Large-scale alkalinization of the open ocean is a promising method for removing gigatons of carbon dioxide (CO₂) from the atmosphere each year. This approach—known as open-ocean alkalinity enhancement (O-OAE)—involves adding alkaline materials (such as lime or quicklime) into surface ocean waters. Once added, these materials dissolve and release substances that increase seawater alkalinity, which promotes greater CO₂ uptake from the atmosphere by the ocean.
The effectiveness of O-OAE depends on two factors:
- How much alkalinity a material can release
- How quickly a material dissolves before sinking below the surface layer of the ocean.
To remove CO₂ from the atmosphere, alkaline materials must dissolve in the ocean’s surface layer, where chemical reactions drive atmospheric CO₂ uptake. Despite growing interest in O-OAE, little is known about how fast these materials dissolve or how quickly they sink. Both behaviors must be understood for large-scale O-OAE deployment.
This project will use laboratory experiments to measure the dissolution rates and sinking speeds of various candidate alkaline materials. The results will help identify the ideal material properties (such as composition and particle size) for effective O-OAE deployment. The findings will also support ongoing work on the large-scale production of carbon-neutral alkaline materials for ocean-based CO₂ removal.
Video: trajectories of sinking particles captured using a Real-Time Sinking Speed Visualizer (RTSSV) and analyzed with machine learning-based image processing.
B. B. Cael
