Ocean alkalinity enhancement approaches and the predictability of runaway precipitation processes: results of an experimental study to determine critical alkalinity ranges for safe and sustainable application scenarios

作者：Niels Suitner, Giulia Faucher, Carl Lim, Julieta Schneider, Charly A. Moras, Ulf Riebesell, Jens Hartmann · 发表于：Biogeosciences · 年份：2024 · DOI：10.5194/bg-21-4587-2024 · 被引用次数：36 · 研究领域：Ocean Acidification Effects and Responses、CO2 Sequestration and Geologic Interactions、Global Energy and Sustainability Research

To ensure the safe and efficient application of ocean alkalinity enhancement (OAE), it is crucial to investigate its impacts on the carbonate system. While modeling studies reported a sequestration potential of 3–30 Gt carbon dioxide (CO 2 ) per year (Oschlies et al., 2023), there has been a lack of empirical data to support the applicability of this technology in natural environments. Recent studies have described the effect of runaway carbonate precipitation in the context of OAE, showing that calcium carbonate (CaCO 3 ) formation was triggered if certain Ω aragonite saturation thresholds were exceeded. This effect could potentially lead to a net loss of the initially added alkalinity, counteracting the whole concept of OAE. The related precipitation can adversely affect the carbon storage capacity and may in some cases result in CO 2 emissions. Experiments at the Espeland marine biological station (Bergen, Norway) were conducted to systematically study the chemical consequences of OAE deployment. The experiments lasted for 20–25 d to monitor the temporal development of carbonate chemistry parameters after alkalinity addition and the subsequent triggered carbonate precipitation process. Identified uniform patterns before and during the triggered runaway process can be described by empirical functional relationships. For approaches equilibrated to the CO 2 concentration of the atmosphere, total alkalinity (TA) levels of up to 6500 µmol kg −1 remained stable without loss of t...