Name: sediment biomarkers for past climate records
Uploaded: 2023-04-30T06:49:01.000Z
Duration: 8 min 28 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

NC K-12 Science Standard Course of Study

9-12

Earth and Environmental Science

Earth's Systems

ESS.EES.3.3

an-overview-of-bgdgt-biomarker-analysis-for-paleoclimatology

An Overview of bGDGT Biomarker Analysis for Paleoclimatology

<div class="chapter_text" id="script_0">
一类称为生物标志物的有机化合物可在地球科学中用作古温度计，以揭示过去气候与环境的相关信息。
这些生物标志物由生物体产生，能够提供其生存环境的信息。它们可作为&#160;代用指标&#160;，告诉我们诸如数百万年前地球温度等历史事件的信息。
陆地古温度可通过淡水盆地沉积物中发现的生物标志物进行分析。其中一类关键的生物标志物是支链甘油二烷基甘油四醚，即支链GDGTs。
本视频将介绍古气候学这一研究领域，该领域探究数亿年来淡水环境的过去变化，有助于阐明当前及未来的气候与环境变化。
</div>
<div class="chapter_text" id="script_1">
在地质时间尺度上，由于流体运动和重力作用，沉积物会逐渐在沉积盆地（即地壳中的低洼区域）中堆积。沉积盆地包括海洋，其沉积物为海洋沉积物，以及湖泊，其沉积物为湖泊沉积物。海洋和湖泊盆地含有不同类型的生物体，这在很大程度上由两者之间盐度的差异所驱动。因此，海洋和湖泊盆地含有不同的生物标志物。
支链型GDGTs被认为是由厌氧酸杆菌产生的跨膜脂质。研究表明，产生这些脂质的生物体会根据温度变化调整其细胞膜的性质。
这种变化是由于在较低温度下，支链GDGTs上的甲基化位点转变为环化位点，从而增强细胞膜的流动性。这种结构上的变化可通过代用指标与温度相关联。代用指标是指可测量的物理现象，其与无法直接测量的变量存在相关性。
该代用指标将生物标志物中的甲基化数量（即MBT）和环化程度（即CBT）与温度关联起来。通过实验推导出的方程可将MBT和CBT与过去的年均气温相关联。
</div>
<div class="chapter_text" id="script_2">
为了研究支链GDGT生物标志物与土壤温度之间的关系，必须采集湖泊沉积物，通过三种技术之一进行提取、纯化并分析。
在开始研究支链GDGT生物标志物与土壤温度之间的关系时，首先需从湖泊沉积物中提取脂类分子，可采用多种技术。超声提取法是从沉积物样品中获取总脂质提取物（TLE）最简单且成本最低的方法。该方法使用超声水浴，在含有有机溶剂的小瓶中震荡样品。采用甲醇与二氯甲烷的混合液可提取具有广泛极性的生物标志物。另一种提取技术是索氏提取法。索氏提取器能够使有机溶剂从圆底烧瓶中加热后上升至冷凝管，在冷凝管中经冷水冷却后回流。冷凝后的溶剂滴入装有样品的玻璃纤维套管中。当溶剂充满提取室后，通过虹吸作用将有机溶剂回流至圆底烧瓶，从而实现长时间连续提取。
该方法适用于大量沉积物的提取，以及用于仪器校准的大体积标准品的制备。最后，加速溶剂萃取（ASE）是一种商标化的提取方法，利用高温和高压提高提取过程的动力学效率。ASE仪器最多可容纳24个独立样品，并允许对提取过程中的所有参数进行精确控制。由于其操作快速且简便，ASE通常被用作溶剂提取的标准方法。
</div>
<div class="chapter_text" id="script_3">
采用上述任一方法提取脂质样品后，需对其进行纯化，以备后续分析。通常使用硅胶柱色谱法根据样品的极性对其进行纯化。具体操作中，将少量细粉状硅胶（称为凝胶）装入小型玻璃柱中，随后用非极性溶剂（通常为正己烷）饱和该柱，再将样品加至柱顶。组分的分离基于目标化合物对固相或溶剂相的亲和力差异。
极性化合物（本例中为支链型甘油二烷基甘油四醚，GDGTs）对极性硅胶的亲和力强于对非极性正己烷的亲和力。因此，非极性化合物（如烃类）、中等极性化合物（如酮类和醇类）以及高极性化合物将在柱中以不同速率迁移，并随洗脱溶剂极性的逐步增加而依次被洗脱。
随后，将洗脱液按不同组分分别收集。
纯化后的GDGTs采用高效液相色谱-质谱联用技术（LC-MS）进行分析。LC-MS首先对化合物进行分离，再根据其质荷比进行检测分析。
通过测定目标质荷比离子峰曲线下的面积，可确定每种GDGT的相对浓度。MBT（甲基支链四醚指数）计算为第1组分子占总分子数的比例。
CBT（环化程度指数）则利用第1组和第2组分子，通过负对数形式计算得出。将MBT与CBT代入经实验标定的经验公式，即可推算出古温度值。
</div>
<div class="chapter_text" id="script_4">
利用生物标志物代用指标测定古温度在地球科学的多种应用中具有重要意义。
首先，古温度测定技术能够确定地球在长时间尺度上的温度变化。通过多种方法，科学家已将地球温度的估算追溯至5亿年前。这些数据揭示了不同生命形式演化所处的温度范围，并为研究过去温度对地球生物圈、水圈、岩石圈和大气圈的影响提供了依据，同时也为预测未来变化提供了参考。
近期地球温度的变化趋势也可通过古温度测定构建的记录进行量化。自1850年以来，地球表面温度已上升近1°C，且在过去二十年中变暖趋势尤为显著。为了理解人类活动对全球气候的影响，必须建立并利用准确的古气候记录作为背景依据。
</div>
<div class="chapter_text" id="script_5">
您刚刚观看了 JoVE 关于支链甘油二烷基甘油四醚古温度测定法的概述视频。您现在应该了解支链 GDGT 生物标志物的应用方法，以及提取和纯化这些化合物的整体技术。本系列的后续视频将更详细地介绍这一复杂过程。
感谢观看！
</div>

