitted to the journal Sustainability MDPI.

 

1. Regarding the Abstract:

Perhaps if the authors had been able to more conceptually formulate the results of the work and the corresponding conclusions, this could significantly increase the significance and impact of this manuscript on the development of the relevant field of investigation, as well as its perception by potential readers.

 

2. Regarding the Introduction section.

It would probably be reasonable if the authors could formulate more explicitly the hypothesis, purpose and objectives of this investigation here.

 

Also some discussion of the concept of model construction would be welcome in more detail.

 

In addition, a greater depth of search for literary sources on the research issue would not be superfluous.

 

Potential readers would certainly be interested in more information about the distribution of aniline in nature of various regions of China, as well as in other countries.

 

3. The authors' research and findings could be discussed in more detail in the context of the sustainability concept, if possible.

 

4. It would be desirable to rework and improve the Conclusion section more thoroughly.

 

5. It would be great if the authors reworked the manuscript as a whole through a more conceptual approach.

 

6. Perhaps the authors have previously published works on this or similar issues that are not mentioned in this manuscript.

If so, then it would be advisable to discuss these in the manuscript.

 

7. Authors should be sure that these research results are being published for the first time, both in whole or in part.

Comments on the Quality of English Language

Could be better.

Author Response

Dear Reviewer:

Thank you very much for your time and effort to provide professional comments on the paper "The Fate of aniline in different soil layers at varying pumping rates", each of your review comments has brought me revisions of this paper and future scientific research work. As you are concerned, there are several issues that need to be resolved. Based on your suggestions, we have made extensive corrections to the previous manuscript.

The main text of the manuscript has been revised in accordance with the comments of the reviewers, and the corrected parts have been highlighted in Red in the article, and the following explanations (in Blue) are made in response to the comments of the reviewers:

Comments and recommendations to the manuscript (MS) "Effect of different pumping speeds-induced soil settlement on the fate and vertical distribution of aniline in the Heterogeneous soil" (authors Rui Gao, Yue Wang, Beidou Xi, Ying Wang, Shunguo Bai , Jianchao Zhu) submitted to the journal Sustainability MDPI.

1. Regarding the Abstract:

Perhaps if the authors had been able to more conceptually formulate the results of the work and the corresponding conclusions, this could significantly increase the significance and impact of this manuscript on the development of the relevant field of investigation, as well as its perception by potential readers.

Reply: Thank you for your suggestions. I have conceptualized the abstract and rewritten it, adding the need for sustainable development of Helan Mountain, and giving suggestions in the context of sustainability, as shown below.

Abstract: Helan Mountain is an important ecological safety barrier in northwest China. In this study, a heterogeneous site polluted by aniline in Helan Mountain was taken as the research object, and the TMVOC model of aniline restoration by pumping was optimized employing a column experiment. Four typical layers of the soil profile were selected to explore the influence of soil settlement caused by different pumping rates on the fate of aniline in different zones. The results show that the optimal pumping speed of the site is 3.24×10⁶ m³/month and the latest remediation time is the 10th month after the start of the remediation. The larger the pumping speed is, the more obvious the sedimentation effect is. When the remediation is carried out at 5.18×10⁶ m³/month, the NAPL phase removal rate decreases by 33.75% and the distribution of aniline to the NAPL phase increases, compared with that without considering the soil settlement. The fate of aniline in the source zone is the least affected by sedimentation, while that in the vadoid zone is the most affected. The phase redistribution phenomenon is the most obvious in the water level fluctuation zone, and the NAPL phase aniline changes into gas and liquid phases. In addition, the NAPL phase concentration in the water level fluctuation zone is two orders of magnitude higher than that at 0.2 m below the water level. NAPL is the most sensitive to the relative settlement in the aquifer. The simulation results can provide a technical reference for the future application of P&T technology in the remediation of organically contaminated sites to facilitate the sustainable use of soil. It is suggested that more attention should be paid to the water level fluctuation zone during the remediation of contaminated sites.

 

2. Regarding the Introduction section.

It would probably be reasonable if the authors could formulate more explicitly the hypothesis, purpose and objectives of this investigation here.Also some discussion of the concept of model construction would be welcome in more detail. In addition, a greater depth of search for literary sources on the research issue would not be superfluous. Potential readers would certainly be interested in more information about the distribution of aniline in nature of various regions of China, as well as in other countries.

