Dear authors,

I have now gratefully received two detailed reviews of your ms. One is suggesting rejection and one is suggesting major revisions of the current ms.
My assessment is that your ms does provide new information from an understudied region and I therefore invite you to submit a thoroughly revised ms and provide a detailed point-by-point response to each reviewer comment where you clearly show what changes are made or provide scientific arguments why some reviewer suggestions are not followed.

I encourage to avoid any type of colloquial language and disrespect of the reviewer's comments, which I sense in your initial responses.

I ask you to first reproduce each full review comment followed by your detailed response.

Additionally, I ask you to address the following points:
1. How your pore-water profiles are effective in ruling out bubble-mediated methane transport.
2. Be more precise about your geographical coverage visavi earlier work. Avoid "East Siberian Margin" and instead describe your study area as something like the slope and rise sedments off the Chuckchi and East Siberian Sea. When refering to earlier work on the shelf system, describe that as Laptev and East Siberian Sea shelves. These two systems are very different and should not be lumped together.
3. I agree with both reviewers that your paper can be substantially reduced in length (by up to 1/3-1/2).

I have now studied your revised ms and author responses, in light of the two original set of reviews and my own initial recommendations.

I recognize your efforts in revising this ms due to its length (original submission was 99 pages, the revised main ms is 77 pages + supplementary material), and the extensive reviews. I already in its current state see many improvements.

After a substantial effort in going through the material, it has become clear that a final decision/action on your ms is not possible based on the material that you have provided. The major problem is that claims in your 24-page response letter of changes to the main ms text cannot be readily verified as you fail to provide information of where in the revised ms to find the specific information. It is not reasonable to expect a handling editor or re-reviewer to sift through a 77-page ms to find each claimed change.
I therefore return the ms to you and ask that you revise the response letter with clear reference to where in the revised ms the relevant new /revised information can be found (page and line number). It would also facilitate the handling if you next to the clean ms would also provide a ms file where revised/new text is highlighted. Please then also describe clearly in the response letter what the changes are encompassing.

In preparing these new files, I ask you to consider the following points for the revisions:
1. The geographical scope of the study
This is a reminder from the last round. The title still reads “north of Siberia”. The margin north of Siberia spans roughly between 67E-180E (Kara Sea, Laptev Sea and East Siberian Sea). Your cores are roughly from 140E-180E, which is the East Siberian Sea.

2. The inference of dissolved methane concentrations
Based on reviewer comments and my own assessment, I also ask you to revise both title and text throughout the ms to reflect that (a) porewater methane is inferred (not directly measured); and (b) the inferred methane refers to dissolved methane. The latter point is particularly salient as there are ample studies demonstrating bubble-mediated transport of methane from Arctic sediments (i.e., ebullition). As stated in a recent review (James et al., 2016, L&O) “methane gas can bypass microbially mediated oxidation reactions because microbes can only access dissolved methane”. I ask you to revise your ms to clearly recognize this aspect.
Taking points 1 and 2 together, I suggest an appropriate title for the revised ms would be: “Pore water geochemistry along the continental slope north of the East Siberian Sea: Inference of low methane concentrations”

I look forward to consider your revised ms.