Ocean alkalinity enhancement reduces silica ballasting during export due to amplified dissolution

Suessle, Philipp; Schulz, Kai Georg; Barcelos e Ramos, Joana; Sievers, Nico Manuel; Schneider, Julieta; Tammen, Juliane Katharina; Kittu, Leila; Marín-Samper, Laura; Boersma, Maarten; Riebesell, Ulf

doi:10.5194/bg-23-4691-2026

Articles | Volume 23, issue 13

https://doi.org/10.5194/bg-23-4691-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-23-4691-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 23, issue 13

Research article

| Highlight paper

|

08 Jul 2026

Research article | Highlight paper |

| 08 Jul 2026

Ocean alkalinity enhancement reduces silica ballasting during export due to amplified dissolution

Philipp Suessle, Kai Georg Schulz, Joana Barcelos e Ramos, Nico Manuel Sievers, Julieta Schneider, Juliane Katharina Tammen, Leila Kittu, Laura Marín-Samper, Maarten Boersma, and Ulf Riebesell

Supplement

https://doi.org/10.5194/bg-23-4691-2026-supplement

Data sets

KOSMOS 2023 Helgoland mesocosm study on ocean alkalinity enhancement: sediment trap particle flux data and water column biogeochemistry P. Suessle et al. https://doi.org/10.1594/PANGAEA.992023

KOSMOS 2023 Helgoland mesocosm study on ocean alkalinity enhancement: dissolved inorganic nutrients, chlorophyll a and suspended particulate organic matter. J. K. Tammen et al. https://doi.org/10.1594/PANGAEA.987501

Carbonate chemistry speciation of the 2023 KOSMOS Helgoland experiment on the effects of ocean alkalinity enhancement on pelagic foodwebs K. G. Schulz et al. https://doi.org/10.1594/PANGAEA.986507

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Editorial statement

This study demonstrated, through an ocean alkalinity enhancement (OAE) experiment using mesocosms, that higher pH levels can reduce the ratio of biogenic silica to particulate organic carbon in sinking particles by promoting the dissolution of diatom-derived silica in seawater. Higher pH conditions might also cause organic carbon produced by diatoms to be remineralized at shallower depths, thereby reducing its ocean residence time and weakening the biological carbon pump for sequestering atmospheric carbon dioxide. This study also provides valuable insights into the linkage between OAE and biogeochemical processes in the ocean.