Lipid Biomarker Isotopic Composition Changes during Early Diagenesis in Variable Biogeochemical Sediment Regimes - Implications for Carbon Cycling and Paleoceanography

详细的化学成分研究保存的脂质分子标记物（也称为分子“化石”或“指纹”）分布在水柱下沉的颗粒物质中，特别是随后在沉积物中，为我们了解海洋中有机碳的输入和加工提供了见解。越来越多的人认为，对古沉积物中特定脂质分子标记物的稳定碳同位素组成（d 13C）的解释可以作为约束过去海洋和气候条件的手段，甚至可以用来重建古大气二氧化碳混合比（pCO2）。PI将使用受控的实验室实验来模拟反映自然成岩过程的过程，测量同位素13C分馏对选定脂质的影响。这项研究将解决另一种默认假设，即成岩作用可以忽略不计。利用从富含13C标记的藻类培养物中获得的目标脂质生物标志物进行孵育实验，将在不同的生物地球化学环境中进行，包括：天然含氧和缺氧海水；模拟氧与缺氧和循环氧/缺氧沉积物-水界面；在有或没有大型动物的均质沉积物岩心中。沉积物中生物标志物“分子化石”的化合物特定同位素分析增强了对产生这些分子的海洋生物过去所经历的条件的理解。利用深海沉积物等自然档案中包含的脂质生物标志物信息是重建过去气候变化的关键，并有助于回答诸如地球气候变化的速度和程度等基本问题。

ABSTRACTOCE-0116786Detailed chemical composition studies of the distribution of preserved lipid molecular markers (also termed molecular 'fossils' or 'fingerprints') in the sinking particulate matter of water columns and especially subsequently in sediments provides insight to our understanding of the inputs and processing of organic matter carbon in the ocean. Interpretation of the stable carbon isotopic composition (d 13C) of specific lipid molecular markers in aged sedimentary deposits has increasingly been suggested as a means of constraining past ocean and climate conditions and even reconstructing paleo atmospheric carbon dioxide mixing ratios (pCO2). The PI will measure isotopic d 13C fractionation effects on selected lipids using controlled laboratory experiments to simulate processes reflecting those undergone during natural diagenesis. This investigation will address the otherwise default assumption that diagenetic effects are negligible. Incubation experiments using target lipid biomarkers obtained from enriched 13C labeled algal cultures will be conducted in different biogeochemical regimes including: natural oxic and anoxic seawaters; simulated oxic vs. anoxic and cycled oxic/anoxic sediment-water interfaces; and in homogenized sediment cores with and without macrofauna. Compound specific isotopic analysis of biomarker 'molecular fossils' in sediments enhances understanding of the past conditions experienced by the marine organisms producing such molecules. Use of lipid biomarker information contained in natural archives such as deep sea sediments is key in reconstructing past climate change and helps answer fundamental questions such as how fast and how much can the planet's climate change.