Effects of Microplastics Addition on Soil Available Nitrogen in Farmland Soil

Round 1

Reviewer 1 Report

Observations

1. In different lines (82, 113, 114, 115, 219), there are various errors with the subscripts, units of measure, or typing.

2. Why you decided to work with PE?

3. What material do you use to store samples and the equipment used for sampling? What do you do to ensure that the sample is not contaminated in the sampling process?

4. The presence of PM has been demonstrated in different environments. Why did you not determine the PM present in the samples? How did you ensure the samples did not contain PM of other types, forms, and amounts?

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

This paper study the effect of PE MPs on farmland soil. In my opinion, the paper has a series of methodological flaws, inconsistencies in the result, and poor discussion that make me not agree with its publication in its current state.

Majors:

-In the introduction it is necessary to refer the papers that have studied the effect of microplastics on microbial diversity.

L55: “anthropogenic”. I think this word does not make sense in this sentence. Please rewrite it.

And in general, all English needs to be reviewed by a team of expert editors

Materials and methods

L96: At what time of year were the samples soil were collected? What kind of crops had been grown on those farmlands?

L119: “dark environment at 28° C” Why were they incubated in the dark and not in cycles of light/dark, to simulate environmental conditions? if the average temperature of the area is 21.1 ºC why the samples were incubated at 28ºC??

L120: “on 1, 2, 4, 6, 10, 15 and 30 days” I consider that the time taken is too short, to see an effect of the MPs on the soil. Discuss why these times were chosen in comparison to those in the existing literature, is essential.

How it was calculate the nitrogen mineralization rate? Please define

Results:

According to table 1, at time zero, the content of ammonium and nitrate are practically the same 8.71 mg/kg, but in figure 1 at time zero there is much more nitrate than ammonium. How is this possible?

Figures. Explain in the legend that it is a, b, ab, c...

Figure 2. I don't understand why at time zero  CK, T1 and T2 have such different values of DON and DOC, or is it that the first data indicated in the graph is not at time zero? The initial values must be reflected in all the graphs.

Figure 2: What is the reason for the fall in time 10, both in T1 and in T2? Explain

Table 2: Please defined what is ASV richness, Shannon, Chao1 and  Evenness indexes.

I do not understand what these data in table 2 mean. If what you did as indicated in materials and methods was the identification of microorganisms by means of 16S rRNA. How was the abundance of each of them quantified in the different incubation periods? the materials and methods do not state that the PCR performed was quantitative. please clarify.

What species of microorganisms in particular have been identified? Why are none of them cited or discussed?

Discussion:

L209: LDPE, define please

L214: . (year) ¿?????

L224: “we conducted incubation in a lower temperature (25 °C)” in the materials and methods it says that it was done at 28ºC. Which one is correct then?

L236: “Plastic particles have a very high content of carbon (Rillig, 2018), and this material will  slowly be decomposed, contributing to a very wide C: N ratio in soil” I think that in this reference they refer to long times, and in this paper, the samples were only incubated for 30 days, are there publications that say that in 30 days the PE MPs decompose and release its carbon? I seriously doubt it.

L237:” PE MPs could be utilized as C source by microorganisms and lead to microbial immobilization enhanced (Rillig et al., 2019)” yes, but how much time is needed for this to happen, 30 days?, I doubt it, if there is a bibliography that says this, please quote and discuss it

L252: Blocker et al. (year),????

I'm sorry but, the conclusion is poorly written, it must be something concise and clear, and not repeat the summary again.

Minors:

Abstract: Please defined what is PE, CK, DON, DOC

Introduccion: POPs? please define this and all abbreviations the first time they appear

L61: PP?

L75: “increased dramatically in China” please also include data from the rest of the world

L100: 20 m ¿*? 20 m

L130: “(company)”???

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

1. It is advise to get the professional editor to edit the English language.

2. Please avoid to use 'we, our' in the manuscript

3. Please write in the full term for any abbreviation use in the first time in manuscript.  

4. Some sentences are contradicted, please check and rephrase

5. Please re-write the conclusion, as the current write-up for conclusion is too lengthy 

6. There are few repeat sentences used in the manuscript

7. Please state and explain the significant of the study.  For example, how does it affect the ecosystem and human health.

8. Please check the correct symbol for micron

9.  Please ensure some number or letter should be superscript (please see the comments in the attached file)

10.  Please check all comments in the attached manuscript

 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

Authors should improve English language. DOD and DOC mus be explained in Abstract.

 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Dear Authors, I believe that the authors have responded correctly to most of my comments and I accept the paper in its current version.

Author Response

Thank you again for your positive comments and valuable suggestions to improve the quality of our manuscript.

Reviewer 3 Report

A minor amendment is needed.  Please refer to the attachment.

Comments for author File: Comments.pdf

Author Response

Thanks. We have corrected these mistakes based on your suggestions in the revised manuscript. The details are as follows:

1、We added the full terms of PE and PLA in line 15 and 215, respectively, in the revised manuscript.

2、We modified the sentence to avoid to use 'we' in the revised manuscript.

3、As you suggested, we removed 'difference' in the sentence.

4、We added the information of CK in line 26 in the revised manuscript.

5、We used the BD instead of the full name in Table 1.

6、We added (P<0.05) at the end of the sentence.

7、We corrected 'our study' into 'this study' in line 238 in the revised manuscript.