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.

对过去气候的良好了解需要准确重建海洋温度和生物生产力等因素。 其中一种古温度方法是“TEX86 proxy”，它基于古生菌（一类重要的海洋微生物）保存的有机分子。 TEX86 记录对于研究过去 1 亿年的气候特别有价值，特别是在其他温度指标无法获得的古代温暖时期。尽管在现代海洋中，TEX86 预测的温度与实际观测到的海面温度 (SST) 之间通常具有良好的一致性，但 TEX86 可能会产生显着的区域或季节误差。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，尽管海洋实际上正在变暖，但 TEX86 有时会预测在这样的时间间隔内气温会变冷。 为了增进对 TEX86 温度记录的了解，该项目将研究 TEX86 的环境和生态控制，从而增强其古海洋学价值。这些结果可能不仅与气候研究相关，而且还有助于了解古细菌在追踪海洋营养物分布和生物地球化学历史方面的重要性。 这项研究的中心假设是，TEX86 中的温度误差是由于古细菌生长速率的区域差异造成的，古细菌生长速率是氨氧化的函数，因此也是海洋出口生产的函数。这意味着 TEX86 是温度和海洋生物地球化学信号的组合。主要分析目标是通过测量各个 TEX86 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 TEX86 温度代理记录中。 同位素测量与温度重建相结合将共同使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生物地球化学结构的重大变化相关。 记录1：地中海上新世-更新世腐泥形成，平均海洋温度没有显着波动，但营养状况发生了重大时间变化。 记录2：更新世和全新世赤道东太平洋，热带环境，缺乏季节性，但温度和生产力都呈现长期变化。 记录 3：古新世-始新世热最大值 (PETM) 及其相关的碳同位素偏移。 这三个记录共同允许将主要变量温度和生产率分开。 为了实现这些目标，该研究需要几种新颖的方法：用于碳同位素分析的绕线微燃烧-IRMS (SWiM-IRMS)、同时测量 TEX86 和 UK37 的一体化 HPLC-MS 方法，以及高温 GC-用于氢同位素分析的 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

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.

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