Summertime aerosol volatility measurements in Beijing, China

Xu, Weiqi; Xie, Conghui; Karnezi, Eleni; Zhang, Qi; Wang, Junfeng; Pandis, Spyros N.; Ge, Xinlei; Zhang, Jingwei; An, Junling; Wang, Qingqing; Zhao, Jian; Du, Wei; Qiu, Yanmei; Zhou, Wei; He, Yao; Li, Ying; Li, Jie; Fu, Pingqing; Wang, Zifa; Worsnop, Douglas R.; Sun, Yele

doi:https://doi.org/10.5194/acp-19-10205-2019

Articles | Volume 19, issue 15

https://doi.org/10.5194/acp-19-10205-2019

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

https://doi.org/10.5194/acp-19-10205-2019

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

Articles | Volume 19, issue 15

Research article

|

13 Aug 2019

Research article |

| 13 Aug 2019

Summertime aerosol volatility measurements in Beijing, China

Weiqi Xu, Conghui Xie, Eleni Karnezi, Qi Zhang, Junfeng Wang, Spyros N. Pandis, Xinlei Ge, Jingwei Zhang, Junling An, Qingqing Wang, Jian Zhao, Wei Du, Yanmei Qiu, Wei Zhou, Yao He, Ying Li, Jie Li, Pingqing Fu, Zifa Wang, Douglas R. Worsnop, and Yele Sun

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Final revised paper (published on 13 Aug 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 Xu et al., acp-2019-135', Anonymous Referee #1, 13 Apr 2019
RC2: 'Review comments on summertime aerosol volatility measurements in Beijing, China Weiqi Xu et al.', Anonymous Referee #2, 14 Apr 2019
AC1: 'Reply to referees' comments', Yele Sun, 15 Jun 2019

Peer-review completion

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

AR by Yele Sun on behalf of the Authors (15 Jun 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (25 Jun 2019) by Manabu Shiraiwa

RR by Anonymous Referee #2 (17 Jul 2019)

Suggestions for revision or reasons for rejection

In the revised manuscript, the authors have extended some of their discussions. I suggest some minor revisions, after which I recommend publication.

1# Table S2: Please report the particle size information for the bulk OA as well, since the particle size is an important parameter for the evaporation kinetic model. In Table S2, the SOA size diameter peak in 2018 data set is 600 mm and 380 mm in 2017 data set. Any explanation for such big difference in SOA size distribution between two years?

#2. Please clarify the plug flow residence time at what temperature? I guess it is at room temperature.

#3. Page5, L-6: Please provide the C* bin range and rationale for choosing that range.

#4. Page 6-7: There are some discussions on volatility comparison between this study and other cities based on TD evaporation data, which are not well supported. I would discourage such comparison. For example, Page-6 “28% of particulate organics evaporated at 50°C, a fraction larger than that observed 5 in Shenzhen (~10%) (Cao et al., 2018), Centreville and Raleigh (Kostenidou et al., 2018;Saha et al., 2017) and Athens (Louvaris et al., 2017), yet similar to the observations in Paris (Paciga et al., 2016), suggesting that OA contained relatively high volatility compounds in Beijing compare to most other sites.”
Since we all know the observed evaporations in TD depend on many experiment specific parameters and thus not a robust measure of volatility, I would suggest to move such discussions in the Sec. 3.3 (Volatility distribution of OA factors) and make comparisons based on the derived volatility distributions.
#5. PMF of TD data: I understand the authors performed the PMF for the MS (ambient) and MS (ambient +TD). I assume here MS (ambient +TD) includes all TD data at all the operating TD temperatures. It would be helpful if they can extend the discussion about how they obtained the PMF factors at different TD temperatures.

#6. Figure 7: In my sense, this is a key figure (summary plot) of this paper. I would recommend extending this figure into three panels showing total OA, SOA, and POA from experimental and WRF-simulated results. In addition to OA mass fraction, I would suggest including absolute OA concentrations at different volatility bins, e.g., the left y-axis can show absolute OA concentration (COA), and the right y-axis can show the OA mass fraction.

#7. The volatility of “BC containing POA (C* 0.69 ug/m3)” and “ambient POA (C* = 0.37 ug/m3)” are substantially different. How does the volatility of BC containing POA compare with the volatility of ambient HOA? I think some related discussion would be helpful for the readers.

#8. The term “ambient OA” and “BC-containing OA” sounds confusing sometimes. All the measured OA are ambient. I think an appropriate term would be “BC-containing ambient OA”. I would suggest to clarify it.

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ED: Publish subject to minor revisions (review by editor) (19 Jul 2019) by Manabu Shiraiwa

AR by Yele Sun on behalf of the Authors (23 Jul 2019) Author's response Manuscript

ED: Publish as is (24 Jul 2019) by Manabu Shiraiwa

AR by Yele Sun on behalf of the Authors (25 Jul 2019) Manuscript

Short summary

We present the first aerosol volatility measurements in Beijing in summer using a thermodenuder coupled with aerosol mass spectrometers. Our results showed that organic aerosol (OA) comprised mainly semi-volatile organic compounds in summer, and the freshly oxidized secondary OA was the most volatile component. We also found quite different volatility distributions in black-carbon-containing primary and secondary OA, ambient OA, ambient secondary OA and the WRF-Chem model.