Collaborative Research: Radiocarbon content of the Southwest Pacific and Southern Ocean waters in the Holocene and late Quaternary

摘要（Sikes/Guilderson 0823487/0823549）学术价值：由于海洋环流的变化在过去深刻地影响了气候，本研究解决了海洋环流在二氧化碳调节中所起的基本作用。这项工作使用了在新西兰附近沉积物中沉积的有孔虫测试中的放射性碳来研究全球海洋环流如何影响海洋和大气之间温室气体二氧化碳的分配。这项研究有两个主要目标：(1)重建南太平洋冰川的放射性碳特征，以证实或反驳存在一个足够古老的深水块来解释冰川？大气CO2的间冰期变化和(2)产生高分辨率的放射性碳记录，以提供南半球的视角，这在全球CO2和放射性碳预算中是缺失的。这些问题可以得到解决，因为海洋环流可以用放射性碳（14C）来追踪，因为大气中的14C含量与海洋中的14C含量之间存在可量化的差异，而海洋中的14C以溶解的碳酸盐和碳酸氢盐的形式存在，这是因为大气中的14C与温盐环流期间孤立水团中的14C的放射性衰变之间存在平衡。该研究利用了来自不同水深的岩心近海沉积物中的火山ask层提供的精确地层控制。浮游生物和底栖有孔虫对将用于构建海洋不同深度的放射性碳垂直剖面，并将收集一组时间序列的氧同位素数据来跟踪浅水(600？2500米)和深水（600-4300m），直到最后一次冰川消退时期（17,500至9,500年前）。更广泛的影响美国和新西兰科学家之间的合作代表了美国研究人员与国际同行的重大投资拓展，以解决加强研究基础设施的标准。该团队包括一名没有获得NSF资助的年轻研究人员，以及一名研究人员所在机构之间的研究生交换，以解决推进培训和学习的标准。

ABSTRACT (Sikes/Guilderson 0823487/0823549)Intellectual merit: Because changes in ocean circulation have profoundly influenced climate in the past, this research addressed the fundamental role that ocean circulation plays in the regulation of CO2. The work uses radiocarbon in foraminifera tests deposited in sediments off New Zealand to examine how global ocean circulation affects the partitioning of the greenhouse gas CO2 between the ocean and atmosphere. This research has two primary goals: (1) to reconstruct the radiocarbon signature of the glacial southern Pacific to confirm or refute the presence of a deep water mass old enough to account for the glacial?interglacial changes in atmospheric CO2 and (2) to produce a high resolution record of radiocarbon at various intervals the time of deglaciation to provide a Southern Hemisphere perspective which is missing from global CO2 and radiocarbon budgets. These issues can be addressed because ocean circulation can be traced with radiocarbon (14C) because there is a quantifiable difference between the 14C content of atmospheric CO2 gas and that in the ocean where it exists in the form of dissolved carbonate and bicarbonate, This is because there is an equilibrium balance between 14C in the atmosphere and the radioactive decay of 14C in isolated water masses during thermohaline circulation. The research takes advantage of the precise stratigraphic control afforded by volcanic ask layers in cored off-shore sediments from different water depths. Planktonic and benthic foraminiferal pairs will be used to construct vertical profiles of radiocarbon at different depths in the ocean and a time series of set of oxygen isotope data will be collected to track the evolution of changes in shallow waters (600?2500 m) and deep waters (600-4300m) through the time of the last period of deglaciation (17,500 to 9,500 years ago. Broader impacts Collaborations among United States and New Zealand scientists represent significant investment outreach with international colleagues by US investigators addressing the criteria of enhancing infrastructure for research. The team includes a young investigator with no prior NSF funding and the exchange of a graduate student among the investigators' institutions, addressing criteria for advancing training and learning.