Tracing the Radiocarbon Signal of the Ocean's CO2 Release During the Last Deglaciation

这项研究将测试总体假设，即南大洋的通风导致低D14 C沃茨通过南极中层水（AAIW）在最后一次冰消期的两个阶段向北扩散。这项工作是根据最近在下加利福尼亚南端的结果进行的，这些结果显示，在两次冰消期大气CO2增加期间，中层水D14 C急剧下降（大气中D14 C减少）;这种观测似乎需要从假定的深海储层注入非常古老的沃茨。这项工作将提供关键的机械证据，将海洋环流中已确定的冰川消退变化联系在一起，大气CO2，以及海洋和大气D14 C。这些研究是根据下加利福尼亚南部和智利南部大陆边缘的沉积物岩心深度剖面中的底层水和表层水D14 C重建的。D14 C重建来自于沉积物中底栖和南极有孔虫14 C测量，具有独立的气候-地层年龄控制。这项研究增加了对海洋在冰川-间冰期大气CO2循环中作用的机械理解，并为用于预测未来变化的海洋-大气数值模型的测试提供了具体目标。该项目还为一名博士生和一名地质科学本科生提供了广泛的培训。

This research will test the overarching hypothesis that ventilation of the Southern Ocean caused low-D14C waters to spread northward via Antarctic Intermediate Water (AAIW) in two stages during the last deglaciation. The work follows on recent results from off the southern tip of Baja California that show dramatic drops in intermediate water D14C during each of the two deglacial atmospheric CO2 increases (atmospheric D14C decreases); such observations appear to require the injection of very old waters from a presumed abyssal reservoir.This work will provide crucial mechanistic evidence tying together established deglacial changes in ocean circulation, atmospheric CO2, and oceanic and atmospheric D14C. Studies are based on bottom- and surface- water D14C reconstructions in a depth transect of sediment cores from the continental margin off southern Baja California and from the southern Chilean Margin. D14C reconstructions are derived from benthic and planktic foraminiferal 14C measurements in sediments with independent climate-stratigraphic age control.This research adds to the mechanistic understanding of the ocean's role in glacial-interglacial atmospheric CO2 cycles and provides concrete targets for testing of ocean-atmosphere numerical models that are used to project future changes. The project also provides extensive training for a PhD student and a Geological Sciences undergraduate.