Dear Dr. Moriarty:

Thank you for submitting this paper to Biogeosciences. Both referees provided a thorough, constructive assessment and in your rebuttal you indicate that you will address all major issues. I believe that a revised version is likely acceptable for publication in Biogeosciences and therefore invite you to submit/upload a revision version along the lines of your rebuttal.

With best regards, Jack Middelburg, Associate Editor

Dear Dr. Moriarty:

Thank you for submitting this nice and interesting paper to Biogeosciences. I have read the revised paper and your rebuttal and believe that your paper is almost ready for publication.
There are a few minor technical issues to be addressed, see below, before going into print.

- All through, if you use bottom-water or water-column as adjectives, please hyphen.
- P.5, title section 2.2. add space
- P.6, I presume it is Sherwood et al. and not Sherwood. Moreover, this paper has not yet been submitted.
- P. 21, l. 20: I presume it is Huettel and not Huettle.
- Same on p. 25
- P. 31: Sherwood et al. status?

Besides these minor technical issues, there is a potential problem, not identified by the referees, and perhaps I might have misunderstood it. In lines 5-21 of page 13, and related Table 6 and Fig. 6, you report that 60 to 85 % of oxygen consumption is due to nitrification. I have problems with these numbers, it suggests to me that a calculation error (or more likely unit conversion mess up from model code output to publication units) has been made. Why? This is the rationale. If we assume a 1:1 ratio for oxygen consumption to aerobic respiration and a C:N ratio of about 7, one would expect that nitrification consumes about 15% of the oxygen. The only way you can increase this fraction substantially is by supplying additional ammonium from elsewhere, i.e. ammonium without additional oxygen consumption due to carbon oxidation or re-oxidation of other reduced substances. ODU do not solve your problem based on my modelling experience in the past. Indeed I would expect a somewhat higher fraction following erosion because you can eat into the pore-water ammonium stock, but never these high numbers. Moreover, all data I am aware are consistent with the 10-20% range of oxygen consumption due to nitrification in marine sediments. Please check carefully, because this type of back-of-the-envelope calculation I just made a quite robust and usually right.

Thank you for submitting this paper to Biogeosciences,

Jack Middelburg, Associate Editor

Dear Dr. Moriarty:

Thank you for promptly making these corrections. I am therefore pleased to inform you that your paper is now accepted for publication.

With best regards,

Jack Middelburg, Associate Editor