P5 Paleoclimatology - Stable oxygen (18O/16O) and hydrogen (2H/1H) isotopic composition of plants, soils and rainfall along altitudinal transects, and in paleoclimate archives of the Bale Mountains

点击翻译按钮获取中文摘要

Ethiopia receives most of its precipitation from southerly winds provided by the East African Summer Monsoon system during Northern Hemispheric summer months. However, the strength of the East African Summer Monsoon varied during the Late Quaternary and the amount of precipitation provided by the westerlies may have been considerably higher in the past as well. During the last decade, certain biomarker and stable isotope techniques emerged as highly innovative and promising tools for (semi-)quantitative paleoclimate/hydrological research. By evaluating and applying such biomarker and stable isotope tools, this project aims at contributing to a (semi-)quantitative reconstruction of the paleoclimate/-hydrological history of the Bale Mountains, Ethiopia. More specifically, temperature, relative air humidity and precipitation source and amount shall be reconstructed.One work package will focus on the spatial and temporal/seasonal isotopic characterisation (2H/1H and 18O/16O) of modern day precipitation. The obtained data shall help to improve the understanding of the modern day atmospheric circulation patterns including their specific isotopic signatures affecting the Bale Mountains. A second work package will evaluate how accurately the isotopic signature of precipitation as well as relative air humidity and temperature are imprinted on the biomarker and stable isotopic composition of plants and soils. This will be achieved by studying climate and altitudinal transects on the Bale Mountains. The methodological focus will lay on compound-specific 2H-analyses of leaf wax-derived n-alkane and fatty acid biomarkers, on compound-specific 18O-analyses of hemicellulose-derived sugar biomarkers and on soil bacteria-derived glycerol dialkyl glycerol tetraether (GDGT) lipid biomarkers. The third work package contributes to the retrieval of sediment cores and the establishment of chronostratigraphies. These cores will be jointly investigated with the subprojects P2-Anthrosols and P4-Paleoecology as archives for the reconstruction of the human occupation history as well as the Late Quaternary paleoenvironmental/climate/hydrological history of the Bale Mountains. The above specified biomarker and stable isotope techniques will therefore be applied within this subproject.