Identification and Assessment of Groundwater and Soil Contamination from an Informal Landfill Site

Round 1

Reviewer 1 Report

This manuscript is well prepared. The findings illustrated in this manuscript has substantial merits and will have a positive impact on this research area. The methods were described straight-forward, and it is reproducible. The results were also explained well. However, there are scope for improvement.

Please revise the manuscript according to the comments below-

1. Add a study area map and show in which part of China the study area is located.
2. Line 73-75: Did you follow the standard procedure of groundwater sampling? Did you filter and acidify the samples that were used for major ion and trace metal analysis? Did you use blank samples to see the degree of contamination due to improper sampling? Explain in few sentences.
3. Figure 1: Add coordinate system (e.g., latitude-longitude) in the map.
4. Figure 2: At least one Google–earth map and one contour map should have coordinate system (e.g., latitude-longitude). Increase the scale and font size in figure 2 (b,d,f).
5. Figure 3: Add scale in the images.
6. Use SI units, e.g., convert all mg/L to mg/kg, and ug/L to ug/kg.
7. Either use mg/kg or ug/kg throughout the manuscript, and be consistent.

Author Response

Dear reviewers,

Thank you very much for your comments and questions on this paper. Your valuable comments are contributed to enhance the manuscript further. According to your comments and questions, the manuscript has been revised with further additions and explanations. All the modifications are highlighted in yellow in the revised manuscript.

Response to Reviewer 1 Comments

Point 1: Add a study area map and show in which part of China the study area is located.

Response 1: We thank the reviewer for the valuable comments. The project site is located in East China, east of Shanghai, in the Taihu Lake Plain of the Yangtze River Delta. We have added the study site to the manuscript. However, we apologize that due to the need for confidentiality of this project, satellite maps or coordinates cannot be attached. Please see the new manuscript Page 2, line 56-57.

Point 2: Line 73-75: Did you follow the standard procedure of groundwater sampling? Did you filter and acidify the samples that were used for major ion and trace metal analysis? Did you use blank samples to see the degree of contamination due to improper sampling? Explain in few sentences.

Response 2: Our sampling process follows strictly the technical specifications for groundwater environmental monitoring, with different pre-treatment methods for the different tests and storage and transport as required. Samples for major ions and trace metals analysis are filtered and acidified. Blank samples were retained, and each batch of water samples was analyzed at the same time as the blank samples for comparative analysis.

Point 3: Figure 1: Add coordinate system (e.g., latitude-longitude) in the map.

Response 3: Thanks for your comments. However, we are very apologetic that due to the confidentiality of the project we are not able to add the coordinate system to the map.

Point 4: Figure 2: At least one Google–earth map and one contour map should have coordinate system (e.g., latitude-longitude). Increase the scale and font size in figure 2 (b,d,f).

Response 4: Thanks for your comments. According to your comments, a scale has been added to Figure 2, and the font size has been increased. Please see the new manuscript, Page 8, Figure 2. But we are very apologetic that due to the confidentiality of the project we are not able to add the coordinate system to the map.

Point 5: Figure 3: Add scale in the images.

Response 5: We thank the reviewer of pointing out this issue. According to the comments of reviewers, we have added the scale in Figure 3. Please see the new manuscript, Page 9, Figure 3.

Point 6: Use SI units, e.g., convert all mg/L to mg/kg, and ug/L to ug/kg.

Response 6: We thank the reviewer of pointing out this issue. According to the comments of reviewers, we have converted all units in the manuscript to mg/kg. Please see the new manuscript Page 10 and Page 11, Table 6 and Table 7.

