Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

The topic of the manuscript is relevant and professionally justified. The number of literature references should be expanded where indicated. More details in the material and methods chapter should be better supported by explanations. In the results section, more thorough explanations are needed in some places (where I indicated). The conclusions are moderate and clear.

I have inserted several comments in the manuscript, please see and correct them (see attachment).

The study could be extended in the future and additional manufacturers' products could be included.

Comments for author File: Comments.pdf

Author Response

Answers to Reviewer 1:

 

• The number of literature references should be expanded where indicated.

 

Some new references to literature sources have been added following the referee indications (Lines 78, 84, 87, 100, 115, 162, 168, 173, 178, 179, 326):

 

11. Rajan, M., Shahena, S., Chandran, V., Mathew, L. Controlled release of fertilizers -concept, reality, and mechanism. Controlled Release Fertilizers for Sustainable Agriculture. 2021, 41–56.
12. Adams, C., Frantz, J., Bugbee, B. Macro- and micronutrient-release characteristics of three polymer-coated fertilizers: Theory and measurements. J. Plant Nutr. Soil Sci. 2013, 176, 76-88.
13. Shah, A. A., Hasan, F., Hameed, A., Ahmed S. Biological degradation of plastics: A comprehensive review. Biotechnology Advances. 2008, 26, 246-265.
14. Alshehrei, F. Biodegradation of Synthetic and Natural Plastic by Microorganisms. J. Appl Environ Microbiol, 2017, 5(1), 8-19.

 

22. Steinmetz, Z., Wollmann, C., Schaefer, M., Buchmann, C., David, J., Tröger, J., Muñoz, K., Frör, O., Schaumann, G. E. Plastic mulching in agriculture. Trading short-term agronomic benefits for long-term soil degradation? Science of the Total Environment. 2016, 550. 690-705.

 

28. Li,Y., Liu J., Wang Y., Tang X.,  Xu J.Liu, X.Contribution of components in natural soil to Cd and Pb competitive adsorption: Semi-quantitative to quantitative analysis. J. of Hazard. Mater. 2023, 441, 129883
29. Brian J. Alloway, Heavy Metals in Soils: Trace Metals and Metalloids in Soils and their Bioavailability. Springer Dordrecht Heidelberg New York London, 2013.
30. Dang V. M., Van H. T., Vinh N. D., Duong T. M. H., Nguyen T. B. H., Nguyen T. T., Tran T. N. H., Hoang T. H., Tran T. P., Nguyen L. H. and Chu M. N., Enhancement of exchangeable Cd and Pb immobilization in contaminated soil using Mg/Al LDH-zeolite as an effective adsorbent. RSC Adv., 2021, 11, 17007-17019.
31. Hummel, D. O., and F. Scholl, Atlas of Polymer and Plastic Analysis. Vol. I. Polymers Structure and Spectra. Verlag Chemie, Weinheim1978, 416.
32. DL, Hansen, Sprouse Collection of infrared spectra, book 1: polymers. Paoli: Sprouse Scientific Systems1987.
33. Kabekkodu, S. N., Faber, J., & Fawcett, T. New Powder Diffraction File (PDF-4) in relational database format: advantages and data-mining capabilities. Acta Crystallographica Section B: Structural Science, 2002, 58(3), 333-337.

 

46. Wang, T., Yu, C., Chu, Q., Wang, F., Lan, T., Wang, J. Adsorption behavior and mechanism of five pesticides on microplastics from agricultural polyethylene films. Chemosphere 2020, 244, 125491.

 

• More details in the material and methods chapter should be better supported by explanations.

More details and explanations on materials and methods have been added in the text (Lines 138, 139, 140-146; 162, 169-178).

• In the results section, more thorough explanations are needed in some places (where I indicated).

Explanations have been added where indicated (Lines 161-162; 168). Moreover, all numeral data was uniformly formatted using a decimal point instead of commas.

• I have inserted several comments in the manuscript, please see and correct them (see attachment).

All these comments have been addressed through the text

• The study could be extended in the future and additional manufacturers' products could be included.

This recommendation has been considered in the description of the planned future work (lines 379 - 382).

Reviewer 2 Report

Comments and Suggestions for Authors

Several comments in the manuscript consider them and resubmit

Comments for author File: Comments.pdf

Author Response

Answers to Reviewer 2:

2. Several comments in the manuscript consider them and resubmit:

2.1 Title: Following the comments of Reviewer 2 we propose the following title:

Analysis of Slow-released Fertilisers as a Source of Microplastics

2.2 If manufacturers give the synthesis of the polymer coating what is the usefulness of the determination?

SRF manufacturers do not disclose the composition of the polymer shells used.

2.3 Since the mineral filling is known what is the purpose of identifying it?

SRF manufacturers list the macronutrient content but do not disclose what chemical compounds provide it.

All other comments have been addressed in the revised text.

Reviewer 3 Report

Comments and Suggestions for Authors

The article is interesting, but before submitting it to a journal, I recommend reformulating certain sections.

References need to be added throughout. There are several sentences that should be supported by citations, such as those in lines 212-215.

The methodology section should be more detailed and explicit.

In the introduction, consider discussing the importance of Cd and Pb ions. For instance, the information in lines 157-161 would be more suitable in the introduction.

