Atmospheric nuclear weapon tests conducted in the 1950s and 1960s have provoked the deposition of anthropogenic fallout radionuclides (FRNs) on Earth’s surfaces. As a consequence, soil particles were “marked” by these FRNs and hence the nuclides can be measured to investigate Anthropocene sediment or soil particle redistribution patterns and rates. So far, the workhorse for such applications has been ¹³⁷Cs, but decreasing global ¹³⁷Cs activities mean that it will become increasingly difficult to measure in coming decades. In addition, applications of ¹³⁷Cs can be complicated due to contaminations from nuclear power plant accidents. Fallout ^239,240Pu measured by Accelerator Mass Spectrometry (AMS) remain largely unaffected by these issues and allow more precise measurements on smaller sample sizes.

The application of ^239,240Pu at the Institute of Geology and Mineralogy benefits from measurement capabilities developed at the Centre for Accelerator Mass Spectrometry (CologneAMS; [1]) as well as published and externally referenced in-house standards [2,3]. Likewise, ¹³⁷Cs is routinely measured by the Division of Nuclear Chemistry, complementing our efforts to contribute to a better understanding of Earth (sub-)surface processes in the Anthropocene. Ongoing projects aim to decipher modern Earth (sub-)surface processes, including deflation processes (South Africa, northern Chile), aspect-induced differential soil erosion (central Chile), and sediment transport (Germany). Where applicable, we seek to compare these data to longer-term background rates of topography formation.

For more information, please contact Dr Joel Mohren (joel.mohren(at)uni-koeln.de) and/or visit:

https://cologneams.uni-koeln.de/

https://nuklearchemie.uni-koeln.de/nuklearchemie

https://portal.uni-koeln.de/en/forschung/interne-forschungsfoerderung-und-auszeichnungen/excellent-research-support-program/ersp/emerging-groups/uldetis

[1] Dewald, A., Heinze, S., Jolie, J., Zilges, A., Dunai, T., Rethemeyer, J., Melles, M., Staubwasser, M., Kuczewski, B., Richter, J., Radtke, U., von Blanckenburg, F., Klein, M., 2013. CologneAMS, a dedicated center for accelerator mass spectrometry in Germany. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 294, 18-23.

[2] Dittmann, B.A., Dunai, T.J., Dewald, A., Heinze, S., Feuerstein, C., Strub, E., Fifield, L.K., Froehlich, M.B., Tims, S.G., Wallner, A., Christl, M., 2015. Preparation of a multi-isotope plutonium AMS standard and preliminary results of a first inter-lab comparison. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 361, 327-331.

[3] Dittmann, B.-A., Buompane, R., Chamizo, E., Christl, M., Dewald, A., Dunai, T., Feuerstein, C., Fifield, K., Fröhlich, M., Heinze, S., Marzaioli, F., Münker, C., Petraglia, A., Sirignano, C., Strub, E., Synal, H.-A., Terrasi, F., Tims, S., Wallner, A., 2019. ColPuS, a new multi-isotope plutonium standard for Accelerator Mass Spectrometry. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 438, 189-192.