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.

对过去气候的良好理解需要准确地重建海洋温度和生物生产力等因素。 一种这样的古温方法是“ Tex86代理”，该方法基于Archaea保留的有机分子，古细菌是一类重要的海洋微生物。 Tex86的记录对于研究过去1亿年的气候特别有价值，尤其是在其他温度代理不可用的古代温暖事件中。尽管在现代海洋中，通常在Tex86预测的温度与实际观察到的海面温度（SST）之间有很好的一致性，但Tex86可能会产生重大的区域或季节性错误。在过去与海洋中低氧水平相关的温室气候中也观察到了分歧。特别是，即使海洋实际上在变暖，Tex86有时有时会预测在此类间隔的温度较低。 为了提高对Tex86温度记录的理解，该项目将检查Tex86的环境和生态控制，从而增强其对古文化的价值。结果不仅与气候研究有关，还与了解古细菌在追踪营养分布和海洋生物地球化学史中的重要性有关。 这项研究的中心假设是，Tex86中的温度误差是由于古细菌的生长速率的区域差异，这是氨氧化的函数，因此是海洋出口产生的函数。这意味着Tex86是一个合并的温度和海洋生物地球化学信号。主要的分析目标是通过测量单个Tex86化合物的同位素比（称为IGDGTS），将稳定的碳和氢同位素信息纳入Tex86温度代理记录中。 与温度重建的同位素测量值将共同使生产力信号与温度信号解耦。 具体而言，这项工作将检查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的三个不同的记录。 记录1：地中海中的上新世 - 偏世腐粉形成，为此，平均海洋温度没有明显的波动，但养分状态的临时变化很大。 记录2：更新世和全新世东部赤道太平洋，一种缺乏季节性但温度和生产力的世俗变化的热带环境。 记录3：古新世 - 新世热最大（PETM）及其相关的碳同位素偏移。 这三个记录共同允许分离主要变量的温度和生产率。 为了实现目标，研究需要几种新颖的方法：用于对碳的同位素分析，同位型碳微型固定企业（游泳企业），同时测量Tex86和UK37的同位素分析，以及高温GC-IRMS以用于氢化的同位素分析；因此，高级同位素技术也在该项目中发挥作用。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

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