Berlin 2014 – wissenschaftliches Programm
MS 11.2: Vortrag
Freitag, 21. März 2014, 11:00–11:15, DO24 1.205
AMS measurements of global fallout U-236 and Pu in an ombrotrophic peat profile: evidence for their post depositional migration — •Francesca Quinto1, Erich Hrnecek1, Michael Krachler1, William Shotyk2, Peter Steier3, Stephan Winkler3, and Robin Golser3 — 1European Commission Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe, Germany — 2Department of Renewable Resources, University of Alberta, 839 General Services Building, Edmonton, AB, Canada T6G 2H1 — 3VERA Laboratory, Faculty of Physics, University of Vienna, Währinger Straße 17, A-1090 Vienna, Austria
U-236, Pu-239, Pu-240, Pu-241 and Pu-242 were analysed in an ombrotrophic peat core representing the last 80 years of atmospheric deposition. The determination of these isotopes at femtogram and attogram levels was possible by using ultra-clean laboratory procedures and accelerator mass spectrometry. Since the Pu isotopic composition characteristic for global fallout, as well as anthropogenic U-236, were identified in peat samples pre-dating the period of atmospheric atom bomb testing, migration of Pu and U within the peat profile is clearly indicated. The vertical profile of the U-236/U-238 isotopic ratio represents the first observation of the U-236 bomb peak in a terrestrial environment. Comparing the abundances of the global fallout derived U-236 and Pu-239 along the peat core, the post depositional migration of plutonium exceeds that of uranium. These results highlight, for the first time, the mobility of Pu and U in a peat bog with implications for their migration in other acidic, organic rich environments.