ORIGINAL RESEARCH article
Front. Clim.
Sec. Carbon Dioxide Removal
This article is part of the Research TopicEnvironmental Engineering Perspectives on Ocean-Based Carbon Dioxide RemovalView all 9 articles
Ocean alkalinity enhancement in an estuary
Provisionally accepted
- 1Southern California Coastal Water Research Project, Costa Mesa, United States
- 2University of California Los Angeles, Los Angeles, United States
- 3[C]Worthy, Boulder, United States
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A high-resolution numerical ocean model is used to assess ocean alkalinity enhancement (OAE) in the San Francisco Bay (SFB) estuary. A novel approach using a tracer to mimic alkalinity release and subsequent CO2 ingassing is introduced. The model is run for 6 days and accurately reproduces observational data of currents, density, and tides. Estuarine dynamics induce mixing, advect buoyant water out of the Bay, and bring the alkalinity addition from the depths of the estuary to the surface of the open ocean. Over 80% of the tracer stays in the top 15 m during the entirety of the simulation. The estimated air-sea equilibration rate of the added alkalinity is approximately 2% per day. Alkalinity that is exported to the open ocean plays a disproportionately large role in enhancing the CO2 ingassing rate compared to alkalinity in the estuary. This rate is relatively fast compared to open-ocean OAE studies due to the San Francisco Bay buoyant plume that confines the released alkalinity to the surface mixed layer. Estuaries offer many beneficial features for OAE releases, although further studies are needed to quantify biogeochemical and ecosystem impacts of such releases.
Keywords: ocean alkalinity enhancement, marine carbon dioxide removal, Estuarine dynamics, Ocean modeling, San Francisco Bay, Wastewater discharge
Received: 14 Jul 2025; Accepted: 24 Nov 2025.
Copyright: © 2025 Ho, Molemaker, Damien, Long, Bianchi and Mcwilliams. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Minna Ho
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