| Summary: | Progress Code: completed Statement: Most samples contained only small amounts of CaCO3 and overall, very few samples contain carbonates. Typically, mineralogy was determined on samples with greater than 3% CaCO3 content. The quality of data from samples with low CaCO3 are likely less reliable. Duplicate or triplicate analysis of some samples showed variability within samples. The dates provided in temporal coverage correspond to the runtime of the project. Purpose This dataset provides information on the carbonate mineralogy in surface sediments. This includes the type and amounts of various carbonate minerals. This information was collected to identify where carbonate-rich sediment occur and which areas are the most vulnerable to ocean acidification. Marine sediments often represent an important reservoir of carbonate minerals that will react rapidly to changing seawater chemistry as a result of ocean acidification. 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. The effect of ocean acidification on carbonates in marine sediments will occur around the world, but due to the lower seawater ...
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