古气候学中支链甘油二烷基甘油二醇（bgdgt）生物标志物分析概述

来源：马萨诸塞大学阿默斯特分校 Jeff Salacup 实验室
在本系列视频中，研究人员提取并纯化了天然样品，以寻找一类称为生物标志物的有机化合物，这些化合物能够提供有关过去气候与环境的信息。所分析的样品之一是沉积物。沉积物在地质历史时期中不断堆积于盆地——即地球表面的凹陷区域，沉积物在流体（水或空气）运动和重力作用下被输送至此。盆地主要分为两种类型：海洋型（海洋和海）和湖泊型（湖泊）。可以预见，由于两者之间盐度差异显著，生存于这些环境中的生物类型也大不相同。在过去的几十年中，有机地球化学家发现了一系列生物标志物代用指标（即可用于表征气候或环境的化合物），其中一些适用于海洋环境，另一些则适用于湖泊环境。本文将重点关注湖泊环境中的支链型甘油二烷基甘油四醚（图1）。
本部分重点介绍利用支链甘油二烷基甘油四醚（图1；brGDGTs）及MBT/CBT代用指标对陆地古温度进行分析。该代用指标最初由Weijers et al.1 描述，其原理基于brGDGTs中环状结构和支链结构的分布特征。他们发现，支链四醚的环化程度（CBT）与土壤pH值直接相关。
CBT = -log ((Ib + IIb) / (I + II))
并且分支四醚的甲基化程度（MBT）由多年平均气温（MAAT）决定，受土壤pH值的影响较小。
MBT = (I + Ib + Ic) / (I + Ib + Ic) + (II + IIb + IIc) + (III + IIIb + IIIc)
因此，综合并校准后，MBT/CBT 将支链甘油二烷基甘油四醚（brGDGTs）的分布与土壤温度和 pH 值相关联。
MBT = 0.122 + (0.187 × CBT) + (0.020 × MAAT)
支链型GDGTs被认为是一类跨膜脂质，最初认为其由生活在土壤和泥炭中的厌氧酸杆菌门（Acidobacteria）细菌产生2-5，但后续研究提示它们也可能在富氧和缺氧的湖泊及海洋水体和沉积物中生成6-9。该假说认为，酸杆菌门细菌在温度降低时会将甲基化位点转化为环化结构，以增加不饱和度（环化实质上会移除两个氢原子），从而维持膜的流动性（类比而言，饱和脂肪（如黄油）在室温下呈固态，而不饱和脂肪（如橄榄油）则为液态）；然而，目前尚未在酸杆菌门的培养菌株中确认支链型GDGTs是其主要的膜脂成分。因此，其确切来源仍不明确。
将支链GDGTs与环境变量（温度、pH、盐度、降水等）进行校准是当前广泛研究的课题。全球各地的有机地球化学实验室正致力于建立支链GDGTs与（主要是）温度之间的全球1,10 和区域11-13校准关系。因此，上述方程正不断得到优化和完善。
通常从湖泊沉积物中提取支链GDGTs，尽管也已对近海海洋沉积物进行了研究。提取物需经过硅胶柱纯化，以去除其他可能不适用于液相色谱或在色谱过程中与GDGTs共洗脱的化合物。GDGTs在甲醇洗脱的极性组分中被洗出。
在总脂质提取物纯化后，将提取并纯化的样品通过高效液相色谱仪与化学电离质谱仪联用进行分析。通过专为此目的设计的计算机软件（如Agilent Chemstation），获取每种化合物所选质荷比（m/z；图1）离子峰的曲线下面积，从而确定GDGTs的相对浓度。然后将这些面积代入选定的校准方程，以获得古温度测定结果。
<img alt="支链GDGTs的示意图，显示其化学结构及质谱数据（m/z值）。" src="/files/ftp_upload/10256/10256fig1.jpg" data-altupdatedat="1761830439000" data-alt="图1"> 
图1. 用于通过MBT/CBT代用指标计算温度的支链GDGTs结构图（经Isla Castañeda博士许可使用，该图由其绘制）。<a href="https://www.jove.com/files/ftp_upload/10256/10256fig1large.jpg" target="_blank">请点击此处查看此图的放大版本。</a>
<div class="chapter_text" id="script_0">
被称为生物标志物的有机化合物可在地球科学中用作古温度计，以揭示过去气候与环境的信息。
生物体产生这些生物标志物，为我们提供其生存环境的相关信息。它们可以作为 代理 告诉我们有关过去事件的信息，例如数百万年前地球的温度。
陆地古温度可通过淡水盆地沉积物中发现的生物标志物进行分析。其中一类关键的生物标志物是支链型甘油二烷基甘油四醚（branched glycerol dialkyl glycerol tetraethers），即支链GDGTs。