Line 129: Clarify why the fertilizer was washed with water.

Figure 1 should be removed.

Table 1 belongs in the results section.

Conduct studies on the degradation of microplastics.

Did you use statistical criteria to determine which model best fits the experimental data?

Improve the quality of the figures.

Consider combining the isotherm figures into a single image.

Specify the pH and agitation conditions used in the adsorption studies.

Change the unit from mg/dm³ to mg/L.

Author Response

Answers to Reviewer 3:

3.1 References need to be added throughout. There are several sentences that should be supported by citations, such as those in lines 212-215.

Several references have been introduced following Reviewer 3 recommendations (see answers to Reviewer1 comments)

3.2 The methodology section should be more detailed and explicit.

More details and explanations on materials and methods have been added in the text (Lines 138, 139, 140-146; 162, 169-178).

3.3 In the introduction, consider discussing the importance of Cd and Pb ions. For instance, the information in lines 157-161 would be more suitable in the introduction.

The importance of Cd and Pb ions has been moved from lines 157-161 to the introduction and further expanded with additional references (Lines 111-115).

3.4 Line 129: Clarify why the fertilizer was washed with water.

This explanation has been duly included in the text (Lines 140-146).

3.5 Figure 1 should be removed.

Fig.1 was removed

3.6 Table 1 belongs in the results section.

Table 1 does not contain results of the study and describes the materials used in this study with information provided by the manufacturers. We think that Table 1 should be included in the Materials and Methods section.

3.7 Conduct studies on the degradation of microplastics.

We agree that in the context of the study of the behavior of slow release fertilizants as a source of microplastics, the degradation of microplastics plays a relevant role on the environmental impact of this substances. In fact we plan to conduct these experiments in our future research activities. However, due to the fact that the polymers currently used in this industrial sector are polymers with a very slow degradation rate we believe that it is important in this phase to report the production of the microplastics and leave the degradation analysis as future work as explained in the revised text.

3.8 Did you use statistical criteria to determine which model best fits the experimental data?

We use linear regression analysis to determine the model parameters that best fit the experimental data.

3.9 Improve the quality of the figures.

The quality of the figures has been improved (See Figures 3 to 10).

3.10 Consider combining the isotherm figures into a single image.

The different isotherms were combined into four image (See Figures 7 to 10).

3.11 Specify the pH and agitation conditions used in the adsorption studies.

The requested specifications have been added in the revised text (Lines 169-177)

3.12 Change the unit from mg/dm³ to mg/L.

The corresponding changes have been introduced in the revised text.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Comments were taken into account

Author Response

Comment of Reviewer 2:

Comments were taken into account

Response: We thank Reviewer 2 for the positive comment

Reviewer 3 Report

Comments and Suggestions for Authors

General comments

The authors should have done what was requested, such as improving the introduction and the quality of the discussion.

XRD has a poor discussion

Author Response

Comments of Reviewer 3:

The authors should have done what was requested, such as improving the introduction and the quality of the discussion.

XRD has a poor discussion

Answers to Reviewer 3:

We here provide more clear answers to all the comments of Reviewer 3 (Revision 1 and 2):

3.1 References need to be added throughout. There are several sentences that should be supported by citations, such as those in lines 212-215.

References 40 and 41 were added as requested. Moreover, the discussion on XRD results was further expanded.

3.2 The methodology section should be more detailed and explicit.

More details and explanations on materials and methods have been added in the text (See lines 152-162; line 178; lines 183-195.

3.3 In the introduction, consider discussing the importance of Cd and Pb ions. For instance, the information in lines 157-161 would be more suitable in the introduction.

The importance of Cd and Pb ions has been moved from lines 157-161 to the introduction and further expanded with new references (lines 114-122 and 125-131).

3.4 Line 129: Clarify why the fertilizer was washed with water.

This explanation has been duly included in the text (lines 156-163)

3.5 Figure 1 should be removed.

Fig.1 was removed

3.6 Table 1 belongs in the results section.

We consider that Table 1 does not contain results of tis study and should not be included in the results section. The table reports the main parameters of the object under study provided by the producer. Therefore it more appropriate for the methods and materials section.

3.7 Conduct studies on the degradation of microplastics.

We agree that in the context of the study of the behavior of slow release fertilisants as a source of microplastics, the degradation of microplastics plays a relevant role on the environmental impact of this substances. In fact we plan to conduct these experiments in our future research activities. However, due to the fact that the polymers currently used in this sector are polymers with a very slow degradation rate we believe that it is important in this phase to report the production of the microplastics and leave the degradation analysis as future work as explained in the revised text.

3.8 Did you use statistical criteria to determine which model best fits the experimental data?

We have used regression analysis and the correlation coefficient to determine which model best fits the experimental data.

3.9 Improve the quality of the figures.

The quality of the figures has been improved (Figs. 3 and 4)

3.10 Consider combining the isotherm figures into a single image.

The different isotherms were combined into two images (See new Figs. 7, 8, 9 and 10)

3.11 Specify the pH and agitation conditions used in the adsorption studies.

The requested specifications have been added in the revised text (lines 191-192 and 194-195).

3.12 Change the unit from mg/dm³ to mg/L.

The corresponding changes have been introduced in the revised text.