Reviews and syntheses: The biogeochemical cycle of silicon in the modern ocean

Tréguer, Paul J.; Sutton, Jill N.; Brzezinski, Mark; Charette, Matthew A.; Devries, Timothy; Dutkiewicz, Stephanie; Ehlert, Claudia; Hawkings, Jon; Leynaert, Aude; Liu, Su Mei; Llopis Monferrer, Natalia; López-Acosta, María; Maldonado, Manuel; Rahman, Shaily; Ran, Lihua; Rouxel, Olivier

doi:https://doi.org/10.5194/bg-18-1269-2021

Articles | Volume 18, issue 4

https://doi.org/10.5194/bg-18-1269-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-18-1269-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 4

Reviews and syntheses

|

18 Feb 2021

Reviews and syntheses |

| 18 Feb 2021

Reviews and syntheses: The biogeochemical cycle of silicon in the modern ocean

Paul J. Tréguer, Jill N. Sutton, Mark Brzezinski, Matthew A. Charette, Timothy Devries, Stephanie Dutkiewicz, Claudia Ehlert, Jon Hawkings, Aude Leynaert, Su Mei Liu, Natalia Llopis Monferrer, María López-Acosta, Manuel Maldonado, Shaily Rahman, Lihua Ran, and Olivier Rouxel

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Final revised paper (published on 18 Feb 2021)
Supplement to the final revised paper
Preprint (discussion started on 03 Aug 2020)
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Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Silicon Biogeochemistry', Anonymous Referee #1, 13 Sep 2020
- AC1: 'Tréguer et al.'s manucript', Paul Tréguer, 16 Oct 2020
RC2: 'Review comment bg_2020_274', Anonymous Referee #2, 22 Sep 2020
- AC1: 'Tréguer et al.'s manucript', Paul Tréguer, 16 Oct 2020
- AC2: 'Tréguer et al.'s manuscript', Paul Tréguer, 16 Oct 2020

Peer-review completion

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

ED: Reconsider after major revisions (19 Oct 2020) by Emilio Marañón

AR by Paul Tréguer on behalf of the Authors (23 Nov 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (24 Nov 2020) by Emilio Marañón

RR by Anonymous Referee #1 (13 Dec 2020)

Suggestions for revision or reasons for rejection

The manuscript has been improved, is up to date in references and reads well. I think it will make a great contribution to the literature and give many scientists new things to work on regarding the global biogeochemical Si cycle.

However, I am still not satisfied with the discussion regarding a possible steady state for the modern ocean Si cycle. Their expression of L55 “possible steady state scenario” and L84 “a possible scenario for the Si cycle at steady state” muddles the meaning of the text. I would like to suggest a few modifications of the text to use their data for both input and output, and to make their point clearer.

L54 - L56 ”we address the steady state hypothesis of the Si cycle for past and modern oceans, and propose a possible steady state scenario for the global ocean (inputs = outputs = 15.6 Tmol-Si yr-1) and boundary exchange zone.”
Rewrite to
”we hypothesize that the modern ocean Si cycle is at approximately steady state with inputs = 14.8 (± 2.6) Tmol-Si yr-1 and outputs = 15.6 (± 2.4) Tmol-Si yr-1.”

L 84 - L85 ”and propose a possible steady state scenario for the modern ocean, with inputs balancing outputs at 15.6 Tmol yr-1 (Fig. 1).”
Rewrite to
and hypothesize that the modern ocean Si cycle is at approximately at steady state with inputs = 14.8 (± 2.6) Tmol-Si yr-1 approximately balancing outputs = 15.6 (± 2.4) Tmol-Si yr-1.” (Fig. 1).

L562 - L564 ”Fig. 1 shows a possible scenario for the Si cycle at steady state in the modern ocean, based on a balance of inputs and outputs at 15.6 Tmol-Si yr-1 , compatible with the geochemical and biological fluxes of Table 1.”
Rewrite to
”Fig. 1 supports our hypothesis that the modern ocean Si cycle is at steady state, based on a balance of inputs and outputs, compatible with the geochemical and biological fluxes of Table 1.”

L570 “Fig. 4 shows a possible steady-state scenario”
Rewrite to
“Fig. 4 shows a steady-state”

With these edits then the text in L565 - L569 should be deleted. Since the Total Input and Output fluxes are within the stand of error there is no need to say that the input flux should be increased. There are a lot of values not well constrained and to point out one estimate is not valid.

Small additional comments

L72 Rewrite ”N a bSi” to “N and bSi”

L72 Delete “that has been named “dark silica.” Many sponges occur in the photic zone and have algal symbionts including diatoms. Calling it “dark silica” confuses the issue.

L79 Delete “the reference value of”. A reference value is a known and correct measurement used for comparison.

L587 - L606 I am not enamored by the discussion of the Chinese Seas (5.3.1). As the authors discussed earlier in the manuscript the flux from GW is poorly constrained, yet it is a large term here. In addition, there is very good discussion (5.4.1) later on river inputs which are also significant in this area. You could pick many coastal zones and regional seas and point them out for important additional studies that are needed. I still think this section, as well as (5.3.2) on the NE Pacific dSi anomaly could easily be deleted and not effect the manuscript.

L730 Could use a concluding sentence here.

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RR by Anonymous Referee #2 (14 Dec 2020)

ED: Publish subject to minor revisions (review by editor) (15 Dec 2020) by Emilio Marañón

AR by Paul Tréguer on behalf of the Authors (18 Dec 2020) Author's response Author's tracked changes Manuscript

ED: Publish subject to technical corrections (23 Dec 2020) by Emilio Marañón

AR by Paul Tréguer on behalf of the Authors (04 Jan 2021) Author's response Manuscript

Short summary

Silicon is the second most abundant element of the Earth's crust. In this review, we show that silicon inputs and outputs, to and from the world ocean, are 57 % and 37 % higher, respectively, than previous estimates. These changes are significant, modifying factors such as the geochemical residence time of silicon, which is now about 8000 years and 2 times faster than previously assumed. We also update the total biogenic silica pelagic production and provide an estimate for sponge production.