Dear Authors,

Thank you for providing detailed responses to the comments and suggestions offered by two reviewers.

While the two reviewers recognized the value and extensiveness of the reported data, they also provided many suggestions for you to improve the presentation and interpretation of data. Your responses seem to have adequately dealt with most of the raised concerns. However, the manuscript would require a substantial revision to address all the raised issues and technical corrections. Therefore, I have to recommend ‘reconsider after major revisions’.

I agree with the second reviewer that you need to strengthen the discussion of controlling mechanisms for the hydrologic export of DOC. In particular, I wondered if your statement “stream water level only poorly contributed to explaining the variability of DOC increases during flood events 25 (Table 3 and Fig.5 a)” would be valid, given the significant p level and, as you mentioned, the “non-linear flow-DOC concentration relationship”. The non-linear hysteresis relationship between discharge and DOC concentrations might lower r square values, but you cannot say that discharge relationships do not play a role in hydrologic DOC export. Please refer to papers on this hysteresis discharge relationship and check out how your data conform to or depart from the reported patterns. An upland case based on high-resolution sensor data: Jeong et al.: Differential storm responses of dissolved and particulate organic carbon in a mountainous headwater stream, investigated by high-frequency, in situ optical measurements, J. Geophys. Res.-Biogeosci., 117, G03013, doi:10.1029/2012JG001999, 2012.

I would like to ask you to make all the changes easily identifiable in a marked-up manuscript based on your point-by-point responses to the comments offered by the two reviewers and myself. If possible, please specify the line numbers of the revised parts in your responses to the reviewer comments.

Sincerely,

Ji-Hyung Park
Associate Editor, Biogeosciences

Dear Authors,

Thank you for thoroughly revising your manuscript. The two reviewers had provided a substantial number of detailed technical comments during the first round of review, so I had to ask them to examine whether your revision had adequately addressed all the reviewer comments and suggestions.

Both reviewers have provided positive evaluations and I agree to their opinion that you had put tremendous efforts to improve the manuscript. However, the reviewers raised a few points that remain to be clarified further before the final acceptance. Please clarify these points (provided in the attached reviewer reports) in your final revision.

I would like to ask you to make all the changes easily identifiable in a marked-up manuscript based on your point-by-point responses to the comments offered by the two reviewers. If possible, please specify the line numbers of the revised parts in your responses to the reviewer comments.

Sincerely,

Ji-Hyung Park
Associate Editor, Biogeosciences



The authors have now clarified most of the issues raised by me. The explanation and approach are plausible. However, the second reviewer raised many valuable points. Although I have dealt with sensor data, I am not an expert on peatland ecosystem per se. Thus, I would value the second reviewer’s opinion on the revised discussion.

Minor corrections are still need to be made.
p. 5, line 8: what do you mean by “the first millimeters?”
p. 5, line 18: I guess that ION 915 and ION 96.4 are reference materials. So, what was the range of recovery for the ION 915 and ION 96.4? In other words, what was the range of measured [DOC] for ION 915 and ION 96.4?
The concentration range of the samples is higher than concentration of ION 915 and ION 96.4. Did you dilute the samples?
Also, you mentioned that analytical uncertainty was estimated at 0.1 mg/L. Is “(+/- 0.41 mg/L)” reported value? What do you mean by the two decimal places?
p. 8, line 20: “pH” is missing.
Table A2: use of “,”? Two decimal places in some numbers need to be cut to one decimal place.



I am happy to see that the authors thoroughly responded to the comments. I acknowledge the effort and see that the manuscript improved. However, there are a few points that have not been answered and I would like to see some short statement addressing these points in the manuscript before publishing:
1. “Furthermore, I am very concerned by the representativeness of the bog site especially when it is compared to a fen as exemplary system (Scientific objective no 3, P3 line 3). There are several factors differing between the sites, besides just fen/bog: climate (e.g. 4 month snow covered – no snow hardly sub-zero temperatures), anthropogenic influence (burned – unburned). Additionally, mentioning agro-pastoral practices: does this mean the bog is used for grazing? Could these systems thus be considered as representative? Besides this, from the location maps I draw conclusions that apparently the monitoring spot also receives water which is not originating from the peatlands itself. Is there any data about it? Do you have any idea about the whole catchment and how much water contributes to the discharge that is not from the peatlands? This is one of my major concerns, as I feel like the authors completely disregard this. If the concentration pattern are driven by discharge from other areas, the discussion of concentration pattern and water levels at the monitoring spot and within the peatland would be difficult.”
You haven’t responded at all to these points. I at least would like you to clarify the role of additional water sources in your concentration pattern. I am in line with you that most DOC is originating from the bog, but this does not mean that there is no other main water source with a different hydrograph dynamic/respond to rain events and dry periods. To evaluate concentrations is something different than fluxes. This would bias your concentration pattern. I read in the respond to reviewer #1 that the peatland area is just covering 3 or 6 % of the catchment area, respectively. I want to read this in the site description and an explanation that you still see only a peatland signal there (similar to statement P4 L7) or a limiting statement also in the discussion. I don’t like that this is completely disregarded.
2. I am glad that your discussion about hydrologic pathways and non-linear responses largely improved. I actually miss the reference of Birkel et al. 2017 (that you cited in Rosset et al. 2019). As this publication also modelled peatland water level and stream DOC concentrations and it seems that their findings are in line with your study. The outcome of that study might be worth discussed in view of your model results.
I looked at your DOC/Q plots with great interest and I just want to note that I am impressed by this data set and that I am convinced that there is so much more information in it, which would be also worth to be evaluated (hysteresis loops, DOC pool dilution/exhaustion effects, different responses by different preconditions) and would greatly improve understanding of DOC export from peatlands. Maybe you can consider this for a future (meta)study.

Dear Authors,

Thank you for your second revision that carefully reflected all reviewer comments and suggestions. I am pleased to let you know that your manuscript can be published after some technical corrections. Please carefully correct the following editorial errors:

- Compound adjectives: Please use hyphens for many compound adjectives in the title and throughout the manuscript (e.g., “event-scale” DOC dynamics, “high-frequency” monitoring)
- Section 5.3: Please separate this long section into 2-3 paragraphs.
- Reference Kalbitz et al. (capital letters in the title) needs to be corrected.
- Fig. A1, Table A1, Fig. A2: Please reorganize these figures and table as a separate Supplementary Information (refer to Author guides). Decimal commas in Table A1 need to be corrected.

Sincerely,

Ji-Hyung Park
Associate Editor, Biogeosciences