Water-Soluble Anions in PM10 Samples Collected in the Metropolitan Area of Costa Rica: Temporal and Spatial Variations
, Tomas Soto-Murillo, José Félix Rojas-Marín, Victor Hugo Beita-Guerrero and María Hidalgo-GutiérrezRound 1
Reviewer 1 Report
PM10 collected from the ambient air of four regions at the site of the great metropolitan area (GAM) in Costa Rica was analyzed. Ion chromatography is used for analysis. Chromatography is used to identify organic and inorganic ions. Using principal component analysis, the following contributions were determined: secondary particle formation process of biomass combustion and fixed emissions, and biological emissions. For each variable, seasonal patterns and trends were analyzed using an additive decomposition time series. The article needs some modifications before it can be accepted.
- The fonts in all figures can not be seen clearly and need to be corrected. The horizontal and vertical coordinates of some figures are not marked, and the font size of the horizontal and vertical coordinates in some figures is also different, which need to be adjusted. Some figures are vague, such as Figure 3 and figure 5.
- the format of table 5 also needs to be adjusted, so it's not very clear.
- The conclusion part needs to add some main conclusions. It is suggested to add some main contents that readers can learn from this article.
Author Response
Revisor 1
The fonts in all figures can not be seen clearly and need to be corrected. The horizontal and vertical coordinates of some figures are not marked, and the font size of the horizontal and vertical coordinates in some figures is also different, which need to be adjusted.
Answer: the format of the figures has been corrected
Some figures are vague, such as Figure 3 and figure 5.
Answer: the format of the figures has been corrected
The format of table 5 also needs to be adjusted, so it's not very clear.
Answer: Table 5 was removed.
The conclusion part needs to add some main conclusions. It is suggested to add some main contents that readers can learn from this article.
Answer: The conclusions section was rewritten including other aspects.
Reviewer 2 Report
The article by Herrera-Murillo et al. presents the results of an 8-year analysis of PM10 concentrations and the main anions that appear in its composition. The samples are collected at four sites with different characteristics in the most important metropolitan region of Costa Rica. From the results obtained, the authors performed different statistical analyses (correlations, PCA, time series analysis, etc...) to try to obtain information on the differences between the different sites and to explain the possible sources of the particulate matter and the evolution of the concentrations over time.
The article is interesting because there are few studies in the region that cover such long time periods. It is a pity that cations have not been analysed, which would give a lot of information about the real compounds in the particulate matter. In spite of what has been said, I think that the authors should make a thorough revision of the manuscript because it is not clear what the conclusions of the study are. I am missing a comparison with other studies in similar locations that could give an idea of whether the values obtained are the usual ones. Comparing 4 sites is not easy and sometimes the reader gets lost when not understanding which one they are talking about. I would recommend the authors to focus on the sites with the most different characteristics and not to include sites with similar results. This would make the article easier to follow.
I attach some comments that in my humble opinion would help to improve the manuscript.
Line 33-38. This part is very general and I am sure it is widely known to the reader.
Line 157-167. The purpose of analysing the time series is to see if there is some kind of trend and to observe if there is a seasonal behaviour? If so, I would include it, it is not very clear what they are analysed for.
Line 173. Giant tables. Consider presenting data only for the most distinct locations.
Line 178. I don't quite understand what relevant information this table adds. Different tests are going to be performed taking into account the non-normality of the data in those years.
Line 180. You are comparing all data for the years 2011 to 2018 or year by year. How is the normality of the data if all years are considered together? Why is the normality assessed year by year but the comparison is made for all data?
Line 192. "striking" Revise this sentence.
Line 194. Differences are expressed in ug/m3?
Line 208. The graph does not look good. Need to ensure that the differences are significant in this comparison between dry and wet season. Units should be expressed with superscripts.
Line 211. Sometimes the chemical species is written with the symbol (Cl) and sometimes with the name (Nitrate). Unify the criteria.
