East Antarctic sediment carbonate mineralogy, 2020

Ocean acidification (the reaction of CO2 with seawater) lowers the saturation state with respect to carbonate minerals and may lead to dissolution of these minerals if undersaturation occurs. There are three main carbonate minerals found in marine sediments: 1. aragonite 2. calcite (also referred to as low-magnesium calcite, containing less than 4mol% MgCO3) 3. high-magnesium calcite (greater than 4 mol% MgCO3) Due to the different structure of these minerals, they have different solubilities with high-Mg calcite the most soluble, followed by aragonite and then calcite.

As seawater CO2 increases and the saturation state with respect to carbonate minerals decreases, high-Mg calcite will be the first mineral subject to undersaturation and dissolution. By measuring the carbonate mineral composition of sediments, we can determine which areas are most at risk from dissolution. This information forms an important baseline with which we can assess future climate change.