Molecular characterization of gaseous and particulate oxygenated compounds at a remote site in Cape Corsica in the  western Mediterranean Basin

Michoud, Vincent; Hallemans, Elise; Chiappini, Laura; Leoz-Garziandia, Eva; Colomb, Aurélie; Dusanter, Sébastien; Fronval, Isabelle; Gheusi, François; Jaffrezo, Jean-Luc; Léonardis, Thierry; Locoge, Nadine; Marchand, Nicolas; Sauvage, Stéphane; Sciare, Jean; Doussin, Jean-François

doi:https://doi.org/10.5194/acp-21-8067-2021

Articles | Volume 21, issue 10

https://doi.org/10.5194/acp-21-8067-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

CHemistry and AeRosols Mediterranean EXperiments (ChArMEx)...

https://doi.org/10.5194/acp-21-8067-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 21, issue 10

Research article

|

26 May 2021

Research article |

| 26 May 2021

Molecular characterization of gaseous and particulate oxygenated compounds at a remote site in Cape Corsica in the western Mediterranean Basin

Vincent Michoud, Elise Hallemans, Laura Chiappini, Eva Leoz-Garziandia, Aurélie Colomb, Sébastien Dusanter, Isabelle Fronval, François Gheusi, Jean-Luc Jaffrezo, Thierry Léonardis, Nadine Locoge, Nicolas Marchand, Stéphane Sauvage, Jean Sciare, and Jean-François Doussin

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Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Comments for Michoud et al.', Anonymous Referee #1, 26 Nov 2020
RC2: 'Revision report for Michoud et al', Anonymous Referee #2, 27 Nov 2020
AC1: 'Final response', Vincent Michoud, 03 Feb 2021

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Vincent Michoud on behalf of the Authors (03 Feb 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (09 Feb 2021) by Andreas Hofzumahaus

RR by Anonymous Referee #2 (21 Feb 2021)

Suggestions for revision or reasons for rejection

The authors addressed the majority of my concerns, but I still have some comments that require either a clarification or to be addressed in the manuscript.

1. Concerning the quantification of VOCs with a PTR-MS I am not entirely sure I understand the answer provided by the authors. From the manuscript I understand that for each VOC both the H3O+ and H3O+(H2O) signals were used for quantification. If this is the case then my comment has not been addressed. While the formula used for VOC quantification is correct (I have never questioned that), its application must change depending on the relevant proton transfer reactions:
- for VOCs that react with H3O+ only and do not react with the water cluster, only the H3O+ signal should be used for the quantification because the VOC+H+ signal will depend only on the proton transfer reaction with H3O+
- for VOCs that react with H3O+ and with H3O+(H2O) via proton transfer, then both the H3O+ and H3O+(H2O) signals should be used for the quantification
- for VOCs that react with H3O+ via proton transfer reaction and with H3O+(H2O) via ligand switching reaction, the product ion will appear at two different masses corresponding to VOC+H+ and VOC+H3O+. If the author decides to base the quantification only on the VOC+H+ signal, which is produced by the main reaction pathway, then only with H3O+ signal should be used for the quantification because the reaction between the VOC and H3O+(H2O) does not produce the VOC+H+.

2. The evaluation of recovery and matrix effects should be part of the validation of any new analytical protocol. Considering that there were discrepancies between the results obtained with different methods I strongly recommend completing the method validation and add this information to the manuscript.

3. Please add to the manuscript the information about the activity coefficients used for equation 3. I see the information in the answers to the reviewers, but I haven’t spotted it in the manuscript (unless it is there, and I missed it).

4. Concerning my comment on page 21 about the Henry’s law constant, please add to the manuscript that you are discussing the transfer from gas phase to deliquescent aerosol. It was not obvious to me, I thought you were discussing the transfer of analytes from the particles to liquid water inside the PILS.

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RR by Anonymous Referee #1 (23 Feb 2021)

ED: Reconsider after major revisions (04 Mar 2021) by Andreas Hofzumahaus

AR by Vincent Michoud on behalf of the Authors (14 Apr 2021) Author's response Author's tracked changes Manuscript

ED: Publish subject to technical corrections (14 Apr 2021) by Andreas Hofzumahaus

AR by Vincent Michoud on behalf of the Authors (19 Apr 2021) Manuscript

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Short summary

A multiphasic molecular characterization of oxygenated compounds has been carried out during the ChArMEx field campaign using offline analysis. It leads to the identification of 97 different compounds in the gas and aerosol phases and reveals the important contribution of organic acids to organic aerosol. In addition, comparison between experimental and theoretical partitioning coefficients revealed in most cases a large underestimation by the theory reaching 1 to 7 orders of magnitude.