Gas-IRMS for high-precision analysis of Δ17O with sample preparation line

• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: Funded in 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426320572

The most recent work of the PI has highlighted novel fields of application for the System of 16O - 17O - 18O in the field of quantitative isotope hydrology of the past and present. In the current project, at first we will build a semi-automated preparation line to convert carbonate-bound oxygen to pure oxygen gas, which is required for the analysis of Delta 17O at sufficient precision. With the applied-for Gas-IRMS we seek to systematically investigate evaporation from soil, from ground water aquifers, and other water reservoirs of the Earth’s surface. The aim of these studies is to quantify the water budget of arid and semi-arid environments. This includes the identification of seasonally varying water sources and local evaporative water recycling. In a pilot study we also seek to apply the method to quantify the water budget of drought-resistant plants. Results from theses systematic studies will then be applied to quantify past evaporation and reconstruct changes in the hydroclimatic cycle, based on Delta 17O analysis in geologic samples of pedogenic carbonate (calcretes from Namibia), lacustrine gypsum (Laguna de Fuente de Piedro, Spain), and lacustrine carbonate (Lake Van, Turkey). In additional projects with co-applicants, we seek to apply classical H, C, N, and O isotope analysis in the fields of paleoceanography and prehistoric archaeology. In the first of the two, the aim is to reconstruct past variability of exchange of water masses between the Mediterranean and the Atlantic and its role in Atlantic thermohaline circulation. A significant part of this undertaking is the development of enhanced proxy-tools for reconstructing contour currents along the continental slope and for reconstructing deep-water ventilation. These tools are based on C and O isotope analysis of benthic foraminifera shells in combination with trace element analysis. In the field of prehistoric archaeology there are two major objectives. By using H, C, and O isotope analysis in wood - partly supplied by the extensive Cologne Dendro-Archive - we seek to reconstruct past climate and environmental variability with annual resolution for the Holocene of central Europe. By combining these findings with C and N isotope analysis from bones, we seek to work out the evolution of residential mobility patterns and changing agricultural practices in the late Neolithic. The other main objective concerns trophic levels and evolution of food resources in the paleolithic, where we first seek to establish the isotopic baseline across various climate oscillations between 90 and 40 ka BP from the numerous animal bones found in the long sequence of deposits from Sesselfelsgrotte, Bavaria. In another study, the objective is to derive movements of hunted animals - in particular reindeer and horse - from isotope analysis of bones found at a number of well-dated hunter camp sites of late pleistocene age across central Europe.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Gas-IRMS zur hochpräzisen Analyse von Δ17O mit Probenaufbereitungsanlage
• Instrumentation Group: 1720 Spezielle Massenspektrometer (Flugzeit-, Cyclotronresonanz-, Ionensonden, SIMS, außer 306)
• Applicant Institution: Universität zu Köln
• Leader: Professor Dr. Michael Staubwasser