Table 6. Excess pollutants in groundwater

Type of pollutant	Min. （mg/kg）	Max. （mg/kg）	Screening value （mg/kg）	Detection rate	Exceedance rate	Pi
As	0.001	0.14	0.05	100%	4%	2.74
Volatile phenols	ND	11.80	0.01	25%	13%	1180.00
Xylene	ND	2.60	1.00	40%	8%	2.60
Ethylbenzene	ND	1.48	0.60	24%	4%	2.47
Benzene	ND	0.14	0.12	56%	4%	1.21
Toluene	ND	42.00	1.40	52%	4%	30.00
Chlorobenzene	ND	4.47	0.6	32%	4%	7.45
1,2-Dichloroethane	ND	0.066	0.04	12%	4%	1.65
Petroleum hydrocarbons	0.04	59.37	5.00**	4%	4%	11.87

**Massachusetts Groundwater Standards; ND below detection limit

Table 7. Excess pollutants in surface water

Type of pollutant	Min.（10-3 mg/kg）	Max.（10-3 mg/kg）	Screening value（10-3 mg/kg）	Detection rate	Exceedance rate	Pi
Oil	ND	5.48	1*	87.5%	50%	5.48
COD	23	526	40*	100%	50%	13.15
BOD5	2.9	42.4	10*	100%	50%	4.24
NH4+-N	0.227	67.4	2*	100%	50%	33.70
TN	1.88	86.8	2*	100%	75%	43.40
TP	0.11	3.16	0.4*	100%	50%	7.90

ND below the outgoing limit; *Class III standard in Environmental Quality Standard for Surface Water (GB 3838-2002)

Point 7: Either use mg/kg or ug/kg throughout the manuscript and be consistent.

Response 7: We thank the reviewer of pointing out this issue. According to the comments of reviewers, we have converted all units in the manuscript to mg/kg. Please see the new manuscript Page 10 and Page 11, Table 6 and Table 7.

 

Author Response File: Author Response.docx

Reviewer 2 Report

This study investigates the distribution of potentially hazardous elements in sediment, groundwater, and surface water around the dumping area of an informal landfill in China and explored the relationships between the quality indicators and the potential risk. The results showed that characteristic contaminants were still detected in the study area and that a risk assessment of contaminants in soil and ground water is required. The manuscript is poorly written and needs to be largely reworked.

Specific comments
- Line 1 The title is too broad, and it is suggested to further point to specific scientific issues.
- Line 10 (Abstract) The abstract is suggested to be summarized into one paragraph, and it should be inclusive enough to give a glimpse of all key facets of the study. And some expressions are wordy. This abstract should be reorganized to give the results and significance of this study.
- Line 24 (Keywords) There is lack of standardization in keywords.
- Line 26-53 (Introduction) It is advisable to reorganize the introduction and make the  expressions clear. It is better to supplement the value of this study and the novelty of the research at the end of the introduction. Point out the aim of the study. which are the hypotesis?what they expect from he results?is this verified?

- Line 66 (Materials and Methods) "There are 3 kind of soils, 66 subclasses, 7 genera, and 13 species in the area". which is the soil classification?

- Line 90 (Materials and Methods) More background information and theory should be given for the method. The advantages and improvements of the selected method are also encouraged to supplement.
- Line 145 (Results & Discussion) the section is messy. I suggest to devide the paragraph. Sufficient discussions should be presented, and they should be well organized. 
- Line 287 (Conclusions) The conclusion is not as it should be because reports part of the introduction istead of summarize more important research results and the enlightenment from them to highlight the research value under the development of risk assessment staregy.

* Figures do not have good resolution, become clearer and better quality
* Literature review in paper is poor.... The references used need to be improved and strengthened. 
* The authors should compare the obtained results with at least 5 articles and present them in a table.

Author Response

Dear reviewers,

Thank you very much for your comments and questions on this paper. Your valuable comments contributed to enhancing the manuscript further. According to your comments and questions, the manuscript has been revised with further additions and explanations. All the modifications are highlighted in yellow in the revised manuscript.

Response to Reviewer 2 Comments

Point 1: Line 1 The title is too broad, and it is suggested to further point to specific scientific issues.