 

Reply: Thank you for your suggestions. 1. According to your suggestions, at the end of the introduction, I will emphasize the purpose of my research through the particularity of the location of Helan Mountain. 2. In the third paragraph of the introduction, the current situation of the simulation of P&T restoration technology is expounds, the TMVOC model is introduced, and the efforts made by this model in other research directions are introduced; 3. As a synthetic substance, aniline is not found in nature, so once it is leaked, even if the amount is small, it will flow with the groundwater all over the world. Generally, it occurs in the soil after the leakage of herbicide and dye production workshops, which I have added in the introduction.

 

The Ningxia Helan Mountain is an important natural ecological barrier in the north of China and a natural laboratory for studying the biogeochemical cycle of arid mountain ecosystems [38–40]. It is sensitive to natural and human interference, and its ecosystem is very fragile [41]. Once pollution occurs, it will not only threaten local water safety, but also affect the surrounding environment of the reserve. In this study, through the establishment of an indoor one-dimensional soil column experiment to simulate the influence of pumping-induced settlement on aniline removal to verify the TMVOC model, the site-scale aniline restoration site model was constructed to analyze the fate, vertical distribution characteristics and phase redistribution law for aniline (Gas, Aq, NAPL) under different pumping rates. By predicting the phase distribution of pollutants in different strata, aniline in different phase states can provide guidance for the formulation of remediation plans and solutions for the sustainable utilization of organic compound-contaminated sites......

Jiang Y ,Kang M ,Zhu Y , et al.Plant biodiversity patterns on Helan Mountain, China[J].Acta Oecologica,2006,32(2):125-133.

Xueping F ,Weiping Z ,Wenli W , et al.Chemical composition and diversity of the essential oils of Juniperus rigida along the elevations in Helan and Changbai Mountains and correlation with the soil characteristics[J].Industrial Crops Products,2021,159.

Mengyao W ,Lin C ,Jinpeng M , et al.Aggregate-associated carbon contributes to soil organic carbon accumulation along the elevation gradient of Helan Mountains[J].Soil Biology and Biochemistry,2023,178.

Jiang Y ,Kang M ,Zhu Y , et al.Plant biodiversity patterns on Helan Mountain, China[J].Acta Oecologica,2006,32(2):125-133.

 

 

At present, most research on the effect of extraction treatment technology for aniline remediation is at the laboratory and field experiment stage, and its design and operation are mostly based on empirical formulas or limited site practice [32,33]. There are still many deficiencies in P&T numerical simulation research. The sub-module TMVOC of the TOUGH model has excellent performance in a multiphase flow simulation. YANG et al. used TMVOC to study the influence of SVE technology on the behavior of benzene series at a low temperature [34]. G et al. determined the dissolution characteristics of gasoline employing the TMVOC model [35]. It can simulate the three-phase flow of water, soil gases and volatile organic compounds (VOCs) in multi-dimensional heterogeneous media. It adopts a modular design and finite integral difference grid subdivision method to simulate the pollution problem of an organic solvent leakage in saturated and unsaturated regions, including soil adsorption, gas phase extraction, groundwater mining, etc. Additionally, it is a tool used to analyze the behavior of non-aqueous liquids (NAPLs) below the vadiferous zone and groundwater level, which can be used for site-level simulations [36,37]......

 

Guo Z ,Brusseau L M ,Fogg E G .Determining the long-term operational performance of pump and treat and the possibility of closure for a large TCE plume[J].Journal of Hazardous Materials,2018,365796-803.

Min P ,Erhu D ,Chunmiao Z .A data-driven approach to exploring the causal relationships between distributed pumping activities and aquifer drawdown.[J].The Science of the total environment,2023,870161998-161998.

Lari S K ,Johnston D C ,Rayner L J , et al.Field-scale multi-phase LNAPL remediation: Validating a new computational framework against sequential field pilot trials[J].Journal of Hazardous Materials,2018,34587-96.

Chao S ,Chao X ,Yao Z , et al.A numerical simulation of thermally-enhanced soil vapor extraction with a validation of an actual contaminated site.[J].Chemosphere,2023,338139413-139413.

Yang Y ,Li J ,Xi B , et al.Modeling BTEX migration with soil vapor extraction remediation under low-temperature conditions[J].Journal of Environmental Management,2017,203(P1):114-122.

