Ocean Alkalinity Enhancement (OAE) has been proposed as a method to increase CO₂ sequestration in the ocean. Yet the viability, scalability, and potential side effects of OAE are not yet clear. Here we develop a dissolution rate model for alkaline materials to test the viability of OAE using different alkaline mineral sources. Current assessments of the implementation potential and environmental impacts of OAE still primarily rely on laboratory experiments under controlled conditions. Although these experiments provide valuable references, they are of questionable environmental relevance compared to natural seawater, which contains abundant particles and dissolved organic material. This study investigates the regulatory mechanisms of complex environmental processes on the dissolution rates, alkalinity release efficiency, and stability of alkaline materials such as brucite and steel slag, by comparing field incubation experiments at 50,000–100,000 L scale with controlled laboratory incubation experiments. The results show that the total alkalinity release rates of both materials in field environments are slower and more difficult to predict than under laboratory conditions. Under laboratory conditions, the dissolution of brucite within one month decreased with increasing material concentration, ranging from 15% to 84% completion; whereas under field conditions, the maximum observed change in alkalinity was equivalent to 23% dissolution over one month. Steel slag showed more complicated dynamics under both laboratory and field conditions, with limited release of total alkalinity and trends that did not conform to the widely assumed first-order kinetic model. Temperature variations also had markedly different effects on the release of different materials, with laboratory results showing that steel slag was significantly more sensitive to temperature than brucite. This study quantifies the major discrepancies between field and laboratory environments, providing a basis for re-evaluating previous carbon sequestration potential predictions derived from laboratory data. We aim to provide more effective data support for OAE through the development of a calibration model.

暂无