Tracing water availability, organic carbon sources, and life at the dry limit using radiocarbon analysis

Our project is about reconstructing changes in water availability and its effect on organic carbon sources in desert soils. We use the information encoded in the distribution and isotopic composition of molecular fossils, i.e. remnants of plant and microbial life, for the identification of microbial communities as well as of climate variability past and present. A major part of our work is dedicated to technical and methodological developments for radiocarbon dating of very small samples (i.e. extremely low organic carbon content).

The most challenging aspect is to extract traces of plant and microbial life and to get age information by radiocarbon dating from soils located in the hyperarid core of the desert that exposes very low organic carbon contents. For instance, we need to extract about 5 kg of soil to obtain few micrograms of plant-derived organic matter. Therefore, major analytical developments are required to enable the analysis of these samples.

“Exploring life at the dry limit is a very fascinating topic and doing fieldwork in the hyperarid core of the Atacama felt like being on Mars. The project gives us the unique opportunity to study distinct plant and microbial communities which developed a very specific life style to grow and survive at such extreme climatic conditions. We were surprised by the good preservation of organic compounds originating from plant remains, which enabled us to analyze their isotopic composition for paleoclimate reconstruction.”
– Janet Rethemeyer

Publication:

• Rethemeyer, J., Gierga, M., Heinze, S., Stolz, A., Wotte, A., Wischhöfer, P., Berg, S., Melchert, J.O., Dewald, A., 2019. Current sample preparation and analytical capabilities of the radiocarbon laboratory at CologneAMS. Radiocarbon, doi.org/10.1017/RDC.2019.16.
• Stolz, A., Dewald, A., Heinze, S.., Altenkirch, R., Hackenberg, G., Herba, S., Müller-Gatermann, C., Schiffer, M., Zitzer, G., Wotte, A., Rethemeyer, J., Dunai, T., 2019. Improvements in the measurement of small ¹⁴CO₂ samples at CologneAMS. Nuclear Instr. and Methods in Physics Res. B 439, 70-75.
• Stolz, A., Dewald, A., Altenkirch, R., Herb, S., Heinze, S., Schier, M., Feuerstein, K., Müller-Gatermann, C., Wotte, A., Rethemeyer, J., Dunai, T., 2017. Radiocarbon measurement of small gaseous samples at CologneAMS. Nuclear Inst. and Methods in Physics Res. B 406, 283-286.

Contact
Prof. Dr. Janet Rethemeyer
Phone: +49 (0)221 470-7317
E-Mail: This email address is being protected from spambots. You need JavaScript enabled to view it.