Further Test for Stable Carbon Isotopic Fractionation of Biomarkers during Diagenetic Processes and Examination of Possible Causes

成岩过程中生物标志物稳定碳同位素分馏的进一步测试和可能原因的检查

• 批准号: 0526111
• 负责人: Ming-Yi Sun
• 金额: $ 44.87万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0526111&HistoricalAwards=false
• 关键词: Further; Test; Stable; Carbon; Isotopic

ABSTRACTOCE-0526111The stable carbon isotopic composition of biomarkers has been widely used to study global carbon cycling and the paleoceanographic record. Among specialists, however, there has been substantial disagreement regarding the impact of diagenetic processes on the carbon isotopic signatures of sedimentary biomarkers. Assumptions abound, but there have been few actual studies to determine how and to what extent the carbon isotopic composition of biomarkers derived from terrestrial higher plants can change during diagenesis. In this study, researchers at the University of Georgia will attempt to assess and to identify the major processes by which the C isotopic composition of plant-derived biomarkers changes during sedimentary diagenesis. There are two primary objectives. The first is to study stable carbon fractionation of various lignin-derived phenol biomarkers from C3 and C4 vascular plants during degradation by incubating natural plant materials in different environmental regimes. The second goal is to test two specific hypotheses related to isotopic fraction mechanisms: (1) that the intrinsic carbon fractionation at a reaction site of a molecule may be kinetics-dependent and responsible for the most of molecular isotopic alteration during degradation, but the heterogeneous 13C distributions within molecules (between reaction and non-reaction sites) may significantly affect the molecular isotopic fractionation; and (2) that the same biomarker molecules bound in different intracellular components (e.g., cell membrane vs. metabolic storage tissue) may carry distinct carbon isotopic compositions because they are biosynthesized at different growth stages, which may result in molecular fractionation when they degrade at different rates and through different pathways.This research could have a number of broader impacts in the fields of organic geochemistry, chemical sedimentology and paleoceanography. Results from this study could potentially set a new criterion for evaluating the applicability of aquatic and terrestrial plant-derived biomarkers and their isotopic compositions in carbon cycling and sedimentary record. Comprehensive understanding for current cycling and past record will help the scientific community to predict the trend of global climate change. The project will also provide for the support and training of a postdoctoral associate and of graduate and undergraduate students. The principal investigator also plans to involve summer high-school interns in this research program.

生物标志物的稳定碳同位素组成已被广泛应用于全球碳循环和古海洋学记录的研究。 然而，在专家中，关于成岩过程对沉积生物标志物的碳同位素特征的影响存在很大分歧。 假设很多，但很少有实际的研究，以确定如何以及在何种程度上来自陆生高等植物的生物标志物的碳同位素组成在成岩作用期间可以改变。 在这项研究中，格鲁吉亚大学的研究人员将试图评估和确定沉积成岩作用期间植物源生物标志物的碳同位素组成变化的主要过程。 有两个主要目标。 第一个是研究稳定的碳分馏的各种木质素衍生的酚生物标志物从C3和C4维管植物降解过程中孵育天然植物材料在不同的环境制度。第二个目标是验证与同位素分馏机制相关的两个具体假设：（1）分子反应位点的本征碳分馏可能是动力学依赖的，并且是降解过程中大部分分子同位素变化的原因，但分子内13 C分布的不均匀性（反应位点和非反应位点之间）可能显着影响分子同位素分馏;和（2）相同的生物标志物分子结合在不同的细胞内成分中（例如，细胞膜与代谢储存组织）可能携带不同的碳同位素组成，因为它们在不同的生长阶段生物合成，当它们以不同的速率和通过不同的途径降解时，这可能导致分子分馏。 该研究结果可能为评价水生和陆生植物源生物标志物及其同位素组成在碳循环和沉积记录中的适用性提供新的标准。 全面了解目前的自行车运动和过去的记录，将有助于科学界预测全球气候变化的趋势。 该项目还将为一名博士后助理以及研究生和本科生提供支助和培训。 首席研究员还计划让暑期高中实习生参与这项研究计划。