Impact of seasonal hydrological variation on the distributions of tetraether lipids along the Amazon River in the central Amazon basin : implications for the MBT/CBT paleothermonneter and the BIT index

Impact of seasonal hydrological variation on the distributions of tetraether lipids along the Amazon River in the central Amazon basin : implications for the MBT/CBT paleothermonneter and the BIT index Zell C. auteur aut IRD Kim J. H. auteur aut IRD Abril G. auteur aut IRD Sobrinho R. L. auteur aut IRD Dorhout D. auteur aut IRD Moreira Turcq Patricia auteur aut IRD Damste J. S. S. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Suspended particulate matter (SPM) was collected along the Amazon River in the central Amazon basin and in three tributaries during the rising water (RW), high water (HW), falling water (FW) and low water (LW) season. Changes in the concentration and the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), i.e., the methylation index of branched tetraethers (MBT) and the cyclization of brGDGTs (CBT), were seen in the Amazon main stem. The highest concentration of core lipid (CL) brGDGTs normalized to particulate organic carbon (POC) was found during the HW season. During the HW season the MBT and CBT in the Amazon main stem was also most similar to that of lowland Amazon (terra firme) soils, indicating that the highest input of soil-derived brGDGTs occurred due to increased water runoff. During the other seasons the MBT and CBT indicated an increased influence of in situ production of brGDGTs even though soils remained the main source of brGDGTs. Our results reveal that the influence of seasonal variation is relatively small, but can be clearly detected. Crenarchaeol was mostly produced in the river. Its concentration was lower during the HW season compared to that of the other seasons. Hence, our study shows the complexity of processes that influence the GDGT distribution during the transport from land to ocean. It emphasizes the importance of a detailed study of a river basin to interpret the MBT/CBT and BIT records for paleo reconstructions in adjacent marine setting. specialized branched tetraethers crenarchaeol Amazon River seasonal changes MBT/CBT BIT AMAZONE BASSIN AMAZONE COURS D'EAU 062 Frontiers in Microbiology 4 228 [14 en ligne] 2013 1664-302X https://www.documentation.ird.fr/hor/fdi:010061781 10.3389/fmicb.2013.00228 1664-302X [F B010061781] https://www.documentation.ird.fr/hor/fdi:010061781 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers15-09/010061781.pdf IRD - Base Horizon / Pleins textes 2014-04-02 2017-08-23 fdi:010061781 fre