Lekmine G ,Lari S K ,Johnston D C , et al.Evaluating the reliability of equilibrium dissolution assumption from residual gasoline in contact with water saturated sands[J].Journal of Contaminant Hydrology,2017,19630-42.

The sustainable development of water and soil resources is critical for the survival of human beings, and the relevant units advocate for the protection and restoration of environmental health. The volatile organic compound aniline is often used as an intermediate product in the production of herbicides and dyes.It were man-made, not natural. It is persistent and not easily decomposed, and can be found in large quantities worldwide......

 

The authors' research and findings could be discussed in more detail in the context of the sustainability concept, if possible.

Reply: Thank you for your suggestion to add the sustainable context in the abstract and introduction section, in addition to which the sustainable context has been added in the analysis. The details are as follows:

Abstract: Helan Mountain is an important ecological safety barrier in northwest China. ......The simulation results can provide a technical reference for the future application of P&T technology in the remediation of organically contaminated sites to facilitate the sustainable use of soil. It is suggested that more attention should be paid to the water level fluctuation zone during the remediation of contaminated sites.

1. Introduction

The sustainable development of water and soil resources is critical for the survival of human beings, and the relevant units advocate for the protection and restoration of environmental health. The volatile organic......

He Ningxia Helan Mountain is an important natural ecological barrier in the north of China and a natural laboratory for studying the biogeochemical cycle of arid mountain ecosystems [38–40]. It is sensitive to natural and human interference, and its ecosystem is very fragile [41]. Once pollution occurs, it will not only threaten local water safety, but also affect the surrounding environment of the reserve.In this study......

aniline in different phase states can provide guidance for the formulation of remediation plans and solutions for the sustainable utilization of organic compound-contaminated sites......

4.Conclusion

,it was not appropriate to design a too-high pumping speed in the process of site restoration, otherwise a large amount of NAPL aniline would have reduced the sustainable use of the site.

4.It would be desirable to rework and improve the Conclusion section more thoroughly.

Reply: Thank you for your suggestion. The conclusion has been rewritten. 

4.Conclusion

Employing the column experiment and model simulation, the behavior law of aniline in the extraction and treatment technology of a pesticide site in Helan Mountain area was studied as follows:

1) Considering the sedimentation effect, the pumping speed should be designed at 3.24×106 m3/month, and the settlement effect had a lag. It should therefore be repaired within 10 months after the repair to reduce the negative impact of settlement effect.

2) The larger the pumping speed was, the more obvious the settlement effect was. When the restoration was carried out at 5.18×106 m3/month, the removal rate reduced by 29.59% considering the settlement effect. The removal rate of the NAPL phase reduced by 33.75%, and the distribution of the NAPL phase by aniline increased by 26.68% due to the sedimentation effect. Because the NAPL phase was hydrophobic and difficult to remove, it was not appropriate to design a too-high pumping speed in the process of site restoration, otherwise a large amount of NAPL aniline would have reduced the sustainable use of the site.

3) The removal rate of aniline in the vadose zone of soil was most affected by sedimentation, which increased by 36.55%. Among them, the phase redistribution in the water-level fluctuation zone was the most obvious, and aniline in the NAPL phase escaped into the gas phase and disposed into the liquid phase. Therefore, efficient control methods should be selected according to the existence of the aniline phase in different strata. With the increase in formation depth, the concentration of aniline decreased, and the concentration of aniline in the NAPL phase was two orders of magnitude higher in the water-level fluctuation zone than 0.2 m below the water surface. Therefore, when using the extraction treatment technology for restoration, wells should be set near the water surface with a high concentration.

In this study, the behavior of aniline under pump-induced subsidence was only considered below the surface. Because the subsidence caused the difficulty of the downward migration of aniline, it was blocked near the source area. Therefore, we suggest performing additional research on the volatilization flux of aniline on the surface.

5. It would be great if the authors reworked the manuscript as a whole through a more conceptual approach.

Reply: Thank you for your advice. We have organized the article to make it more conceptual.

 

6. Perhaps the authors have previously published works on this or similar issues that are not mentioned in this manuscript.If so, then it would be advisable to discuss these in the manuscript.

Reply: As you said, but the contents of this manuscript have never been published in any other journal or in the public. In this manuscript, experiments and models are used to accurately investigate the behavior of aniline in different layers at different pumping speeds.

 

7.Authors should be sure that these research results are being published for the first time, both in whole or in part.

