Analysis of the Spatial Distribution Characteristics of Livestock and Poultry Farming Pollution and Assessment of the Environmental Pollution Load in Anhui Province

Round 1

Reviewer 1 Report

The manuscript entitled " Analysis of the spatial distribution characteristics of livestock and poultry farming pollution and assessment of the environmental pollution load in Anhui Province " is well organized. The idea and design of this study are good although it is not clear.

However, I suggest the authors should address the following comments for further consideration of the manuscript for publication.

Abbreviations must be defined at first mention and used consistently thereafter in the entire manuscript.
There are some grammatical corrections throughout the manuscript. Your manuscript would greatly improve from editing by a native speaker.
Re-write the focal aim section in the Abstract.
Suggested improving the background of the study.
The introduction must be improved with more relevant information about the core plot of the manuscript.
The software package should be included in the materials and method section and the statistical analyses were poorly explained. Please rewrite

The authors should clearly define the protocol use in this experiment and this is applied to the results part.

Results: all descriptions of the results should be reworked. The following parts are required, 1) the comparison of the significant difference among the values of three treatments; The result descriptions should be presented in subsections based on the type of indicators.
Discussion: Revise the manuscript with strong justification for background.
Conclusion: write the conclusion again and be more concise to the major findings and suggestions.

Author Response

Dear reviewers:

We thank all the reviewers and the editor for their careful reading of our manuscript entitled “Analysis of the spatial distribution characteristics of livestock and poultry farming pollution and assessment of the environ-mental pollution load in Anhui Province” (No. sustainability-1629336) and constructive comments and suggestions. Those comments are all valuable and very helpful for improving our paper, as well as the important guiding significance to our researches. We have tried our best to revise and improve the manuscript and made changes in the manuscript according to the reviewers’ good comments. Besides, our current manuscript followed the journal formatting guidelines of Sustainability. Revised portion are marked in red throughout the revised manuscript. Moreover, all language problems or grammatical flaws are improved by native English speaker. We appreciate the editors/reviewers’ hard work earnestly, and hope that the corrections will meet with approval. Thank you very much for your comments and suggestions.

We look forward to your information about our revised paper and thank you for your good comments.

Yours sincerely,

Prof. Dr. Youhua Ma

NOTE: All the page and line numbers where revisions were made refer to the manuscript and highlight with marked changes (Manuscript Revised Version).docx. The Manuscript Clean Version was the same version of the Manuscript Revised Version with cleaned from all the marks.

Responses to the Reviewer 1#’s comments:

The manuscript entitled "Analysis of the spatial distribution characteristics of livestock and poultry farming pollution and assessment of the environmental pollution load in Anhui Province " is well organized. The idea and design of this study are good although it is not clear. However, I suggest the authors should address the following comments for further consideration of the manuscript for publication.

Response: Thank you for your precious comments and advice. Those comments are all valuable and very helpful for revising and improving our paper. We have revised the manuscript accordingly, and our point-by-point responses are presented as follow.

• Abbreviations must be defined at first mention and used consistently thereafter in the entire manuscript.  
• Response: We really appreciate your efforts in reviewing our manuscript. We have revised the manuscript accordingly and defined the abbreviations at first mention.

• There are some grammatical corrections throughout the manuscript. Your manuscript would greatly improve from editing by a native speaker.  
• Response: Thanks for your comments. We apologize for the language problems in the original manuscript. The language presentation was improved with assistance from a native English speaker with appropriate research background. Besides, our current manuscript followed the journal formatting guidelines of Sustainability. 

• Re-write the focal aim section in the Abstract.  
• Response: We agree with the comment and re-wrote the sentence in the revised manuscript as following: “In this study, the spatial distribution of the livestock and poultry pollution in Anhui Province was analyzed, effect of the pollution load of the livestock and poultry on the cultivated land and water environment was evaluated, and suggestions for environmental protection measures were provided.” (Page 1, Line 22-26)

