Decision on BG 2018-51

Dear Authors,

After reading the very comprehensive and detailed comments by the two referees, as well as those from Dr Lee, it appears that your MS will need important revisions and probably a second round of review before it can be considered for final publication in BG. These three scientists well specialized in the field of your MS have raised very important points that must be carefully addressed in your revised MS. In particular, methodological aspects of carbon fluxes calculation deserve a detailed attention. I was in general satisfied with your answers to most of theses comments, and I strongly recommend you deeply re-work and re-organize your MS in consequence. I will be happy to read soon a revised version of your paper.

With best Regards
Gwenaël Abril, Biogeosciences Associate Editor

Dear authors
Following the recommendations of the two referees, I am pleased to accept your paper for publication in BG after some minor revisions. Please incorporate in a revised MS the corrections suggested by the two reviewers.
Thank you for submitting your work to Biogeosciences
Best regards
Gwenaël Abril

Dear authors
thanks for this revised version. This makes your MS an important contribution to BG. Before sending your manuscript for publication, please address this final comment:

« Assuming the water surface area remained constant (i.e., no significant seasonal fluctuations), the spring and autumn CO2 effluxes were summed to 246 million mol and the summer CO2 efflux was -208 million mol (Table 1). These added up to an annual net CO2 efflux of 38 million mol (or 0.05×1010 g C) with great uncertainties due largely to the spatial variation between the sandy and loess subcatchment reservoirs in spring (Table 1). When added with the river efflux estimate, the catchment total CO2 efflux was (3.7±0.6)×1010 g C in the year 2015."


In accordance with Dr Hemingway comments, insert here the idea that statistically, such small residual flux calculated as the difference between two large numbers with great uncertainties is probably not different from zero. The reservoir annual CO2 flux is closed to balanced and accounts for less than x% of total CO2 outgassing, mostly by rivers.


Thanks for submitting your work to BG
with best regards,

Gwenaël Abril