Response 1: We thank the reviewer for the valuable comments. According to your comments, we have revised the title to Identification and Assessment of Groundwater and Soil Contamination from an Informal Landfill Site.  

Point 2: Line 10 (Abstract) The abstract is suggested to be summarized into one paragraph, and it should be inclusive enough to give a glimpse of all key facets of the study. And some expressions are wordy. This abstract should be reorganized to give the results and significance of this study.

Response 2: Thank you for your significant comments. We have revised the summary in accordance with your comments.

Abstract: Landfills are a potential source of local environmental pollution of all kinds, and the gradual destruction of seepage-proof structures in informal landfills will lead to contamination of the surrounding soil and groundwater environment. In this study, an informal landfill site in East China is used as the research object. Using technologies such as unmanned vessels and monitoring well imaging to delineate the amount and distribution of polluting media, sampling of the surrounding soil, sediment, groundwater, and surface water is testing and analysis and evaluation are carried out visually and finely for heavy metals, petroleum hydrocarbons, volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) and other indicators. The test results show that volatile phenols are the main contaminant species in the shallow groundwater, chlorinated hydrocarbons, and benzene in the deep groundwater, hexachlorobenzene and lead in the surface soil, and di(2-ethylhexyl) phthalate in the deep soil (5.5 m), with a maximum exceedance of 1.24 times. Nearly 10 years have passed since the waste dumping incident at the landfill, but characteristic contaminants are still detected in the topsoil of the dumping area, which shows the long-term nature of the environmental impact of illegal dumping on the site. The study recommends that when developing a comprehensive remediation plan, the persistence of the environmental impact of the waste should be considered and appropriate remediation measures should be screened.

Point 3: Line 24 (Keywords) There is a lack of standardization in keywords.

Response 3: We thank the reviewer for pointing out this issue. According to the comments of reviewers, we have revised the keywords in the manuscript.

Keywords: landfill; soil; groundwater; risk assessment

 

Point 4: Line 26-53 (Introduction) It is advisable to reorganize the introduction and make the expressions clear. It is better to supplement the value of this study and the novelty of the research at the end of the introduction. Point out the aim of the study. which are the hypothesis? what do they expect from the results?is this verified?

Response 4: Thank you for your significant comments. According to the comments of reviewers, we have revised the introduction in the manuscript. Please see the new manuscript Page 1-2, line 29-69.

Revised part of the introduction: Landfills are a potential source of local environmental pollution[1] and have the potential to produce leachate for hundreds of years after closure, so it is important to ensure the proper operation of all landfill systems during landfill closure[2].Formal landfills must meet strict design, operational, and containment requirements, separat-ing waste from the surrounding environment through bottom liners and daily soil cover[3]. However, many informal landfills still exist[4,5]. The data shows that the countries with the highest number of illegal landfills in Europe are Albania (9046) and Slovakia (8334). Italy, Russia, and France have similar problems with illegal landfills. 2020 saw over 2,000 existing illegal "wild" landfills inventoried in Poland, covering a total area of almost 2 km²[6]. In China, most of the simple landfills established in the early years of rapid economic development were informal. These informal landfills were not built and operated by applicable standards and were immature in construction and lacked environmental protection measures[7]. The landfill method used at such sites is mainly open-air disposal[8], and the only measure to prevent seepage is the physical and biochemical action of the seepage zone or clay layer on the various contaminants in the leachate[9,10]. Such landfills usually do not have leachate collection systems, and over time, impermeable structures in informal landfills gradually break down, and landfills adjacent to surface water bodies can discharge leachate into surrounding sediments and watercourses[11], leading to impacts on nearby soil and groundwater quality[12,13], potentially exacerbating the degradation of the soil environment[14] and posing significant health risks to local residents[15,16]. Based on the perspective of en-vironmental protection and human health, it is crucial to understand the long-term impact of informal landfills on the surrounding soil and water environment, and it is urgent to strengthen the environmental control of landfills[17].

