Experiment on Sediment Ammonia Nitrogen Release of Chaohu Lake in Varying Hydrodynamic Disturbance
Round 1
Reviewer 1 Report
The paper is hard to understand. I recommend rewriting using help of a native speaker. Some comments were posted in the PDF file.
Comments for author File: 
Comments.pdf
Author Response
The reply were in the word below.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments in the attachment.
Comments for author File: Comments.pdf
Author Response
The reply were in word below
Author Response File: Author Response.pdf
Reviewer 3 Report
The article “Experiment on Sediment Ammonia Nitrogen Release of Chaohu Lake in Varying Hydrodynamic Disturbance” discusses the highly relevant topic of ammonia release by sediments following hydrodynamic disturbances. However, there are critical gaps in the experimental design, as described in detail below. Also, the manuscript should be critically improved, it requires a full revision of English and writing style. The use of direct writing is strongly recommended, and the quality of the discussion needs to be improved. I hope the authors will find the following comments helpful in improving the quality of the paper:
Abstract
Line11 – The phrase is incomplete
Line 19 –Results should be reported in terms of release rates. Average temperatures and pH should be also reported.
Line 19-22 – These lines are repeating information provided in lines 11-13.
What is the main value of the results? not only in terms of the experimental results but the environmental consequences in relation to Chaohu Lake and similar water bodies?
Introduction
Line 28 – “were”? should be “are”?
Line 29 – 31 – the phrase is not properly connected with the previous lines
Line 27. Check grammar
Lines 44-54. Please check the writing style. Ideas are not well connected
Lines 82-92- Overall, the introduction presents many previous studies but fails at properly introducing the research question and how the results achieved fulfilled the identified gap. Also, it is not clear how the mentioned objectives of the research were achieved.
Line 91 – “law of ammonia nitrogen release” -Which law is this? Is this really being discussed in the MS?
Experimental design
Lines 93 -106: basic climate information (temperatures, wind) is required. Also, sources of TN pollution should be mentioned.
Line 108 – Figure 1 – the figure should display land uses in the areas responsible for discharges of pollutants to the lake. Tributaries are also required since they are mentioned in the Analysis section.
Lines 109-120 - what was the temperature during the experiments? What was the pH? How the experimental conditions of pH, temperature and hydrodynamics replicated the real conditions in Chaohu lake. Besides, did the authors perform the experiment using replicates? How did authors maintain the sediment cake without serious disturbances when transferring it to the acrylic tubes? Please provide further information details.
Lines 129 -131 – Did the authors use Chaohu lake water in the column or a synthetic preparation? It is not clear from these lines. Also, how did the authors measure TN / ammonia concentrations?
Lines 148- - 152 – Phosphorus is mentioned in these lines. Since only NH4/TN are studied, this mention of phosphorus is confusing.
Line 153 - Eq. 1- “Ci+1” – better Ci-1?/ Authors show discuss the potential extrapolation of this equation to releases in real environments.
Results
Line 163 – “ammonia nitrogen content in water bodies” – from this line it seems that authors used the same Chaohu lake water in the experiments. If this is the case, it must be mentioned that variations in ammonia nitrogen concentrations are related to sediment release during the experiments. Besides, it is not clear from the Methods section if the authors measured ammonia or TN? Also, what evidence is provided to attribute ammonia variations only to hydrodinamic disturbances and not to any physicochemical or biological processes?
Line 164: “declining slowly not until the end” – please check English
Line 169: “exchanged with various nutrients in the water” – what experimental evidence (besides TN) do the authors have to support this statement?
Line 164 – Figure 4: title should provide more description of data (e.g., sampling point names, conditions of each experiment, etc)
Line 218 – 227 – Which internal biochemical reactions? What evidence is provided to support these types of reactions? TN concentrations in sediments and water (including the organic nitrogen) would be required to discuss these processes. On the other hand, ammonia equilibrium is highly affected by pH and T but there is no mention of these parameters in the MS. Also, there are no references to gas/liquid equilibria? Is ammonia volatilization considered negligible, and under what arguments?
