Collaborative Research: Investigation of pCO2 Changes Since the Pliocene Based on Alkenone Carbon Isotopes

合作研究：基于烯酮碳同位素的上新世以来pCO 2变化Mark帕加尼/A. Christina RaveloYale University/UC Santa Cruz摘要该提案旨在重建过去500万年上新世/更新世气候转变的大气pCO 2，这将提供一个框架来测试上新世-更新世气候转变的可能原因。该提案的主要目的是检验上新世早期温暖期的变暖模式以及随后的冷却是由pCO 2的相应增加和减少所迫使的假设。PI将通过重建藻类光合作用（Ep）期间发生的总碳同位素分馏记录来评估pCO 2变化。该方法将提取和确定从全球分布的DSDP和ODP岩心中获得的附着菌衍生的长链酮生物标志物（烯酮）的碳同位素（d13 C）值。此外，碳同位素和镁/钙组成的一个或多个物种的浮游有孔虫将从同一个样本进行分析，以限制海水和表面温度的碳同位素组成的变化。之间的差异d13 C的烯酮和同时代的近地表居住的浮游有孔虫表示近似的碳同位素分馏过程中发生的光合作用碳固定特定的烯酮生产haptophytes藻类。该技术已被用于重建新生代期间pCO 2变化的幅度，并被认为是目前可用的最可靠的古pCO 2代理之一。更广泛的影响包括美国两个主要机构之间的双边合作，两名本科生和一名博士后参与该项目，PI帕加尼参与了一个初中和高中教育项目，该项目将把这项研究的结果纳入该项目的学生和实习生的演讲中。

Collaborative Research: Investigation of pCO2 Changes Since the Pliocene Based on Alkenone Carbon IsotopesMark Pagani/A. Christina RaveloYale University/UC Santa CruzAbstractThis proposal seeks to reconstruct atmospheric pCO2 across the Pliocene/Pleistocene climate transition of the last 5 million years, which will provide a framework to test possible causes of the Plio-Pleistocene climatic transition. The primary objective of this proposal is to test the hypothesis that the pattern of warming during the early Pliocene warm period, as well as the subsequent cooling, was forced by a corresponding increase and decrease in pCO2. The PI's will evaluate pCO2 changes by reconstructing records of the total carbon isotopic fractionation that occurs during algal photosynthesis (Ep). The approach will be to extract and determine the carbon isotopic (d13C) values of haptophyte-derived long-chain ketone biomarkers (alkenones) obtained from a globally distributed set of DSDP and ODP cores. In addition, the carbon isotopic and Mg/Ca composition of one or more species of planktonic foraminifers will be analyzed from the same sample to constrain changes in the carbon isotopic composition of seawater and surface temperatures respectively. The difference between the d13C of alkenones and of the coeval near-surface dwelling planktonic foraminifera represents the approximate carbon isotopic fractionation that occurs during photosynthetic carbon fixation specific to alkenone-producing haptophyte algae. This technique has been used to reconstruct the magnitude of pCO2 change during the Cenozoic and is considered one of the most reliable paleo- pCO2 proxies presently available. Broader impacts include the bi-coastal collaboration between two major U.S. institutions, participation in the project by two undergraduates and a post-doc, and PI Pagani's participatetion in a middle and high school education program that will incorporate the results of this study into presentations to students and interns in the program.