INVESTIGATING DEEP-WATER CIRCULATION CHANGES ALONG THE EAST SCOTIA SEA

The Southern Ocean is considered an important high-latitude region in controlling atmospheric carbon dioxide (CO₂) due to the circulation of deep-water masses, such as the Antarctic Circumpolar Current. Changes in circulation and ventilation of the Southern Ocean are interconnected to changes in atmospheric CO₂, which results in glacial/interglacial cycles. Sedimentary redox proxies are indicative of oxygenation changes in the overlying water at the time of sediment deposition, therefore they can be used to investigate ventilation changes. We investigated several sediment cores recovered along a northern and southern transect in the East Scotia Sea during the R/V Polarstern 119 Expedition to evaluate paleoclimate changes using redox-sensitive trace metals. The Scotia Sea is located in the Atlantic portion of the Southern Ocean, and is bounded by the Scotia Arc and the Shackleton Fracture Zone, as well as a volcanic island arc loop of eleven islands and the East Scotia Ridge. Sediment cores were digested using a multi-acid digestion technique and analyzed via an Inductively Coupled Plasma Mass Spectrometry. Our data indicate that the proxy application of redox-sensitive metals was influenced by circulation patterns driving hydrothermal fluid deposits from west to east along the northern transect. Interestingly, redox-sensitive metals were on average lower in concentration in the (west) northern transect in comparison to the southern transect. While these results do not indicate deep-water oxygenation changes, the higher concentration of redox proxies in the southern transect likely points to a (regional) change in deep-water circulation. Over time, changes in deep-water circulation can result in changes in oxygenation and influence the distribution of deep-water masses. Given the Southern Ocean connects other oceanic basins, this can have an impact on the carbon storage capacity of the oceans.