Review Reports - Importance of the Submerged Zone during Dry Periods to Nitrogen Removal in a Bioretention System

Round 1

Reviewer 1 Report

The work presented by Kangmao et al. studies the influence and importance of the submerged zone during dry periods to nitrate and ammonium removal in a bioretention system, which is very interesting. To achieve this goal, appropriate experimental procedures and analyses have been employed. I recommend accepting the manuscript after the following revisions.

Broad comments

There are several abbreviations throughout the text that lack an appropriate definition the first time they’re used (e.g. ON, TN). Please, clarify this point.

Please, remove the “–N” following NH4 and NO3 throughout the text.

The Materials and Methods section lacks important information that must be provided.

The Results and Discussion section will benefit from more discussion regarding biological factors.

Some specific comments are given below.

Specific comments

Introduction:

Lines 45, 51 and 64: Please remove the underline within these citations.

Line 66: The term “denitrification” should be defined before in Line 39.

Materials and methods

Line 99: Please, express it in “mm”.

Line 114: Please, provide the source of this information.

Line 135: “there was”

Line 150-154: What sort of analyzer is this? Please, describe it and the analysis methods in more detail.

Line 155: Please, describe the statistical analyses performed (correlation, etc) including the software employed.

Results and Discussion

Line 217: “are shown in”

Lines 217-218: Please, explain why this observation is obvious.

Lines 230-231: If it’s a range please replace “~” by “to” or by a hyphen.

Lines 230 and 240: If these results are not supported by an statistical analysis then remove the words “significantly” and “significant”.

Line 246: Please, replace “this paper” by “these experiments”.

Lines 248-249: These variations are only described in the Materials and Methods for the wet period. Please, clarify this point.

Lines 261 and 271: Please, explain in the Materials and Methods section how these analyses were performed.

Line 271: What about the biological factors? In this regard, more discussion is needed in this section.

Lines 286-287: “plots are shown in Figure 7.”

Line 318: Please, remove “…and V₁ is shown in…”

Lines 329-331: Please, indicate where these data can be observed.

Line 345-347: Please, remove the sentence starting by “This section…”.

Line 352: “as follow:”

Figures and figure legends:

Figure 3: Please provide the units for nitrogen concentration here.

Figure 4: Please, provide the units for nitrogen removal rate here. Also replace NH3^--N by NH4⁺

Figures 5 and 7: Please, replace NH3^--N by NH4⁺.

Figure 5, 6, 7 and 9 legends: Explain the meaning of the bars and symbols present in these figures.

Figure 10 legend: “nitrogen species removal”. Also, please, explain the meaning of the bars and symbols present in these figures.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

General comments. The manuscript “Importance of the submerged zone during dry periods to nitrogen removal in a bioretention system” is very interesting. The Authors investigated the variation of nitrogen concentration of the submerged zone, under consecutive cycles of wet and dry alternation with varied rainfall amount, based on the experiment in a mesocosm bioretetion system.

The experimental design is appealing and the Authors used a very interesting approach. The results are worthy of note and the survey is well conducted and presented. The proposed methodology is of good technical quality and research depth. Overall the paper is well structured. Specific comments are provided in what follows.

Keywords well chosen and appropriate

Title and abstract.

The paper’s title is suitable, concise and appealing.
The abstract conveys the purpose of the study in a readable way.

Introduction

The introduction informs the reader about the objectives of the paper that are well-focused.

Methods.

The analysis is appropriate

Results.

The discussion of results is very clear,
The study proposes a very interesting methodology.
Captions of Figures and Table are adequate.

Conclusions.

The conclusions are appropriate and focused results.

Bibliography/References are appropriate.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Generalities

The manuscript entitled “Importance of the submerged zone during dry periods to nitrogen removal in a bioretention system” aims to evaluate the importance of a submerged zone on nitrogen remocal in a bioretention system. The manuscript is lacking of in-depth scientific discussion about the nitrogen dynamics inside the system about which processes are occurring and who are performing them (plants, bacteria, algae, etc…).

Specifications

In the Introduction section it is missing an explanation about the possible denitrification mechanisms occurring in bioretention systems.
Organic matter analyses are lacking. They could be helpful on elucidating denitrification performance. Also the analysis of metals such as iron could be interesting to assess possible autotrophic denitrification role.
In general, the results section is lacking of a in-depth discussion of the results obtained.