ORIGINAL RESEARCH article
Front. Clim.
Sec. Carbon Dioxide Removal
Volume 7 - 2025 | doi: 10.3389/fclim.2025.1652680
This article is part of the Research TopicEnvironmental Engineering Perspectives on Ocean-Based Carbon Dioxide RemovalView all 5 articles
Determining the net influence of biological processes on aqueous hydroxide-based ocean alkalinity enhancement: a mesocosm approach
Provisionally accepted
- 1Ecology and Evolution, Stony Brook University, Stony Brook, United States
- 2Chemistry, Stony Brook University, Stony Brook, United States
- 3Earth and Planetary Sciences, Yale, Yale, United States
- 4Ebb Carbon Inc, South San Francisco, United States
- 5Electrical Engineering, Stony Brook University, Stony Brook, United States
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Ocean alkalinity enhancement (OAE) presents a promising means to leverage the ocean carbon sink to mitigate the effects of anthropogenic climate change. We report on a series of mesocosm experiments simulating electrodialysis-based OAE through the addition of aqueous sodium hydroxide to seawater in large tanks (∼ 6000 L) and small aquaria (∼ 10 L) at Flax Pond Marine Laboratory, NY. In previous studies, the confounding effects of biological processes were controlled by imposing a sterilization treatment to seawater throughout each experiment. Here, we take the first steps in characterizing the influence of biological processes on OAE-based CO2 uptake through comparisons between sterilized and unsterilized mesocosms and aquaria. We combine our results with those of similar Flax Pond mesocosm experiments and develop a model to identify the most influential variables for determining the rate and magnitude of CO2 uptake. We found that the rate of CO2 uptake varies with changes in initial carbonate chemistry, the amount of alkalinity added, whether the mesocosm was sterilized, and the season in which the seawater was collected. Our model suggests that sterilized tanks did not differ in the amount of CO2 sequestered, but experienced a slower rate of equilibration relative to unsterilized tanks. These results indicate that laboratory mesocosm experiments could reasonably represent CO2 uptake in the field even with the complication of biological processes over the timeline of air-sea CO2 equilibration. This finding is valuable in supporting the measurement, reporting and verification of OAE, which must rely on a combination of laboratory data, near-field measurements, and modeling exercises.
Keywords: ocean alkalinity enhancement, mesocosms, NaOH, Carbon dioxide removal, MCDR
Received: 24 Jun 2025; Accepted: 27 Aug 2025.
Copyright: © 2025 Fucich, Lynch, Shaw, Eisaman and Ringham. 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: Derek Fucich, Ecology and Evolution, Stony Brook University, Stony Brook, United States
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