本视频将介绍一个名为古气候学的研究领域，该领域探究数亿年来淡水环境的演变过程，有助于阐明当前及未来的气候与环境变化。
</div>
<div class="chapter_text" id="script_1">
在地质时间尺度上，由于流体运动和重力作用，沉积物会逐渐在沉积盆地（即地壳中的低洼区域）中堆积。沉积盆地包括海洋，其沉积物为海洋沉积物，以及湖泊，其沉积物为湖泊沉积物。海洋和湖泊盆地含有不同类型的生物体，这在很大程度上由两者之间盐度的差异所驱动。因此，海洋和湖泊盆地含有不同的生物标志物。
支链型GDGTs被认为是由厌氧酸杆菌产生的跨膜脂质。研究表明，产生这些脂质的生物体会根据温度变化调整其细胞膜的性质。
这种变化是由于在较低温度下，支链GDGTs上的甲基化位点转变为环化位点，从而增强细胞膜的流动性。这种结构上的变化可通过代用指标与温度相关联。代用指标是指可测量的物理现象，其与无法直接测量的变量存在相关性。
该代用指标将生物标志物中的甲基化数量（即MBT）和环化程度（即CBT）与温度关联起来。通过实验推导出的方程可将MBT和CBT与过去的年均气温相关联。
</div>
<div class="chapter_text" id="script_2">
为了研究支链GDGT生物标志物与土壤温度之间的关系，必须采集湖泊沉积物，通过三种技术之一进行提取、纯化并分析。
在开始研究支链GDGT生物标志物与土壤温度之间的关系时，首先需从湖泊沉积物中提取脂类分子，可采用多种技术。超声提取法是从沉积物样品中获取总脂质提取物（TLE）最简单且成本最低的方法。该方法使用超声水浴，在含有有机溶剂的小瓶中震荡样品。采用甲醇与二氯甲烷的混合液可提取具有广泛极性的生物标志物。另一种提取技术是索氏提取法。索氏提取器可实现有机溶剂从圆底烧瓶经加热回流，向上进入由冷水冷却的冷凝管后返回的连续循环过程。冷凝后的溶剂滴入装有样品的玻璃纤维套管中。当 chamber 装满后，通过虹吸作用将有机溶剂回流至圆底烧瓶，从而实现长时间的连续提取。
该方法适用于大量沉积物的提取，以及用于仪器校准的大体积标准品的制备。最后，加速溶剂萃取（ASE）是一种利用高温和高压以提高萃取过程动力学的专利萃取方法。ASE仪器最多可容纳24个独立样品，并允许对萃取过程中的所有参数进行精确控制。由于其操作快速且简便，ASE通常被用作溶剂萃取的标准方法。
</div>
<div class="chapter_text" id="script_3">
采用上述方法之一提取脂质样品后，需对其进行纯化，以备分析。通常使用硅胶柱色谱法根据样品的极性进行纯化。具体操作中，将少量细粉状硅胶（称为凝胶）装入小型玻璃柱中。随后用非极性溶剂（通常为正己烷）饱和该柱，再将样品加在柱顶。提取物的分离基于目标化合物对固相或溶剂相的亲和力差异。
极性化合物（本例中为支链型甘油二烷基甘油四醚，branched GDGTs）对极性硅胶的吸引力强于对非极性正己烷的吸引力。因此，非极性化合物（如烃类）、中等极性化合物（如酮类和醇类）以及高极性化合物会在柱中以不同速率迁移，并通过极性逐步增加的溶剂洗脱。
随后将洗脱液按不同组分分别收集。
纯化后的GDGTs随后采用高效液相色谱-质谱联用技术（LC-MS）进行分析。LC-MS首先对化合物进行分离，然后根据其质荷比进行分析。
通过测定所选质量离子色谱峰下的面积，可确定每种类型GDGT的相对浓度。MBT通过第1组分子占总分子数的比例计算得出。
CBT则利用第1组和第2组中的分子，通过负对数形式计算得到。将MBT和CBT代入经实验确定的经验公式，即可推算出古温度值。
</div>
<div class="chapter_text" id="script_4">
利用生物标志物代用指标测定古温度在地球科学的多个应用领域中具有重要意义。
首先，古温度测定技术能够确定地球在长时间尺度上的温度变化。通过多种方法，科学家已将地球温度的估算追溯至5亿年前。这些数据揭示了不同生命形式演化所处的温度范围，并为研究过去温度对地球生物圈、水圈、岩石圈和大气圈的影响提供了依据，同时也为预测未来变化提供了参考。
利用古温度测定构建的记录还可对近期地球温度变化趋势进行量化。自1850年以来，地球表面温度已上升近1°C，且在过去二十年中变暖趋势尤为显著。为了理解人类活动对全球气候的影响，必须建立并利用准确的古气候记录作为背景依据。
</div>
<div class="chapter_text" id="script_5">
您刚刚观看了 JoVE 关于支链甘油二烷基甘油四醚古温度测定法的概述视频。您现在应该了解支链 GDGT 生物标志物的应用方法，以及提取和纯化这些化合物的整体技术。本系列的后续视频将更详细地介绍这一复杂过程。
感谢观看！
</div>