In this study, soil, substrate, groundwater, and surface water were sampled and analyzed around an informal landfill in eastern China, and the amount and distribution of contaminated media were accurately determined using techniques such as unmanned vessels and monitoring well imaging techniques to study the extent of soil and groundwater contamination around the landfill and to analyze the lasting effects of illegal dumping on the study area. This study can provide theoretical support for the analysis, evaluation, and redevelopment of informal landfills.

References:

1. Cerar, S.; Serianz, L.; Koren, K.; Prestor, J.; Mali, N. Synoptic Risk Assessment of Groundwater Contamination from Landfills. Energies 2022, 15, 5150.
2. Kamal, A.; Makhatova, A.; Yergali, B.; Baidullayeva, A.; Satayeva, A.; Kim, J.; Inglezakis, V.J.; Poulopoulos, S.G.; Arkhangelsky, E. Biological Treatment, Advanced Oxidation and Membrane Separation for Landfill Leachate Treatment: A Review. Sustainability 2022, 14, 14427.
3. Wan, Y.; Chen, X.; Liu, Q.; Hu, H.; Wu, C.; Xue, Q. Informal landfill contributes to the pollution of microplastics in the surrounding environment. Environmental Pollution 2022, 293, 118586, doi:https://doi.org/10.1016/j.envpol.2021.118586.
4. Yang, H.; Ma, M.; Thompson, J.R.; Flower, R.J. Waste management, informal recycling, environmental pollution and public health. J Epidemiol Community Health 2018, 72, 237-243, doi:10.1136/jech-2016-208597.
5. Zhang, W.; Chen, Y. Transport of leachate through vertical curtain grouting in landfills. Acta Scientiae Circumstantiae 2008.
6. Szulc, J.; Okrasa, M.; Nowak, A.; Nizioł, J.; Ruman, T.; Kuberski, S. Assessment of Physicochemical, Microbiological and Toxicological Hazards at an Illegal Landfill in Central Poland. Int J Environ Res Public Health 2022, 19, doi:10.3390/ijerph19084826.
7. Yin, Q.; Yan, H.; Guo, X.; Liang, Y.; Wang, X.; Yang, Q.; Li, S.; Zhang, X.; Zhou, Y.; Nian, Y. Remediation Technology and Typical Case Analysis of Informal Landfills in Rainy Areas of Southern China. Int J Environ Res Public Health 2020, 17, doi:10.3390/ijerph17030899.
8. Huang, Q.; Cheng, Z.; Yang, C.; Wang, H.; Zhu, N.; Cao, X.; Lou, Z. Booming microplastics generation in landfill: An exponential evolution process under temporal pattern. Water Research 2022, 223, 119035, doi:https://doi.org/10.1016/j.watres.2022.119035.
9. Gu, Z.; Feng, K.; Li, Y.; Li, Q. Microbial characteristics of the leachate contaminated soil of an informal landfill site. Chemosphere 2022, 287, 132155, doi:https://doi.org/10.1016/j.chemosphere.2021.132155.
10. Rao, S.M.; Sekhar, M.; Raghuveer Rao, P. Impact of pit-toilet leachate on groundwater chemistry and role of vadose zone in removal of nitrate and E. coli pollutants in Kolar District, Karnataka, India. Environmental Earth Sciences 2013, 68, 927-938, doi:10.1007/s12665-012-1794-9.
11. Xue, Q.; Li, J.-s.; Liu, L. Experimental study on anti-seepage grout made of leachate contaminated clay in landfill. Applied Clay Science 2013, 80-81, 438-442, doi:https://doi.org/10.1016/j.clay.2013.06.026.
12. Wydro, U.; Wołejko, E.; Sokołowska, G.; Leszczyński, J.; Jabłońska-Trypuć, A. Investigating Landfill Leachate Influence on Soil Microbial Biodiversity and Its Cytotoxicity. Water 2022, 14, 3634.
13. Yadav, V.; Sherly, M.A.; Ranjan, P.; Tinoco, R.O.; Boldrin, A.; Damgaard, A.; Laurent, A. Framework for quantifying environmental losses of plastics from landfills. Resources, Conservation and Recycling 2020, 161, 104914, doi:https://doi.org/10.1016/j.resconrec.2020.104914.
14. Zeng, D.; Chen, G.; Zhou, P.; Xu, H.; Qiong, A.; Duo, B.; Lu, X.; Wang, Z.; Han, Z. Factors influencing groundwater contamination near municipal solid waste landfill sites in the Qinghai-Tibetan plateau. Ecotoxicology and Environmental Safety 2021, 211, 111913, doi:https://doi.org/10.1016/j.ecoenv.2021.111913.
15. Qi, C.; Huang, J.; Wang, B.; Deng, S.; Wang, Y.; Yu, G. Contaminants of emerging concern in landfill leachate in China: A review. Emerging Contaminants 2018, 4, 1-10, doi:https://doi.org/10.1016/j.emcon.2018.06.001.
16. Masoner, J.R.; Cozzarelli, I.M. Spatial and Temporal Migration of a Landfill Leachate Plume in Alluvium. Water, Air, & Soil Pollution 2015, 226, 18, doi:10.1007/s11270-014-2261-x.
17. Lal, R. Restoring Soil Quality to Mitigate Soil Degradation. Sustainability 2015, 7, 5875-5895.
18. Nagarajan, R.; Thirumalaisamy, S.; Lakshumanan, E. Impact of leachate on groundwater pollution due to non-engineered municipal solid waste landfill sites of erode city, Tamil Nadu, India. Iranian Journal of Environmental Health Science & Engineering 2012, 9, 35, doi:10.1186/1735-2746-9-35.
19. Breza-Boruta, B.; Lemanowicz, J.; Bartkowiak, A. Variation in biological and physicochemical parameters of the soil affected by uncontrolled landfill sites. Environmental Earth Sciences 2016, 75, doi:10.1007/s12665-015-4955-9.
20. Gu, B.; Jiang, S.; Wang, H.; Wang, Z.; Jia, R.; Yang, J.; He, S.; Cheng, R. Characterization, quantification and management of China’s municipal solid waste in spatiotemporal distributions: A review. Waste Management 2017, 61, 67-77, doi:https://doi.org/10.1016/j.wasman.2016.11.039.