Reply：After revisions, I made sure these findings were published in whole or in part for the first time.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

I am happy with changes made to the reviewed version. I would like to accept the article after some changes especially the figure 6, where the text in the figure is hard to read. Please read the article again and make sure that all the figures/tables referred in the text where needed. 

Comments on the Quality of English Language

Overall acceptable 

Author Response

Dear Reviewer:

Thank you very much for your time and effort to provide professional comments on the paper "The Fate of aniline in different soil layers at varying pumping rates", each of your review comments has brought me revisions of this paper and future scientific research work As you are concerned, there are several issues that need to be resolved. Based on your suggestions, we have made extensive corrections to the previous manuscript.

The main text of the manuscript has been revised in accordance with the comments of the reviewers, and the corrected parts have been highlighted in Red in the article, and the following explanations (in Blue) are made in response to the comments of the reviewers:

Dear authors,

I am happy with changes made to the reviewed version. I would like to accept the article after some changes especially the figure 6, where the text in the figure is hard to read. Please read the article again and make sure that all the figures/tables referred in the text where needed. 

Reply: Thank you for your suggestions. For the readability of the article, I have added some data in Figure 6, which echoes the data conclusions in the article. The reader can simply subtract the data in the figure to get the data in the description. In addition, I have checked other graphs and tables in the article to ensure that there are no mistakes.Detailed changes have been made below the file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript certainly looks much better now in terms of greater presentation and scientific validity.

Perhaps authors could also carefully review the data in the tables and figures to be completely sure of their accuracy.

 

Overall, I would recommend going through all the previous recommendations carefully again with fresh eyes in order to achieve the highest quality of presentation, conceptualization, discussion and conclusion.

Comments on the Quality of English Language

Could be better.

Author Response

Dear Reviewer:

Thank you very much for your time and effort to provide professional comments on the paper "The Fate of aniline in different soil layers at varying pumping rates", each of your review comments has brought me revisions of this paper and future scientific research work As you are concerned, there are several issues that need to be resolved. Based on your suggestions, we have made extensive corrections to the previous manuscript.

The main text of the manuscript has been revised in accordance with the comments of the reviewers, and the corrected parts have been highlighted in Red in the article, and the following explanations (in Blue) are made in response to the comments of the reviewers:

Summary：

1 . As for the language quality of the article, we used the polishing service of MDPI company.

 

2. This manuscript certainly looks much better now in terms of greater presentation and scientific validity. Perhaps authors could also carefully review the data in the tables and figures to be completely sure of their accuracy.

Reply: Thank you for your suggestion. I have re-checked the full text. Due to clerical error, the header of Table 2 was written backwards, and now it has been changed correctly. In addition, I have checked the data in the text and confirmed that there are no errors.

3.Overall, I would recommend going through all the previous recommendations carefully again with fresh eyes in order to achieve the highest quality of presentation, conceptualization, discussion and conclusion.

Reply: Thank you for your suggestions. I have reconsidered the previous suggestions and revised them. In order to make the writing of the abstract more conceptual, I use the total writing technique of the total score in the writing technique of the abstract. In order to make the investigation hypothesis, method, purpose and objective more accurate expression, I rewrote this part; In terms of the model, I have added the introduction of the model and the work done by those who use the TMVOC model. In 2.3, I have introduced the model in detail and described the model construction in detail. In addition, for the source of aniline you mentioned, I have added its international and domestic distribution location in the introduction. You mentioned that the research and findings can be discussed in more detail under the background of the concept of sustainability. According to your suggestion, first of all, I added the research background of sustainable development in the introduction, and added its relationship with sustainable development when analyzing the data. How to control the development of aniline so as to realize the sustainable use of the plot. I have revised these contents in detail and presented them in the following document. Thank you again for your hard suggestions. They are very valuable and will also be of great help to this paper and the author's future scientific research life.

Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

Comments within the bounds of the third round of peer review.

I still recommend doing a very thorough proofreading of the entire text again one again.

Starting with the title and continuing, with each section of the manuscript.

More conceptual reworking and re-editing is required.

Greater originality and quality of the text, contents, abstract, introduction, discussion and conclusions needs to be ensured.

Comments on the Quality of English Language

Could be better.

Author Response

I have revised the article with the title: Effect of pumping speeds on the fate of aniline in different soil layer. In addition, the article was re-checked, the noun concept was proofread, and the language of the article was polished with the polishing function of MDPI to ensure accurate expression.