古气候学中支链甘油二烷基甘油二醇（bGDGT）生物标志物分析概述

来源：马萨诸塞大学阿默斯特分校 Jeff Salacup 实验室  
在本系列视频中，天然样品被提取并……

被称为生物标志物的有机化合物可在地球科学中用作古温度计，以揭示过去气候和环境的相关信息。生物体产生这些生物标志物，为我们提供其生存环境的相关信息。它们可作为“代用指标”，告诉我们过去事件的信息，例如数百万年前地球的温度。利用淡水盆地沉积物中发现的生物标志物可以分析陆地古温度。其中一类关键的生物标志物是支链型甘油二烷基甘油四醚，即支链GDGTs。本视频将介绍一个名为古气候学的研究领域，该领域探究数亿年来淡水环境的过去变化，有助于阐明当前及未来的气候与环境变化。沉积物由于流体运动和重力作用，在地质时间内逐渐堆积于沉积盆地或地壳中的低洼区域。沉积盆地包括海洋，其汇集海洋沉积物，以及湖泊，其汇集湖泊沉积物。海洋和湖泊盆地含有不同类型的生物体，这在很大程度上由两者之间盐度的差异所决定。因此，海洋和湖泊盆地含有不同的生物标志物。支链GDGTs被认为属于厌氧酸杆菌的跨膜脂质。研究表明，产生这些脂质的生物体会根据温度变化调整其细胞膜特性。这种变化是由于在较低温度下，分支型 GDGT 上的甲基化位点转变为环化位点，从而增强了膜的流动性。这种结构变化随后可通过代用指标与温度相关联。代用指标是指可测量的物理现象，其与无法直接测量的变量存在相关性。该代用指标将生物标志物中甲基化数量（MBT）与环化反应数量（CBT）与温度关联起来。通过实验得出的方程可将MBT和CBT与过去的年均气温相关联。为了研究支链GDGT生物标志物与土壤温度之间的关系，必须采集湖泊沉积物，采用三种技术之一进行提取，纯化并分析。为了开始研究支链GDGT生物标志物与土壤温度之间的关系，首先需要从湖泊沉积物中提取脂类分子，可采用多种技术进行提取。通过超声处理进行提取是从沉积物样品中获得总脂质提取物（TLE）最简单且成本最低的方法。该方法使用超声水浴使含有有机溶剂的小瓶中的样品产生振动。采用甲醇与二氯甲烷的混合液可提取具有广泛极性的生物标志物。另一种提取技术是索氏提取法。索氏提取器能够使有机溶剂从圆底烧瓶中加热蒸发，上升至冷凝管，在冷凝管中被冷水冷却后回流。冷凝后的溶剂滴入装有样品的玻璃纤维套管中。当溶剂充满提取室时，装置通过虹吸作用将有机溶剂重新排回圆底烧瓶，从而实现长时间的连续提取。该技术有助于提取大量沉积物，并制备用于仪器校准的大体积标准样品。最后，加速溶剂萃取（Accelerated Solvent Extraction，简称ASE）是一种利用高温和高压以提高萃取过程动力学的专利萃取方法。ASE仪器最多可容纳24个独立样品，能够精确控制萃取过程中的所有参数。由于其操作快速且简便，ASE通常被用作溶剂萃取的标准方法。采用上述方法之一提取脂质样品后，需对其进行纯化，以备分析之用。通常使用硅胶柱层析法根据脂质的极性对其进行纯化。具体操作中，将少量细粉状硅胶（称为凝胶）装入小型玻璃柱中。随后用非极性溶剂（通常为正己烷）饱和该柱，再将样品加在柱顶。提取物的分离基于目标化合物对固相或溶剂相的亲和力差异。极性化合物在此情况下为支链GDGTs，比非极性正己烷更易被极性硅胶吸附。因此，非极性化合物（如烃类）、中等极性化合物（如酮类和醇类）以及强极性化合物会以不同的速率沿色谱柱移动，并随着溶剂极性的增加而依次洗脱。然后将洗脱液收集到不同的组分中。纯化的GDGT随后采用高效液相色谱-质谱联用技术（LC-MS）进行分析。LC-MS首先对化合物进行分离，然后根据其质荷比进行分析。这使得能够通过选定质荷比离子的峰面积来确定每种GDGT的相对浓度。MBT被计算为第1组分子占总量的比例。然后使用第1组和第2组中的分子，通过负对数计算得到CBT。随后将MBT和CBT代入基于实验得出的方程，以获得古温度的测定结果。利用生物标志物代用指标测定古温度在地球科学的多种应用中具有重要意义。首先，古温度测定法能够确定地球在长时间尺度上的温度变化。利用多种技术，科学家已将地球温度的估算追溯至5亿年前。这些数据揭示了不同生命形式演化所处的温度范围，并为研究过去温度对地球生物圈、水圈、岩石圈和大气圈的影响提供了依据，同时也可推演其对未来的影响。利用古温度测量技术构建的记录，也可以对地球温度的近期变化趋势进行量化。自1850年至今，地球表面温度已升高了近1度，其中过去二十年的变暖趋势尤为显著。为了理解人类活动对全球气候的影响，必须建立并利用准确的古气候记录作为背景依据。您刚刚观看了 JoVE 关于支链甘油二烷基甘油四醚古温度测定法的概述视频。您现在应该了解支链 GDGT 生物标志物的应用方式，以及提取和纯化这些标志物的整体技术。本系列的后续视频将更详细地介绍这一复杂过程。感谢观看！

