Preprints
https://doi.org/10.5194/egusphere-2025-3223
https://doi.org/10.5194/egusphere-2025-3223
10 Jul 2025
 | 10 Jul 2025

Spatial and temporal distribution of fine aerosol acidity in the Eastern Mediterranean

Anna Maria Neroladaki, Maria Tsagkaraki, Kyriaki Papoutsidaki, Kalliopi Tavernaraki, Filothei Boufidou, Pavlos Zarmpas, Irini Tsiodra, Eleni Liakakou, Aikaterini Bougiatioti, Giorgos Kouvarakis, Nikos Kalivitis, Christos Kaltsonoudis, Athanasios Karagioras, Dimitrios Balis, Konstantinos Mihailidis, Konstantinos Kourtidis, Stelios Myriokefalitakis, Nikos Hatzianastassiou, Spyros N. Pandis, Athanasios Nenes, Nikolaos Mihalopoulos, and Maria Kanakidou

Abstract. Aerosol acidity (pH) affects aerosol composition and properties, and therefore climate, human health and ecosystems. Fine aerosol acidity and its seasonal variation at 6 sites (Finokalia, Patras, Thissio, Ioannina, Thessaloniki, and Xanthi) in Greece were investigated during 2019–2020. The thermodynamic model ISORROPIA-lite was used to calculate aerosol water and acidity based on measurements of the chemical composition of PM2.5 and available gas-phase concentrations of HNO3, NH3, and HCl. During winter the fine aerosols were acidic to moderately acidic throughout Greece with an overall mean aerosol pH of 3.57±0.44 in urban areas and 3.05±0.50 in remote locations. The highest aerosol pH (4.08±0.42) in January 2020 was found in Ioannina due to, among others, high K+ levels from biomass burning emissions. Aerosols in Xanthi were the most acidic due to high sulfate levels. Similar seasonal profiles of aerosol pH were observed at all sites studied with different factors contributing to this seasonality. During the summer PM2.5 at Thissio, Ioannina and Finokalia was acidic with a mean aerosol pH across all three sites of 1.76±0.40. During this season, sulfates were the driver of the higher acidity conditions at Thissio and Finokalia, with other factors such as the semivolatiles and temperature contributing to a lesser extent. At Ioannina, temperature along with the total ammonia and nitrate were the main contributors to the seasonal difference of the aerosol pH, while some of the nonvolatile species also contributed. In most cases, the importance of organics for aerosol pH was small.

Competing interests: At least one of the (co-)authors is a member of the editorial board of Atmospheric Chemistry and Physics.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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Anna Maria Neroladaki, Maria Tsagkaraki, Kyriaki Papoutsidaki, Kalliopi Tavernaraki, Filothei Boufidou, Pavlos Zarmpas, Irini Tsiodra, Eleni Liakakou, Aikaterini Bougiatioti, Giorgos Kouvarakis, Nikos Kalivitis, Christos Kaltsonoudis, Athanasios Karagioras, Dimitrios Balis, Konstantinos Mihailidis, Konstantinos Kourtidis, Stelios Myriokefalitakis, Nikos Hatzianastassiou, Spyros N. Pandis, Athanasios Nenes, Nikolaos Mihalopoulos, and Maria Kanakidou

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Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-3223', Anonymous Referee #1, 01 Aug 2025
  • RC2: 'Comment on egusphere-2025-3223', Anonymous Referee #2, 20 Aug 2025
Anna Maria Neroladaki, Maria Tsagkaraki, Kyriaki Papoutsidaki, Kalliopi Tavernaraki, Filothei Boufidou, Pavlos Zarmpas, Irini Tsiodra, Eleni Liakakou, Aikaterini Bougiatioti, Giorgos Kouvarakis, Nikos Kalivitis, Christos Kaltsonoudis, Athanasios Karagioras, Dimitrios Balis, Konstantinos Mihailidis, Konstantinos Kourtidis, Stelios Myriokefalitakis, Nikos Hatzianastassiou, Spyros N. Pandis, Athanasios Nenes, Nikolaos Mihalopoulos, and Maria Kanakidou
Anna Maria Neroladaki, Maria Tsagkaraki, Kyriaki Papoutsidaki, Kalliopi Tavernaraki, Filothei Boufidou, Pavlos Zarmpas, Irini Tsiodra, Eleni Liakakou, Aikaterini Bougiatioti, Giorgos Kouvarakis, Nikos Kalivitis, Christos Kaltsonoudis, Athanasios Karagioras, Dimitrios Balis, Konstantinos Mihailidis, Konstantinos Kourtidis, Stelios Myriokefalitakis, Nikos Hatzianastassiou, Spyros N. Pandis, Athanasios Nenes, Nikolaos Mihalopoulos, and Maria Kanakidou

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Short summary
Aerosol acidity affects aerosol composition and properties, and therefore climate, human health and ecosystems. We use summer and winter fine aerosol observations at 6 sites across Greece, and a thermodynamic model to calculate the spatial and seasonal variability of aerosol acidity. Aerosols were acidic to moderately acidic and more acidic during summer than winter. The importance of organics for aerosol acidity was small. Depending on location different factors controlled aerosol acidity.
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