REVISITING THE SILICIC ACID LEAKAGE HYPOTHESIS IN THE PACIFIC SECTOR OF THE SOUTHERN OCEAN

Marine sediment cores from the Pacific Sector of the southern ocean, north of, on or just south of the polar front were analyzed in order to constrain the silicic acid leakage hypothesis (SALH). The SALH suggests that during the Last Glacial Maximum (LGM) there was an excess of silicic acid in the southern ocean that was exported to the equatorial region, allowing diatoms to out-compete coccolithophorids and other calcium carbonate producing organisms, causing the drawdown of carbon dioxide thereafter. Anderson and Burckle (2003) determined that the hypothesis does not apply to the Indian and Atlantic sectors of the southern ocean, but there is evidence to point out that it may apply to the Pacific sector.

In order to analyze the appropriate sections of the cores, the Holocene and the LGM were located by determining the glacial/interglacial time periods. This was done by using magnetic susceptibility and 300-point counts of Eucampia Antarctica, a species of diatom which is more prevalent during glacial times than during interglacial periods. Calcium carbonate and opal burial rates were determined. More detailed analyses need to be carried out in order to constrain the SALH due to a hiatus in one of the key cores.