Influence of Urban-Road Green Space Plant Configurations on NO₂ Concentrations in Nanjing City during Winter

Round 1

Reviewer 1 Report

A few suggestions for enhancing the quality of the manuscript entitled "Influence of Urban Road Green Space Plant Configurations on Air Pollutant Concentrations in Nanjing City During Winter":

Abstract - Line 27 and 28 mentioned on the excessive or insufficient planting density. However, the extent to which it was emphasised in the result and discussion section was restricted. Kindly incorporate the following information into the result and/or discussion section(s) of the document.

1) Introduction - The present portion has a commendable level of writing proficiency.

2) Study Area - Referring to Table 1, kindly elucidate the concept of elevation ratio, denoted as 1:300. Enhance the table segmentation to effectively segregate the information pertaining to different road names.

Refer to Table 2. The title of Table 2 should be revised to provide greater specificity. The table provided lacks information regarding the covered area and plant density at each respective location. Please kindly consider providing this information.

3) Methods - The present portion has a commendable level of writing proficiency.

4) Results - Please refer to the same comment in Abstract. 

Figure 3 does not present any data or findings pertaining to traffic volumes. The findings presented in lines 169 to 171 should be supported by conducting a correlation study or by visually representing the trend of traffic volumes through a plotted graph. A considerable quantity of pollution data was found to be absent. Could you please provide further clarification on this matter?

Line 173: Dotted line in Table 3 or Figure 3? Air Quality Guidelines was mention, but which guideline? Please specifically mention it.

Line 197 to 199:How can the negative connections between PM10 and temperature at certain road locations be elucidated, whereas positive correlations are observed at other road locations?

Section 4.4: Possible effects of finer vs coarser particulates shall be considered in the explanation.  It is likely that coarser particles will concentrate at significantly lower heights above the ground in comparison to finer particles. The spatial separation of sources will also contribute to the dispersion of particulate matter.

5) Conclusion - This section should incorporate the concluding remarks derived from the findings and discussions of each observation, as organised within the subsections of the Results and Discussion sections.

Author Response

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Reviewer 2 Report

The manuscript by Sheng et al. describes how different plant arrangements in urban road green spaces affect winter air pollution levels in Nanjing. By examining the effect of various plant designs on air pollution, the authors establish the basis for developing road green spaces in Nanjing City. The study design is appropriate, and an excellent discussion supports the results. I recommend the MS for publication after a minor revision by the authors, as suggested below:  

1. The font size in the figures needs to be increased for better visualization.

2. Section 5.1.3 needs to be elaborated. 

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Abstract

Line 16 to 17

As one goes through the manuscript, it is discovered that NO2 is the subject of study in this research project. The authors of this manuscript are recommended to state explicitly NO2 instead of generally mentioning air pollution.

Line 20

Readers would like to know the period of data collection of this study, as the time of the year can affect vegetation growth. The authors of this manuscript are recommended to supplement the relevant dates to aid the reading process.

Line 20 to 21

Are these the study objectives? If they are, the authors should state explicitly these are the objectives, e.g. "The objectives of this study are: ……". This can improve the clarity of the manuscript.

Line 29 to 30

Apart from the selection of plant orders, plant configuration is also a spatial concept. It implies how plants are arranged along roads and streets. Therefore, the term "plant configuration" should be further described. The authors of this manuscript are recommended to provide and state the implications such as planting density.

Introduction

Line 48

The authors should be careful with the use of citation in this paper. Please state the year for the citation item Li et al. in this line. The authors of this manuscript are recommended to go through the manuscript and check the citation items.

Line 50 to 51

It is relevant for the authors to spot this major knowledge gap. A differentiation should be made here.

Canopy density and turf coverage are the vegetative characteristics that are related to the capacity of the vegetation to mitigate pollution. On the other hand, atmospheric pressure is a meteorological or microclimatic variable that influences the flux of air pollutants in urban areas.

Since this manuscript is about planting configuration, can the authors relate the mentioned variables to their findings? Or incorporate the mentioned variables in the current study?

I raise this comment because the introduction should serve as a section that gradually narrows down the scope of interest and guides the readers to the research methodology.

Line 71 to 76

I believe that the following points are the objectives of this study:

-          Investigate the influence of meteorological factors on air pollutants, including temperature, humidity, wind speed, atmospheric pressure, radiation, sunlight, and noise.

-          Explore the influence of various plant configurations in road green spaces on air pollution, providing a theoretical basis for road green space construction and predicting the road environment in Nanjing City.

If they are, I strongly recommend the authors to state that these are the objectives. Very often, readers search for the objectives to prepare themselves for reading the rest of the paper.

Study area & Methods

Line 82 to 83

Climate and weather can affect the growth of trees as well as the magnitude of air pollution, i.e. NO₂. The authors of this manuscript are recommended to state the Koppen & Geiger climate classification of Nanking.

Line 85

In order to improve the readability of the manuscript, please insert a space between a number and a unit. The authors of this manuscript are recommended to go through the paper and complete this check.

Line 93 to 94

I have personally reviewed a number of research studies which was conducted in Nanking. It is believed that the study area of the current research project is representative of the Nanking city. However, it is suggested that more information can be supplemented in the caption of Fig. 1.

Some readers may read the captions of all figures and tables before digging into the main text.

Line 97

As an arborist, I have come across with a paper on plant taxonomy which is related to the re-classification of Cinnamomum camphora. The authors of this manuscript are recommended to check the new scientific name of this species.

The authors of this manuscript are recommended to read the following study.

The link is provided below:

https://onlinelibrary.wiley.com/doi/10.1002/ece3.9378

Results

Line 104 to 109

The leftmost column of Table 1 seems to be too narrow. The texts in the cells are wrapped and hard to read. The formatting should be revised.

Line 172 to 173

It is a noteworthy observation. The authors of this manuscript are recommended to state the numerical figures of the observed or published records of air pollution (NO₂) in Nanking as well as the Chines National Standards. Therefore, the readers can directly compare the numbers while reading this section.

Line 198

What do the authors mean by the term "atmospheric radiation"?

Is it solar radiation or thermal radiation?

The authors of this manuscript are recommended to clarify the concept because the formation of some air pollutants are known to be influenced by the level of solar radiation.

Line 201

Please change the unit of radiation to μW instead of uW. The authors of this manuscript are recommended to go through the paper and complete this check.

Discussion

Line 229

Please delete plant variety information in Table 5.

Readers will find it sufficient when species information is supplied.

Line 299 to 322

Air pollution can be interpreted as time-series data. I believe that the authors can give a hint on the possibility of the use of time-series analysis techniques over the collected data.

I believe that the language of this manuscript is easily understandable by international readers

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

This study provides important data on the deployment of green areas to reduce pollutants in cities. This data is highly valuable for urban green planning and represents a highly timely study.

This experiment was measured in multiple locations, and I'm curious whether these measurements were taken simultaneously at all these locations or if there was a temporal gap between them. If there was a temporal gap in the measurements, how was the data corrected or adjusted?

Why do you exclude SO2 and NO when explaining the results of the monitoring data?

Author Response

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Author Response File: Author Response.docx