• The introduction must be improved with more relevant information about the core plot of the manuscript. “Mallin et al. ^[8] found that on the coastal plains of North Carolina, livestock produced an estimated 124000 t of nitrogen and 29000 t of phosphorus per year. Many farms are located in nutrient-sensitive watershds, where the discharge of untreated waste can lead to eutrophication of streams, rivers, and estuaries. It is suggested that the federal government should protect the environment and human health from livestock and poultry pollution. Centner et al. ^[9] reported that LPE makes an important contribution to the soil nutrient input. In many developing countries, LPE is an important input. In some developed countries with large animal husbandry industries, such as the Netherlands and Japan, the proportion of fertilizer is expected to increase and the demand for fertilizer will decline.” (Page 2, Line 63-73);  
• “Livestock rearing in China was found to be within the environmental carrying capacity, but some regions faced potential livestock pollution. In the middle and lower reaches of the Yangtze River, LPE can be accommodated in the farmland environment if the livestock breeding quantity does not increase^[16]. However, it has also been reported that N and P transfer from agriculture is the main cause of poor water quality. A comprehensive evaluation of the risks posed by N and P runoff into surface water bodies and risk analysis of nutrient losses to water from manure management is needed. The regions where N and P concentrations are too high should be defined as vulnerable zones, in which immediate policies and actions should be implemented ^[17].”(Page 2, Line 86-95)
• Response: We are extremely grateful to reviewer for the insightful and constructive comments and suggestions. We agree with the comment and re-wrote the sentence in the revised manuscript as following:

[8] Mallin, M.A.; Michael, A. Industrialized animal production a major source of nutrient and microbial pollution to aquatic ecosystems. Popul. Environ., 2003,24(5), 369-385.

[9] Centner, T. J.  Developing institutions to encourage the use of animal wastes as production inputs. Agr. Hum. Values,2003, 21(4), 367-375.

[16] Zheng, L.; Zhang, Q.; Zhang, A.; Hussain, H. A.; Liu, X.; Yang, Z. Spatiotemporal characteristics of the bearing capacity of cropland based on manure nitrogen and phosphorus load in mainland china. J. Clean. Prod., 2019,233(OCT.1), 601-610.

[17] Bai, Z.; Zhao, H.; Velthof, G. L.; Oenema, O.; Chadwick, D.; Williams, J.; Jin, S., Liu, H.; Wang, M.; Stroka,M. Designing vulnerable zones of nitrogen and phosphorus transfers to control water pollution in china. Environ. Sci. Technol., 2018,52(16), 8987-8988.

• The software package should be included in the materials and method section and the statistical analyses were poorly explained. Please rewrite. “The SPSS 22.0 (Version 22.0, SPSS Inc., Chicago, USA) data statistical analysis module was used for the statistical processing of the original data. The data import module in the Origin 8.0 software (Origin Lab, Northampton, USA) toolbox was used to import the production amount and diffusion concentration of the LPE pollutants, and bar charts were drawn using the drawing module. The data import module in the ArcGIS10.2 (Environmental Systems Research Institute, Inc., USA) toolbox was used to import the map of Anhui Province and the production of LPE and other data, and the spatial analysis tool was used to process and analyze the data. The spatial distribution map of the production and loss of LPE was drawn in the map layer for Anhui Province, and the spatial information visualization of the data was realized through the layout.” (Page 6, Line 225-234) 
•  
• Response: Thank you for your comments. We agree with the comment and re-wrote the sentence in the revised manuscript as following:
• The authors should clearly define the protocol use in this experiment and this is applied to the results part.  
• Response: Thank you for underlining this deficiency. We apologize for not describing the inclusion criteria clearer. We have modified this expression throughout the text according to the comment. (Page 5, Line 191-200，Page 16, Line 416-428)
• Results: all descriptions of the results should be reworked. The following parts are required, 1) the comparison of the significant difference among the values of three treatments; The result descriptions should be presented in subsections based on the type of indicators. The result descriptions in the original manuscript had been presented in subsections based on the production of LPE, the amount of pollutants produced by LPE, the carrying capacity and early warning value of LPE cultivated land, and the load of livestock and LPE release into water bodies.  
• Because the specific evaluation indicators of LPE production and load are different, it is difficult to describe the results in subsections based on the type of indicators.
• Response: According to the quantities, feeding cycles, and discharge coefficients of the different types of livestock and poultry, the livestock and poultry excreta (LPE) output, pollutant output, and pollutant release in Anhui Province were calculated using the output coefficient model. The research data are the calculation results of the output coefficient model, thus, it is unrealistic to compare the significant difference of these data.
• Discussion: Revise the manuscript with strong justification for background.  
• Response: We are grateful for the comments . As suggested by the reviewer, we have added the information required as explained above ( Page19, Line452-464)
• Conclusion: write the conclusion again and be more concise to the major findings and suggestions. 
• Response: Thank you very much for your comments. We have revised the conclusion accordingly and made the sentences more concise in the revised manuscript. (Page 20, Line 510-525) 

