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

这项博士论文研究项目将表征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，这项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提供对北极大气环流对放大的热配置的反应的更全面的了解。该项目承诺了一个重要的STEM教育组成部分，由三名职业早期女性领导，其中包括让几名本科生参与研究活动。此外，这名博士生将与PI合作，为来自芝加哥和埃文斯顿公立学校的K-12 STEM教师举办讲习班，将当前的科学信息纳入他们的教育材料。作为博士论文研究改进奖，该奖项将为有前途的学生建立强大的独立研究生涯提供支持。现有的古气候记录为北极地区与水文循环有关的气候如何在时间上变化提供了独特的视角。然而，目前没有足够的数据样本和没有充分校准的指标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，这位博士生将开发新的方法，沿着广泛的纬度和气候样带表征湖泊沉积物和现代植物中现代脂肪的分布和氢同位素价值。将对湖泊沉积物岩心进行气相色谱和质谱分析，以得出植物生物标记物及其相关物质(烷烃和酸)的数据集。将测量沉积叶蜡和水生植物脂肪氢同位素，并通过应用分馏校正来推断源水氢同位素。通过回答脂肪生物标志物的表征以及脂肪生物标志物与源水的关系等基本问题，该研究将推动氢脂肪生物标志物在沉积档案中作为古水文代理的更广泛的应用。

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.