Iodine-129 and plutonium isotopes in Arctic kelp as historical indicators of transport of nuclear fuel-reprocessing wastes from mid-to-high latitudes in the Atlantic Ocean |
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| Authors: | L W Cooper T M Beasley X-L Zhao C Soto K L Vinogradova K H Dunton |
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| Institution: | (1) Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, MS 6038, Oak Ridge, Tennessee 37831-6038, USA, US;(2) U. S. Department of Energy, 201 Varick Street, 5th Floor, New York, New York 10014, USA, US;(3) IsoTrace Laboratory, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7, Canada, CA;(4) Komarov Botanical Institute, 2 Professor Popova Street, 197376 St. Petersburg, Russia, RU;(5) Marine Science Institute, University of Texas at Austin, Port Aransas, Texas 78373, USA, US |
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| Abstract: | Iodine-129:iodine-127 ratios were determined using accelerator mass spectrometry in 34 Arctic marine algae collected between
1930 and 1993. A smaller set (5) of marine algae were also analyzed mass spectrometrically to determine plutonium-isotope
ratios. The 129I:127I ratio increased as much as three orders of magnitude from a mean of <1×10−11 (atom/atom) in the pre-nuclear era (before 1945) to nearly 1000×10−11 in 1993 for marine algae collected from the Novaya Zemlya archipelago separating the Barents and Kara Seas. The predominant
basis for the higher ratios in the Novaya Zemlya kelps appears to be upcurrent sources of 129I from nuclear fuel-reprocessing facilities at Sellafield (UK) and La Hague (France). Relatively high 241Pu:239Pu ratios (compared to observed bomb fallout at boreal latitudes, decay corrected to the date of collection) also corroborate
the influence of non-fallout sources. The small size of the data set precludes determining if there are significant contributions
of 129I and other radionuclides from Russian sources. In contrast, marine algae collected between 1969 and 1993 in the Bering, Beaufort
and East Siberian Seas had much lower 129I:127I ratios (mean=14.04×10−11±3.15 SD) than those observed in the European Arctic. The narrow range of ratios in Ameriasian Arctic kelps, and the modest
change over that time period, indicate that there were no major contributions of non-fallout 129I to North American Arctic surface waters at the time that the algae were collected. The potential for timing the transport
of fuel-reprocessed 129I through analysis of additional archived samples is outlined.
Received: 10 November 1997 / Accepted: 24 February 1998 |
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