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

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。 通过推断过去的降水模式和湖泊沃茨的同位素组成，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。 改进过去的水文气候重建将提供一个更全面的了解北极的大气环流放大热配置的反应。 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，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育材料。 作为博士论文研究改进奖，该奖项将提供支持，使有前途的学生建立一个强大的独立的研究生涯。现有的古气候记录提供了独特的视角如何气候相关的水文循环变化的时间在北极。 然而，目前没有足够的数据样本和不适当的校准代理，以自信地评估水文气候的变化。 为了促进改善过去的水文气候环境的重建，博士生将开发新的方法来表征现代脂质在湖泊沉积物和现代植物沿着广泛的纬度和气候样带的分布和氢同位素值。 将在湖泊沉积物岩心上使用气相色谱和质谱法，以获得植物生物标志物及其相关物（烷烃和酸）的数据集。 将测量沉积物叶蜡和水生植物脂氢同位素，并通过分馏校正用于推断源水氢同位素。 通过回答有关脂质生物标志物的表征以及脂质生物标志物与水源水之间的关系的基本问题，该研究将推进使用氢脂质生物标志物作为沉积档案中的古水文代用品的更广泛应用。

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.