The Migration and Transformation of Nitrogen in the Danjiangkou Reservoir and Upper Stream: A Review

Round 1

Reviewer 1 Report

The research project of the paper is very important. I suggest changing the title because the current one indicates the impact of something on water quality, but not clearly.

There are many themes in the work. There are also many answers to some of them in the literature. This would complete the paper as proposed solutions.

I have included comments and suggestions in the attached text

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The article presents a review of the N loading on a reservoir. Overall, the paper has an acceptable and useful scientific value and it adheres to the “Water” standards.

Author Response

The article has carried on the meticulous modification to the text expression, the figure, the table, has reduced the error, has increased the explanation to the problem. See the revised article for details.

Reviewer 3 Report

The presented MS aims to summarize the existing research on N in the Danjiangkou Reservoir. The readers expect to achieve estimation and clarification of the important pressures and processes concerning N cycle in the investigated region. There are some parts of the MS which fail to contribute to the above mentioned aim.

Introduction

1. In order to “classify” the environmental problem, referencing to the Chinese (give some information about mentioned Classes) and international legislation norms (for example EU Nitrate directive) should be included.
2. Table 1 could be provided as supplementary material.
3. There is no analysis of the references in Table 1 and sequential detailed determination of the important topics for investigation.

Part 2

1. There is nothing mentioned about data used in this part. What are the sources: previous studies (as it is indicated in Fig. 4), your data or data from the state monitoring program? I would suggest clarifying this in a separate subchapter. If data comes from established monitoring program, please indicate them in Figure 2.
2. Figure 3: please include a legend.
3. Trend analysis (2.2.2) is performed by the comparison of annual mean values (Figure 4) followed by monthly variation trends in Figs 5 and 6. Please use and explain in a separate subpart Time Series Analysis. There is no indication if the seasonal fluctuations/trends are removed from the time series before estimation of the trend and seasonality.
4. I would suggest TN load (2.3.2) map incorporating the main pollution sources to be presented. This or similar information could be very useful for the reader.
5. Apportioning of N loads depending on pollution sources should be presented (on map(s) if it is possible. Now it is very difficult to follow the discussion in part 3.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The revised MS is of better quality and addresses many of the remarks to the original version. However, some details should be clarified before publication:

1. Figure 3: please specify the concentration ranges instead of low, middle, high TN concentrations.
2. Figure 4: use “this study” instead of “our team”. You can omit the text “(Data sources: red-our team's monitoring station, other colors-previous studies from other teams)”.
3. Figure 5 (previous Fig. 6): My previous remark concerning trend in case that no Time Series Analysis is performed is not taken into account.
4. Figure 7: There is no apportioning of N loads (contributions of different pollution sources). The figure presents water quality status based on TN.

Author Response

Please see the attachment.

Author Response File: Author Response.doc