Molecular characterization of atmospheric particulate organosulfates in  three megacities at the middle and  lower reaches of the Yangtze River

Wang, Xin Ke; Rossignol, Stéphanie; Ma, Ye; Yao, Lei; Wang, Ming Yi; Chen, Jian Min; George, Christian; Wang, Lin

doi:https://doi.org/10.5194/acp-16-2285-2016

Articles | Volume 16, issue 4

https://doi.org/10.5194/acp-16-2285-2016

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

https://doi.org/10.5194/acp-16-2285-2016

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

Articles | Volume 16, issue 4

Research article

|

26 Feb 2016

Research article |

| 26 Feb 2016

Molecular characterization of atmospheric particulate organosulfates in three megacities at the middle and lower reaches of the Yangtze River

Xin Ke Wang, Stéphanie Rossignol, Ye Ma, Lei Yao, Ming Yi Wang, Jian Min Chen, Christian George, and Lin Wang

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Final revised paper (published on 26 Feb 2016)
Supplement to the final revised paper
Preprint (discussion started on 10 Aug 2015)
Supplement to the preprint

Interactive discussion

Status: closed

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

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- Supplement

RC C6565: 'Review', Anonymous Referee #4, 04 Sep 2015
- SC C7783: 'reply to Referee #4', Christian George, 09 Oct 2015
- AC C9298: 'A point-to-point response to referee #4’s comments', Lin Wang, 16 Nov 2015
RC C6597: 'referee comment', Anonymous Referee #1, 06 Sep 2015
- SC C7790: 'Reply to Referee #1', Christian George, 09 Oct 2015
- AC C9313: 'A point-to-point response to referee #1’s comments', Lin Wang, 16 Nov 2015
SC C6818: 'Some References and Suggestions to the Authors that Might be Helpful', Jason Surratt, 13 Sep 2015
- SC C7767: 'Response to the comments from JDS Surratt and M Riva', Christian George, 09 Oct 2015
  - RC C7779: 'Anonymous Referee #1 comment', Anonymous Referee #1, 09 Oct 2015
    - SC C7781: 'CAnswer to referee #1', Christian George, 09 Oct 2015
      - RC C7798: 'response to 'CAnswer to referee #1', Christian George, 09 Oct 2015', Anonymous Referee #1, 09 Oct 2015
        
        AC C9324: 'A point-to-point response to referee #1’s third comments', Lin Wang, 16 Nov 2015
    - AC C9321: 'A point-to-point response to referee #1’s second comments', Lin Wang, 16 Nov 2015
- AC C9306: 'A point-to-point response to reviewers’ comments', Lin Wang, 16 Nov 2015
RC C7972: 'Interactive comment for the acp-2015-393 manuscript', Anonymous Referee #5, 14 Oct 2015
- AC C9294: 'A point-to-point response to referee #5’s comments', Lin Wang, 16 Nov 2015
RC C8060: 'Review', Anonymous Referee #2, 15 Oct 2015
- AC C9288: 'RE: A point-to-point response to referee #2’s comments', Lin Wang, 16 Nov 2015
RC C8196: 'Review', Anonymous Referee #3, 18 Oct 2015
- AC C9283: 'A point-to-point response to referee #3’s comments', Lin Wang, 16 Nov 2015

Peer-review completion

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

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

ED: Referee Nomination & Report Request started (18 Nov 2015) by Willy Maenhaut

RR by Anonymous Referee #1 (03 Dec 2015)

RR by Anonymous Referee #5 (13 Dec 2015)

RR by Anonymous Referee #3 (16 Dec 2015)

Suggestions for revision or reasons for rejection

I applaud the authors for thoroughly addressing the review comments. I only have a few minor comments on the revise ms as given below.

