Formation of secondary aerosols from gasoline vehicle exhaust when mixing  with SO<sub>2</sub>

Liu, T.; Wang, X.; Hu, Q.; Deng, W.; Zhang, Y.; Ding, X.; Fu, X.; Bernard, F.; Zhang, Z.; Lü, S.; He, Q.; Bi, X.; Chen, J.; Sun, Y.; Yu, J.; Peng, P.; Sheng, G.; Fu, J.

doi:https://doi.org/10.5194/acp-16-675-2016

Articles | Volume 16, issue 2

https://doi.org/10.5194/acp-16-675-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-16-675-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 16, issue 2

Research article

|

21 Jan 2016

Research article |

| 21 Jan 2016

Formation of secondary aerosols from gasoline vehicle exhaust when mixing with SO₂

T. Liu, X. Wang, Q. Hu, W. Deng, Y. Zhang, X. Ding, X. Fu, F. Bernard, Z. Zhang, S. Lü, Q. He, X. Bi, J. Chen, Y. Sun, J. Yu, P. Peng, G. Sheng, and J. Fu

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Final revised paper (published on 21 Jan 2016)
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Preprint (discussion started on 02 Sep 2015)

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

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RC C7134: 'Review of Liu et al.', Anonymous Referee #2, 23 Sep 2015
- AC C9272: 'Response to the comments from Reviewer #2', Xinming Wang, 14 Nov 2015
RC C7261: 'Review of Liu et al', Anonymous Referee #3, 25 Sep 2015
- AC C9273: 'Response to the comments from Reviewer #3', Xinming Wang, 14 Nov 2015
RC C8458: 'Review of Liu et al., ACPD, 2015', Anonymous Referee #1, 24 Oct 2015
- AC C9271: 'Response to the comments from Reviewer #1', Xinming Wang, 14 Nov 2015

Peer-review completion

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

AR by Xinming Wang on behalf of the Authors (14 Nov 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (23 Nov 2015) by Delphine Farmer

RR by Anonymous Referee #1 (26 Nov 2015)

Suggestions for revision or reasons for rejection

1. I was not implying that the sCIs themselves form SOA. Rather I was speculating on the role of sCIs to oxidize SOA precursors to form SOA. Nonetheless, the response and the conclusions in the paper about evidence for acid-catalyzed reactions is weak and needs to be revised even further.
2. I am confused by the interpretation offered by the authors based on results of the new experiment. Ammonium sulfate at 59% RH should be a solid. The experiment has merely tested the availability of a condensation sink on SOA formation; it's nice to see that the experiments are not surface area limited. However, the experiment says nothing about whether the SOA enhancement is a result of increased acidity. The experiment that should have been performed, in my opinion, is with wet aerosol to test the role of acidity and rule out the possibility of enhanced gas-phase chemistry.
3. I do not think the authors have offered a correct explanation of the influence of vapor wall-losses on these set of experiments. Zhang et al. (2014) see a large influence of wall losses on SOA production not from the loss of the 'final' semi-volatile product species but because of the loss of intermediary (potentially intermediate volatility) species that are lost to the walls before they form SOA.
4. In the introduction, the manuscript would benefit from the hypotheses surrounding the poor model-measurement comparison of SOA from light-duty gasoline vehicles.
5. I am concerned that the experiment includes passing emissions through a pump where depending on the pump type, you could get substantial loss of gas and particle species on the impeller/diaphragm. On a related note, have the authors performed blanks to look at SOA formation in the absence of emissions?

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RR by Anonymous Referee #3 (04 Dec 2015)

ED: Reconsider after minor revisions (Editor review) (13 Dec 2015) by Delphine Farmer

AR by Xinming Wang on behalf of the Authors (16 Dec 2015) Author's response Manuscript

ED: Publish as is (07 Jan 2016) by Delphine Farmer

AR by Xinming Wang on behalf of the Authors (08 Jan 2016)

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Short summary

The formation of SOA and sulfate aerosols from the photooxidation of gasoline vehicle exhaust (GVE) when mixing with SO₂ was investigated in a smog chamber. We found that the presence of GVE enhanced the conversion of SO₂ to sulfate predominantly through reactions with stabilized Criegee intermediates. On the other hand, the elevated particle acidity enhanced the SOA production from GVE. This study indicated that SO₂ and GVE could enhance each other in forming secondary aerosols.

Formation of secondary aerosols from gasoline vehicle exhaust when mixing with SO2

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Formation of secondary aerosols from gasoline vehicle exhaust when mixing with SO₂