Schlagwort: ocean alkalinity enhancement

Peer-reviewed Publications

Zabihihesari et al. (2026): High frequency in situ total alkalinity measurement for monitoring ocean alkalinity enhancement field trials

Alireza Zabihihesari, Will Burt, Colin Sonnichsen, Shahrooz Motahari, Alex Whitworth, Robert Izett, Caroline Fradette, Douglas Wallace & Vincent Sieben, IN: Communications Engineering, https://doi.org/10.1038/s44172-026-00665-w

Ocean alkalinity enhancement increases seawater alkalinity to boost carbon dioxide uptake. They report the first field deployment of an autonomous Lab-on-a-Chip total alkalinity analyzer during an ocean alkalinity enhancement trial using magnesium hydroxide slurry. In 2023, the analyzer—co-deployed with pH, salinity, and temperature sensors 60 m from the discharge—performed 314 total alkalinity and 52 onboard certified reference material measurements over 40 days, totaling ~3300 optical readings.

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Peer-reviewed Publications

Acksen et al. (2026): Influence of Deep-Sea Carbonate Sediments on the Durability of Carbon Storage from Ocean Alkalinity Enhancement

Sina Acksen, Wolfgang Koeve, Markus Pahlow, Christopher J. Somes, and Andreas Oschlies, IN: ESS Open Archive, https://doi.org/10.22541/essoar.15001952/v1

Ocean Alkalinity Enhancement (OAE) is a marine carbon dioxide removal strategy with a theoretical sequestration potential of 3–30 Gt CO₂ yr⁻¹. The durability of OAE-induced carbon storage depends on the persistence of the added alkalinity in the ocean, which is influenced by sedimentary processes, terrestrial weathering, and biological and physical feedbacks. Using the UVic v2.10 Earth System Model of intermediate complexity, the authors investigated the millennial-scale durability of OAE-induced carbon storage and the role of deep-sea calcium carbonate sediments.

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Peer-reviewed Publications

Sonar et al. (2026): Marine carbon dioxide removal (mCDR) in the Indian seas: current understanding, regional opportunities, and future directions

Sumit S. Sonar, Susmita Raulo, Suchismita Srichandan, Dhanya M. Lal, Sanjiba K. Baliarsingh, Alakes Samanta, Sudheer Joseph and T.M. Balakrishnan Nair, IN: Mitigation and Adaptation Strategies for Global Change, https://doi.org/10.1007/s11027-026-10311-7

As the global community confronts the escalating threat of climate change driven by anthropogenic greenhouse gas emissions, carbon dioxide removal (CDR) has emerged as an essential strategy to complement emissions reductions, achieve net-zero goals, and plays an important role in removing legacy carbon emissions. Marine Carbon Dioxide Removal (mCDR), which influences the ocean’s natural carbon uptake processes, is gaining increasing attention for its vast sequestration potential. Despite the ocean absorbing a significant quantum of anthropogenic CO₂ emissions, rising emissions are outpacing its natural buffering capacity. This paper synthesizes current understanding of mCDR approaches, including biological (e.g., seaweed cultivation, ocean fertilization), chemical (e.g., ocean alkalinity enhancement), and physical (e.g., artificial upwelling and downwelling) techniques, and evaluates their applicability to the Indian Seas, a region characterized by unique monsoon-driven dynamics, stratified biogeochemistry, and large CO₂ outgassing.

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Peer-reviewed Publications

Yee et al. (2026): Tracer release experiments in Halifax Harbour and implications for coastal ocean alkalinity enhancement

Ruby M. Yee, Ruth Musgrave, Dariia Atamanchuk, Mathieu Dever et al., IN: ESS Open Archive, https://doi.org/10.22541/essoar.15001904/v1

Seven hours-long dye tracer experiments were performed during different months and tidal phases to study the dispersion of a tracer released from a coastal outfall in the Halifax Harbour estuary, a location where alkalinity is also being added for the purpose of the carbon dioxide removal method known as ocean alkalinity enhancement (OAE).

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Peer-reviewed Publications

Myridinas et al. (2026): Prospective site-specific life cycle assessment of ocean alkalinity enhancement

Maria Myridinas, Katja Fennel, Arnaud Laurent, Romain Sacchi, Andrea Stöckli, Karin Treyer, Christian Bauer and Stephan Pfister, IN: Environmental Research Letters, https://doi.org/10.1088/1748-9326/ae5a4e

Ocean alkalinity enhancement (OAE) is a promising marine carbon dioxide removal (CDR) option, but its net climate benefit and wider environmental implications depend strongly on where, and how it is implemented and on decarbonized energy and material supply chains. The authors develop a prospective, site-specific, life cycle assessment (pLCA) that couples a field trials’ validated high-resolution ocean biogeochemical model with LCA for five OAE pathways deployed via wastewater outfalls in Halifax Harbor, Canada: three on magnesium hydroxide (two from serpentinite, via ammonium sulfate (AS) and HCl leaching (HCl), one from bischofite brine (BIS)) and two on sodium hydroxide (from industrial-grade sodium chloride (NaOHs) and seawater desalination brine hydroxide (NaOHb)). Using the functional unit of removing and permanently storing 1 t of atmospheric CO₂, the authors compare present-day conditions with a 2050 scenario and quantify eighteen ReCiPe 2016 midpoint impacts.