Specific comments
1. In comparison with earlier studies using LC/MS for detecting OS compounds in ambient samples, one notable difference is that a significantly higher number of isomers were detected in this work (Section 3.1). The authors suggest that different chromatographic conditions and additional precursors available at the sampling sites in this study are the causes for the observed difference. Could different detection sensitivity between Orbitrap MS and the lower resolution MS another contributing cause? It will be helpful if the authors could report the detection limits by the Orbitrap-MS of the few OS standards used in their work. This will add value to the study by providing guidance to future LC/MS analysis of OS compounds.
2. Isomeric pattern differs significantly among locations. For example, in the WH samples, OSs with six isomers account for the largest proportion; in contrast, in the SH and NJ samples, OSs with one isomer only are dominant (Lines 304-309). Does this reflect diversity in precursors or oxidation mechanism or both? This may suggest that simultaneous measurements of VOCs and semi-volatile organic compounds may shed more insights in future studies. Some discussion on this will be useful. I also feel the point of isomeric pattern difference among the sites is a noteworthy point to include in the abstract. This finding is something unique and certain coming out of this study, while the statements on OS reaction pathways are largely speculative due to the limited sample size and lack of other collaborative masurements.

Minor comments:
(1) Abstract: specify the percentage is by number of formulas or by intensity
(2) Line 74: less abundant --> more abundant

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RR by Anonymous Referee #6 (23 Dec 2015)

RR by Anonymous Referee #7 (05 Jan 2016)

Suggestions for revision or reasons for rejection

Overall Recommendation:

The authors have done a very good job in addressing all the reviewer comments and short comments posted during the discussion. Most of the issues, including the English writing, have been resolved enough to warrant publication. However, there remain a few minor issues that need to be resolved before full publication is considered in ACP. Specifically, I still wonder why the authors did not consider conducting tandem MS experiments to confirm the presence of organosulfates versus sulfonates? Also, tandem MS experiments could have provided deeper insights into the the structures of some of these OSs. The authors need to specifically say in the discussion of the results that "one limitation of this work is the lack of using tandem MS experiments to provide insights into the structures of these organosulfates." Although high-resolution MS was used, and in many instances consistent with prior studies, it is not enough on its own to fully identify these organosullfur compounds as organosulfates or sulfonates, especially since sulfonates recently identified in Riva et al. (2015, ES&T) can be multifunctional and thus contain many O atoms. I highly recommend that a word of caution is added in the text about this. The authors now rightly emphasize throughout many places in the text now that these are "tentative assignments." Lastly, I think the authors need to be really careful when using words like "abundant, more abundant, or less abundant" when describing the differences in types of organosulfates or differences between sites. For example, in the abstract the authors state "Aliphatic OSs represented more than 78% of the detected OSs at the three locations, while OSs were much less abundant." Statements like this are not good since you don't know the response factor of aromatic organosulfates versus aliphatic organosulfates. Thus, I suggest using words like "numerous, less numerous, or more numerous" when trying to describe differences between sites or types of OSs.

Remaining Minor Comments:

1.) Page 3, Line 50: Change "isoprene-derived epoxide (IEPOX)" to isomeric isoprene epoxydiols (IEPOX) to be consistent with the original paper by Paulot et al. (2009, Science).

2.) Page 3, Lines 52-54: The authors state that "subsequent acid catalyzed reactions of IEPOX and MAE in the presence of sulfates can lead to the formation of OSs" but the fail to cite Lin et al. (2013, PNAS). Lin et al. (2013, PNAS) demonstrated for the first time that MAE in fact does this. Further, Lin et al. (2012, ES&T) was the first study to demonstrate with "true" IEPOX that it does in fact produce OSs. These papers should be cited here in the introduction.

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ED: Reconsider after minor revisions (Editor review) (06 Jan 2016) by Willy Maenhaut

AR by Lin Wang on behalf of the Authors (15 Jan 2016) Author's response Manuscript

ED: Reconsider after minor revisions (Editor review) (30 Jan 2016) by Willy Maenhaut

The authors have reasonably addressed the comments of the 5 anonymous referees.
However, several minor alterations are needed before this manuscript and its Supplement can be published in ACP.

