New constraints on 14C reservoirs around the Antarctic Peninsula and the Southern Ocean based on historically-harvested whale bones

我们对由于温度变暖而导致的冰盖行为的理解，在很大程度上是基于过去的冰盖对与2万年前最后一个冰河时代结束有关的变暖的反应。这些研究依赖于对过去冰盖留下的特征的精确测年。在过去4万年里，测定这些特征的年龄最常用的方法是放射性碳定年法。然而，放射性碳测年并非没有细微差别，在南极洲周围尤其明显。其中一个细微差别是确定测量的放射性碳年龄与其真实年龄之间的偏移量。这项研究的目的是利用历史上从南极半岛采集的鲸骨来确定这种抵消，这些鲸骨的年龄是独立已知的。更好地了解这种抵消将使我们能够更准确地估计过去4万年来整个南极半岛的冰盖和海平面变化速度。我们对南极冰盖将如何应对未来气候变化的理解，在很大程度上是基于对其过去行为的研究。这些研究通常依赖于重建自2万年前末次冰期以来的演变。放射性碳测年是这些重建中最常用的第四纪沉积物测年方法。然而，在南极洲使用放射性碳受到地球上一些最大和最不受限制的放射性碳储存库的阻碍。这项研究的目的是确定鲸鱼骨骼的放射性碳储藏库。这项研究将利用现有的25块鲸鱼骨骼，用于先前的DNA研究，以确定南极半岛的全新世晚期放射性碳储量。这些鲸骨来自20世纪初采集的标本，在20世纪50年代核试验之前。因此，它们的放射性碳年龄将为南极洲周围浅水的放射性碳储层提供有价值的新限制。这种方法的另一个好处是，考虑到DNA的测定，我们还将能够确定放射性碳储存库在三种鲸鱼之间是否存在差异，从而验证放射性碳储存库在不同物种之间没有显著差异的普遍假设。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Much of our understanding of ice sheet behavior due to warming temperatures is based on how past ice sheets responded to warming associated with the end of the last ice age, 20,000 years ago. These studies rely on accurate dating of features left behind by the past ice sheets. The most commonly used method for determining the age of these features over the last ~40,000 years is radiocarbon dating. However, radiocarbon dating is not without its nuances, which are particularly pronounced around Antarctica. One of these nuances is determining the offset between the materials measured radiocarbon age and its true age. The purpose of this research is to use historically harvested whale bones from the Antarctic Peninsula, whose age is independently known, to determine that offset. A better understanding of that offset will allow more accurate estimates of past rates of ice sheet and sea-level changes across the Antarctic Peninsula over the last ~40,000 years. Much of our understanding of how the Antarctic Ice Sheet will respond to future climate changes is based on studies of its past behavior. Those studies often rely on reconstructing its evolution since the Last Glacial Maximum, 20,000 years ago. Radiocarbon dating is the most commonly used method of dating Quaternary deposits for these reconstructions. However, the use of radiocarbon in Antarctica is hampered by some of the largest and least constrained radiocarbon reservoirs on the planet. The purpose of this research is to determine the radiocarbon reservoir for whale bones. This research will leverage an existing collection of 25 whale bones used for prior DNA research to determine the late Holocene radiocarbon reservoir for the Antarctic Peninsula. The whale bones are from specimens harvested at the turn of the 20th century prior to nuclear testing in the 1950s. Thus, their radiocarbon age will provide valuable new constraints on the radiocarbon reservoir for shallow waters around Antarctica. An added benefit of this approach is that given the DNA determination, we will also be able to determine if that radiocarbon reservoir varies across three species of whales, thus testing the common assumption that the radiocarbon reservoir does not vary significantly across different species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.