October 23, 2016

Dear Dr. Hyun,
Thanks for providing responses to three Reviewers of your BG discussion paper (bg-2016-222). I would like to invite you to submit a revised version of the article based on your responses, and considering the following issues:

1) Reviewer 1: Question 4) Line 606: “The statement about the probable importance of bioturbation seems to be in contradiction with the well-defined utilization of the electron acceptors according to the order of decreasing energy yield for organic C oxidation that has been underscored in lines 412-417? Again, I suggest clarifying this point.”

Reviewer 1 asked clarification to the following: There is a clear biogeochemical zonation in these sediments (lines 412-417) and your response agreed with that, but still in line 606 it says “Thus, it is realistic that 
 bioturbation drives Mn cycling in the UB. ”. To me is contradictory with lines 412-417 as well, unless you meant something else. Please clarify that and proceed accordingly in the revised version.


2) Reviewer 1: Minor 4) Line 276: I suspect that the units (ml/g) are erroneous?

(Response): “It is presented in Thamdrup et al (2000). “

Something being published cannot be a proper response to a colleague reviewer. What are unit ml/g of?

3) Reviewer 2.” 40) L. 638: I still do not understand why the Ulleung Basin is a “biogeochemical hotspot”? Is it because organic matter mineralization is dominated by metal reduction? This is not clear at all and I would therefore suggest to better explain or to delete this.

(Response): It is not because organic carbon mineralization is dominated by metal reduciton. The reason that we stated the UB as a biogeochemical hot spot is that the overall organic carbon oxidation in the UB is higher than those measured in major up- welling system such as Benguela upwelling system and is even comparable to those reported at the continental slope of the Chilean upwelling system at a similar depth range of 1000 – 2500 m. Please see the line 640 – 662 in the revised manuscript. ”

Please demonstrate that Ulleung Basin is a “biogeochemical hotspot” showing numbers to compare in the revised version. I agree with Reviewer 2 (S Kasten) that there is no need of spending time/space highlighting this issue since uniqueness of your scientific contribution is what matters here.

4) Reviewer 3: 8). I suggest moving evidence in lines 526-527 to paragraph starting in line 498 to support your argument.

Looking forward to hearing from you
Sincerely yours

Silvio Pantoja
Associate Editor

7 January 2017
Review 2
Dear Dr. Hyun,

Thanks for your responses.

The comment below:
1) Reviewer 1: Question 4) Line 606: “The statement about the probable importance of bioturbation seems to be in contradiction with the well-defined utilization of the electron acceptors according to the order of decreasing energy yield for organic C oxidation that has been underscored in lines 412-417? Again, I suggest clarifying this point.”

Reviewer 1 asked clarification to the following: There is a clear biogeochemical zonation in these sediments (lines 412-417) and your response agreed with that, but still in line 606 it says “Thus, it is realistic that 
 bioturbation drives Mn cycling in the UB. ”. To me is contradictory with lines 412-417 as well, unless you meant something else. Please clarify that and proceed accordingly in the revised version.

Refers to this:
If there is zonation, then bioturbation is not high enough otherwise biochemical zonation would disappear (or masked). This is the contradiction raised by Reviewer 1, which is not clarified in your response since the statement “Thus, it is realistic that 
 bioturbation drives Mn cycling in the UB” is still there.

Please revise accordingly

Sincerely yours
Silvio Pantoja
Associate Editor