Dear Dr Schiedung,

Thank you for your detailed responses to the reviewer reports, in which you address all points raised in good detail. I would like to invite you to submit your manuscript with revisions as outlined in the responses.

I look forward to receiving the revised manuscript.

With best wishes,
Jens-Arne Subke

Dear Dr Abiven,

Many thanks for revising the manuscript, which I think has improved following the input of both referees. I have two remaining significant points that I would like you to address before I make a final decision regarding acceptance.

Line 33: I share referee 2’s concern regarding the very general statement about PyC residence times of being “on the order of 10,000 years”. Whilst this is within the range of measured residence times, the actual mean turnover of the PyC pool in terrestrial ecosystems is lower. Coppola et al refer to ages of “up to 17,000 years”, while Masiello & Druffel present data from specific deep sea sediments, and even there residence times are above 10,000 years only at one site. Your statement here needs qualifying as the long residence time suggests a mean value that is not correct for the majority of conditions. You later illustrate this in lines 49/50, so I’m not sure why this very general (and in its brevity misleading) statement is provided here.

A further issue that needs to be addressed is the very high rate of percolation in your experiment. The initial flush is equivalent of 1000 l per m2, or 1000 mm of precipitation, significantly more than annual rainfall at both your sites. The total amount of flow through your columns (18,000 l m-2) is equivalent of 25 years of precipitation, which you applied over only 5 days. Please address this issue in the discussion. Even if the lab set-up can’t simulate natural field conditions, I think that the choice of a magnified flow regime on this scale has to be justified, and the impact of PyC transport under more natural conditions discussed.


I also have a short list of relatively minor edits, and hope that you are happy to include these:

Line 48: Please delete “to” before “one”.

Line 50: “condensed”

Line 54: put comma after brackets and delete “and”

Line 60: comma after “phase”

Line 71: “affected” rather than “effected”.

Line 317: I think you refer to “general conclusions” here, rather than “general assumptions”. Please revise.

Table captions (both T1 and T2): please delete “the used”.

Table 2: Please round d13C values to whole numbers (i.e. 4 significant figures); error terms with one decimal place are ok.

Best wishes,
Jens-Arne Subke

Dear Dr Abiven and co-authors,

Many thanks for the quick response. I'm satisfied with your edits and am happy to accept the manuscript for publication.

Best wishes,
Jens-Arne Subke