Education

教育

JoVE Science Education

Environmental Sciences

环境科学

Earth Science

地球科学

概述了 bGDGT 古气候学的生物标志物分析

sediment biomarkers for past climate records

Sediment biomarkers can record past climate conditions, and branched GDGTs are one example used to study temperature in freshwater basins. These organic compounds are extracted from natural samples, purified, and then measured to help reconstruct environments from the past. In paleoclimatology, scientists use these records to better understand climate change over time.

Sediments build up over geologic time in sedimentary basins, which are low areas in the Earth’s crust where material is carried by water, air, movement, and gravity. Two main basin types are marine basins, such as oceans and seas, and lacustrine basins, such as lakes. Because these settings support different organisms and often differ in salinity, they contain different biomarkers.

Branched glycerol dialkyl glycerol tetraethers, or branched GDGTs, are studied in lacustrine sediment as paleothermometers. They are linked to the MBT/CBT proxy, which uses the number of methylation and cyclization features in the molecules. CBT, or cyclization of branched tetraethers, has been related to soil pH, while MBT, or methylation of branched tetraethers, is linked mainly to mean annual air temperature and also to soil pH.

Branched GDGTs are thought to be membrane-spanning lipids made by anaerobic Acidobacteria, which are bacteria found in soils and peat. Some research also suggests these compounds can form in oxic and anoxic lake and marine water columns and sediments. Scientists think colder conditions may shift methylated sites toward cyclized sites to help maintain membrane fluidity, but the exact source of the lipids is still not fully known.

To study these biomarkers, lacustrine sediments are collected, extracted, purified, and analyzed. The total lipid extract can be obtained by sonication, Soxhlet extraction, or accelerated solvent extraction, also called ASE. Sonication is the simplest and least expensive method, Soxhlet uses continuous solvent cycling, and ASE uses high temperature and pressure and is often used as the standard method because it is fast and easy to control.

After extraction, the sample is usually purified with silica gel column chromatography. In this step, the sample moves through silica using solvents of increasing polarity. Polar branched GDGTs are retained differently from apolar, mid-polar, and highly polar compounds, so the eluents are collected in separate fractions. The purified GDGTs are then ready for analysis.

The final measurement uses high performance liquid chromatography coupled to mass spectrometry, or LC-MS. This method separates the compounds and measures them by mass-to-charge ratio, or m/z. The relative abundance of each GDGT is calculated from the area under the curve for the selected ion, and those values are entered into the calibration equation to estimate paleotemperature.

