Plutonium Isotopes ( ^239-241Pu) Dissolved in Pacific Ocean Waters Detected by Accelerator Mass Spectrometry

Author(s)

Karin Hain, Thomas Faestermann, Leticia Fimiani, Robin Golser, Jose Manuel Gomez-Guzman, Gunther Korschinek, Florian Kortmann, Christoph Lierse von Gostomski, Peter Ludwig, Peter Steier, Hirofumi Tazoe, Masatoshi Yamada

Abstract

The concentration of plutonium (Pu) and the isotopic ratios of

²⁴⁰Pu to

²³⁹Pu and

²⁴¹Pu to

²³⁹Pu were determined by accelerator mass spectrometry (AMS) in Pacific Ocean water samples (20 L each) collected in late 2012. The isotopic Pu ratios are important indicators of different contamination sources and were used to identify a possible release of Pu into the ocean by the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. In particular,

²⁴¹Pu is a well-suited indicator for a recent entry of Pu because

²⁴¹Pu from fallout of nuclear weapon testings has already significantly decayed. A total of 10 ocean water samples were prepared at the Radiochemie München of the TUM and analyzed at the Vienna Environmental Research Laboratory (VERA). Several samples showed a slightly elevated

²⁴⁰Pu/

²³⁹Pu ratio of up to 0.22 ± 0.02 compared to global fallout (

²⁴⁰Pu/

²³⁹Pu = 0.180 ± 0.007), whereas all measured

²⁴¹Pu-to-

²³⁹Pu ratios were consistent with nuclear weapon fallout (

²⁴¹Pu/

²³⁹Pu < 2.4 × 10

^-3), which means that no impact from the Fukushima accident was detected. From the average

²⁴¹Pu-to-

²³⁹Pu ratio of 8-2+3×10

^-4 at a sampling station located at a distance of 39.6 km to FDNPP, the 1-σ upper limit for the FDNPP contribution to the

²³⁹Pu inventory in the water column was estimated to be 0.2%. Pu, with the signature of weapon-grade Pu was found in a single sample collected around 770 km off the west coast of the United States.

Organisation(s)

Isotope Physics

External organisation(s)

Technische Universität München, Hirosaki University

Journal

Environmental Science & Technology

Volume

51

Pages

2031-2037

No. of pages

7

ISSN

0013-936X

DOI

https://doi.org/10.1021/acs.est.6b05605

Publication date

02-2017

Peer reviewed

Yes

Austrian Fields of Science 2012

103014 Nuclear physics, 105904 Environmental research

Keywords

Sustainable Development Goals

SDG 14 - Life Below Water

Portal url

https://ucrisportal.univie.ac.at/en/publications/5d755024-4320-4145-b487-e6a2115d7875