For the main text:

Throughout the manuscript: "m/z" should be in italic.
Line 26: Replace "in WH sample" by "in the WH samples".
Line 27: Replace "in SH" by "in the SH".
Line 86: Replace "also showed" by "showed".
Line 125: Although "UHPLC" was defined in the Abstract it should also be defined here.
Line 126: The same applies to the "MS" of "Orbitrap-MS".
Line 154: Replace "100 lpm" by "100 Lpm".
Line 161: Replace "0.2µm" by "0.2 µm".
Line 167: Replace "5µL" by "5 µL".
Line 170: Replace "MS" by "mass spectrometer". According to the IUPAC guidelines MS stands for the technique and not for the instrument.
Line 178: Replace "1.8µm" by "1.8 µm".
Line 179: Replace "2.1mm" by "2.1 mm".
Line 186: Replace "-3.0kV" by "-3.0 kV".
Line 280: Replace "MSs" by "mass spectrometers".
Line 284: Replace "from Diabla" by "from the Diabla".
Line 287: Replace "isomer has been" by "isomers have been".
Line 341: Replace "in NJSN" by "in the NJSN".
Line 362: Replace "CHOSs" by "CHOS".
Line 395: Replace "formula of" by "formulas of".
Line 430: Replace "those series 6" by "those for series 6".
Line 432: Replace "most of CHNOS" by "most CHNOS".
Line 449: Replace "WH sample" by "WHS sample".
Line 455: Replace "in three" by "in the three".
Line 501: Replace "both SHWN" by "both the SHWN".
Line 503: Replace "showed higher" by "showed a higher".
Line 538: Replace "MS" by "mass spectrometer".
Line 541: Replace "nitrooxy-organosulfates respectively" by "nitrooxy-organosulfates, respectively".
Page 26, heading of Table 1: Replace "Molecular Weight (MW), Double Bond Equivalents (DBE), and Elemental Ratios" by "molecular weight (MW), double bond equivalents (DBE), and elemental ratios".
Page 27, third line of the caption of Figure 3: Replace "of identified species" by "of the identified species".
Page 27, third line of the caption of Figure 4: Replace "formula of" by "formulas of".
Page 27, third line of the caption of Figure 5: Replace "formula of" by "formulas of".

For the Supplement:

First page, last but one line: Replace "five tables" by "four tables".
Heading of Table S1: Replace "A comparison" by "Comparison".
Third page, second line: Replace "acid, were" by "acid were".
Third page, fourth line: Replace "1µM" by "1 µM".
Third page, sixth line: Replace "LOD" by "Limits of detection (LODs)".
Table S3: The word "2-methylnaphtalene" cannot be split over two lines as done in this table; one possibility is to split it as "2-methyl-" and "naphtalene". Also the word "β-caryophyllene" is split incorrectly; one possibility here is "β-caryo-" and "phyllene"
Table S3, footnote m: Replace "formula within" by "formulas within".
Heading of Table S4: Replace "The isomer" by "Isomer".
Figure S1c: Replace "(C)" by "(c)" both above the figure and in the figure caption.
Caption of Figure S1c: Replace "sample is not included" by "sample are not included".
Caption of Figure S2: Replace "a pound sign" by "a # sign".

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AR by Lin Wang on behalf of the Authors (31 Jan 2016) Author's response Manuscript

ED: Publish as is (12 Feb 2016) by Willy Maenhaut

AR by Lin Wang on behalf of the Authors (13 Feb 2016)

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Short summary

PM_2.5 filter samples have been collected in three megacities at the middle and lower reaches of the Yangtze River: Wuhan, Nanjing, and Shanghai. The samples were analyzed using ultra-high-performance liquid chromatography coupled with Orbitrap mass spectrometry, which allowed for detection of about 200 formulas of particulate organosulfates, including dozens of formulas of nitrooxy-organosulfates, with various numbers of isomers for each tentatively determined formula at each location.