Branched GDGT paleothermometry helps scientists estimate Earth’s temperature over very long time spans. Temperature records have been reconstructed as far back as 500 million years, which helps show the range of conditions in which life evolved. These records also provide context for modern warming, including the rise in Earth’s surface temperature since 1850 and the stronger warming trend seen in recent decades.

Sediment Biomarkers for Past Climate Records

lacustrine-bgdgt-climate-records-analysis

determining spatial orientation of rock layers with the brunton compass

determining-spatial-orientation-rock-layers-with-brunton

Measuring Rock Layer Strike and Dip

The Brunton compass is used to measure the spatial orientation of rock layers and other rock features. Many rock units show planar surfaces or linear features. These include bedding surfaces, fault surfaces, fracture surfaces, joint surfaces, foliation, and mineral alignment. These measurements give geologists the raw data they need to study how rock units formed and how they changed over time. The directions are recorded as strike and dip. Strike is the direction of a flat surface, and dip...

using topographic maps to generate topographic profiles

using-topographic-maps-to-generate-topographic-profiles

Reading Contour Lines on Topographic Maps

Topographic maps show Earth’s surface in a plan view, which means an overhead view. They give a clear look at land shape from above. These maps are a standard way to represent three-dimensional terrain on a flat page. Contour lines are the key feature of a topographic map. Each line connects places with the same elevation, or height above sea level. The spacing between contour lines is called the elevation interval, and it depends on how much detail the map shows and on the land itself. <br...

making a geologic cross section

Reading Geologic Maps in 3D

Geologic maps show rock units at Earth’s surface and help geologists infer what lies below it. They began in Europe in the mid-to-late 18th century and have since become a key tool for studying rock distribution, subsurface structure, and changes through time. A modern geologic map is a data-rich, two-dimensional plan view built on a topographic map. On these maps, color variations mark specific rock units. The lines where one unit meets another are called contacts. Geologic maps also use...

physical properties of minerals i: crystals and cleavage

physical-properties-of-minerals-i-crystals-and-cleavage

Mineral Crystal Shapes and Cleavage

Mineral crystal shapes and cleavage reveal how a mineral is built at the atomic level. These physical properties are measurable and visible traits that help identify minerals. They include color, streak, magnetic properties, hardness, crystal growth form, and crystal cleavage. Each of these properties is specific to a mineral. They are tied to the mineral’s chemical make-up and atomic structure. Crystal growth form and crystal cleavage both come mainly from the repeated pattern of basic atomic...

physical properties of minerals ii: polymineralic analysis

physical-properties-of-minerals-ii-polymineralic-analysis

Mineral Clues for Rock Identification

Mineral color, streak, luster, hardness, magnetism, and acid reaction help identify minerals and rocks. These physical properties can be seen or measured in hand samples and in the field. They are tied to a mineral’s chemical makeup and, to a lesser extent, its atomic structure. The video also explains why these clues work for rocks as well as minerals. Rocks are made of mineral grains, and most rocks contain more than one mineral type, which means they are polymineralic. Some rocks are...

igneous volcanic rock

How Volcanic Rock Forms From Lava

Volcanic rock forms when magma reaches Earth’s surface and cools. It is a type of igneous rock, which means it comes from cooling and crystallization of molten material. When magma is on the surface, it is called lava. Magma is molten rock that is usually between about 800 °C and 1,200 °C. It forms inside Earth through three main melting processes. These are the addition of heat, the addition of volatiles, and decompression. Each way of making magma can produce a different kind of magma. That...

igneous intrusive rock

Magma Cooling and Igneous Rock

Igneous rocks form when hot liquid rock, called magma, cools and crystallizes. Magma temperatures typically range from about 800 °C to 1,200 °C. These rocks record the freezing of molten material inside Earth.

an overview of bgdgt biomarker analysis for paleoclimatology

Sediment biomarkers can record past climate conditions, and branched GDGTs are one example used to study temperature in freshwater basins. These organic compounds are extracted from natural samples, purified, and then measured to help reconstruct environments from the past. In paleoclimatology, scientists use these records to better understand climate change over time. Sediments build up over geologic time in sedimentary basins, which are low areas in the Earth’s crust where material is...

an overview of alkenone biomarker analysis for paleothermometry

an-overview-of-alkenone-biomarker-analysis-for-paleothermometry

Sea Surface Temperature from Alkenone Ratios

Sea surface temperature can be reconstructed from alkenone ratios preserved in marine sediment. Alkenones are long-chain, unsaturated alkyl ketones made by some haptophyte algae, especially coccolithophores such as Emiliania huxleyi and Gephyrocapsa oceanica in the open ocean. The most widely used proxy is the U K'37 index, which compares the C37:2 and C37:3 alkenones. Because the ratio changes with growth temperature, it can be used to estimate past sea surface temperature. The U K'37 proxy...

