Life Sciences Commons^™

Molecular Fossils From Phytoplankton Reveal Secular Pco2 Trend Over The Phanerozoic, Caitlyn R. Witkowski, Johan W. H. Weijers, Brian S. Blais, Stefan Schouten, Jaap S. Sinninghe Damsté

Science and Technology Department Faculty Journal Articles

Past changes in the atmospheric concentration of carbon dioxide (PCO2) have had a major impact on earth system dynamics; yet, reconstructing secular trends of past PCO2 remains a prevalent challenge in paleoclimate studies. The current long-term PCO2reconstructions rely largely on the compilation of many different proxies, often with discrepancies among proxies, particularly for periods older than 100 million years (Ma). Here, we reconstructed Phanerozoic PCO2 from a single proxy: the stable carbon isotopic fractionation associated with photosynthesis (Ɛp) that increases as PCO2 increases. This concept has been widely applied to alkenones, but here, we …

Interpreting Long Chain N-Alkyl Lipids In Lake Sediments: A Critical Evaluation Of Their Sources And Isotope Signals, Hong Yang, Qin Leng, Katelynn Howard, Kai-Lou Yue

Science and Technology Department Faculty Conference Proceedings

Stable carbon and hydrogen isotopic values of n-alkyl lipids extracted from lake sediments have been widely used for the reconstruction of ancient vegetation, climate, altitude, hydrology, etc. Compound-specific isotope analysis has taken the advantage of source-specific environmental signals from both autochthonous and allochthonous lipids, assuming that long chain n-alkyl lipids are primary derived from terrestrial plants. In recent years, substantial progresses have been made toward lipids produced by lacustrine macrophytes (aquatic plants and macro-algae) regarding their abundance, metabolism, chain length distribution, and isotope values.

Accumulating evidence indicates that long chain (C26– C31) n-alkyl lipids in lacustrine sediments are derived from …