Plutonium in Arctic Surface and Sub-Surface Waters at the St. Anna and Voronin Troughs

• Published in: Radiation Protection Dosimetry
• Main Authors: Mitchell, P.I., McMahon, C.A., León Vintró, L., Ryan, R.W.
• Format: Text
• Language: English
• Published: Oxford University Press 1998
• Subjects: Article; Arctic; Arctic Ocean; Kara Sea; St. Anna Trough; Fram Strait
• Online Access: http://rpd.oxfordjournals.org/cgi/content/short/75/1-4/247; https://doi.org/10.1093/oxfordjournals.rpd.a032238

The St Anna Trough has been identified as a key region for water-mass exchange between the Arctic Shelf and the Central Arctic Ocean. Here, the results are presented of a recent study of 239,240Pu (and 238Pu) concentrations in filtered surface and sub-surface water collected along a latitudinal section across the St Anna and Voronin Troughs in summer 1996. The data show no evidence of enhanced plutonium concentrations arising from nuclear waste dumping in the Kara Sea. Absolute 239,240Pu levels are extremely low, being in the range 2-8 mBq.m-3 (n=23), and are consistent with expected background levels arising mainly from global fallout. Further, the 238Pu/239,240Pu ratio was found to be <0.07 at each station, indicating that the contribution from European spent fuel reprocessing plants to the observed plutonium concentrations in this zone must be very small at the present time. However, comparison of the plutonium levels with temperature and salinity data confirms that the different water masses are characterised by differences in absolute 239,240Pu concentrations. Specifically, the intrusion of modified Atlantic water, labelled by higher levels of plutonium, into the Kara Sea via the Fram Strait and the continental shelf slope has been identified in the St Anna Trough.