Doctoral Dissertation Research: An Evaluation of Sedimentary Lipid Hydrogen Isotopes as an Arctic Precipitation Proxy

博士论文研究：沉积脂质氢同位素作为北极降水代理的评估

• 批准号: 1634118
• 负责人: Yarrow Axford
• 金额: $ 1.6万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2018-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1634118&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Evaluation; Sedimentary

This doctoral dissertation research project will characterize the distribution and hydrogen isotopic composition of plant biomarkers in lake sediments and modern plants to reconstruct past hydroclimate environments in the Arctic. By inferring the isotopic composition of past precipitation patterns and lake waters, this research will facilitate better modeling of the impacts of environmental change on Arctic ecosystems. Improved reconstruction of past hydroclimates will provide a more comprehensive understanding of the Arctic's atmospheric circulation responses to amplified thermal configurations. The project promises a significant STEM education component led by three early-career women that includes the engagement of several undergraduate students in research activities. In addition, the doctoral student will work with the PI on workshops for K-12 STEM teachers from Chicago and Evanston public schools to incorporate current scientific information into their educational materials. As a Doctoral Dissertation Research Improvement award, this award will provide support to enable a promising student to establish a strong independent research career.Existing paleoclimate records provide unique perspectives on how climate related to the hydrologic cycle varied temporally over the Arctic. However, there presently are insufficient data samples and inadequately calibrated proxies to confidently assess changes in hydroclimate. To facilitate improved reconstructions of past hydroclimate environments, the doctoral student will develop new methodologies for characterizing the distributions and hydrogen isotopic values of modern lipids in lake sediments and modern plants along an extensive latitudinal and climatic transect. Gas chromatography and mass spectrometry will be used on lake sediments cores to derive a dataset of plant biomarkers and their correlates (alkanes and acids.) Sedimentary leaf wax and aquatic plant lipid hydrogen isotopes will be measured and used to infer source water hydrogen isotopes by applying a fractionation correction. By answering fundamental questions about the characterization of lipid biomarkers and the relationship between lipid biomarkers and source water, the research will advance the broader application of using hydrogen lipid biomarkers as a paleohydrologic proxy in sedimentary archives.

本博士论文研究项目将描述湖泊沉积物和现代植物中植物生物标志物的分布和氢同位素组成，以重建北极过去的水文气候环境。通过推断过去降水模式和湖水的同位素组成，本研究将有助于更好地模拟环境变化对北极生态系统的影响。对过去水文气候的改进重建将使我们更全面地了解北极大气环流对放大热配置的响应。该项目承诺由三名早期职业女性领导一个重要的STEM教育组成部分，其中包括几名本科生参与研究活动。此外，该博士生将与PI合作，为来自芝加哥和埃文斯顿公立学校的K-12 STEM教师举办研讨会，将当前的科学信息纳入他们的教材中。作为博士论文研究改进奖，该奖项将为有前途的学生提供支持，使他们能够建立强大的独立研究事业。现有的古气候记录提供了独特的视角来研究北极地区与水文循环有关的气候如何在时间上发生变化。然而，目前没有足够的数据样本和不充分校准的代理来自信地评估水文气候的变化。为了更好地重建过去的水文气候环境，博士生将开发新的方法来表征湖泊沉积物和现代植物中现代脂质的分布和氢同位素值，沿着广泛的纬度和气候样带。气相色谱法和质谱法将用于湖泊沉积物岩心，以获得植物生物标志物及其相关物（烷烃和酸）的数据集。将测量沉积叶蜡和水生植物脂质氢同位素，并通过应用分馏校正来推断源水氢同位素。通过对脂质生物标志物表征及脂质生物标志物与源水关系等基础性问题的解答，将推动氢质生物标志物作为古水文指标在沉积档案中的广泛应用。