Author Response File: Author Response.pdf

Reviewer 2 Report

Analysis of the spatial distribution characteristics of livestock and poultry farming pollution and assessment of the environmental pollution load in Anhui Province is a manuscript that has enough quality and might be published after minor revision

- In order to facilitate reading, please include a list of the main abbreviations used.

- How TN, TP and Chemical Oxygen demand were estimated?

- It might be possible to compare results with other similar works from the same geographic area or nearby?

Author Response

Dear reviewers:

We thank all the reviewers and the editor for their careful reading of our manuscript entitled “Analysis of the spatial distribution characteristics of livestock and poultry farming pollution and assessment of the environ-mental pollution load in Anhui Province” (No. sustainability-1629336) and constructive comments and suggestions. Those comments are all valuable and very helpful for improving our paper, as well as the important guiding significance to our researches. We have tried our best to revise and improve the manuscript and made changes in the manuscript according to the reviewers’ good comments. Besides, our current manuscript followed the journal formatting guidelines of Sustainability. Revised portion are marked in red throughout the revised manuscript. Moreover, all language problems or grammatical flaws are improved by native English speaker. We appreciate the editors/reviewers’ hard work earnestly, and hope that the corrections will meet with approval. Thank you very much for your comments and suggestions.

We look forward to your information about our revised paper and thank you for your good comments.

Yours sincerely,

Prof. Dr. Youhua Ma

NOTE: All the page and line numbers where revisions were made refer to the manuscript and highlight with marked changes (Manuscript Revised Version).docx. The Manuscript Clean Version was the same version of the Manuscript Revised Version with cleaned from all the marks.

Responses to the Reviewer 2#’s comments:

Analysis of the spatial distribution characteristics of livestock and poultry farming pollution and assessment of the environmental pollution load in Anhui Province is a manuscript that has enough quality and might be published after minor revision.

Response: Thank you very much for your reviewing and such nice comments. Those comments are all valuable and very helpful for revising and improving our paper. We have revised the manuscript accordingly，and our point-by-point responses are presented as follow.

• In order to facilitate reading, please include a list of the main abbreviations used. 

Response: We agree with the comment and re-wrote the sentence in the revised manuscript as following: “The major pollutant indicators used in this paper are as follows: total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), and ammonia nitrogen (NH₃-N).” (Page 3, Line 141-143)  

• How TN, TP and Chemical Oxygen demand were estimated? 

Response: We deeply appreciate the reviewer’s suggestion. According to the reviewer’s comment, we provided more details to describe this mechanism as following (Page 3, Line 145-149, Page 4, Line 150-166):

 According to the quantities, feeding cycles, and discharge coefficients of the different types of livestock and poultry, the LPE output, pollutant output, and pollutant release in Anhui Province were calculated using the output coefficient model, using Equations (1), (2), and (3), respectively.The formula can be viewed in the revised manuscript.(Responses to the Reviewer 2#’s comments- sustainability1629336.docx)

In Equations (1-3), W is the annual LPE output (t), Lq is the number of livestock and poultry (item), T is the feeding cycle (d), C is the daily discharge coefficient (kg/d), Lp is the LPE pollutant output (t), Lc is the pollutant content (kg/t), Vq is the pollutant release (t), and Vr is the rate of release into the water (%). The quantity of the relevant livestock and poultry was calculated according to the amount of pigs and poultry slaughtered and the cattle and sheep stock. Based on the concept the one pig is defined as the one pig equivalent, 100 pigs are equivalent to 20 cattle, 250 sheep, or 2,500 poultry^[23]. The feeding cycle of cattle and sheep is 365 d, while those of pigs and poultry are 199 d and 210 d, respectively^[24]. The parameters of the discharge coefficient and average LPE pollutant content^[24-26] were mainly obtained from relevant recent research results. The details are provided in Table 1. Furthermore, the percentage of LPE pollutants released into the water was defined as 30%^[24].

