Seawater analysis by ambient mass-spectrometry-based seaomics

Zabalegui, Nicolás; Manzi, Malena; Depoorter, Antoine; Hayeck, Nathalie; Roveretto, Marie; Li, Chunlin; van Pinxteren, Manuela; Herrmann, Hartmut; George, Christian; Monge, María Eugenia

doi:https://doi.org/10.5194/acp-20-6243-2020

Articles | Volume 20, issue 10

https://doi.org/10.5194/acp-20-6243-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Marine organic matter: from biological production in the ocean...

https://doi.org/10.5194/acp-20-6243-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 20, issue 10

Research article

|

28 May 2020

Research article |

| 28 May 2020

Seawater analysis by ambient mass-spectrometry-based seaomics

Nicolás Zabalegui, Malena Manzi, Antoine Depoorter, Nathalie Hayeck, Marie Roveretto, Chunlin Li, Manuela van Pinxteren, Hartmut Herrmann, Christian George, and María Eugenia Monge

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Final revised paper (published on 28 May 2020)
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Preprint (discussion started on 10 Dec 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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- Supplement

RC1: 'Review for acp-2019-852', Anonymous Referee #2, 11 Dec 2019
- AC1: 'Responses to Reviewer #2', Maria Monge, 24 Jan 2020
RC2: 'Review of Zabalegui et al', Anonymous Referee #1, 02 Jan 2020
- AC2: 'Responses to Reviewer #1', Maria Monge, 24 Jan 2020
RC3: 'Review of “Seawater Analysis by Ambient Mass Spectrometry-Based Seaomics and Implications on Secondary Organic Aerosol Formation” by Zabalegui et al. (2019)', Anonymous Referee #3, 07 Jan 2020
- AC3: 'Responses to Reviewer #3', Maria Monge, 24 Jan 2020

Peer-review completion

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

AR by Maria Monge on behalf of the Authors (13 Feb 2020) Author's response

ED: Referee Nomination & Report Request started (07 Mar 2020) by Paul Zieger

RR by Anonymous Referee #2 (16 Mar 2020)

RR by Anonymous Referee #3 (16 Mar 2020)

Suggestions for revision or reasons for rejection

Overall comments:

This manuscript looks almost identical to the one I reviewed previously, and the main strengths and weaknesses largely remain. It is a highly descriptive account of a novel method of characterizing sea surface microlayer (SML) and bulk seawater composition with the aim of ultimately connecting surface ocean composition with marine volatile organic compound and aerosol formation. Attached to this, with limited analysis and synthesis (but large weighting in the study conclusions), is an experiment that tested secondary organic aerosol (SOA) generation by irradiation of a subset of the SML samples.

The authors seem not to have taken to heart the criticism of the reviewers that the connections between the composition measurements and the SOA formation experiments are very tenuous. Put simply, there is nothing that shows that the detected compounds enhanced in the SML are contributing to SOA formation. I proposed in my original review that the authors either dramatically expand the discussion/analysis, or temper their conclusions. The authors seem not to have been persuaded that there was much of a need for either. They have held back from meaningfully editing the manuscript to make their arguments clearer or more convincing to the reader.

I see three possible paths to publication for this manuscript:

1. Change the conclusions in the Conclusions and Abstract to things clearly supported by the manuscript without other major changes (suggestions below). It’s not clear if the manuscript in that form would be suitable for publication in ACP or not, as little could be concluded about the relationship between the seawater composition measurements and SOA formation.

2. Dramatically expand the analysis and interpretation and synthesis of the SOA-related section to draw a compelling link to the “seaomics” work. This may or may not be doable given the available data, but it could lead to material support for the conclusions as currently stated.

3. Remove the SOA-focused experiments from the paper and submit the detailed, useful description of the SML and bulk seawater composition method and results to a more appropriate journal.

Specific major Issues with claims in the manuscript by section:

Abstract:
“Tentative identification of these species suggest that saturated fatty acids, peptides, fatty alcohols, halogenated compounds, and oxygenated boron-containing organic
compounds may be involved in water-air transfer processes and in photochemical reactions at the water- air interface of the ocean.”
I would revise to “…boron-containing organic compounds are available at the surface for water-air transfer processes…” There’s no evidence here that these things are specifically participating- they are simply present.

“Results from these experiments and the analytical seaomics strategy provide a proof of concept that organic compounds may play a key role in aerosol formation processes at the water/air interface. “
I would revise to “These results provide a proof on concept for an approach to identifying organic molecules involved in aerosol formation processes at the water/air interface.” Writing “proof of concept” isn’t a license to state a desired conclusion that isn’t supported by the present data.

Line 425:
I am repeating myself from my previous review, but the compounds present in SML particles (“endometabolome”) may not be available to participate in the sea surface SOA-forming chemistry in the real environment. That should be pointed out to the reader with at least a single sentence. It is highly relevant to the question of how relevant these results may be to the ambient environment, and glossing over it (i.e. merely pointing out in review that those components are included in the analysis) does a disservice to the reader.

Conclusions:
I disagree with the conclusion that the results here “suggest that organic compounds enriched at the water/air interface may play a key role in aerosol formation processes.” It seems likely to be true based on previous work, but I don’t see how these results support that claim. If the experiment had included OFR oxidation runs using the underlying water and showed that those samples showed no SOA formation, such a conclusion could be supported. Lacking such data, the authors would need to be able to say something about which compounds may be contributing to the differential SOA forming ability of the different SML samples, and then argue that those compounds are enhanced in the SML.

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ED: Reconsider after major revisions (25 Mar 2020) by Paul Zieger

AR by Maria Monge on behalf of the Authors (02 Apr 2020) Author's response Manuscript

ED: Publish as is (13 Apr 2020) by Paul Zieger

AR by Maria Monge on behalf of the Authors (16 Apr 2020)

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Short summary

A new approach to bridging different fields of science by studying the air–sea interface is described. An untargeted ambient mass-spectrometry-based metabolomics method enables the study of enriched organic compounds found on the sea surface for air–water transfer processes. Results from the metabolomics experiments and a lab-to-field approach provide new opportunities for characterizing the seawater organic-matter content and discovering compounds involved in aerosol-formation processes.