Line 215. In theory and due to thermal decomposition of ammonium nitrate and increased photooxidation of SO2 one would expect to get high values of these ratios during the winter and lower values during the winter. Why does this not happen in this case? What do the authors think are the compounds present in PM10?
Line 220. This should be confirmed by a Mann-Kendall trend analysis.
Line 222. This could be seen by simply checking for an increase in nitrate concentrations without the need to assess the ratio. The same is true for point 2, a decrease in sulphate values should be observed. The interesting effect of the Turrialba Volcano could be evaluated by using a back trajectory analysis.
Line 245. A curious result, as they usually correlate due to increasing production with increasing photoxidation. Some explanation for this.
Line 247-261. This part needs to be rewritten. It becomes difficult to read. It needs to be presented in a way that highlights the factors that are common to all sites and highlights those that are distinct. As it is, it is difficult to draw any conclusions.
Line 274. This graph is cut off.
Line 276-292. I recommend the authors to use some kind of test (Mann-Kendall) to see if there is really a trend. This will allow us to confirm many of the conclusions presented here.
I encourage the authors to improve the article following the above comments.
Author Response
Revisor 2
Line 33-38. This part is very general and I am sure it is widely known to the reader.
That section of the text was removed
Line 157-167. The purpose of analysing the time series is to see if there is some kind of trend and to observe if there is a seasonal behaviour? If so, I would include it, it is not very clear what they are analysed for.
Suggested purpose included in text
Line 173. Giant tables. Consider presenting data only for the most distinct locations.
We know this table is a little bigger than the average, but it’s a comprehensive summary of the results. We think it’s essential to keep that table intact so that future readers can compare their results and trends with ours. Further or extended data analysis will be available for other researchers or reviews.
Line 178. I don't quite understand what relevant information this table adds. Different tests are going to be performed taking into account the non-normality of the data in those years.
Line 180. You are comparing all data for the years 2011 to 2018 or year by year. How is the normality of the data if all years are considered together? Why is the normality assessed year by year but the comparison is made for all data?
The table was removed from the text
Line 192. "striking" Revise this sentence.
Wording adjustment made
Line 194. Differences are expressed in ug/m3?
It is unified throughout the text
Line 208. The graph does not look good. Need to ensure that the differences are significant in this comparison between dry and wet season. Units should be expressed with superscripts.
The format adjustment of the figures was carried out
Line 211. Sometimes the chemical species is written with the symbol (Cl) and sometimes with the name (Nitrate). Unify the criteria.
It is unified throughout the text
Line 215. In theory and due to thermal decomposition of ammonium nitrate and increased photooxidation of SO2 one would expect to get high values of these ratios during the winter and lower values during the winter. Why does this not happen in this case? What do the authors think are the compounds present in PM10?
Nitrate concentration values are higher in the rainy season as explained in the text, due to lower temperatures and the decrease in solar radiation.
Line 220. This should be confirmed by a Mann-Kendall trend analysis.
Requested test results are included
Line 222. This could be seen by simply checking for an increase in nitrate concentrations without the need to assess the ratio. The same is true for point 2, a decrease in sulphate values should be observed. The interesting effect of the Turrialba Volcano could be evaluated by using a back trajectory analysis.
Not all of the information required to perform the requested analysis is available
Line 245. A curious result, as they usually correlate due to increasing production with increasing photoxidation. Some explanation for this.
A possible explanation was given at the end of section 3.2.
Line 247-261. This part needs to be rewritten. It becomes difficult to read. It needs to be presented in a way that highlights the factors that are common to all sites and highlights those that are distinct. As it is, it is difficult to draw any conclusions.
This section was rewritten and more concisely.
Line 274. This graph is cut off.
The figure was corrected
Line 276-292. I recommend the authors to use some kind of test (Mann-Kendall) to see if there is really a trend. This will allow us to confirm many of the conclusions presented here.
Requested test results are included
