Reconstructing tropical African hydrology using hydrogen isotope ratios of lacustrine sedimentary biomarkers: a calibration transect across Cameroon

• Antragsteller: Dr. Yannick Garcin
• Fachliche Zuordnung: Mineralogie, Petrologie und Geochemie
• Förderung: Förderung von 2009 bis 2014
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 160487544

Hydrogen isotope signatures ((D) in ancient leaf-wax lipids potentially record isotopic properties of ancient plant water, which may indirectly reflect isotopic signatures of rainfall. There is a tight relationship between leaf-wax (D and source-water (D as demonstrated for material collected in several mid- and high-latitude lacustrine environments. In contrast, for the tropical realm, where both vegetation and processes associated with isotope fractionation in the hydrologic system strongly differ from those at higher latitudes, calibration studies for this proxy are not yet available. Here, I propose to analyse the compound-specific hydrogen isotope ratios of lipids deposited in lake sediments from tropical Africa. The overall aim of this project is to: I. Identify the hydro-climatological factors and plant physiological processes that determine the hydrogen isotopic composition of leaf-wax lipid biomarkers in the tropical realm, II. Develop a robust framework for the quantitative application of compound-specific hydrogen isotopes in tropical Africa. For this purpose, (D values of biomarkers from living plants, soils, living phytoplankton and recent lake surface sediments will be analyzed along a N-S transect spanning Cameroon. These values will be then compared with the (D values of lake water, water from tree sap, and rainfall along this transect. This 10°-long latitudinal transect was chosen because it is unique as it encompasses a wide range of contrasting vegetation classes and climates that are representative for tropical Africa. This calibration will be the first study in the tropical realm. The tropics are the main source of heat and water vapour for Earth’s atmospheric convection, and the accurate reconstruction of their past climatic dynamics strongly rely on new, adequately calibrated climate-proxy.

• DFG-Verfahren: Sachbeihilfen