Barium stable isotopes as a fingerprint of biological cycling in the Amazon River basin

Charbonnier, Quentin; Bouchez, Julien; Gaillardet, Jérôme; Gayer, Éric

doi:https://doi.org/10.5194/bg-17-5989-2020

Articles | Volume 17, issue 23

https://doi.org/10.5194/bg-17-5989-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-17-5989-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 17, issue 23

Research article

|

03 Dec 2020

Research article |

| 03 Dec 2020

Barium stable isotopes as a fingerprint of biological cycling in the Amazon River basin

Quentin Charbonnier, Julien Bouchez, Jérôme Gaillardet, and Éric Gayer

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Final revised paper (published on 03 Dec 2020)
Supplement to the final revised paper
Preprint (discussion started on 21 Apr 2020)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review', Anonymous Referee #1, 12 May 2020
- AC2: 'Response to Anonymous Referee #1', Quentin Charbonnier, 03 Jul 2020
RC2: 'Review Charbonnier et al.', Anonymous Referee #2, 16 Jun 2020
- AC1: 'Response to Anonymous Referee #2', Quentin Charbonnier, 03 Jul 2020
- AC3: 'Final response to all referee comments', Quentin Charbonnier, 03 Jul 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (06 Jul 2020) by Edzo Veldkamp

AR by Quentin Charbonnier on behalf of the Authors (30 Jul 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (28 Aug 2020) by Edzo Veldkamp

RR by David Uhlig (16 Sep 2020)

Suggestions for revision or reasons for rejection

Dear Edzo Veldkamp,

I thoroughly reviewed an earlier version of this manuscript. Given that the authors convincingly addressed all main concerns and almost all minor comments raised by both reviewers, reviewing this manuscript again was a real pleasure. Also, the English is very good now. In cases in which the authors did not follow the reviewer suggestions they provide convincing arguments for their opposite view. All in all, the revisions helped to improve the previous and anyhow very good manuscript. I suggest publication of this manuscript after addressing the only few and very minor comments below.

Cheers, David Uhlig

Minor comments:

L.1 better should read “…element cycles on the Earth surface …”
L.4 please add the abbreviation (Ba) next to word barium
L.25 Typo: the multiply symbol reads like a comma and the citation style in the abstract should be checked for journal style
L.49 Typo: long-term
L.70 Please add the half-life time
L.114 Typo: remove spacing before the comma
L.121 “consist of” instead of “consist in”?
L.145 plural for “concentration” to be consistent with e.g. L. 149
L.176 “total procedural blank” instead of “blank procedure” as the latter reads like a method
L.362 Typo: “mm/yr” to be consistent with e.g. t/km2/yr
L.398 replace “strong” by “high”?
L. 419 Provided that F^Ba_sec is also increasing with D it reads misleading to emphasize the biological uptake flux is this sentence only. This sentence needs a slight rewording
L.624 I do not understand the wording “after important deforestation” and suggest the deletion of the word “important”.
L.649 To my understanding it should read NPP (net primary productivity) in equation 17 because according to Chapin et al. (2012) (page 161, eq. 6.2) NPP = GPP – R_plant where R is respiration. To my understanding this is exactly what the authors mean by NEE = GPP-TER in the manuscript. Thus, there is no need to introduce the “NEE”.
L.651 Typo: “values … differ” not differs
L.671 Typo: should read “behavior”
L.674 To me it reads that the recycling strategy causes less uptake of “new” nutrients. But actually, the lack of substantial litter export in the described scenario does not require “new” nutrient uptake by plants. Thus, in my opinion the wording “minimizes” (which I understand as causing a strategy) is not correctly used here and needs rewording.
L.702 Please add in brackets “R(sil+bio)/sil” behind “weathering fluxes”
L.718 Typo: should read “nutrient cycling” and a point is missing at the end of the sentence.
L.761 Provided that isotope fractionation factors (in this manuscript the capital delta) are used I found it quite confusing to read the alpha as a symbol for proportions in appendix A and B and would encourage the authors to use an alternative symbol, e.g. “f” for a relative fraction.
L.775 Typo: should read “… influence of …”
L.789 Typo should read “as shown in …”
L.840 Typo: should read “… in detail …”
L.871 Typo: please add “eq” to (3)
L.879 Typo: should read “… which is a …”
L.881 Typo: should read “dimensional value …”. Also, this sentence is difficult to read. I suggest ending the sentence after f^Ba_bio and begin a new sentence.

Supplement:
L.6 should read “… of the river dissolved load”?
L.32 Typo: should read “… stacked to produce one …”
L.35 should better read “… to reconstruct the …”
L.40 Typo: should read “… to Li”
L.46 preposition missing, should better read “river mass budget equations for the …”
L.52 better should read “… but applied it to Li”

Reference used in this review
Chapin SF, Matson PA, Vitousek PM (2012) Principles of terrestrial ecosystem ecology, Second. Springer New York Dordrecht Heidelberg London

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ED: Publish subject to minor revisions (review by editor) (21 Sep 2020) by Edzo Veldkamp

AR by Quentin Charbonnier on behalf of the Authors (04 Oct 2020) Author's response Manuscript

ED: Publish as is (14 Oct 2020) by Edzo Veldkamp

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Short summary

The abundance and isotope composition of the trace metal barium (Ba) allows us to track and quantify nutrient cycling throughout the Amazon Basin. In particular, we show that the Ba biological fingerprint evolves from that of a strong net nutrient uptake in the mountainous area of the Andes towards efficient nutrient recycling on the plains of the Lower Amazon. Our study highlights the fact that the geochemical signature of rock-derived nutrients transported by the Amazon is scarred by life.