sonication extraction of lipid biomarkers from sediment

sonication-extraction-of-lipid-biomarkers-from-sediment

How Organic Carbon Becomes Biomarkers

Organic material and inorganic material are chemically different. In an ecosystem, living material includes leaves, fungi, bark, and tissue. Non-living material includes rocks, their minerals, oxygen, water, and metals. Organic matter contains carbon linked to other carbon and hydrogen molecules, which sets it apart from inorganic matter. Carbon is especially flexible in the kinds of bonds it can form. Its valence range from -4 to +4 lets it make up to four separate covalent bonds with nearby...

soxhlet extraction of lipid biomarkers from sediment

soxhlet-extraction-of-lipid-biomarkers-from-sediment

Large-Volume Sediment Extraction for Standards

Large-volume sediment extraction is used to isolate compounds for chemical standards. These standards help labs track the performance, accuracy, and precision of instruments over time. That way, a measurement made today can be compared with one made a year later. Because standards must be checked over long periods, labs often need large amounts of material. Many chemical standards can be bought from companies such as Sigma-Aldrich and Fisher. But some natural compounds needed for paleoclimatic...

extraction of biomarkers from sediments - accelerated solvent extraction

extraction-of-biomarkers-from-sediments-accelerated-solvent-extraction

Sediment biomarkers can help scientists reconstruct past air and water temperatures. In this method, a group of organic biomarkers called glycerol-dialkyl glycerol-tetraethers, or GDGTs, is studied in modern sediments and in older sediment layers of known age. GDGTs are produced by a suite of archaea and bacteria. Their distribution changes in a predictable way in response to temperature. That pattern lets researchers use sediment records to track how climate changed over time. These...

conversion of fatty acid methyl esters by saponification for uk'37 paleothermometry

conversion-fatty-acid-methyl-esters-saponification-for-uk-37

Saponification for Cleaner GC-FID Analysis

Saponification helps clean up complex lipid samples before gas chromatography analysis. A total lipid extract, or TLE, from an organic solvent extraction can contain hundreds or even thousands of compounds. Researchers may only need a few target compounds. They may also need to remove unwanted material that gets in the way or co-elutes, meaning it comes off the gas chromatograph at the same time as another compound. This sample cleanup supports measurement on a gas chromatograph coupled to a...

purification of a total lipid extract with column chromatography

purification-of-a-total-lipid-extract-with-column-chromatography

Separating Lipid Classes by Column Chromatography

Column chromatography is used to separate lipid classes in a total lipid extract. A total lipid extract, or TLE, is often a complex mixture made up of hundreds or even thousands of compounds. Researchers may only need a few target compounds, so they remove the compounds they are not studying. Those target compounds can belong to different classes, including alkanes, ketones, alcohols, and acids. In some studies, a sample may contain many compounds, but only a small set matters for analysis.

removal of branched and cyclic compounds by urea adduction for uk'37 paleothermometry

removal-branched-cyclic-compounds-urea-adduction-for-uk-37

Urea Adduction Separates Lipid Shapes

Urea adduction separates straight-chain lipids from branched and cyclic compounds in a total lipid extract. Researchers use this step when they want only a small set of target molecules from a sample that may contain hundreds or even thousands of compounds. For paleothermometry, the target compounds are the alkenones used in U k'37 and the isoprenoidal glycerol dialkyl glycerol tetraethers, or GDGTs, used in MBT/CBT. Together, these organic paleothermometers depend on only six compounds: two...

earth science

该系列专题包括地质学、地球化学等。各种示范, 包括矿物的物理化学性质和岩石形成的分析。

Learn how branched GDGTs in lake sediments are extracted, purified, and measured with LC-MS to reconstruct past temperature and climate records.

Sediment Biomarkers for Past Climate Records | JoVE K12

Pennsylvania State Academic Standards

Earth and Space Science

Human Sustainability

3.3.9-12.M

Louisiana Student Standards for Science

High School

Earth’s Systems

HS-ESS2-4

HS-ESS3-6

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Physical Geology

Minerals

properties-minerals-hardness-luster-cleavage-streak-crystal-shape

Properties of minerals (hardness, luster, cleavage, streak, crystal shape, fluorescence, flammability, density/specific gravity, malleability)

Earth's History

The geologic rock record

Plate Tectonics

Historical review

Glacial Geology

Glaciers and glaciation

Virginia  Standards of Learning

HIgh School

ES.5

ES.5.a

ES.10

ES.10.d

Texas Essential Knowledge and Skills

Earth Systems Science

112.49.c.11

112.49.c.11.E.

