Air Quality at Ponta Delgada City (Azores) Is Unaffected so Far by Growing Cruise Ship Transit in Recent Years
Round 1
Reviewer 1 Report
This a very interesting study in which the authors link local sources of pollution originating from CS with air pollution conditions in the city of Ponta.
- However, something needs to be added to the analysis and discussion of wind movement and air pollution trajectory, considering the location of the measuring station is not exactly at the port.
- Would it be possible for the author to include air quality measurement conditions at the port utilizing the sampling approach and compare them to the data from the current measurement station?
Author Response
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Author Response File: 
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Reviewer 2 Report
Since cruise tourism industry has recently showed a strong increase in activity, the monitoring of air quality variation owing to cruise ships is essential. Combustion of low-grade marine fuels releases many pollutants such as sulfur and nitrogen oxides, poly-cyclic aromatic hydrocarbons, and metals, which are harmful for human health and environment.
The presentation of the results is impressive. However, the following points should be considered before publishing the paper.
Abstract
· Line 21 – Define GHG, NOx, SOx at first mention even those are very common.
Introduction
· Impacts of air pollution on human health and environmental should be described. There are short term and long term health impacts. Asthma, cough, throat irritation are some of short term health impacts. Chronic obstructive pulmonary disease and cardiovascular health disease can be considered as long term impacts.
· Describe about International, European, and local air quality standards.
Materials and methods
· Line 101, “17.304 inhabitants”, please check this.
· Lines 87–96 – Weather parameters can be described numerically. Average or range can be used.
· Line 129 – The urban background monitoring station located at about 1.3 km from the ship harbor. Normally, pollution levels decreased rapidly with distance from point sources. How do you justify this?
· What other local urban activities affect air quality?
Results and Discussion
· Since there are various on-board services on cruise ships, a continuous supply of fossil fuel energy is required. Have authors considered the impact of docking (hoteling) time on air quality?
· Did authors consider metals and poly-cyclic aromatic hydrocarbons in this study?
· Line 257 – In spring, daily mean concentrations of O3, NO2 and NOx were increased in days with CS docking. Authors can discuss impacts of high concentrations of O3, NO2 and NOx.
Ex- when increasing nitrogen oxides due to cruise ship emissions, nitrogen levels in epiphytic vegetation can be increased.
· Also, nitrogen and sulfur containing pollutants have a much longer residence time in vegetation and soils.
· Figure 2,3 – Add Y axis labels.
FORMATTING/TYPOS ERRORS
· Lines 59,60 – “10x”, It should be multiplication symbol.
· Line 177 – remove the additional full stop after figure caption.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
The authors present observations on air quality at Ponta Delgada city, Azores, in a view of cruise ships presence. Although the presentation is clear and easy to follow, the merit of the study is very limited due to serious flows in the research design. Moreover, the paper consist a lot of non-relevant information which may be fine for tourist brochure but has no merit in scientific literature. I will point out here the main issues.
The whole paper is based on single measurement station located relatively far from the port. Therefore, one can not assume that the measurements reflect the effects from cruise ships. Why not from other directions? Are there other pollution sources? What are main wind directions and how they affect the measurements? The authors need to use some, even basic, atmospheric transport model to study the effect of cruise ships in comparison with other possible sources. The study become pointless without this.
Also, the effect of COVID (year 2020) is not convincing considering that the number of cruise ships dramatically decline while measured values remain intact, sometimes even increased? Indeed, some values declined, but is this not the effect of changing of habits of people at Azores during lockdowns rather than cruise ships? Based on the paper, we do not know.
After pointing these issues, I am regret that I must suggest the rejection of the paper.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Thank you for adding several parts to your manuscript in response to my suggestions, which has improved the quality of your manuscript. However, there are several aspects of the research that you leave out, like wind movement and trajectory models to identify the sources of pollutants. Please offer this analysis to support your study.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 3 Report
In the revised manuscript, the authors bring a number of relevant information regarding the meteorology and others conditions, however, I still miss some new insight based on these data. Is it e.g. possible to sort days according to wind directions and analyze effects of different directions? According to the reviewer, the authors should increase the merit of the study significantly.
Author Response
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Author Response File: Author Response.pdf