 

Point 5: Line 66 (Materials and Methods) "There are 3 kind of soils, 66 subclasses, 7 genera, and 13 species in the area". which is the soil classification?

Response 5: The three soil types in the study area are Powder Soil， Clay， and Silty Clay.

 

Point 6: Line 90 (Materials and Methods) More background information and theory should be given for the method. The advantages and improvements of the selected method are also encouraged to supplement.

Response 6: We thank the reviewer for the valuable comments. The single-factor index method is in all participates in the comprehensive water quality assessment of water quality standards, with the worst water quality of a single indicator belonging to the category to evaluate the water quality level. The method is simple and clear, can directly understand the relationship between water quality conditions and evaluation criteria, and gives the evaluation of the factors of the rate of compliance, exceedance rate and exceedance multiples, and other characteristic values. However, only one water quality factor is considered, and the water quality condition of the river cannot be evaluated comprehensively. We have revised the part in the manuscript. Please see the new manuscript, Page 3, line 109-116.

Reference:

1. Li Linjin, M.B.; Rui, P. Water Quality Evaluation of Wenyu River Based on Single Factor Evaluation and Comprehensive Pollution Index Method. School of Water Resources and Hydropower Engineering, North China Electric Power University, Beijing 102206, China 2021, Vol.20, 1041-1046, doi:10.46488/NEPT.2021.v20i03.011.
2. Liu, X.; Chen, S.; Yan, X.; Liang, T.; Yang, X.; El-Naggar, A.; Liu, J.; Chen, H. Evaluation of potential ecological risks in potential toxic elements contaminated agricultural soils: Correlations between soil contamination and polymetallic mining activity. Journal of Environmental Management 2021, 300, 113679, doi:https://doi.org/10.1016/j.jenvman.2021.113679.