Table 1. Discharge coefficients and pollutant contents of LPE.

Notes: TN: total nitrogen; TP, total phosphorus; COD, chemical oxygen demand.

• It might be possible to compare results with other similar works from the same geographic area or nearby? 

Response: Our deepest gratitude goes to you for your careful work and thoughtful suggestions that have helped improve this paper substantially. We agree with the comment and re-wrote the sentence in the revised manuscript as following:

“The equivalent pollution index for livestock and poultry pollutants in the water bodies in Anhui Province in 2008 was 7.03 ^[19]; while in this study, it was found that the equivalent pollution index for the livestock and poultry pollutants in the water bodies in Anhui Province in 2019 was 5.23. This comparison shows that the risk posed by livestock and poultry breeding related pollution to the water environmental is decreasing. The emission of LPE in Anhui Province in 2018 was 45,110,000 t ^[20]. The emission of LPE in Anhui Province in 2019 calculated in this study was 47,778,600 t. The increase in the breeding quantity was the main reason for the change in the LPE emissions. Geng et al. ^[21] showed that the risk posed by animal husbandry waste related pollution to agricultural land in Anhui Province was not high. The main reason for this is that their study took cultivated land, grassland, and forest land in agricultural land as the consumption place; while in this study, only farmland was taken as the consumption place of livestock and poultry breeding pollutants.” (Page 19, Line 452-464) 

1. Song, D.P.; Zhuang, D.F.; Chen, W.; Risk assessment of the farmland and water contamination with the livestock manure in Anhui province. Environ. Sci., 2012, 35(1): 110-116.
2. Zhang, J.Y.; Wang, B.W.; Yyan, X. J. Spatial and temporal distribution features of livestock and poultry manure and nutrient content in Anhui Province. J. Agri. Resourc.Environ., 2021, 38(2): 295-304. 
3. [21] Geng, W.; Sun, Y.X.; Yuan, M.M.; Wu, G.; Wang, J. B. Evaluation of environmental carrying capacity and manure organic fertilizer instead chemical fertilizer potential of animal husbandry in Anhui. Trans. Chin. Socie. Agri. Engin., 2018, 34(18): 252－260.

Author Response File: Author Response.pdf

Reviewer 3 Report

The article reveals one of the important problems of environmental pollution, including water resources, in regions with excessive levels of animal husbandry and low level of technologies for their waste disposal. To improve the methodological part and the quality of research results, the authors need to:

1. In the methodological part, paragraph 2.3, provide a detailed description of methods and working software modules that were used for data processing;
2. Present a map of the location of animal farms (type of object "point") and calculate the densityof their placement, as the main sources of pollution;
3. Present a map of the distribution of agricultural land and water bodies;
4. To map the boundaries of river basins on the administrative map and calculate the value of LPE within individual river basins;
5. Additionally develop environmental measures within individual river basins.

Author Response

Dear reviewers:

We thank all the reviewers and the editor for their careful reading of our manuscript entitled “Analysis of the spatial distribution characteristics of livestock and poultry farming pollution and assessment of the environ-mental pollution load in Anhui Province” (No. sustainability-1629336) and constructive comments and suggestions. Those comments are all valuable and very helpful for improving our paper, as well as the important guiding significance to our researches. We have tried our best to revise and improve the manuscript and made changes in the manuscript according to the reviewers’ good comments. Besides, our current manuscript followed the journal formatting guidelines of Sustainability. Revised portion are marked in red throughout the revised manuscript. Moreover, all language problems or grammatical flaws are improved by native English speaker. We appreciate the editors/reviewers’ hard work earnestly, and hope that the corrections will meet with approval. Thank you very much for your comments and suggestions.

We look forward to your information about our revised paper and thank you for your good comments.

Yours sincerely,

Prof. Dr. Youhua Ma

NOTE: All the page and line numbers where revisions were made refer to the manuscript and highlight with marked changes (Manuscript Revised Version).docx. The Manuscript Clean Version was the same version of the Manuscript Revised Version with cleaned from all the marks.

