Radioactivity - The Changing Arctic Environment: The Arctic Messenger - page 54

The 2009 AMAP radioactivity assessment confirmed that traces of radionuclide deposition
from weapons testing and the Chernobyl accident could still be detected in the Arctic but
that levels are now very low. However, their legacy continues to linger. Cold Arctic tem-
peratures result in 137 Cs still being retained in the upper layers of thin nutrient-poor Arc-
tic soils even 50 years after deposition. Meanwhile, 137 Cs that has been incorporated in-
to boreal sub-Arctic trees is released again to the atmosphere during forest fires - a phe-
nomenon that may become more common with global warming. One further point illus-
trates the long-term legacy of Cold War atmospheric testing and the futility of nuclear war.
You will recall that one of the dose definitions we struggled through earlier in this chapter
was called collective effective dose equivalent commitment . Well, the total collective ef-
fective dose equivalent commitment from all atmospheric nuclear explosions conducted up
until the last one in 1980 was 30 million man-sieverts. At that time, only 12% had actually
been delivered. The rest will reach humankind over millions of years.
Thisreviewhasnotconsideredundergroundtests.Providedtheydonot“vent”,under-
ground tests do not lead to the atmospheric transport of radionuclides. The long-term and
poorly understood issue is the potential impact on groundwater. In addition to the testing of
nuclear weapons, between 116 and 239 peaceful underground nuclear explosions (PUNES)
have been reported to have taken place in the former Soviet Union, usually for mining,
civil engineering purposes, stimulating oil and gas recovery and controlling runaway gas
well fires. Seventeen of these PUNES occurred above or close to the Arctic Circle. In the
United States, 26 PUNES were reported to have occurred between 1961 and 1973 under a
programme called Operation Plowshare. The Peaceful Nuclear Explosions Treaty of 1976
set limits on how powerful PUNES could be, but the 1996 Comprehensive Test Ban Treaty
has banned all such explosions.