Dear Karin Eusterhues and Co-workers,

after intensely reading through your revision and answers to reviewers I found your manuscript publishable after just some very minor technical correction. Please find the details below.

Best wishes
Tina Treude
BG Editor

Minor technical points:
L23: Ferrihydrite (not ferrihydrite) at the beginning of the sentence.
L29: Please provide subject for "this", e.g., "this difference".
L54: Please provide a subject for "their", e.g., "the aggregation behavior of coprecipitates".
L99: are = were
L105: I suggest a short introduction of "Oa" and "Oe". Part of our readers are working in marine research (like me).
L124: C/Fe ratio
L127: C/Fe ratio
L153: "1.6, 1.6, and 1.1" Correct (2 x 1.6)?
L248-250: Start sentence with "We assume that the nitrate...."
L319 comparable = similar
L361-366: I have trouble understanding this sentence, probably because of its length. Please simplify.
L405: species-dependent
L407: by = through
L407-408: Write "Similar to Shimizu et al. (2013) our study shows..."
L452: is = was
L478: Start sentence with "In the present study mineral-bound...."
L485: Add or/and after "matter,"?
L517: "which protect their mineral-bound organic matter" sounds a bit anthropomorphized for Fe oxides. Refrase.
Table 1 caption: C/Fe ratios
Table 1/2 caption: refer to text for abbreviations
Figure 1: ppm of what? Unit of y-axis? Please explain abbreviation CPMAS NMR
Figure 2/4: refer to text for abbreviations
Figure 5B: Please explain in figure caption the meaning of the dashed circles
L814: is = was (2x)
L815:"...of the experiment in this sample (further details see text)...."
L822: "..., which is unreasonalbe (further details see text)."