A record of Pleistocene diatom preservation from the Amundsen Sea, West Antarctica with possible implications on silica leakage

Higher overall silica dissolution is observed during each glacial period and enhanced silica preservation during interglacials. This result is consistent with the predictions of the silicic acid leakage hypothesis (SALH), whereby reduced rates of Si usage in the Southern Ocean lead to shifts in marine primary productivity in the tropics from coccolithophorid dominance during interglacials to diatom dominance during glacials. This would fuel a decrease in atmospheric pCO2 during glacials. Silica acid leakage is driven by a decrease in the Si:N ratio of diatoms, caused by increased iron input to glacial-aged Southern Ocean waters. This resulted in more lightly silicified diatom valves in the Southern Ocean, which dissolved more quickly in the upper water column, thereby maintaining the high silica content of glacial-aged SO waters, and allowing for export of Si to upwelling zones in the lower latitudes.