Beyond ocean temperature: Extracting new dimensions of paleoclimatic information from archaeal lipids and their isotopic compositions

超越海洋温度：从古细菌脂质及其同位素组成中提取新维度的古气候信息

• 批准号: 1702262
• 负责人: Ann Pearson
• 金额: $ 33.25万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1702262&HistoricalAwards=false
• 关键词: Beyond; ocean; temperature; Extracting; new

A good understanding of past climate requires accurate reconstruction of factors such as ocean temperature and biological productivity. One such paleotemperature method is the "TEX86 proxy", which is based on the preserved organic molecules of Archaea, an important class of ocean microbes. TEX86 records have been particularly valuable for studying climate of the last 100 million years, especially during ancient warm episodes where other temperature proxies are unavailable. Although in the modern ocean there generally is good agreement between temperatures predicted from TEX86 and the actual observed sea surface temperatures (SSTs), TEX86 can yield significant regional or seasonal errors. Disagreement also has been observed during past greenhouse climates associated with low oxygen levels in the oceans; in particular, TEX86 sometimes predicts colder temperatures during such intervals, even though the ocean actually is warming. To improve understanding of TEX86 temperature records, this project will examine environmental and ecological controls on TEX86, thereby strengthening its value for paleoceanography. The results may be relevant not only to climate studies, but also to understanding the importance of Archaea in tracing nutrient distributions and the biogeochemical history of the ocean. The central hypothesis of this research is that temperature errors in TEX86 are due to regional differences in growth rate for Archaea, which is a function of ammonia oxidation and therefore of marine export production. This implies that TEX86 is a combined temperature and marine biogeochemistry signal. The major analytical goal is to incorporate stable carbon and hydrogen isotopic information into TEX86 temperature proxy records, by measuring isotopic ratios for the individual TEX86 compounds (called iGDGTs). Isotopic measurements in tandem with temperature reconstruction will collectively allow productivity signals to be decoupled from temperature signals. Specifically, the work will examine three distinct records that are associated with major shifts in biogeochemical structuring of the ocean over different time scales. Record 1: the Pliocene-Pleistocene sapropel formation in the Mediterranean Sea, for which no significant fluctuations in mean ocean temperature but major temporal changes in the nutrient regime have been inferred. Record 2: the Pleistocene and Holocene Eastern Equatorial Pacific, a tropical environment lacking seasonality but showing secular changes in both temperature and productivity. Record 3: the Paleocene-Eocene Thermal Maximum (PETM) and its associated carbon isotope excursion. These three records collectively allow for separation of the major variables temperature and productivity. To achieve the goals, the research requires several novel methods: Spooling Wire Microcombustion-IRMS (SWiM-IRMS) for isotopic analysis of carbon, all-in-one HPLC-MS approaches to measuring TEX86 and UK37 simultaneously, and high-temperature GC-IRMS for isotopic analysis of hydrogen; advanced isotopic technologies therefore also play a role in this project. The project supports career development for a postdoctoral researcher.

要想更好地了解过去的气候，需要准确地重建海洋温度和生物生产力等因素。 其中一种古温度测定方法是“TEX 86代用指标”，它是根据保存下来的海洋微生物中的一个重要类别-海洋微生物的有机分子。 TEX 86记录对于研究过去1亿年的气候特别有价值，特别是在其他温度代用品不可用的古代温暖时期。虽然在现代海洋中，TEX 86预测的温度与实际观测的海表温度（SST）之间通常有很好的一致性，但TEX 86可能会产生显著的区域或季节性误差。在过去与海洋低氧水平相关的温室气候中也观察到了分歧;特别是，TEX 86有时预测在这样的间隔期间会出现更冷的温度，即使海洋实际上正在变暖。 为了提高对TEX 86温度记录的理解，该项目将研究TEX 86的环境和生态控制，从而加强其在古海洋学中的价值。这些结果可能不仅与气候研究有关，而且还有助于了解海洋营养盐分布和海洋地球化学历史的重要性。 本研究的中心假设是，温度误差在TEX 86是由于区域差异的增长率为dichroea，这是一个功能的氨氧化，因此海洋出口生产。这意味着TEX 86是一个温度和海洋地球化学组合信号。主要分析目标是通过测量单个TEX 86化合物（称为iGDGT）的同位素比率，将稳定的碳和氢同位素信息纳入TEX 86温度代用记录。 同位素测量与温度重建相结合将共同允许生产率信号与温度信号解耦。 具体来说，这项工作将检查三个不同的记录，这些记录与不同时间尺度上海洋地球化学结构的重大变化有关。 记录一：在地中海的上新世-更新世腐泥形成，没有显着的波动，平均海洋温度，但主要的时间变化的营养状况已被推断。 记录二：更新世和全新世东赤道太平洋，热带环境缺乏季节性，但显示长期变化的温度和生产力。 记录3：古新世-始新世热峰（PETM）及其碳同位素漂移。 这三个记录共同允许分离主要变量温度和生产率。 为了实现这些目标，该研究需要几种新的方法：用于碳同位素分析的线轴微燃烧IRMS（SWiM-IRMS），同时测量TEX 86和UK 37的多合一HPLC-MS方法，以及用于氢同位素分析的高温GC-IRMS;因此，先进的同位素技术也在该项目中发挥了作用。该项目支持博士后研究人员的职业发展。

项目成果

Comparison of Late Neogene U k′ 37 and TEX 86 Paleotemperature Records From the Eastern Equatorial Pacific at Orbital Resolution

东赤道太平洋新近纪晚期 U kâ2 37 和 TEX 86 古温度记录在轨道分辨率上的比较

• DOI: 10.1029/2020pa003858
• 发表时间: 2020
• 期刊: Paleoceanography and Paleoclimatology
• 影响因子: 3.5
• 作者: Lawrence, K. T.;Pearson, A.;Castañeda, I. S.;Ladlow, C.;Peterson, L. C.;Lawrence, C. E.
• 通讯作者: Lawrence, C. E.

Linking diatom-diazotroph symbioses to nitrogen cycle perturbations and deep-water anoxia: Insights from Mediterranean sapropel events

将硅藻-固氮菌共生与氮循环扰动和深水缺氧联系起来：来自地中海腐泥事件的见解

• DOI: 10.1016/j.epsl.2021.117110
• 发表时间: 2021
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Elling, Felix J.;Hemingway, Jordon D.;Kharbush, Jenan J.;Becker, Kevin W.;Polik, Catherine A.;Pearson, Ann
• 通讯作者: Pearson, Ann

Archaeal lipid biomarker constraints on the Paleocene-Eocene carbon isotope excursion

• DOI: 10.1038/s41467-019-12553-3
• 发表时间: 2019-10-04
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Elling, Felix J.;Gottschalk, Julia;Pearson, Ann
• 通讯作者: Pearson, Ann

Controls on the hydrogen isotope composition of tetraether lipids in an autotrophic ammonia-oxidizing marine archaeon

• DOI: 10.1016/j.gca.2023.04.033
• 发表时间: 2023-05
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: W. Leavitt;S. Kopf;Y. Weber;B. Chiu;J. McFarlin;F. Elling;S. Hoeft-McCann;A. Pearson

CO2-dependent carbon isotope fractionation in Archaea, Part I: Modeling the 3HP/4HB pathway

古细菌中 CO2 依赖性碳同位素分馏，第一部分：3HP/4HB 途径建模

• DOI: 10.1016/j.gca.2019.06.042
• 发表时间: 2019
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Pearson, Ann;Hurley, Sarah J.;Elling, Felix J.;Wilkes, Elise B.
• 通讯作者: Wilkes, Elise B.