Characterization of Sedimentary n-alkyl Lipids in a Holocene Record from Lake Kivu, East Africa

Lake Kivu is an East African rift lake unique for its hydrothermal activity that contributes to permanently stratified conditions and high concentrations of carbon dioxide and methane at depth. Autochthonous organic matter production likely incorporates methane-derived carbon prior to sedimentation, but its influence upon potential paleoclimate signals derived from allochthonous sources is unknown. This project utilized abundance and compound-specific carbon isotopic analysis of n-alkyl lipids to characterize the relative effects of hydrothermal activity on Lake Kivu’s Holocene sediment record. Non-emergent aquatic macrophytes were the main source of organic matter to the sediments, and preliminary compound-specific carbon isotope analysis indicate a methane-derived signal in the n-alkyl lipid pool. Further analyses on compound-specific isotopes, relevant biomarker classes, and the vegetation and microbial ecology surrounding Lake Kivu are needed to better constrain the sources of organic matter to Lake Kivu’s sediment archive.