Aragonite Saturation State
D1. Physical and chemical oceanography and marine meteorologyDefinition
Indicator of whether seawater is corrosive or favorable to aragonite-shelled organisms.
The aragonite saturation state (omega-arag) is the ratio of the in-situ product of calcium and carbonate ion concentrations to aragonite’s solubility product. Above 1 the water favors aragonite shell formation; below 1 it is corrosive and shells dissolve. Aragonite is the more soluble of the common calcium-carbonate minerals, so pteropods, corals, and many larvae feel acidification first. The saturation horizon is shoaling as the ocean takes up CO2.