Measurements of U-236 in Ancient and Modern Peat Samples and Implications for Postdepositional Migration of Fallout Radionuclides

Autor(en)

Francesca Quinto, Erich Hrnecek, Michael Krachler, William Shotyk, Peter Steier, Stephan R. Winkler

Abstrakt

²³⁶U was analyzed in an ombrotrophic peat core representing

the last 80 years of atmospheric deposition and a minerotrophic peat

sample from the last interglacial period. The determination of ²³⁶U at levels of 10⁷ atoms/g was possible by using ultraclean laboratory procedures and accelerator mass spectrometry. The vertical profile of the ²³⁶U/²³⁸U isotopic ratio along the ombrotrophic peat core represents the first observation of the ²³⁶U bomb peak in a terrestrial environment. A constant level of anthropogenic ²³⁶U with an average ²³⁶U/²³⁸U isotopic ratio of (1.24 ± 0.08) × 10^–6 in the top layers of the core was observed. Comparing the abundances of the global fallout derived ²³⁶U and ²³⁹Pu along the peat core, the post depositional migration of plutonium clearly exceeds that of uranium. However, the cumulative ²³⁶U/²³⁹Pu

ratio of 0.62 ± 0.31 is in agreement with previous studies on the

global fallout uranium and plutonium. In the interglacial peat samples a

²³⁶U/²³⁸U isotopic ratio of (3.3 ± 0.7) × 10^–12

was detected; although this measurement is an upper limit, it

constitutes a significant step forward in the experimental determination

of the natural ²³⁶U abundance and represents a true background sample for the ombrotrophic peat core.

Organisation(en)

Isotopenphysik

Externe Organisation(en)

Institute for Transuranium Elements, University of Alberta

Journal

Environmental Science & Technology

Band

47

Seiten

5243-5250

Anzahl der Seiten

8

ISSN

0013-936X

DOI

https://doi.org/10.1021/es400026m

Publikationsdatum

05-2013

Peer-reviewed

Ja

ÖFOS 2012

1030 Physik, Astronomie, 103031 Strahlenschutz, 103005 Atomphysik, 104023 Umweltchemie

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/67c56d42-e462-4ef6-a755-9d4a4b55f1d7