A study of volatility by composition, heating, and dilution measurements of secondary organic aerosol from 1,3,5-trimethylbenzene

Sato, Kei; Fujitani, Yuji; Inomata, Satoshi; Morino, Yu; Tanabe, Kiyoshi; Hikida, Toshihide; Shimono, Akio; Takami, Akinori; Fushimi, Akihiro; Kondo, Yoshinori; Imamura, Takashi; Tanimoto, Hiroshi; Sugata, Seiji

doi:https://doi.org/10.5194/acp-19-14901-2019

Articles | Volume 19, issue 23

https://doi.org/10.5194/acp-19-14901-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-19-14901-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 23

Research article

|

10 Dec 2019

Research article |

| 10 Dec 2019

A study of volatility by composition, heating, and dilution measurements of secondary organic aerosol from 1,3,5-trimethylbenzene

Kei Sato, Yuji Fujitani, Satoshi Inomata, Yu Morino, Kiyoshi Tanabe, Toshihide Hikida, Akio Shimono, Akinori Takami, Akihiro Fushimi, Yoshinori Kondo, Takashi Imamura, Hiroshi Tanimoto, and Seiji Sugata

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Final revised paper (published on 10 Dec 2019)
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Preprint (discussion started on 16 Jan 2019)
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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: 'review of Sato et al.', Anonymous Referee #1, 22 Feb 2019
- AC1: 'Reply to comments of refrees #1 and #2', Kei Sato, 22 Jul 2019
RC2: 'Review of Sato et al.', Anonymous Referee #2, 14 Apr 2019
- AC1: 'Reply to comments of refrees #1 and #2', Kei Sato, 22 Jul 2019

Peer-review completion

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

AR by Kei Sato on behalf of the Authors (22 Jul 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (02 Aug 2019) by Neil M. Donahue

RR by Anonymous Referee #1 (17 Aug 2019)

RR by Anonymous Referee #3 (04 Oct 2019)

Suggestions for revision or reasons for rejection

Comments on previous referee reports:
The authors seemed to have addressed most of the comments from the referees to a satisfactory extent. However, there are a number of places in which the text was changed and the remaining language seems vague as a result (for example, response to comment 6 in the response document). Also, the response to comment 11 includes some helpful ‘scoping’ calculations that it seems should be included in the actual paper text, as the importance of RO2+RO2 chemistry was highlighted by both referees.

General comments:
In general I found the paper to be interesting and mostly clear description of these experiments and analysis. There were a number of instances where assumptions or approaches are not well justified and this reduces confidence in the quantitative results, though the general point (that TMB SOA contains low volatility material not captured in yield experiment-based product distributions) is well supported. One general comment is that there is quite a bit of literature on the potential influence of chamber walls on SVOC/IVOC measurement, and none of that is mentioned/discussed here, either in terms of influence on your measurements or interpretation of yield experiments. I think this and other lines of evidence have pointed to the fact that the ‘traditional’ yield-experiment-based VBS parameters are probably wrong and missing material. A bit more discussion of this would be helpful.

Specific points (Page/Line number):
P6, L10 – This should mention particle diameter for SOA experiments. Also, ‘other processes’ is very vague and could this be attributable for different loss in the chamber? Did you monitor loss with and without oxidant?
P8, L17 – there appears to be an extra or missing word: ‘are and dimers’
P8, L31 – assuming gas-particle equilibrium? (missing word).
P9, L10 – Not very clear what equation you’re mentioning here.
P9, L13 – There are many ways to average here, presumably this is weighted by total mass fraction? Should be specified
P10, L34 – I don’t believe this statement is justified. You have one ‘aged’ experiment and if error bars are similar to the one shown, they might well overlap. How is ‘significantly higher’ defined? Variation in particle loading, diameters and other properties can lead to changes in observed evaporation as well. Similarly, should not compare thermograms across studies (e.g. P11, L6).
P11, L21 – Is there evidence of thermal decomposition of dimers? Did you try LC/MS analysis on thermally treated aerosol?
P12, L2 – I think you are fitting this alpha value, but it seems like it is assumed. This section needs to be made more clear and the actual fit approach/uncertainty discussed.
P12, L24 – Why should volatility distribution and alpha be linked? One is thermodynamics and the other kinetics?
P13, L1-13 – I find this section unconvincing. Given the lack of very low concentration data, it’s unclear how well constrained bins down to 0.01 ug /m3 are constrained by this dilution data. Could the same fits be achieved using a narrower range of volatility? This seems like it might be over-fitting since you’re using 4 data points to fit 6 parameters (or maybe 5). Also, the effects of walls is not mentioned at all. Is the aerosol concentration measured at equilibrium used? This will reflect the loss to your secondary chamber wall, which may not be a good representation of the conditions dictating partitioning of the suspended particles (or else wouldn’t things keep evaporating away?)

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ED: Publish subject to minor revisions (review by editor) (09 Oct 2019) by Neil M. Donahue

AR by Kei Sato on behalf of the Authors (24 Oct 2019) Author's response Manuscript

ED: Publish as is (08 Nov 2019) by Neil M. Donahue

Short summary

The volatility distributions of secondary organic aerosol (SOA) formed from the photooxidation of 1,3,5-trimethylbenzene were investigated by composition, heating, and dilution measurements. Fresh SOA, formed from 1,3,5-trimethylbenzene, included low-volatility compounds with < 1 μg m^–3 saturation concentrations, which are not assumed to exist in fresh SOA particles in the standard volatility basis-set approach. Improvements in the organic aerosol model will be necessary.