The Role of Vegetation on Urban Atmosphere of Three European Cities. Part 2: Evaluation of Vegetation Impact on Air Pollutant Concentrations and Depositions
, Rafael Borge 2, Sandro Finardi 3, Gino Briganti 1, Felicita Russo 1, David de la Paz 2, Massimo D’Isidoro 1, Giuseppe Cremona 1, Maria Gabriella Villani 1, Andrea Cappelletti 1, Mario Adani 1, Ilaria D’Elia 1, Antonio Piersanti 1, Beatrice Sorrentino 1, Ettore Petralia 1, Juan Manuel de Andrés 2, Adolfo Narros 2, Camillo Silibello 3, Nicola Pepe 3, Rossella Prandi 4 and Giuseppe Carlino 4add
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Round 1
Reviewer 1 Report
This article contains data on how vegetation affects the concentrations and deposition of pollutants in urban environments. Overall, the article is technically sound, however, there are some comments on the work.
Should we stop creating green spaces in urban areas based on research findings?
What is the reason for selecting these three cities for research? These cities vary greatly in terms of meteorological conditions, the types and levels of air pollution, and the level of greenery in urban areas.
Why were only these three contaminants chosen for examination (O3, PM10 and NO2)?
Why was 2015 used as the base year for the calculation?
What is the "scale of influence" of woody vegetation on changes in air pollutant concentrations? Is the "effect" only noticeable in proximity to the tree stands? Or does the "effect" extend further (by how many metres or kilometers) away from tree stands?
Changes in meteorological parameters (for example, lower wind speed) and, as a result, changes in pollutant concentrations are impacted by factors other than species features of woody plants. More so than other factors, tree stand characteristics have an impact on how certain meteorological parameters vary. Tree height. Stand density (number of tree trunks per area). Were the stands with open or closed canopies? Understorey (shrubs or/and second layer of woody plants) presence or absence. Did the writers take these factors into account while calculating?
Author Response
Responses to Reviewers
We would like to thank the reviewers for their useful and constructive suggestions that helped us improving the quality of the paper. We address below each specific issue raised by reviewers (blue text) updating the manuscript accordingly.
Reviewer#1: We thank very much the reviewer for the careful reading of manuscript and for the comments.
This article contains data on how vegetation affects the concentrations and deposition of pollutants in urban environments. Overall, the article is technically sound, however, there are some comments on the work.
Should we stop creating green spaces in urban areas based on research findings?
Thank you very much for your question. As mentioned in the last paragraph of the Conclusions, we think that the urban planning strategies should consider the multiple effects of cities’ morphology, including green spaces, on atmosphere. Green spaces have an enormous positive impact on human health, therefore their creation should be carefully planned in order to avoid excessive exposure to pollution levels.
What is the reason for selecting these three cities for research? These cities vary greatly in terms of meteorological conditions, the types and levels of air pollution, and the level of greenery in urban areas.
Thank you very much for your question. As we stated in the companion paper D’Isidoro&Mircea, this work reflects the outcomes of the EU-LIFE project VEG-GAP. Therefore, we aimed to evaluate the vegetation impact in cities located in two member states of European Union. A prerequisite for choosing a city was the availability of tree inventory as well as a good knowledge of air quality based on previous studies. The two Italian cities, Bologna and Milan, allowed us to evaluate the impact of vegetation in similar meteorological and pollution conditions (they are both located in Po Valley) while the comparison with Madrid showed what can be expected when they differ.
Why were only these three contaminants chosen for examination (O3, PM10 and NO2)?
We thank the referee for this question. The first reason of choosing these pollutants is that the European Ambient Air Quality Directive 2008/50/EC set limit values for them. Besides, O3, NO2 and PM10 are interdependent through nonlinear chemical and physical atmospheric processes, depending on the same anthropogenic and biogenic emissions; therefore, they have to be concomitantly addressed. In addition to that, Richards et al. (2013) showed that the summer ozone maximum in the Mediterranean basin has a dominant sensitivity to BVOC emissions over anthropogenic VOC emissions.
Richards, N. A. D., et al.,2013, The Mediterranean summertime ozone maximum: global emission sensitivities and radiative impacts, Atmos. Chem. Phys.,13, 2331-2345
Text has been added at the end of Introduction.
Why was 2015 used as the base year for the calculation?
We thank the referee for this question. A similar question was addressed in the companion paper D’Isidoro&Mircea, some explanatory text was added in Section 2. We choose 2015 for two aspects: 1) Because it was an “extreme” warm meteorological year for which we could test our methodology in conditions that are more and more frequently happening in the last decades and that will be the “normal” in the next future; 2) it is also useful to the companion paper that investigates the vegetation effects on air quality since 2015 is a reference year for air quality assessments at national level in many countries (Italy and Spain in this case) as required by the Air Quality Directive.
