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

基于历史上捕获的鲸骨对南极半岛和南大洋周围 14C 水库的新限制

• 批准号: 2200448
• 负责人: Alexander Simms
• 金额: $ 5.89万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2200448&HistoricalAwards=false
• 关键词: New; constraints; 14C; reservoirs; around

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.

我们对气候变暖导致的冰盖行为的理解，很大程度上是基于过去的冰盖对气候变暖的反应，这与两万年前最后一个冰河时代的结束有关。这些研究依赖于对过去冰盖留下的特征进行准确的年代测定。在过去的40,000年中，最常用的确定这些特征的年龄的方法是放射性碳测年。然而，放射性碳测年并不是没有它的细微差别，这在南极洲周围特别明显。这些细微差别之一是确定所测量的材料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鱼骨骼来确定这一偏移量，这些鲸骨的年龄是独立已知的。对这一偏移量的更好理解将有助于更准确地估计南极半岛过去约4万年来冰盖和海平面的变化速度。我们对南极冰盖将如何应对未来气候变化的理解，很大程度上是基于对其过去行为的研究。这些研究往往依赖于重建自2万年前最后一次冰川盛期以来的演化。放射性碳测年是用于这些重建的第四纪沉积物最常用的测年方法。然而，地球上一些最大、限制最少的放射性碳库阻碍了放射性碳库在南极洲的使用。这项研究的目的是确定鲸骨的放射性碳库。这项研究将利用现有的25块鲸鱼骨骼，用于先前的DNA研究，以确定南极半岛晚全新世的放射性碳库。这些鲸鱼的骨头来自20世纪初在20世纪50年代核试验之前采集的标本。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库提供有价值的新限制。这种方法的另一个好处是，鉴于DNA的测定，我们还将能够确定放射性碳库是否在三种鲸鱼中存在差异，从而检验放射性碳库在不同物种之间没有显著差异的普遍假设。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。