Alabama Course of Study Science

9-12.ESS.2.5.d

9-12.ESS.2.6.a

Next Generation Science Standards

Earth’s Place in the Universe

HS-ESS1-6

Florida Department of Education

SC.912.E.7

SC.912.E.7.7

new-york-state-science-learning-standards

New York State Science Learning Standards

Physical Science

HS. Structure and Properties of Matter

HS-PS1-10.

HS. Waves and Electromagnetic Radiation

HS-PS4-5.

Life Science

matter-and-energy-in-organisms-and-ecosystems

Matter and Energy in Organisms and Ecosystems

HS-LS1-6.

HS-LS2-4.

Earth and Space Sciences

History of Earth

HS-ESS1-6.

HS-ESS2-6.

HS-ESS2-7.

Jeff Salacup

Overview

Principles of Branched Glycerol Dialkyl Glycerol Tetraether Biomarkers

Branched GDGT Extraction

Biomarker Purification and Analysis

Applications

Summary

Igneous Volcanic Rock

Source: Laboratory of Alan Lester - University of Colorado Boulder
Igneous rocks are the products of cooling and crystallization of magma. Volcanic rocks ...

The Carbon Cycle

Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among ...

Igneous Intrusive Rock

Source: Laboratory of Alan Lester - University of Colorado Boulder
Igneous rocks are products of the cooling and crystallization of high temperature ...

Using Topographic Maps to Generate Topographic Profiles

Source: Laboratory of Alan Lester - University of Colorado Boulder
Topographic maps are &#34;plan-view&#34; representations of Earth&#39;s ...

Determining Spatial Orientation of Rock Layers with the Brunton Compass

Source: Laboratory of Alan Lester - University of Colorado Boulder
Most rock units exhibit some form of planar surfaces or linear features. Examples ...

Making a Geologic Cross Section

Source: Laboratory of Alan Lester - University of Colorado Boulder
Geologic maps were first made and utilized in Europe, in the mid-to-late 18th century. ...

Use models to explain how mantle convection powers plate tectonics.

ESS.EES.2.1

Analyze and interpret data to predict locations of volcanoes and earthquakes based on plate boundaries.

ESS.EES.2.2

An Overview of Alkenone Biomarker Analysis for Paleothermometry

Source: Laboratory of Jeff Salacup&#160;- University of Massachusetts Amherst
Throughout this series of videos, natural samples were extracted and ...

Topographic Surveying and Contours

Topographic surveying is critical for documenting the Earth's surface, focusing on capturing elevations, slopes, and natural and man-made features. It is ...

Plotting of Topographic Maps

Topographic maps represent the Earth's surface features using contour lines, which connect points of equal elevation to create a two-dimensional ...

Methods of Obtaining Topography

Topography involves measuring and mapping land elevations, natural features, and artificial structures to create accurate representations of the terrain. ...

Use models to explain how plate tectonics influence topography.

ESS.EES.2.3

The Soil Ecosystem

Plants obtain inorganic minerals and water from the soil, which acts as a natural medium for land plants. The composition and quality of soil depend not ...

Conditions on Early Earth

What are Biogeochemical Cycles?

The most common elements in organic molecules, carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus, are only available in the ecosystem in limited ...

The Water Cycle

The Earth&rsquo;s hydrosphere includes all of the areas where the storage and movement of water occurs. Since water is the basis of all living processes, ...

The Nitrogen Cycle

Nitrogen atoms, present in all proteins and DNA, are recycled between abiotic and biotic components of the ecosystem. However, the primary form of ...

The Phosphorus Cycle

Unlike carbon, water, and nitrogen, phosphorus is not present in the atmosphere as a gas. Instead, most phosphorus in the ecosystem exists as compounds, ...

The Sulfur Cycle

Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the ...

Bioremediation

Bioremediation is the use of prokaryotes, fungi, or plants to remove pollutants from the environment. This process has been used to remove harmful toxins ...

Carry out investigations to explain how the rock cycle and rates of weathering, erosion, and soil formation influence Earth's systems.

ESS.EES.2.4

What is Climate?

Climate refers to the prevailing weather conditions in a specific area over an extended period. As the saying goes, &#8220;Climate is what you expect. ...

What is Weather?

Overview

Weather refers to the current state of atmospheric conditions at a specific time and place. Weather is temporary and is influenced by the ...

Variation of Atmospheric Pressure

Change in atmospheric pressure with height is particularly interesting. The decrease in atmospheric pressure with increasing altitude is due to the ...

/files/media/science-education/science-education-thumbs/14711.jpg

Analyze and interpret data to explain how volcanic activity influences changes in Earth's atmosphere, geosphere, biosphere, and hydrosphere.

ESS.EES.2.5

Analyze how the geosphere is shaped by plate tectonics and the rock cycle.

Sediment Biomarkers for Past Climate Records

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