Responses to the Reviewer 3#’s comments:

The article reveals one of the important problems of environmental pollution, including water resources, in regions with excessive levels of animal husbandry and low level of technologies for their waste disposal. To improve the methodological part and the quality of research results, the authors need to:

Response: Thank you for your precious comments and advice. Those comments are all valuable and very helpful for revising and improving our paper. We have revised the manuscript accordingly, and our point-by-point responses are presented as follow.

• 1. In the methodological part, paragraph 2.3, provide a detailed description of methods and working software modules that were used for data processing;

Response: We are very grateful to your comments. We have added the detailed description of methods and working software modules in the revised manuscript as following:

“The SPSS 22.0 (Version 22.0, SPSS Inc., Chicago, USA) data statistical analysis module was used for the statistical processing of the original data. The data import module in the Origin 8.0 software (Origin Lab, Northampton, USA) toolbox was used to import the production amount and diffusion concentration of the LPE pollutants, and bar charts were drawn using the drawing module. The data import module in the ArcGIS10.2 (Environmental Systems Research Institute, Inc., USA) toolbox was used to import the map of Anhui Province and the production of LPE and other data, and the spatial analysis tool was used to process and analyze the data. The spatial distribution map of the production and loss of LPE was drawn in the map layer for Anhui Province, and the spatial information visualization of the data was realized through the layout.” (Page 6, Line 225-234)

• 2. Present a map of the location of animal farms (type of object "point") and calculate the density of their placement, as the main sources of pollution; 

Response: We are grateful for the suggestion. We have added a map of the location of animal farms in the latest version of the manuscript. The brief description of this map was as following (Page 7, Line 257-262; Page 8, Line 263-270):

By analyzing the spatial distribution and density of the main livestock and poultry farms in Anhui Province in 2019 (Figure 1), it was found that the number of farms in the northern cities in Anhui Province, such as Fuyang City, Huainan City, Bengbu City, and Huaibei City, was relatively large, the farms were concentrated, and the breeding scale of each farm was large. The distribution of the livestock and poultry farms in the southern cities in Anhui Province, such as Anqing City, Chizhou City, and Xuancheng City, was relatively scattered, and the number and size of the farms were small. Overall, the spatial distribution of the livestock and poultry farms in Anhui Province was concentrated in the north and scattered in the south.(The figure can be viewed in the Responses to the Reviewer 3#’s comments- sustainability1629336)

Figure 1. Spatial distribution and density of the main livestock and poultry farms in Anhui Province in 2019. The cities include Hefei, Huaibei, Bozhou, Suzhou, Bengbu, Fuyang, Huainan, Chuzhou, Lu’an, Ma’anshan, Wuhu, Xuancheng, Tongling, Chizhou, Anqing, and Huangshan. Legend: major animal farm; Farm density, high to low.

• 3. Present a map of the distribution of agricultural land and water bodies; 

Response: Thank you very much for your comments. We have added a map of the distribution of agricultural land and water bodies in the revised manuscript. (Page 13, Line 356-361; Page 15, Line 391-395; Page 16, Line 409-415; Page 17, Line 424-437) 

• 4. To map the boundaries of river basins on the administrative map and calculate the value of LPE within individual river basins; 

Response: Thank you for the comments. We have added the information according to your suggestion (Page 9, Lines 291-297, Page 10, Lines 298-312).

• 5. Additionally develop environmental measures within individual river basins. 

Response: Thanks very much for your comments. We agree with the comment and re-wrote the sentence in the revised manuscript as following:

“Standardized production in large-scale livestock and poultry farms and the resource utilization mode of LPE should be promoted in the Huaihe River Basin. Further improvement of the livestock and poultry breeding technology should be encouraged, to achieve the transformation to technology-intensive modern animal husbandry. The optimization of the farm layout should be promoted, and the construction of digital and information-based intelligent pasture should be supported. The layout of pig breeding should be optimized and the total amount of pig breeding should be reduced in the Yangtze River Basin. We should give full play to the advantages of centralized poultry breeding in southern Anhui to guide the appropriate development of waterfowl in the basin. We should actively develop herbage farming and support the standardization and upgrading of large-scale livestock and poultry farms and enclosures and the upgrading of equipment. The Xin'an River Basin should adhere to moderate scale operations as the main task and standardize production as the direction. The inexpensive return of LPE to fields should be promoted, and the pollution control of breeding should be actively and steadily promoted.” (Page 20, Line 510-526)

Author Response File: Author Response.pdf

Reviewer 4 Report

The article explores the potential pollution risk from livestock and poultry farming on agricultural land and water systems in Anhui Province of China. The assessment was based on statistical data on the amount of livestock and poultry present in the agricultural area of the province in 2019. The ArcGIS software allowed to analyse the characteristics of the spatial distribution of livestock, and the equivalent pollution load method was adopted to compare and assess the release of pollutants in various cities, analysing the causes.

