Continuous in situ measurement of dissolved methane in Lake Kivu using a membrane inlet laser spectrometer

Grilli, Roberto; Darchambeau, François; Chappellaz, Jérôme; Mugisha, Ange; Triest, Jack; Umutoni, Augusta

doi:https://doi.org/10.5194/gi-9-141-2020

Articles | Volume 9, issue 1

https://doi.org/10.5194/gi-9-141-2020

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

https://doi.org/10.5194/gi-9-141-2020

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

Articles | Volume 9, issue 1

Research article

|

20 Apr 2020

Research article |

| 20 Apr 2020

Continuous in situ measurement of dissolved methane in Lake Kivu using a membrane inlet laser spectrometer

Roberto Grilli, François Darchambeau, Jérôme Chappellaz, Ange Mugisha, Jack Triest, and Augusta Umutoni

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Final revised paper (published on 20 Apr 2020)
Preprint (discussion started on 20 Nov 2019)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Comments on ‘Continuous In Situ Measurement of Dissolved Methane in Lake Kivu Using a Membrane Inlet Laser Spectrometer’ by Grilli et al., GI-2019-29', Anonymous Referee #1, 17 Dec 2019
- AC1: 'Reply to RC#1', Roberto Grilli, 14 Jan 2020
RC2: 'reviewer comments', Anonymous Referee #2, 25 Dec 2019
- AC2: 'Reply to RC#2', Roberto Grilli, 14 Jan 2020

Peer-review completion

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

AR by Anna Mirena Feist-Polner on behalf of the Authors (20 Jan 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (20 Jan 2020) by Flavia Tauro

RR by Anonymous Reviewer #1 (06 Feb 2020)

RR by Anonymous Reviewer #2 (17 Feb 2020)

Suggestions for revision or reasons for rejection

The manuscript has improved by the revision, the necessary context is now included, the new structure is in somewhat better shape, and the technical details are presented in sufficient depths. Still, I find that the authors didn’t show a satisfactory effort in condensing the manuscript, which is therefore quite long, presents a range of unrelated information bits, and both aspects make it difficult to read. For a manuscript like this, lacking a testable biogeochemical hypothesis, to warrant publication it is necessary that all elements are clearly structured and the (necessary) information is complete and easily accessible. In my opinion, the combination of results and discussion section is not ideal, and I cannot recommend the manuscript in its present form for publication if the scale is clarity. If Geoscientific Instrumentation .. is happy with the presented kind of report it would be acceptable, though, after some specific points were addressed.
Specific points.
L26-30 Usually such statements would be accompanied by one or more references.
L33 replace “incomes” with “fluxes”
L42 There is of course also “life” in the anoxic zone (bacteria, archaea,…)
L69-70 omit this sentence
L287 While there is some relation between water depth and methane concentration, the critical point I wanted the authors to make is the horizontal distribution, which is dependent on the distance from the LITTORAL sediments. The title of the reference I was suggesting says it all “No Longer a Paradox: The Interaction Between Physical Transport and Biological Processes Explains the Spatial Distribution of Surface Water Methane Within and Across Lakes”, del Sontro 2018. Revise accordingly.
If the journal’s copy editing isn’t very strong, the manuscript will require thorough checking by a native speaker. Some examples
L46 constitutes
L49 lake not Lake
L55 hypothesis excluded? temporal variability slower?
L97 a word seems missing
L279 indicate neither…nor
L297 “for a correctly determine”

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ED: Reconsider after major revisions (20 Feb 2020) by Flavia Tauro

AR by Svenja Lange on behalf of the Authors (17 Mar 2020) Author's response Manuscript

ED: Publish as is (17 Mar 2020) by Flavia Tauro

Short summary

We report the results from the deployment of a newly developed in situ sensor for dissolved gas measurements. Its adaptation to high gas concentrations and dissolved gas pressures was proven. The campaign leads to a first continuous profile of methane on the first 150 m and allowed us to compare the data with previous measurements. The fast response of the instrument makes this technique a good candidate for regular monitoring of those type of lakes, for anticipating disastrous gas eruptions.