Collaborative Research: Uncovering marine carbon chemistry dynamics during the deglaciation with boron isotopes and radiocarbon

合作研究：用硼同位素和放射性碳揭示冰消过程中的海洋碳化学动力学

基本信息

批准号：
2032340
负责人：
Patrick Rafter
金额：
$ 8万
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：
2021
资助国家：
美国
起止时间：
2021-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2032340&HistoricalAwards=false
关键词：
Collaborative Research Uncovering marine carbon

项目摘要

The global carbon cycle underwent a major transition at the end of the last ice age ~12,000 years ago – atmospheric carbon dioxide levels rose abruptly at that time. This project will use naturally-occurring “radiocarbon” (the radioactive carbon isotope 14C) to study how global carbon pools changed during that deglacial transition. The project will test previous radiocarbon evidence for a pulse of carbon release from seafloor volcanoes in the eastern Pacific Ocean at that time. That result challenges the idea that carbon release from the solid Earth is relatively slow and steady. Chemical and isotope measurements on fossil shells from deep-sea sediment cores will show whether the carbon pulse came in the form of acid or base. This will help pin down the source of the carbon. Carbon cycle models will be used to estimate the scale of these carbon pulses and their impact on ocean acidity and atmospheric carbon dioxide levels. Preliminary data and initial model results suggest that the carbon source was acid/base neutral. If so, then enormous quantities of carbon could have been released without causing strong ocean acidification or a strong atmospheric carbon dioxide rise. Carbon dioxide is a greenhouse gas and human activities are responsible for a large release of carbon dioxide today. Documenting the scale and nature of the natural carbon release at the end of the last ice age will help predict the environmental consequences of human carbon release. It will also help predict whether the human carbon release may be neutralized by natural processes.The Gulf of California study site was selected because it contains: (1) a high-quality wood fragment-based chronology, (2) abundant and well-preserved benthic foraminifera for boron and carbon isotope analysis, (3) replicated evidence for regionally and temporally coherent 14C anomalies, and (4) known local sources of geologic carbon associated with the East Pacific Rise. The main thrust of the proposed work comes from d11B and B/Ca measurements to establish if there was any seawater carbonate chemistry and/or pH change associated with the 14C anomalies, but the proposed work also includes a wider set of complementary isotope geochemical measurements (14C/C, d13C) to enhance the value of the database as a constraint on the possible explanations for the regional 14C anomalies. The project also includes regional and global carbon cycle modeling to assimilate the multi-proxy constraints and quantitatively assess the implied effects on global seawater carbon chemistry and atmospheric CO2. This work will inform the active debate about the contribution of deglacial carbon release to deglacial CO2 rise. The working hypothesis is that significant pulses of geologic carbon releases explain the observed 14C anomalies but would not significantly contribute to CO2 change because that carbon came in neutralized bicarbonate ion form. Overall, the study will take on a significant gap in understanding natural carbon cycle change on human-relevant timescales by collaboratively integrating novel multi-proxy measurements with carbon cycle modeling. Both PIs are early career scientists with demonstrated domain expertise and track record.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.

全球碳循环在大约 12,000 年前的最后一个冰河时代末期发生了重大转变——当时大气中的二氧化碳水平突然上升。该项目将利用天然存在的“放射性碳”（放射性碳同位素 14C）进行研究。该项目将测试之前东太平洋海底火山释放碳的放射性碳证据，这一结果对碳释放的观点提出了挑战。固体地球相对缓慢而稳定。对深海沉积物核心化石壳的化学和同位素测量将显示碳脉冲是以酸还是碱的形式出现，这将有助于确定碳循环的来源。模型将用于估计这些碳脉冲的规模及其对海洋酸度和大气二氧化碳水平的影响。初步数据和初始模型结果表明，如果是这样，那么碳源是酸/碱中性的。已被释放而没有引起强烈的海洋影响二氧化碳是一种温室气体，当今人类活动导致了二氧化碳的大量排放，记录上一个冰河时代末期自然碳排放的规模和性质将有助于预测。它还将有助于预测人类碳释放是否可以被自然过程中和。选择加利福尼亚湾研究地点是因为它包含：（1）基于高质量木材碎片的年代学，（2）底栖生物丰富且保存完好有孔虫用于硼和碳同位素分析，(3) 区域和时间相干 14C 异常的复制证据，以及 (4) 与东太平洋海隆相关的已知当地地质碳源。拟议工作的主要推力来自 d11B 和 B。 /Ca 测量以确定是否存在与 14C 异常相关的任何海水碳酸盐化学和/或 pH 变化，但拟议的工作还包括更广泛的互补同位素集地球化学测量（14C/C、d13C），以提高数据库作为对区域 14C 异常可能解释的约束的价值。该项目还包括区域和全球碳循环建模，以吸收多代理约束并定量评估。对全球海水碳化学和大气二氧化碳的隐含影响这项工作将为有关冰消碳释放对冰消二氧化碳上升的贡献的活跃争论提供信息。工作假设是地质碳的显着脉冲。释放解释了观察到的 14C 异常，但不会对二氧化碳变化产生显着影响，因为碳以中和的碳酸氢根离子形式出现。总体而言，该研究将通过协作整合新颖的多元素，在理解与人类相关的时间尺度上的自然碳循环变化方面取得重大差距。 - 碳循环建模的代理测量。两位 PI 都是早期职业科学家，具有丰富的领域专业知识和跟踪记录。该奖项反映了 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进行评估，被认为值得支持。审查标准。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Constraining Earth’s geologic influence on the global carbon cycle during the last ice age from the planetary radiocarbon budget

从行星放射性碳预算中限制上一个冰河时期地球地质对全球碳循环的影响

DOI：
10.7185/gold2021.8208
发表时间：
2021-01
期刊：
Constraining Earth’s geologic influence on the global carbon cycle during the last ice age from the planetary radiocarbon budget
影响因子：
0
作者：
Green, Ryan;Hain, Mathis;Rafter, Patrick
通讯作者：
Rafter, Patrick

OS33A-04 - Global reorganization of deep-sea circulation and carbon storage after the last ice age

OS33A-04 - 最后一个冰河时代后全球深海循环和碳储存的重组

DOI：
发表时间：
2022-01
期刊：
AGU Fall Meeting
影响因子：
0
作者：
PA Rafter; WR Gray
通讯作者：
WR Gray

OS13A-04 - Interconnected global deep-sea circulation changes over the past 25,000 years

OS13A-04 - 过去 25,000 年来相互关联的全球深海环流变化

DOI：
发表时间：
2021-01
期刊：
AGU Fall Meeting
影响因子：
0
作者：
Rafter; Gray
通讯作者：
Gray

New measurements and compilation provide a 25,000 year view of global deep-sea radiocarbon

新的测量和汇编提供了 25,000 年全球深海放射性碳的视图

DOI：
10.7185/gold2021.6487
发表时间：
2021-01
期刊：
New measurements and compilation provide a 25,000 year view of global deep-sea radiocarbon
影响因子：
0
作者：
Rafter, Patrick;Costa, Kassandra;Hines, Sophia;Devries, Timothy;Rae, James;Gray, William;Burke, Andrea;Southon, John;Gottschalk, Julia;Hain, Mathis
通讯作者：
Hain, Mathis

PP12B-05 and CO2 14C - Constraints on the Deglacial Release of Geologic Carbon Using Atmospheric Records

PP12B-05 和 CO2 14C - 使用大气记录限制冰期地质碳释放