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Peer-reviewed Publications

Murthy et al. (2026): Regulation of Coastal Weathering in Massachusetts

Ashwin Murthy, Korey Silverman-Roati and Romany M. Webb, IN: Sabin Center for Climate Change Law, https://scholarship.law.columbia.edu/sabin_climate_change/270/

This white paper reviews the U.S. federal and state laws that could apply to coastal enhanced weathering projects in Massachusetts, as part of a broader Sabin Center project exploring the role of U.S. states in regulating Carbon dioxide removal activities.

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Peer-reviewed Publications

Bhaumik et al. (2026): Resilience of the gelatinous zooplankton species Oikopleura dioica to ocean alkalinity enhancement

Amrita Bhaumik, Nicolás Sánchez, Silvan Urs Goldenberg, Synne Spjelkavik, María Couret, Ulf Riebesell, Maarten Boersma, Cornelia Jaspers, IN: PLOS ONE, https://doi.org/10.1371/journal.pone.0344503

Here, the authors assessed the response of a key gelatinous zooplankton species to OAE in a 53-day mesocosm experiment in a temperate Norwegian fjord. Oikopleura dioica is a globally distributed zooplankton member, known for its high secondary production capacity and key role in vertical carbon flux. O. dioica continuously produces mucous feeding structures (‘houses’), which efficiently retain submicron particles. Once discarded, these houses can sink rapidly and contribute to vertical carbon exports. To test the impacts of OAE on O. dioica abundances and their house production capacity, the authors exposed natural plankton communities to non-CO₂-equilibrated OAE scenarios spanning a ΔTA range from 0–600 μmol kg⁻¹, using silicate-based (olivine) and calcium-based (slaked lime) minerals. Population dynamics of O. dioica were monitored alongside the plankton community, and targeted bottle incubations were used to quantify house production and feeding rates.

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Peer-reviewed Publications

Nguyen et al. (2026): Kinetic insights into measurable marine carbon dioxide removal via carbonation of electrolytically alkalinized seawater

Trinh Thao My Nguyen, Arnaud Boussonnie, Aaron Sabin, Naga Boppana, Thomas Traynor, Fabian Rosner, Dante Simonetti, Gaurav Sant, and Erika La Plante, IN: Chemical Engineering Journal, https://doi.org/10.1016/j.cej.2026.175396

The rising levels of atmospheric carbon dioxide (CO₂) necessitate solutions for effective mitigation strategies, such as marine CO₂ removal (mCDR). This study investigates the kinetics of aqueous carbonation of seawater that has been alkalinized.

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Peer-reviewed Publications

Baltruschat et al. (2026): Assessment of solid ikaite release into seawater – implications for ocean alkalinity enhancement

Stefan Baltruschat, Jens Hartmann, Niels Suitner, Charly A. Moras, Carl Lim, Laura Bastianini and Phil Renforth, IN: Applied Geochemistry, https://doi.org/10.1016/j.apgeochem.2026.106781

Alkaline feedstocks for ocean alkalinity enhancement (OAE) must guarantee efficient alkalinity release while having limited impact on marine ecosystems and carbonate mineral saturation levels (ΩCaCO₃). When considering mineral powder addition as a deployment option, currently considered feedstocks either exhibit slow dissolution kinetics or may require additional water treatment to limit rapid pH changes. Carbonate minerals, on the other hand, feature fast dissolution when undersaturated, accompanied with a reduced impact on pH and ΩCaCO₃. However, traditional (non-hydrated) carbonate minerals such as calcite and aragonite are insoluble in seawater and therefore impractical as direct-to-use feedstocks for OAE. Here, the authors examine the dissolution kinetics and alkalinity release efficiency of ikaite (CaCO₃·6H₂O) — a hydrated carbonate mineral producible from limestone and dissolvable in seawater — across a range of global sea surface temperatures through a series of controlled laboratory-scale experiments.

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Peer-reviewed Publications

Campbell et al. (2026): Harnessing naturally occurring sodium carbonate and bicarbonate for gigatonne-scale carbon dioxide removal

James Campbell, Spyros Foteinis, Reinaldo Juan Lee Pereira, Mohamad Katish, Phil Renforth, IN: EarthArXiv, https://doi.org/10.31223/X5276Q

Ocean alkalinity enhancement is a promising carbon dioxide removal (CDR) approach, but scaling up to gigatonnes (Gt) of CO₂ per year will require safe, sustainable, and abundant alkaline feedstocks. Here, the authors propose the use of a relatively unexplored resource for OAE, namely naturally occurring sodium (bi)carbonates. They identified and mapped 109 such deposits globally, although quantitative resource information is available for only 16. Quantified deposits collectively contain >200 Gt of sodium (bi)carbonate-rich minerals and brines, dominated by trona (Na₂CO₃·NaHCO₃·2H₂O) and nahcolite (NaHCO₃) mainly concentrated in the USA, China, Turkey, and Kenya. They then assessed three OAE pathways using trona as a feedstock, i.e., 1) Mining, crushing, and ocean dispersal of trona (gross CDR capacity 0.16 tCO₂ t⁻¹); 2) Calcine trona with carbon capture and storage to produce soda ash (Na₂CO₃) (0.31 tCO₂ t⁻¹) prior to dispersal; and 3) Purification of soda ash via dissolution, crystallisation, and drying prior to dispersal. Using Green River, Wyoming, USA (~116 Gt of bedded trona) as a case study, life cycle assessment informed on the net-negativity of each pathway.

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