A quantification method for heat-decomposable methylglyoxal oligomers and its application on 1,3,5-trimethylbenzene SOA

Rodigast, Maria; Mutzel, Anke; Herrmann, Hartmut

doi:https://doi.org/10.5194/acp-17-3929-2017

Articles | Volume 17, issue 6

https://doi.org/10.5194/acp-17-3929-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-17-3929-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 17, issue 6

Research article

|

23 Mar 2017

Research article |

| 23 Mar 2017

A quantification method for heat-decomposable methylglyoxal oligomers and its application on 1,3,5-trimethylbenzene SOA

Maria Rodigast, Anke Mutzel, and Hartmut Herrmann

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Final revised paper (published on 23 Mar 2017)
Preprint (discussion started on 10 Aug 2016)

Interactive discussion

Status: closed

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

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RC1: 'Review of Rodigast et al.', Anonymous Referee #1, 24 Aug 2016
- AC1: 'Author´s comment to Referee #1', Hartmut Herrmann, 05 Jan 2017
RC2: 'Review of Rodigast et al.', Anonymous Referee #2, 11 Nov 2016
- AC2: 'Author´s comment to Referee #2', Hartmut Herrmann, 05 Jan 2017

Peer-review completion

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

AR by Hartmut Herrmann on behalf of the Authors (05 Jan 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (10 Jan 2017) by Frank Keutsch

RR by Anonymous Referee #1 (18 Jan 2017)

Suggestions for revision or reasons for rejection

The revised version addresses the concerns of the reviewers, with two notable exceptions. First, the authors still do not correct for wall losses, but now clearly state this and mention that this will affect the reported yields. I’m willing to accept that, as long as they state the direction of this effect (see comment regarding line 272 below). Second, the authors make an argument that particle phase may influence the results, but cannot be predicted. This is generally true, but in my opinion some of the information provided in their responses to reviewers’ comments would be very helpful to readers if included in the manuscript. Specifically, the differences between the inorganic components ammonium sulfate (solid at all RH used in the study) and ammonium bisulfate (liquid at all RH used in the study except <2% RH) are significant and should be mentioned. The authors could also mention the caveats (also given in their response to reviewers’ comments) that the organic phase could lower the DRH of ammonium sulfate and cause it to deliquesce at 75% RH (but not likely at 0 or 50% RH), and that the formation of significant quantities of methylglyoxal oligomers could cause liquid aerosol particles (or liquid organic particle phases) to become semi-solid. Based on the work of Bertram et al.,(1) I think the authors can confidently state that at 0 and 50% RH, ammonium sulfate will be present in crystalline form along with an organic phase (of unknown viscosity), while at 50 and 75% RH crystalline ammonium bisulfite will not be present. If the authors included seed particle loadings, readers could interpret the ammonium sulfate data according to the organic / sulfate ratio framework of Bertram et al.(1)

Other comments:
Line 75: The statement “The method is applicable for all oligomeric compounds, which can be decomposed into methylglyoxal monomers” is misleading as currently stated. It would be clearer to state “The method is applicable for any oligomeric compound which can be decomposed into methylglyoxal monomers.”

Line 133: Technically, the filter extract that was not heated is not measuring only methylglyoxal monomers, but also any compound that can be hydrolyzed at room temperature into methylglyoxal monomers. This likely includes some acetal oligomers. Also, the authors should make clear at some point in the manuscript that “methylglyoxal monomers” includes singly and doubly hydrated methylglyoxal.

Line 394: There also might be oligomers originating from methylglyoxal monomers that are not heat-decomposible back to methylglyoxal monomers, which would also not be determined in the present study.

Technical corrections:
Line 20: The phrase “emitted hydrocarbons contributing with up to …“ would be clearer if written as “emitted hydrocarbons, contributing up to …”
Line 24: “low-volatile” should be “low-volatility”
Line 111: “m” should be “m3” (cubic meters)
Line 127 and 271: I think that “Noticeably” should be “Notably”
Line 148: it would be helpful to give essential parameters of this method here.
Line 272: The phrase “ …might have an influence on the reported SOA yields.” would be more informative as “…might exert a downward influence on the reported SOA yields.”
Line 299: The phrase “… controversially discussed in the literature” could be changed to a single word “… controversial”
Table 4: It would be good to include the results of the present study in Table 4.

References cited:
1. Bertram, A. K.; Martin, S. T.; Hanna, S. J.; Smith, M. L.; Bodsworth, A.; Chen, Q.; Kuwata, M.; Liu, A.; You, Y.; Zorn, S. R., Predicting the relative humidities of liquid-liquid phase separation, efflorescence, and deliquescence of mixed particles of ammonium sulfate, organic material, and water using the organic-to-sulfate mass ratio of the particle and the oxygen-to-carbon elemental ratio of the organic component. Atmos. Chem. Phys. 2011, 11, 10995-11006.

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RR by Anonymous Referee #2 (27 Jan 2017)

ED: Reconsider after minor revisions (Editor review) (20 Feb 2017) by Frank Keutsch

AR by Hartmut Herrmann on behalf of the Authors (22 Feb 2017) Author's response Manuscript

ED: Publish as is (27 Feb 2017) by Frank Keutsch

AR by Hartmut Herrmann on behalf of the Authors (03 Mar 2017) Manuscript

Short summary

The study presents, for the first time, a quantification method for methylglyoxal oligomers and highlights their importance for SOA formation. The method was applied to determine the fraction of methylglyoxal oligomers of 1,3,5-trimethylbenzene SOA dependent on relative humidity and seed particle acidity. An oligomer contribution of up to 8 % was calculated varying with experimental conditions and thus further hints for the dependency of the oligomer formation mechanism on conditions were found.