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

Francesca Quinto (Korresp. Autor*in), Erich Hrnecek, Michael Krachler, William Shotyk, Peter Steier, Stephan R. Winkler

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed

Abstract

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.
OriginalspracheEnglisch
Seiten (von - bis)5243-5250
Seitenumfang8
FachzeitschriftEnvironmental Science & Technology
Jahrgang47
Ausgabenummer10
DOIs
PublikationsstatusVeröffentlicht - 21 Mai 2013

ÖFOS 2012

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

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