Size distribution and source of black carbon aerosol in urban Beijing during winter haze episodes

Wu, Yunfei; Wang, Xiaojia; Tao, Jun; Huang, Rujin; Tian, Ping; Cao, Junji; Zhang, Leiming; Ho, Kin-Fai; Han, Zhiwei; Zhang, Renjian

doi:https://doi.org/10.5194/acp-17-7965-2017

Articles | Volume 17, issue 12

https://doi.org/10.5194/acp-17-7965-2017

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

Special issue:

Pan-Eurasian Experiment (PEEX)

https://doi.org/10.5194/acp-17-7965-2017

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

Articles | Volume 17, issue 12

Research article

|

30 Jun 2017

Research article |

| 30 Jun 2017

Size distribution and source of black carbon aerosol in urban Beijing during winter haze episodes

Yunfei Wu, Xiaojia Wang, Jun Tao, Rujin Huang, Ping Tian, Junji Cao, Leiming Zhang, Kin-Fai Ho, Zhiwei Han, and Renjian Zhang

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Final revised paper (published on 30 Jun 2017)
Supplement to the final revised paper
Preprint (discussion started on 06 Dec 2016)
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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 Wu et al.', Anonymous Referee #1, 12 Feb 2017
- AC1: 'Reply to comments of anonymous Referee#1 to Wu et al. "Size distribution and source of black carbon aerosol in urban Beijing during winter haze episodes"', Yunfei Wu, 27 Apr 2017
RC2: 'review', Anonymous Referee #2, 17 Mar 2017
- AC2: 'Reply to comments of anonymous Referee#2 to Wu et al. "Size distribution and source of black carbon aerosol in urban Beijing during winter haze episodes"', Yunfei Wu, 27 Apr 2017

Peer-review completion

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

AR by Yunfei Wu on behalf of the Authors (27 Apr 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (06 May 2017) by Imre Salma

RR by Anonymous Referee #1 (11 May 2017)

Suggestions for revision or reasons for rejection

The authors made a genuine effort in responding to the reviewers concerns and overall most of the issues have been adequately addressed. However, I am surprised how little of the response material has been included into the revised manuscript. Reviewers typically raise questions/comments not for themselves, but rather from the readers perspective. I recommend that a lot more of the response material would be included into the revised manuscript. For example, the response on the neutralization degree can briefly be mentioned in the text and the Figure included into Supplementary Material; discussion on validation of the proposed method by carbon isotope analysis did not make into revised manuscript; and so on.
Response on defining thickly coated particles makes sense now and I suggest to look at the rBC size of the thinly coated particles. This presents some sort of validation (the major deficiency of the paper) where traffic related rBC core size derived from regression should roughly match the core size of thinly coated particles. Considering urban Beijing area having no major industrial sources, traffic related particles should stay thinly or non coated due to a short residence time after being emitted. Two peaks in lag time suggest two distinct populations with the traffic related particles clustering around short lag time while traffic related particles from long ranges and produced by biomass burning possessing larger lags (the more severe pollution the larger the percentage of thickly coated particles). Therefore, while the regression may indeed point correctly at traffic related rBC cores having VED of 150nm, similar VED should be revealed by thinly coated particles which should arise from nearby traffic sources. My question is what is the rBC VED of the particles having a lag of approximately 1us and 0us? If the above question is positively responded it would significantly strengthen the paper.

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ED: Reconsider after minor revisions (Editor review) (29 May 2017) by Imre Salma

AR by Yunfei Wu on behalf of the Authors (01 Jun 2017) Author's response Manuscript

ED: Publish as is (04 Jun 2017) by Imre Salma

AR by Yunfei Wu on behalf of the Authors (05 Jun 2017)

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Short summary

As black carbon (BC) aerosols play an important role in the climate and environment, the size distribution of refractory BC (rBC) was investigated. On this basis, the source of rBC was further analyzed. The local traffic exhausts contributed greatly to the rBC in urban areas. However, its contribution decreased significantly in the polluted period compared to the clean period, implying the increasing contribution of other sources, e.g., coal combustion or biomass burning, in the polluted period.