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

摘要(赛克斯/吉尔德森0823487/0823549)学术价值：由于海洋环流的变化在过去曾深刻影响气候，这项研究阐述了海洋环流在二氧化碳调节中所起的基础作用。这项工作使用新西兰附近沉积物中沉积的有孔虫中的放射性碳来研究全球海洋环流如何影响温室气体二氧化碳在海洋和大气之间的分配。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，以证实或否认存在足够古老的深水团，以解释冰期-间冰期大气二氧化碳的变化；(2)在不同的时间间隔产生高分辨率的放射性碳记录，以提供全球二氧化碳和放射性碳预算中缺失的南半球视角。这些问题可以解决，因为可以用放射性碳(14C)追踪海洋环流，因为大气中二氧化碳气体的14C含量与以溶解碳酸盐和碳酸氢盐形式存在的海洋中的14C含量之间存在可量化的差异，这是因为在温盐循环期间，大气中的14C与孤立水团中14C的放射性衰变之间存在平衡。这项研究利用了来自不同水深的取心近海沉积物中的火山岩层所提供的精确的地层控制。利用浮游有孔虫和底栖有孔虫对建立海洋不同深度的放射性碳垂直剖面，收集一组氧同位素数据的时间序列，追踪浅水(600~2500m)和深水(600~4300m)自末次冰川消融(17500~9500年前)以来的变化。更广泛的影响美国和新西兰科学家之间的合作代表着美国调查人员在处理加强研究基础设施的标准时与国际同行进行的重大投资接触。该团队包括一名以前没有NSF资金的年轻调查人员，以及在调查机构之间交换一名研究生，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.