Glacial Radiocarbon Constraints from Drake Passage Deep-Sea Corals

该项目使用深海珊瑚中的放射性碳来了解南大洋在调节全球气候方面的作用。作为深水形成的关键地点，南大洋对深海和大气之间的热量和碳交换至关重要。它的变化可能与上一次冰川盛期大气二氧化碳含量较低有关，因为生物碳消耗增加或大气-海洋二氧化碳交换减少。由于缺乏有关南大洋生物地球化学和环流的适当记录，测试这些假说具有挑战性。深海珊瑚的文石骨架可以提供洞察力，因为它们非常适合放射性碳分析--反映过去水柱的14C含量--同时还可以通过U系列年龄测量来确定事件的时间。总体而言，这些测量将对大气-海洋气体交换、极地水柱分层以及来自南方的深水流向世界其他海洋的流量造成新的限制。作为这项工作的一部分，德雷克海峡海底的新部分将被绘制和成像，以及现在和过去深海珊瑚及其栖息地的分布。这项工作的一个重要的更广泛的影响是表征可能是大气二氧化碳含量的关键控制的运作，这可能被证明对于充分了解二氧化碳持续排放的影响和制定缓解战略很重要。此外，这项工作将描述人们知之甚少、但作为渔业资源日益被开发的深海海洋生态系统。

This project uses radiocarbon in deep-sea corals to understand the Southern Ocean's role in modulating global climate. A key site of deep-water formation, the Southern Ocean is critical to exchange of heat and carbon between the deep-ocean and atmosphere. Changes in it may be linked to low atmospheric CO2 during the last glacial maximum through increased biologic carbon draw down or decreased air-sea CO2 exchange. Testing these hypotheses is challenging because of the scarcity of suitable records of the Southern Ocean's biogeochemistry and circulation. The aragonitic skeletons of deep-sea corals may offer insight because they are well suited for radiocarbon analyses-reflective of the 14C content of the past water column--while also allowing for timing of events through U-series age measurements. Overall, these measurements will put new constraints on the extent of air-sea gas exchange, polar water-column stratification, and the flux of Southern-sourced deep water to the rest of the world's oceans. As a part of this work, new sections of the Drake Passage sea floor will be mapped and imaged, along with the present and past distributions of deep-sea corals and their habitats. A significant broader impact of this work is characterizing the functioning of what may be a key control of atmospheric CO2 content, which could prove important for fully understanding the impacts of continued CO2 emissions and developing mitigation strategies. As well, the work will characterize deep marine ecologies that are poorly understood, but increasingly exploited as fisheries resources.