 

Point 7: Line 145 (Results & Discussion) the section is messy. I suggest to devide the paragraph. Sufficient discussions should be presented, and they should be well organized.

Response 7: We thank the reviewer for pointing out this issue. According to your suggestions, we have revised the conclusions to highlight the most important acting results and presented the conclusions in the form of a list of items. Please see the new manuscript Page 7-13.

 

Point 8: Line 287 (Conclusions) The conclusion is not as it should be because reports part of the introduction istead of summarize more important research results and the enlightenment from them to highlight the research value under the development of risk assessment staregy.

Response 8: Thank you for your significant comments. According to your comments, we have revised the conclusions and presented them in the form of a list of items. Please see the new manuscript Page 13, line 344-359.

Conclusions: The main findings of this study are as follows: (1) A total of 5 contaminants in the site soil exceeded the screening or control values for soil contamination risk, with 4.34% of the total number of samples exceeding the standard. (2) A total of nine contaminants in groundwater exceeded the relevant screening standards for groundwater, with 12.5% of the total number of samples exceeding the standards. Among them, the Pi value of volatile phenols was as high as 1180, which is serious contamination. Contaminants were detected at some points in the pressurized water aquifer. (3) The exceedance points are adjacent to the former waste dumping area, which shows that the waste dumping has affected part of the substrate area of the pond. (4) Characteristic pollutants were still detected in the project area. Although nearly 10 years have passed since the waste dumping incident, characteristic pollutants were still detected in the surface soil of the dumping area (below the screening value), which shows the long-term impact of illegal dumping on the site environment.

This study recommends that the persistence of the environmental impact of the waste is considered when developing a comprehensive remediation plan and that appropriate remediation measures be screened.

 

* Figures do not have good resolution, become clearer and better quality

Response: We thank the reviewer for the valuable comments. We have reorganized and analyzed the data in depth. Please see the new manuscript.

 

* Literature review in paper is poor.... The references used need to be improved and strengthened.

Response: Thanks for your comments. We have reorganized the reference and analyzed it in conjunction with this research. Please see the new manuscript.

 

* The authors should compare the obtained results with at least 5 articles and present them in a table.

Response: We thank the reviewer for pointing out this issue. According to the comments of reviewers, We have added five references to compare the results obtained in this study (Table 9.). These results are consistent: illegal dumping and informal landfills have long-term ecological and human health impacts, and attention should be paid to pollution prediction and remediation measures for these sites, and to proposing post-remediation land use options.

Table 9. Comparison of other site survey results

Type of site	Location	Source of pollution	Characteristic pollutants	Conclusion	Reference
Three illegal waste landfill sites	The forest area in the Bydgoszcz commune	Mixed waste, including debris and ceramic waste, glass, plastics, metals, textiles, and used electrotechnical equipment Organic waste from households	Heavy metal	The accumulation of waste on the site inhibits the development of microorganisms and their enzymatic activity. The fact that operating illegal waste dumps are a potential threat to the natural environment is confirmed by this study.	[1]
An illegal dumping site	The boundary of the town of Takko and Ninohe City in Japan.	Ash, waste oils, sludge, waste plastic, and bark	PCE, Dichloromethane, Benzene, Cis-1,2-dichloroethylene, 1,2-dichloroethane	The study proposed a new needs analysis method for developing a conceptual land-use plan following the remediation of illegal dumping sites by considering economic and social aspects based on the potential needs of the region’s residents.	[2]
A landfill	Lagos, Nigeria	Municipal Solid Waste	Heavy metal (Pb, Cr)	Active sites in landfills are a potential source of toxic lead, cadmium, and zinc, and if the current trend of indiscriminate waste disposal at the site is not controlled, environmental contamination can occur. Waste management and treatment policies should be developed for landfills and waste disposal must be pre-treated prior to disposal.	[3]
Brownfield site	In the eastern part of the Guanzhong Plain	Food-grade fumaric acid (antisuccinic acid)	1,2,3-trichloropropane	Most of the soils within this fumaric acid brownfield site were at a severe contamination level. 1,2,3-TCP was the primary exceeded pollutant in the fumaric acid brownfield site, and it could be the focus of subsequent studies on fumaric acid brownfield sites.	[4]
An illegal waste dumping site	In the Tohoku region of Japan	Incinerator ash, sludge, and refuse-derived fuel materials	1,4-dioxane	The study shows that it is possible to predict and remedy pollution from illegal waste dumps and encourages further extensive research into the complex geological structure and groundwater changes at illegal waste dump.	[5]

