Eastern Pacific carbon chemistry after the ice age: gaining insight to a persistent carbon cycle mystery

冰河时代后的东太平洋碳化学：深入了解持久的碳循环之谜

• 批准号: 2015647
• 负责人: Patrick Rafter
• 金额: $ 32.61万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2015647&HistoricalAwards=false
• 关键词: Eastern; Pacific; carbon; chemistry; after

The current rise in atmospheric carbon dioxide (CO2) due to human activities such as fossil fuel burning is warming the planet. One way to better predict future climate is to study past natural changes in atmospheric CO2. Such changes occurred through the ice ages of the past 1 million years. The ocean is thought to have played a key role in ice age atmospheric CO2 changes because ocean uptake of CO2 contributes to global cooling and CO2 release by the ocean contributes to warming. One of the most useful tools for reconstructing past ocean CO2 cycles is the radioactive isotope of carbon, 14C. Radiocarbon is measured in marine microfossils which record the 14C of seawater. This study will develop microfossil 14C records from ocean sediment cores and use them to unravel the causes of a low-radiocarbon anomaly that occurred in the eastern North Pacific Ocean at the time of the Last Glacial Maximum (roughly 20,000 years ago). Understanding this anomaly will improve our knowledge of ocean-atmosphere CO2 exchange in the past, and thus will help us predict the impact of rising atmospheric CO2 on future climate. The project will support research participation by undergraduate students at UC Irvine. The project also includes support for a series of workshops designed to introduce prospective First Generation college students to the Earth Sciences.The proposed work will use a set of new sediment 14C/ records along the Eastern North Pacific margin to address a long-standing paleoceanographic question—what is the origin of the anomalously low 14C in the Eastern North Pacific during the deglaciation? This feature has alternately been explained as evidence for: (i) an anomalously low seawater 14C/C advected to the eastern North Pacific sites, (ii) the local or regional addition of low-14C carbon from seafloor volcanism, or (iii) post-depositional alteration of the proxy record. The proposed analyses will yield four new benthic foraminifera 14C/C records from Eastern North Pacific core sites upstream of the sites with anomalously low deglacial 14C. These records will be synchronized using benthic foraminifera d18O records and will be used to create a new map of Eastern North Pacific deglacial seawater 14C. This map will be used to distinguish between advected and local sources for the low-14C signal. The study will support the training of undergraduate students at UC Irvine (a Minority Serving Institution). The project will also support organization of a 3-day workshop for prospective First Generation college students from local high schools with high under-represented minority populations, with the goal of increasing the participation of under-represented minorities in the Earth Sciences.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.

由于人类活动（例如化石燃料燃烧）引起的大气二氧化碳（CO2）的目前增加正在加热地球。更好地预测未来气候的一种方法是研究大气二氧化碳的自然变化。这种变化发生在过去一百万年的冰河时代。人们认为海洋在冰河时代大气二氧化碳的变化中起着关键作用，因为二氧化碳的吸收有助于全球冷却和海洋释放的二氧化碳释放，从而有助于变暖。重建经过海洋二氧化碳周期的最有用的工具之一是碳的放射性同位素，14c。在记录海水14C的海洋微化石中测量了放射性碳。这项研究将开发从海洋沉积物核心的微化石14C记录，并用它们来揭示在最后一次冰川最大值（大约20，000年前）时在北太平洋东部发生的低降射碳异常的原因。了解这种异常将改善我们过去对海洋大气二氧化碳交换的了解，因此将有助于我们预测大气二氧化碳对未来气候的影响。该项目将支持UC Irvine大学本科生的研究参与。该项目还包括对一系列旨在将潜在的第一代大学生介绍到地球科学的研讨会的支持。拟议的工作将使用北部太平洋东部边缘沿线的一套新的沉积物14C/记录来解决一个长期存在的古生物学问题 - 在退化期间，北部太平洋地区东部北部的14C偏低的起源是什么？或者，该特征被解释为：（i）向北太平洋东部地点的异常低海水14c/c，（ii）局部或区域添加了海底火山症中低14c碳，或（iii）代理记录的沉积后变化。拟议的分析将产生来自北部太平洋核心地点的四个新的底栖有孔虫14c/c记录，其位点上游具有异常低的冰冰14c。这些记录将使用底栖有孔虫D18O记录进行同步，并将用于创建新的北太平洋脱水海水14C的新地图。该地图将用于区分低14C信号的对流和局部源。该研究将支持加州大学尔湾分校（少数派服务机构）的本科生的培训。该项目还将支持为期三天的研讨会组织，该研讨会为来自代表性不足的少数群体人口不足的当地高中的前瞻性第一代大学学生提供支持，目的是增加代表性不足的少数群体在地球科学中的参与。这项奖项反映了NSF的法定任务，并通过使用基金会和广泛的评估来评估支持NSF的法定任务，并获得了评估。