The analysis of the previous literature was complete and well-argued, evidencing the lack of systematic research on the scope of calculation standards and pollution assessment methods and of a comprehensive assessment of pollutant impact of livestock and poultry manure on regional farmland and the water environment.

The methods used in the article were robust and coherent to ensure high quality in the accuracy of the estimates, and they have been well described and reasoned in the article. The theoretical issues are also well treated in the article.

Interesting results were well-argued, suggesting optimising the layout of livestock and poultry farming areas to prevent the environmental pollution, smoothing the crop and livestock farming cycles, and vigorously promoting the resource utilisation of livestock and poultry wastes.

The article is well written and very detailed in the methodology and discussion, making it an interesting reading for researchers on this topic. I think that it should be published in the actual form.

Author Response

Dear reviewers:

We thank all the reviewers and the editor for their careful reading of our manuscript entitled “Analysis of the spatial distribution characteristics of livestock and poultry farming pollution and assessment of the environ-mental pollution load in Anhui Province” (No. sustainability-1629336) and constructive comments and suggestions. Those comments are all valuable and very helpful for improving our paper, as well as the important guiding significance to our researches. We have tried our best to revise and improve the manuscript and made changes in the manuscript according to the reviewers’ good comments. Besides, our current manuscript followed the journal formatting guidelines of Sustainability. Revised portion are marked in red throughout the revised manuscript. Moreover, all language problems or grammatical flaws are improved by native English speaker. We appreciate the editors/reviewers’ hard work earnestly, and hope that the corrections will meet with approval. Thank you very much for your comments and suggestions.

We look forward to your information about our revised paper and thank you for your good comments.

Yours sincerely,

Prof. Dr. Youhua Ma

NOTE: All the page and line numbers where revisions were made refer to the manuscript and highlight with marked changes (Manuscript Revised Version).docx. The Manuscript Clean Version was the same version of the Manuscript Revised Version with cleaned from all the marks.

Responses to the Reviewer 4#’s comments:

The article explores the potential pollution risk from livestock and poultry farming on agricultural land and water systems in Anhui Province of China. The assessment was based on statistical data on the amount of livestock and poultry present in the agricultural area of the province in 2019. The ArcGIS software allowed to analyse the characteristics of the spatial distribution of livestock, and the equivalent pollution load method was adopted to compare and assess the release of pollutants in various cities, analysing the causes.

• The analysis of the previous literature was complete and well-argued, evidencing the lack of systematic research on the scope of calculation standards and pollution assessment methods and of a comprehensive assessment of pollutant impact of livestock and poultry manure on regional farmland and the water environment.

Response: We are very grateful to your comments for the manuscript. We appreciate the reviewer’s positive evaluation of our work. 

• The methods used in the article were robust and coherent to ensure high quality in the accuracy of the estimates, and they have been well described and reasoned in the article. The theoretical issues are also well treated in the article.

Response: Thanks you for your comments. Your careful review has helped to make our study clearer and more comprehensive.

• Interesting results were well-argued, suggesting optimising the layout of livestock and poultry farming areas to prevent the environmental pollution, smoothing the crop and livestock farming cycles, and vigorously promoting the resource utilisation of livestock and poultry wastes.

Response: We appreciate the reviewer’s positive evaluation of our work. 

• The article is well written and very detailed in the methodology and discussion, making it an interesting reading for researchers on this topic. I think that it should be published in the actual form.

Response: Thank you for your careful review. We really appreciate your efforts in reviewing our manuscript during this unprecedented and challenging time. We wish good health to you, your family, and community.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear authors

Thank you for addressing the comments. Correction was satisfied. So, I recommend the manuscript for publication.

However, there are some English errors and I recommend to be checked by an English editing company.

Best regards