Reference:

1. Breza-Boruta, B.; Lemanowicz, J.; Bartkowiak, A. Variation in biological and physicochemical parameters of the soil affected by uncontrolled landfill sites. Environmental Earth Sciences 2016, 75, doi:10.1007/s12665-015-4955-9.
2. Ishii, K.; Furuichi, T.; Nagao, Y. A needs analysis method for land-use planning of illegal dumping sites: A case study in Aomori–Iwate, Japan. Waste Management 2013, 33, 445-455, doi:https://doi.org/10.1016/j.wasman.2012.10.008.
3. Szulc, J.; Okrasa, M.; Nowak, A.; Nizioł, J.; Ruman, T.; Kuberski, S. Assessment of Physicochemical, Microbiological and Toxicological Hazards at an Illegal Landfill in Central Poland. Int J Environ Res Public Health 2022, 19, doi:10.3390/ijerph19084826.
4. Yang, Y.; Li, C.; Chen, Z.; Dong, Y.; Zhang, N.; Wei, Y.; Xi, H.; Wang, W. Characterization and Assessment of Organic Pollution at a Fumaric Acid Chemical Brownfield Site in Northwestern China. Sustainability 2022, 14, 12476.
5. Pongritsakda, T.; Nakamura, K.; Wang, J.; Watanabe, N.; Komai, T. Prediction and Remediation of Groundwater Pollution in a Dynamic and Complex Hydrologic Environment of an Illegal Waste Dumping Site. Applied Sciences 2021, 11, 9229.

Author Response File: Author Response.docx

Reviewer 3 Report

1.       Introduction - Authors should better emphasize the novelty of the research carried out.

2.       Please add the geographical coordinates of the place where the research was conducted.

3.       Please add information regarding the LOD for each heavy metal analyzed, which is given in Table 1.

4.       It is important to check that the writing text clearly expresses and explains each idea and result obtained.

5.       A better discussion would be necessary in order to emphasize the main findings.

6.       The conclusions needs improvement - highlight the most important findings and identify the added value of the main finding. In the conclusion, please consider adding a bullet list.

7.       References do not include items from the journal Sustainability to which the authors submitted their manuscript. Please add references to articles from this journal to emphasize that the submitted article is a match for this journal.

Author Response

Dear reviewers,

Thank you very much for your comments and questions on this paper. Your valuable comments are contributed to enhance the manuscript further. According to your comments and questions, the manuscript has been revised with further additions and explanations. All the modifications are highlighted in yellow in the revised manuscript.

Response to Reviewer 3 Comments

Point 1: Introduction - Authors should better emphasize the novelty of the research carried out.

Response 1: We thank the reviewer of pointing out this issue. According to your comments, we have revised the introduction in the manuscript. Please see the new manuscript Page 1, line 32-41, Page 2, line 44-47,53-68.

Point 2: Please add the geographical coordinates of the place where the research was conducted.

Response 2: Thanks for your comments. The project site is located in East China, east of Shanghai, in the Taihu Lake Plain of the Yangtze River Delta. We have added the study site to the manuscript. We apologize that due to the confidential nature of the project we are not able to include the coordinates of the project location.

