Reviewer 1 mainly concerned with the details of expt set and methods of DNA-SIP (the 2nd reviewer also has been puzzled by this), also he encorveraged the authors link their data with present study.

Reviewer 2 raised his concerns about several issures. Like, to clarify the pathway in the introduction. It was added by the authors, but at the first glance it looks like it is overloaded with too many words, thus please reduce the length of this paragraph, or separate to two sections foucus on 1) the pathway and 2) environmental effects regulating this process.

Reviewer 1 also raised his concerns about the writing (awful in logic, result description and interpretation). This is also my concerns. For example, the Introduction was very poorly written, like, line58, what is the relevant of “sequestered carbon is also present in the form of inorganic carbon” with this work? Line66 too absolute that “microbes 66 may be the main source of organic carbon in mine tailings”……

I found this manuscript difficult to follow, sometimes. It is unorganized and the general focus changes from one section to the other. This needs to be largely improved before consideration of publication in Biogeosciences.

In the end, the response to reviewers’ comments are not clear, please give the dot point and order clear, reduce the irrelevant sentences to answer what has been raised, in the next reply.

There are still some concerns raised by the second reviewer. Also, i would expect the authours improve the logic through the whole ms, English native speaker is also required to improve the writing.

Dear Dr Li,

Both reviewers are satisfied. there are, however, still some minors needs to be revised, before consideration of being acceptance.

Line 14: Add % after 1.76±0.06;
Line 12: Repetitive: 13C-labeled CO2 was evaluated using 13C isotope;
Line 18: Sulfobacillus (8.04%) and Novosphingobium(8.60%) dominating in which site? And changes from xxx?
Line 175: you can not say “duringthe pyrite oxidation process”, as the samples were collected at one time point.
Fig. 1b 13C should be 13C

In the end, I still doubt TOC can be increased as 0.20±0.11mg/g in just 14 days. Please give some support (lieteratures, proposed mechanisms, etc) in the section of “Discussion”.

Kind regards
Yu

This ms is largely improved now and most of the questions raised are answered. It can be considered as being accepted.