Seasonal variations in the highly time-resolved aerosol composition, sources and chemical processes of background submicron particles in the North China Plain

Li, Jiayun; Cao, Liming; Gao, Wenkang; He, Lingyan; Yan, Yingchao; He, Yuexin; Pan, Yuepeng; Ji, Dongsheng; Liu, Zirui; Wang, Yuesi

doi:https://doi.org/10.5194/acp-21-4521-2021

Articles | Volume 21, issue 6

https://doi.org/10.5194/acp-21-4521-2021

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

Special issue:

Multiphase chemistry of secondary aerosol formation under...

https://doi.org/10.5194/acp-21-4521-2021

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

Articles | Volume 21, issue 6

Research article

|

24 Mar 2021

Research article |

| 24 Mar 2021

Seasonal variations in the highly time-resolved aerosol composition, sources and chemical processes of background submicron particles in the North China Plain

Jiayun Li, Liming Cao, Wenkang Gao, Lingyan He, Yingchao Yan, Yuexin He, Yuepeng Pan, Dongsheng Ji, Zirui Liu, and Yuesi Wang

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Final revised paper (published on 24 Mar 2021)
Supplement to the final revised paper
Preprint (discussion started on 18 May 2020)
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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', Anonymous Referee #1, 26 May 2020
- AC1: ' 'Response to Anonymous Referee #1', Zirui Liu, 25 Aug 2020
RC2: 'Referee comment', Anonymous Referee #2, 18 Jun 2020
- AC2: ' 'Response to Anonymous Referee #2', Zirui Liu, 25 Aug 2020

Peer-review completion

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

AR by Zirui Liu on behalf of the Authors (10 Sep 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (25 Sep 2020) by Aijun Ding

RR by Anonymous Referee #2 (15 Oct 2020)

Suggestions for revision or reasons for rejection

While the dataset is valuable, there are still many mistakes or improper interpretations in this study. For example,
Line 215: This reviewer does not agree that higher acidity of sulfate is due to the low volatility.
Line 245: The indication is quite confusing as the strong influence of fossil fuel combustion is due to regional transport at this background site.
Line 268: The indication here is not correct. How previous studies in urban Beijing indicate the formation mechanisms in background atmosphere?
Line 275: The authors should not draw a conclusion that the impact of regional transport weakened as the regional transport can be related to air masses both from clean and polluted areas. With the decrease in wind speed, do the authors see changes in back trajectories?
Line 277: The authors should conclude the important role of photochemistry in the formation of sulfate and OOA based on the relationship between OA/sulfate and RH.
Line 293: Did the greater level of NPF in winter occur in Xinglong? It’s confusing by adding this description.
Line 296-321: This part regarding the evaluation of PMF results is partly repetitive of those in the Methods.
Line 322-325: The characteristics of f44 and f43 are indicators to name the factors as MO-OOA or LV-OOA. It’s not because of these behaviors that MO-OOA has a higher oxidation state than LO-OOA.
Line 344: The diurnal of nitrate is not only related to the PBL influence but also contributions from lower temperature and higher RH at night.
Line 347: It’s not correct to conclude the importance of N2O5 hydrolysis based on low NO concentration and high O3 concentration. Do they check NO2 concentration?
Line 362: The high sulfate concentration at night can also be contributed by lower PBL.
Line 387: The high O/C ratio indicates the high aging of the aerosols.
Line 439-441: The reviewer cannot understand the meaning or the main point here.
Line 468-473: The authors said that the medium-distance cluster (1, 3, 4, and 5) were dominant in summer but then they focused on cluster 2 and 3 from the southern regions and said southern transport played a dominant role. This is contradictory.
Line 507: The reviewer cannot agree that sulfate dominates submicron particles in southern and western China generally.

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RR by Anonymous Referee #3 (31 Oct 2020)

Suggestions for revision or reasons for rejection

This paper presented a four-season measurement of aerosol composition using an AMS at Xinglong site and reported the seasonal variation, diurnal variation, as well as the source appointment. The authors revised the manuscript largely according to the referee’s comments, especially add the calculation of aerosol acidity by the thermodynamic model of ISORROPIA II. This is a good improvement. However, similar to the comments of Referee II, this study is to date more like a data report without too much insight to improve the current understanding. I, therefore, recommend a major revision before it can be published in ACP.

1. I did suggest to make the analysis more focus on 1-2 scientific question, other than report the data as seasonal variation, diurnal variation et al
2. In section 3.4: the authors drew their conclusions without enough supports. E.g. it’s hard to conclude the role of aqueous-phase reactions solely by the observational that MO-OOA increased with RH.
3. Line 194-195: Similarly, it’s hard to evaluate the role of aqueous-phase reactions in nitrate formation solely by the observational fact that nitrate proportion increased with PM1.
4. The language writing needs to be polished.
5. Line 146: there is a lack of evidence to support the identification/definition of FFOA.
6. Figure2: Figure numbers did not match with the figure capture
7. Correlation analysis for the PMF factors: since a regional background site, the temporal variation of most aerosol compositions can be predicted to be correlated to each other, but cannot say too much on the source appointment. For instance, in Figure 4, the LO-OOA, MO-OOA, nitrate, and sulfate were correlated well to each other.

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RR by Anonymous Referee #1 (16 Nov 2020)

ED: Reconsider after major revisions (30 Nov 2020) by Aijun Ding

AR by Zirui Liu on behalf of the Authors (11 Jan 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (16 Jan 2021) by Aijun Ding

RR by Anonymous Referee #3 (20 Jan 2021)

ED: Publish as is (28 Jan 2021) by Aijun Ding

AR by Zirui Liu on behalf of the Authors (01 Feb 2021)

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Short summary

For the first time, we investigated the highly time-resolved chemical characterization, sources and evolution of atmospheric submicron aerosols at a regional background site in the North China Plain (NCP) using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer and evaluated the seasonal differentials of photochemical and aqueous-phase processing on SOA composition and oxidation degree of OA. The results will help to understand air pollution in the NCP on a regional scale.