Point 3: Please add information regarding the LOD for each heavy metal analyzed, which is given in Table 1.

Response 3: Thanks for your comments. According to your suggestion, we have added the LODs for the relevant heavy metals to Table 1. Please see the new manuscript Page 3-Page 4, Table 1.

Point 4: It is important to check that the writing text clearly expresses and explains each idea and result obtained.

Response 4: We thank the reviewer for the valuable comments. Based on your suggestions, the article has been touched up and the data analyzed. Please see the new manuscript.

 Point 5: A better discussion would be necessary in order to emphasize the main findings.

Response 5: We thank the reviewer of pointing out this issue. According to the comments of reviewers, the two sections, Results and Discussion, have been divided and the language reorganized for in-depth discussion. Please see the new manuscript.

Point 6: The conclusions needs improvement - highlight the most important findings and identify the added value of the main finding. In the conclusion, please consider adding a bullet list.

Response 6: Thank you for your significant reminding. According to your comments, we have revised the conclusions and presented them in the form of a list of items. Please see the new manuscript Page 13, line 333-348.

Point 7: References do not include items from the journal Sustainability to which the authors submitted their manuscript. Please add references to articles from this journal to emphasize that the submitted article is a match for this journal.

Response 7: Thanks for your comments. According to the comments of reviewers, I have added 5 references from the journal Sustainability. Please see the new manuscript, Page 1, line 33,37,41, Page 2, line 58 and Page 3, line 133.

References:

1. He, T.; Niu, D.; Chen, G.; Wu, F.; Chen, Y. Exploring Key Components of Municipal Solid Waste in Prediction of Moisture Content in Different Functional Areas Using Artificial Neural Network. Sustainability 2022, 14, 15544.
2. Xu, X.; Li, G.; Ni, D.; Feng, C.; Xu, S. Laboratory Model Tests of Leachate Drawdown Using Vertical Drainage Wells with Vacuum Pumping in Municipal Solid Waste Landfills with High Leachate Levels. Sustainability 2022, 14, 8101.
3. Kamal, A.; Makhatova, A.; Yergali, B.; Baidullayeva, A.; Satayeva, A.; Kim, J.; Inglezakis, V.J.; Poulopoulos, S.G.; Arkhangelsky, E. Biological Treatment, Advanced Oxidation and Membrane Separation for Landfill Leachate Treatment: A Review. Sustainability 2022, 14, 14427.
4. Lal, R. Restoring Soil Quality to Mitigate Soil Degradation. Sustainability 2015, 7, 5875-5895.
5. Yang, Y.; Li, C.; Chen, Z.; Dong, Y.; Zhang, N.; Wei, Y.; Xi, H.; Wang, W. Characterization and Assessment of Organic Pollution at a Fumaric Acid Chemical Brownfield Site in Northwestern China. Sustainability 2022, 14, 12476.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The Authors made a great job! The manuscript improved a lot and it is worth publication for Sustainability 

Author Response

Dear reviewers,

We would like to express our sincere appreciation for your constructive comments concerning our article. These comments are all valuable and helpful for improving our article.

Kind regards,

Xinyang Liu

Author Response File: Author Response.docx

Reviewer 3 Report

The comments are addressed properly and necessary corrections have been done. After minor corrections, the manuscript can be accepted. 

1. Please delete the empty table in References (lines 365-374).

Author Response

Dear reviewers,

We would like to express our sincere appreciation for your constructive comments concerning our article. These comments are all valuable and helpful for improving our article. According to your comments, the manuscript has been revised. All the modifications are highlighted in yellow in the revised manuscript.

Response to Reviewer 3 Comments

Point 1: Please delete the empty table in References (lines 365-374).

Response 1: We thank the reviewer of pointing out this issue. According to your comments, we have deleted the empty tables in References. Please see the new manuscript Page 16, line 365-374.

Author Response File: Author Response.docx