Measurement report: Chemical characterization of cloud water at Monte Cimone (Italy). Impact of air mass origin and &nbsp;assessment of atmospheric processes

Nibert, Pauline; Wu, Yi; Joly, Muriel; Amato, Pierre; Cristofanelli, Paolo; Calzolari, Francescopiero; Piro, Jean-Luc; Putero, Davide; Montaguti, Simonetta; Renzi, Laura; Vogel, Franziska; Rapuano, Marco; Brigante, Marcello; Verhaege, Christophe; Baray, Jean-Luc; Deguillaume, Laurent; Marinoni, Angela; Zanatta, Marco; Bianco, Angelica

doi:10.5194/egusphere-2025-5976

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https://doi.org/10.5194/egusphere-2025-5976

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27 Jan 2026

| 27 Jan 2026

Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Measurement report: Chemical characterization of cloud water at Monte Cimone (Italy). Impact of air mass origin and assessment of atmospheric processes

Pauline Nibert, Yi Wu, Muriel Joly, Pierre Amato, Paolo Cristofanelli, Francescopiero Calzolari, Jean-Luc Piro, Davide Putero, Simonetta Montaguti, Laura Renzi, Franziska Vogel, Marco Rapuano, Marcello Brigante, Christophe Verhaege, Jean-Luc Baray, Laurent Deguillaume, Angela Marinoni, Marco Zanatta, and Angelica Bianco

Abstract. In this article, we present the results of the chemical and microbiological characterization of clouds water collected at Monte Cimone (CMN) in Italy at 2165 m a.s.l. during the MC3 (Molecular Composition of Clouds at Mt. Cimone) campaign, which took place in October 2024. Twenty-six cloud samples are analyzed. Chemical analyses, including ions, oxidants, trace metals, and microbiological analyses with cell counting, are performed. The chemical characterization and back-trajectories analysis reveal that Mt. Cimone is a site under the influence of marine air masses, coming mainly from southern Europe and from the Mediterranean region. During the measurement campaign, 3 sampling periods are identified: period (1) October 07–10, with air masses mainly originating from Spain and Atlantic Ocean with a majority of Cl⁻and Na⁺ that are characteristics of marine origin; period (2) October 16–18 with air masses originating from North of Africa, impacted by a Saharan dust event with a high concentration in Ca²⁺; period (3) October 22–23 marked by air masses originated from southern Italy under polluted influence with a high concentration in NO₃⁻. This study paves the way to further scientific campaigns intended to better comprehend cloud water composition at Mt. Cimone.

How to cite. Nibert, P., Wu, Y., Joly, M., Amato, P., Cristofanelli, P., Calzolari, F., Piro, J.-L., Putero, D., Montaguti, S., Renzi, L., Vogel, F., Rapuano, M., Brigante, M., Verhaege, C., Baray, J.-L., Deguillaume, L., Marinoni, A., Zanatta, M., and Bianco, A.: Measurement report: Chemical characterization of cloud water at Monte Cimone (Italy). Impact of air mass origin and assessment of atmospheric processes, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2025-5976, 2026.

Received: 01 Dec 2025 – Discussion started: 27 Jan 2026

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RC1:
'Comment on egusphere-2025-5976', Anonymous Referee #3, 08 Feb 2026 reply
The manuscript titled “Chemical characterization of cloud water at Monte Cimone (Italy): impact of air mass origin and assessment of atmospheric processes” presents a detailed description on the cloud water chemistry in Italy mountaintop by emphasizing the significant impact of air mass sources. In general, this study shows a very comprehensive analysis of inorganic and organic ions, dissolved organic carbon (DOC), H2O2, trace metals and microbial cells in the collected 26 cloud water samples. I very appreciate the field work and valuable data provided by the authors. Although the authors show nearly all matters about individual samples, I have some concerns regarding the logical structure, figures/tables organization, and reasonable explanations. Substantial revision is still necessary for a better readability. My comments, either major or minor, are listed below in the order of main text.
The abstract summarized the three types of origins of cloud chemistry with major ions, but didn’t mention the other important subsections studied, for example the oxidants, DOC, metals and microorganisms. That partial abstract will mislead my first view of this paper. Please revise the abstract with key findings of cloud components.

