Preprints
https://doi.org/10.5194/egusphere-2024-1706
https://doi.org/10.5194/egusphere-2024-1706
10 Jun 2024
 | 10 Jun 2024

Dissolved Mn(III) is a key redox intermediate in sediments of a seasonally euxinic coastal basin

Robin Klomp, Olga M. Żygadłowska, Mike S. M. Jetten, Véronique E. Oldham, Niels A. G. M. van Helmond, Caroline P. Slomp, and Wytze K. Lenstra

Abstract. Manganese (Mn) is an essential micronutrient and key redox intermediate in marine systems. The role of organically complexed dissolved Mn(III) (dMn(III)-L) as an electron acceptor and donor in marine environments is still incompletely understood. Here, we use geochemical depth profiles and a reactive transport model to reconstruct the seasonality in sedimentary dMn(III)-L dynamics and benthic Mn release in a eutrophic, seasonally euxinic coastal basin (Lake Grevelingen, the Netherlands). We find that dMn(III)-L is a major component of the dissolved Mn pool throughout the year. Our model indicates that, when O2 is present in the bottom water, there are three major sources of pore water dMn(III)-L, namely reduction of Mn oxides coupled to the oxidation of Fe(II), reduction of Mn oxides coupled to organic matter degradation and oxidation of Mn(II) with O2. Removal of pore water dMn(III)-L primarily takes place through reduction by dissolved Fe(II). When bottom waters are euxinic in summer, rates of sedimentary Mn cycling decrease strongly, because of a lower supply of Mn oxides. The dMn(III)-L transformations in summer mostly involve reactions with Fe(II) and organic matter. Benthic release of Mn mainly occurs as dMn(III)-L when bottom waters are oxic, as Mn(II) upon initial bottom water euxinia and as both Mn(II) and dMn(III)-L when the euxinia becomes persistent. Our findings highlight strong interactions between the sedimentary Fe and Mn cycles. Dissolved Mn(III)-L is a relatively stable and mobile Mn species, when compared to Mn(II), and is therefore more easily transported laterally throughout the coastal zone and possibly also to open marine waters.

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Journal article(s) based on this preprint

11 Feb 2025
Dissolved Mn(III) is a key redox intermediate in sediments of a seasonally euxinic coastal basin
Robin Klomp, Olga M. Żygadłowska, Mike S. M. Jetten, Véronique E. Oldham, Niels A. G. M. van Helmond, Caroline P. Slomp, and Wytze K. Lenstra
Biogeosciences, 22, 751–765, https://doi.org/10.5194/bg-22-751-2025,https://doi.org/10.5194/bg-22-751-2025, 2025
Short summary
Robin Klomp, Olga M. Żygadłowska, Mike S. M. Jetten, Véronique E. Oldham, Niels A. G. M. van Helmond, Caroline P. Slomp, and Wytze K. Lenstra

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1706', Anonymous Referee #1, 02 Aug 2024
    • AC1: 'Reply on RC1', Robin Klomp, 02 Oct 2024
  • RC2: 'Comment on egusphere-2024-1706', Aubin Thibault de chanvalon, 30 Aug 2024
    • AC2: 'Reply on RC2', Robin Klomp, 02 Oct 2024

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1706', Anonymous Referee #1, 02 Aug 2024
    • AC1: 'Reply on RC1', Robin Klomp, 02 Oct 2024
  • RC2: 'Comment on egusphere-2024-1706', Aubin Thibault de chanvalon, 30 Aug 2024
    • AC2: 'Reply on RC2', Robin Klomp, 02 Oct 2024

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Reconsider after major revisions (03 Oct 2024) by Sebastian Naeher
AR by Robin Klomp on behalf of the Authors (06 Nov 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (20 Nov 2024) by Sebastian Naeher
RR by Aubin Thibault de chanvalon (22 Nov 2024)
RR by Anonymous Referee #1 (07 Dec 2024)
ED: Publish as is (17 Dec 2024) by Sebastian Naeher
AR by Robin Klomp on behalf of the Authors (17 Dec 2024)  Manuscript 

Journal article(s) based on this preprint

11 Feb 2025
Dissolved Mn(III) is a key redox intermediate in sediments of a seasonally euxinic coastal basin
Robin Klomp, Olga M. Żygadłowska, Mike S. M. Jetten, Véronique E. Oldham, Niels A. G. M. van Helmond, Caroline P. Slomp, and Wytze K. Lenstra
Biogeosciences, 22, 751–765, https://doi.org/10.5194/bg-22-751-2025,https://doi.org/10.5194/bg-22-751-2025, 2025
Short summary
Robin Klomp, Olga M. Żygadłowska, Mike S. M. Jetten, Véronique E. Oldham, Niels A. G. M. van Helmond, Caroline P. Slomp, and Wytze K. Lenstra
Robin Klomp, Olga M. Żygadłowska, Mike S. M. Jetten, Véronique E. Oldham, Niels A. G. M. van Helmond, Caroline P. Slomp, and Wytze K. Lenstra

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Short summary
In marine sediments, dissolved Mn is present as either Mn(III) or Mn(II). We apply a reactive transport model to geochemical data for a seasonally anoxic and sulfidic coastal basin to determine the pathways of formation and removal of dissolved Mn(III) in the sediment. We demonstrate a critical role for reactions with Fe(II) and show evidence for substantial benthic release of dissolved Mn(III). Given the mobility of Mn(III), these findings have important implications for marine Mn cycling.
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