Analysis
The discussion with results from other studies is scarce. Authors need to improve the discussion by including more comparisons with previous works
Line 258 – Figure 6. What is the effect of ammonia concentrations in sediments? It is clear that higher releases are also related to higher concentrations in sediments. I guess that this figure needs at least to somehow show individual data with initial ammonia concentrations in sediments and water.
Line 286 – Which index?
Line 288 – different lakes?
Lines 312-332 – What is the purpose of these calculations? Does release data explain ammonia concentrations in each area of the lake? Is this release increasing ammonia volatilization or nitrification and thus eutrophication?
Conclusion
Lines 333-348 – It seems to me that the results should be interpreted and discussed only in relation to hydrodynamic parameters. Using area is too generalist, and at least further explanation on pH, temperature, and balances of nitrogen compounds should be provided to validate the results. Also, what is the relation between the results and environmental conditions in the Chaohu lake and similar environments?
Author Response
The reply were in word below.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The manuscript has been improved.
Author Response
Thanks for your comments.
Reviewer 3 Report
This reviewed version of the article “Experiment on Sediment Ammonia Nitrogen Release of Chaohu Lake in Varying Hydrodynamic Disturbance” shows some improvements when compared with the original version. However, the English style was not critically improved, thus the reading continues to be complicated and confusing with many circular ideas. Some further comments are provided below:
1. A clean (without track changes activated) version of the manuscript could be provided to improve reading.
Abstract
2. Abstract: Despite improving the quality of the abstract, it seems that the text is still prolix, making it difficult to understand the main achievements and their scientific value
3. There are several problems with style and typos (e.g units written without space after the number)
Introduction:
4. line 38 – environmental impacts caused by whom? The manuscript is full of similar English-style issues.
5. Lines 117-125. Many English style issues. These lines present the aim of the manuscript, but it is written in future tense and is too wordy.
Experimental Design
6. Lines 130-135- What are the sources for this information?
7. Figure 2 title: there should be “a” and “b”. The title is not providing enough information to easily understand the figures. My previous suggestion of including nearby land uses were not attended to.
8. Lines 154-157 are out of format
9. Line 162 – Method HJ 162 634-2012. More details are required to really understand the form of nitrogen that is being measured. Is it a commercial kit? Is it a local standard method?
10. Lines 164-166 - - What are the sources for this information?
11. Lines 165- 175 – These lines seem to be results but are being presented in the experimental design.
12. Figure 3 – Again, there should be “a” and “b”. The title is not providing enough information to easily understand the figures.
13. Lines 196-197 are repeating information provided in lines 185-187.
14. Line 200 – Pre-configurated water? Is it synthetic wastewater?
15. Line 207- “pH” is written “PH” throughout the entire manuscript
Results
16. Figure 4 and 5 – Are they really different figures?
17. Figure 6 – How are initial concentrations in this figure related to concentrations reported in Table 2?
18. Reported values of ammonia concentrations after disturbances do not clearly follow the data in Figure 6.
19. DO results (Figure 332-341, lines 332-341). The authors did not really prove that biochemical reactions were the main responsible for the decrease in oxygen during the experiment. At least, the writing style might suggest that this hypothesis is highly probable but not proven.
20. If biochemical reactions are taking place, how do ammonification and nitrification affect the release of ammonia? What was the effect of these processes on final ammonia concentrations in figure 6? What was the role of nitrogen in the sediments and in water? How much was really volatilized?
21. Table 5- Cumulative release of DO? – How was it calculated? How did authors consider variables such as oxygenation due to the propellers and atmospheric equilibrium?
22. Overall, the results and discussion section is still too wordy and it is very hard to follow the ideas. The paper required a critical revision of the English style, which was not included in this new manuscript version.
Author Response
The replies were in the pdf file.
Author Response File: Author Response.pdf
Round 3
Reviewer 3 Report
The paper in its current form seems more suitable for publication after minor changes and edition work. Only some minor observations:
Figure 1a. Please indicate north and coordinates, sampling points, and conventions. They were in the previous version of the figure but now they appear only in Figure 3.
Figure 3 is unnecessary. Consider presenting north, sampling points, and conventions in Figure 1a
Please use SI units and verify concordance throughout the entire manuscript: mL, L, etc
Figure titles´ have poor descriptions of the content of figures.
Author Response
The replies were in the word file.
Author Response File: 
Author Response.docx
