Page 171 - Soil and water contamination, 2nd edition

158 Soil and Water Contamination

Table 8.8 Deposition density of selected radionuclides in the 40°-50° N latitude band (Values not corrected for
radioactive decay )(source: Aarkrog, 2001).
Radionuclide Total deposition density to 1990
-2
(Bq m )
89
Sr 20000
90
Sr 3230
131 I 19000
137 Cs 5200
140
Ba 23000
238 Pu 1.5
239 Pu 35
240
Pu 23
241 Pu 730
241 Am 25

fallout mainly deposited in the same hemisphere as the test site (UNSCEAR, 1993). The
137
90
total global fallout amounted to 604 PBq of Sr and 940 PBq of Cs (value not corrected
for radioactive decay ). Since most of the tests were carried out in the northern hemisphere,
about three quarters was deposited there. Table 8.8 lists the deposition density of some
selected radionuclides resulting from weapons fallout in the 40°–50° N latitude band, which
represents the global maximum belt of fallout from weapons testing.
On two occasions, nuclear weapons have led to environmental contamination by
transuranic elements due to crashes of aircraft carrying nuclear weapons. This happened on
uncultivated farmland near Palomares, Spain, in January 1966, and in the Atlantic Ocean
near Thule, Greenland, in January 1968. Furthermore, eight nuclear submarine losses have
been reported. Two were lost by the USA and six by the USSR. The submarines contained
nuclear reactors and probably also nuclear weapons. Most losses have occurred in the North
Atlantic.
Recently, concern has been growing about another potential source of radioactive
contamination by radiological weapons, also called dirty bombs. These weapons have been
suggested as a possible terrorist weapon to create panic in densely populated areas. They do
not require weapons-grade materials: common materials such as 137 Cs used in radiological
medical equipment could be used. So far, such weapons have never been deployed.
As mentioned above, metallic depleted uranium (DU) is also used in conventional
weapons, such as penetrators of shells and bombs to increase the penetration depth during
impact. Ammunition containing DU is known to have been used in Iraq during the first
Gulf war in 1991, in Bosnia–Herzegovina in 1995, and in Kosovo, Serbia, and Montenegro
in 1999. The forming of aerosols containing DU during impact on hard surfaces and the
corrosion of the penetrators in soil may give rise to localised spots of DU contamination.
Nevertheless, the hazards related to such contamination points in terms of possible
contamination of water and plants are considered to be negligible (UNEP, 2002).

8.3.4 Environmental behaviour and effects of selected man-made radionuclides
The most important man-made radionuclides from a radioecological perspective are 131 I,
137 Cs, Sr, and 239 Pu. A brief overview of their behaviour in soils, plants and ingestion
90
pathways is given below.

10/1/2013 6:44:39 PM
Soil and Water.indd 170 10/1/2013 6:44:39 PM
Soil and Water.indd 170