What is the "scale of influence" of woody vegetation on changes in air pollutant concentrations? Is the "effect" only noticeable in proximity to the tree stands? Or does the "effect" extend further (by how many metres or kilometers) away from tree stands?
We thank the referee for this question. Our results, both for meteorology and air quality, shows that the vegetation effects should be addressed at city scale. CTMs do not “see” the effects of individual “tree stands” but their “statistical” effects on atmosphere in a cell with horizontal size of 1 km x 1km. The magnitude of these effects depends on city’s peculiarities and on the time interval when they are evaluated depending on synoptic atmospheric circulation and anthropogenic emission levels.
Changes in meteorological parameters (for example, lower windspeed) and, as a result, changes in pollutant concentrations are impacted by factors other than species features of woody plants. More so than other factors, tree stand characteristics have an impact on how certain meteorological parameters vary. Tree height. Stand density (number of tree trunks per area). Were the stands with open or closed canopies? Understorey (shrubs or/and second layer of woody plants) presence or absence. Did the writers take these factors into account while calculating?
We thank the referee for this question. The answer is yes. We have considered the effects of single tree’s characteristics such as height, crown, etc as well as the effect of forested areas both on meteorology and air quality.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Line 10, 36, 496 and so on (818...): PM10 instead of PM10 (Please check the rest of the manuscript). Line 595: g/m3 instead of g/m3;
Line 53: Simmilarly to Part 1 of your research, please add that the European Union approved a regulatory package, being one of their exponents the Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe (AAQ Directive).
Line 54-70: are there only one reference for all those information? Please complete the citation of those text. In addition. Is is allowed in the journal the presence of listing points (1, a, b)? Please consider to rephrase it if necessary.
Line 183, 192, 200, 225 etc: is D'Isidoro formating reference correct in the journal? Please review in the whole manuscript.
Line 310-311: scientific names should be written in italics.
Line 643: Milan instead of Milano.
Minor editing of English language required. For example: Line 140: cities area or areas of the cities instead of cities' areas. Simmilar thing in Line 363.
Author Response
Responses to Reviewers
We would like to thank the reviewers for their useful and constructive suggestions that helped us improving the quality of the paper. We address below each specific issue raised by reviewers (blue text) updating the manuscript accordingly.
Reviewer#2: We thank very much the reviewer for helping us to improve the manuscript.
Line 10, 36, 496 and so on (818...): PM10 instead of PM10 (Please check the rest of the manuscript).
We appreciate the suggestion of reviewer, but we prefer to use PM10 since it is not a chemical compound as NO2 or an element as O3.
Line 595: g/m3 instead of g/m3;
Done. Thank you for notifying this.
Line 53: Simmilarly to Part 1 of your research, please add that the European Union approved a regulatory package, being one of their exponents the Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe (AAQ Directive).
Text has been added at the end of Introduction. Thank you.
Line 54-70: are there only one reference for all those information? Please complete the citation of those text. In addition. Is is allowed in the journal the presence of listing points (1, a, b)? Please consider to rephrase it if necessary.
Thank you for pointing out these aspects. We will check the format with the journal. The brief list of qualitative effects of vegetation aims to draw the conceptual context of the study. Several reviews would be necessary to acknowledge and make understandable the outcomes of the studies that addressed each point or disentangle the results corresponding to each point.
Line 183, 192, 200, 225 etc: is D'Isidoro formating reference correct in the journal? Please review in the whole manuscript.
Thank you.
Line 310-311: scientific names should be written in italics.
Done. Thank you.
Line 643: Milan instead of Milano.
Done. Thank you.
Minor editing of English language required. For example: Line140: cities area or areas of the cities instead of cities' areas.
Thank you.
Simmilar thing in Line 363.
Thank you.
Author Response File: Author Response.pdf
Reviewer 3 Report
A good paper, well set out and explained, with good figures and tables and detailed results, though there are some issues:
Figure 3b is missing and so couldn't be checked
Lines 386 and 393 refer to figure 2a, not figure 1a
References 48 and 49 are not referred to in the text
Author Response
Responses to Reviewers
We would like to thank the reviewers for their useful and constructive suggestions that helped us improving the quality of the paper. We address below each specific issue raised by reviewers (blue text) updating the manuscript accordingly.
Reviewer#3: We thank very much the reviewer for appreciating the manuscript.
A good paper, well set out and explained, with good figures and tables and detailed results, though there are some issues:
Figure 3b is missing and so couldn't be checked
Figure is on page 13. Thank you.
Lines 386 and 393 refer to figure 2a, not figure 1a
Done. Thank you.
References 48 and 49 are not referred to in the text
Thank you. Done. Reference 48 may be found on line 413: Zhang et al. (2021) while reference 49 may be found on line 567: Mircea et al., (2022).
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors revised the manuscript with consideration of all comments and suggestions. With this background, I believe the manuscript can be accepted for publication.