Page 6, line 132, and Table S4, Figure 6: as the BOOGIE cloud impactor is made by aluminum (Vaitilingom et al., 2025), it may contain other metals besides Al. For example, the blank sample had a concentration of Cu, Mn, and Sb higher than that of cloud samples as shown in Table S4. Therefore, when the authors discuss the metals in cloud water in section 3.5, please make it clear that if the sample concentrations have deduced the blanks, and if the high blanks of some metals affect the conclusion. That is to say, could we believe the determined concentrations of specific metals with high blanks for cloud water sampler.

Section 2.4.1: Here the authors provided the measurements of trace gases. I am also interested in SO2, the important precursor of sulfate, for comprehensive understanding. Is that possible to add the information of SO2?

Section 3.1 is an important part of the paper, but it is too detailed and sometimes verbose for me to follow. I am afraid that most of the discussed figures are in the supporting information, rather than Figure 1 in the main text, which is the most inconvenient thing to be improved. I suggest to add a time-series figure of the full set of major chemical compositions (like Fig. S5 and Table S2) to the main text. The pies in Figure 1 should have different size indicating their relative concentrations. Also, why does Figure 1 only show 6 out of 8 measured ions and exclude DOC?

Why the main text did not explain Figure 2 or should Figure 2 be replaced by other type of figures?

Line 286: all ions concentrations of Period 2 are low, for which part? Cloud water, or PM1? Please show the concentrations of Ca2+ in Figure S5 for clarifying the dust effect on cloud and PM.

Line 348: “Nevertheless, the absence of Cl^‒_PM and the depletion of NO₃^‒_PM in particles, compared to cloud water, attest the marine input, similarly to samples of Period 1.” Why SO₄^2‒ in particles are due to pollution but NO₃- is depleted? And is it possible that the Cl- depletion in particles can be further discussed for atmospheric conversion?

Line 395: “The concentration of Fe2+/Fe3+ is below…”, please reword this statement to avoid misleading of the measurement of total dissolved Fe rather than speciated Fe ions in this study.

Lines 408-414: I did not find SO2 concentration in Figure S1. The high concentrations of H2O2 were attributed to direct industrial emission. Can you estimate how long time will the released H2O2 exist in the atmosphere and transport to the observation site at which concentration level?

Line 426: “Figure 4a reports in yellow the concentration in daytime samples and in blue in night-time. The concentrations in night-time samples are generally higher than in day-time samples, except for sample 16/10 G, collected at sunset.” The sentences are redundant to the caption of Figure 4.

Please revise the caption of Figure 3 to be more concise.

What does the error bar mean in Figure 4a for individual sample? Set the same y-axis scale for nitrate and sulfate concentrations in Figure 4b using only left y-axis.

Line 430 suggests the positive correlations between H2O2 and nitrate or sulfate. It is contrast to line 414 stating low SO2 concentration to explain high H2O2. Can we imagine that H2O2 had similar anthropogenic sources with other pollutants?

Figure 5: As it shows much less information and is discussed in 3 sentences in the main text, I suggest move it to SI.

Section 3.6: there are too much short paragraphs, which can be shortened into about four paragraphs.

Line 540: it seems that air masses originating from continental areas contain one order of magnitude more microbial cells. Besides the altitude, can you find data or literatures comparing the abundant of atmospheric microbials in land and marine areas to support your findings?

Lines 546-549: can you further explain the primary factors influencing culturable microbials?

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Citation: https://doi.org/10.5194/egusphere-2025-5976-RC1

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https://doi.org/10.5194/egusphere-2025-5976-supplement

Data sets

Dust event identification product dataset collection over Monte Cimone, Italy 2003-2023, Version 1 F. Vogel et al. https://doi.org/10.71763/XDZA-FA77

Equivalent black carbon product dataset collection over Monte Cimone, Italy 2007-2024 (Version 1) M. Zanatta et al. https://doi.org/10.71763/itineris-hub/nfy7-yz86

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Short summary

This study provides the first chemical and microbiological characterization of cloud samples collected at Monte Cimone (ACTRIS, ICOS, GAW - CMN) in the Mediterranean basin. The chemical characterization is deeply discussed in relationship with back-trajectories and cloud processing. Air mass history do not fully explain the variability observed in the chemical composition. This highlights the complexity of emission sources, multiphasique exchanges, and transformations in clouds.


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