by Mahalingam Baskaran
Sidebar to Studies of nuclear contamination in the Russian Arctic
Effluents transported from elsewhere come from nuclear facilities in Europe such as Sellafield in the United Kingdom which discharges into the northeastern Irish Sea, Dounreay in northeast Scotland which discharges into the Pentland Firth, and La Hague reprocessing plant near Cherbourg, France which discharges into the English Channel.
The relative contribution of different plutonium sources to the total radioactive material in surface sediments of the study area can be evaluated using the atomic and activity ratios of different plutonium isotopes.
Radioactive materials from different sources exhibit distinctive proportions of the plutonium-239, 240 and plutonium-238. The table below shows Pu-238/Pu-239, 240 activity ratios for nuclear effluents from Sellafield (U.K.) and Cap de la Hague (France), discarded reactors in the Kara Sea, global fallout, and the surface sediments in the Kara Sea and adjoining areas. The latter ratio was measured at Texas A&M University.
The activity ratios of plutonium-238 to plutonium-239, 240 and plutonium-239, 240 to cesium-137 in the surface sediments we analyzed match that of nuclear materials derived from global fallout, suggesting that most radioactive cesium and plutonium in the Kara Sea is a result of global nuclear weapons testing. Fortunately, the concentrations of radioactive isotopes remain so low that they pose no immediate threat to the Arctic environment.
Table optimized for Netscape 1.1 [Text version]
|Sample||Location||Pu-238 to Pu-239,240 Activity Ratios in 1993||Source|
|Effluents from Sellafield||Irish Sea||.29±0.02||British Nuclear Fuels, 1985|
|Effluents from Cap de la Hague||English Channel||0.46||Calmet and Guegueniat, 1985|
|Dumped reactors in the Kara Sea||Kara Sea||0.26-0.49||Mount, et al. 1993|
|Global fallout (+SNAP)||Northern Hemisphere||0.30||Aarkrog, 1989|
|Surface sediments||Kara Sea and the Ob and Yenisey Rivers||0.035±0.003||TAMU study|
Editor's Note: A peer-reviewed article by Dr. Baskaran and others which reports the results of this research will appear later this year in Applied Radiation and Isotopes. A similar article has been submitted to Earth Planetary Science Letters.
Oceanography, Texas A&M University
Updated September 13, 1995