Lipid biomarkers in tree rings: chemotaxonomy, diagenesis and potential for palaeoenvironmental reconstructions

• Main Authors: Riausset, S, Gauthier, Caroline, Pierre, Monique, Jacob, Jérémy, Daux, Valérie
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Géochrononologie Traceurs Archéométrie (GEOTRAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), European Association of Organic Geochemists
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2023
• Subjects: Panoply; GEOF; [SDE.MCG]Environmental Sciences/Global Changes; [CHIM.ANAL]Chemical Sciences/Analytical chemistry; Amsterdam Island
• Online Access: https://hal.science/hal-04213717

International audience Tree rings are reputed paleoenvironemental and palaeoclimate archives. In addition to an annually-resolved absolute chronology, they afford crucial palaeoclimate information from tree-rings thickness, and carbon and oxygen isotopes of cellulose. To our knowledge, lipid biomarkers preserved in tree rings have received little attention. Here we explore their palaeoenvironmental and palaeoclimate potential by focusing on the impacts of (1) taxonomy, (2) diagenesis/ageing, (3) provenance and/or climatic conditions on biomarker imprints. Additionally, we provide quantitative data to discuss the feasibility of further analyses such as compound-specific isotope measurements. We have analyzed lipid biomarkers extracted from tree species belonging to the Gymnosperms (Austrocedrus chilensis, Fitzroya cupressoides, Sequoia sp., Araucaria araucana, Cedrus sp., Picea linzhiensis, Pinus sylvestris) and Angiosperms (Nothofagus pumilio, Phylica arborea, Phylica nitida, Psidium guajava, Quercus sp.) divisions. Samples were collected in France, Patagonia, Amsterdam Island, Sweden, Indian Ocean and Himalaya. Two samples of P. sylvestris are dated at -1300 and ~-8200 BP. Initial and final wood in annual tree rings were distinguished in samples from Quercus sp.The extracts contained fatty acids, tricyclic diterpenes, sterols and pentacyclic triterpenes. Fatty acids (analyzed as their methyl esters), were the most abundant compounds in all extracts (up to 50 μg/g). These concentrations are too low to envisage compound-specific H isotope analyses at the tree ring scale, considering the usual weight of tree ring samples ranging between 10 and 100mg. Their distribution exhibit a strong even/odd predominance and a maximum at C24. As expected, tricyclic diterpenes (or their diagenetic derivatives such as abietatriene) were exclusively found in Gymnosperms. Sterols were found in all samples. No distinction could be found in sterols distribution related to taxa, age or provenance could be evidenced. The presence of ...