Geoscience Reference
In-Depth Information
Plate 24.22
This section of the Trans-Alaska pipeline goes underground to allow animals to migrate without obstruction,
although there is little evidence that animals do not move under the pipeline!
Photo: Bill Barr
liable to accumulate. Because of their chemical persist-
ence, stability in biological systems and solubility in fat,
polychlorinated biphenyls (PCBs) illustrate how pollu-
tion levels can be biomagnified by each link in the food
chain, so that levels in the blubber of seals and whales
are about 400 M times those in the Arctic Ocean, and
are biomagnified about 3,200 M times in polar bears
and humans (
Figure 24.22
).
Table 24.3
lists the main
contaminants from urban and industrial areas which have
been detected in polar regions. Owing to proximity, the
levels are higher in the Arctic than in the Antarctic.
Chlorinated organics have been in widespread use in
agriculture since the insecticide DDT was introduced in
the 1940s. PCBs have been used in paints, plastics and
electrical and mechanical equipment since the early 1930s.
The commonest pollutant of this group detected in the
Arctic is hexa-chloro-cyclohexane (HCH) in terrestrial
ecosystems, and toxaphene, chlordane and PCBs in
marine ecosystems. The effects on wildlife can be very
serious, with reproductive failure in mammals, eggshell
thinning in birds, and reduced egg hatching in fish, in
addition to increased cancers in animals. Heavy metal
concentrations are more difficult to interpret, as there is
a background concentration from local rock sources.
However, mercury and lead are extremely high in the
kidneys and liver of marine mammals.
Radioactive pollution by radionuclides, or long-lived
fission products, has various sources, namely inefficient
waste disposal from nuclear power stations in Russia;
nuclear weapons testing in arctic Russia between 1952 and
1978; the accident at the Chernobyl nuclear power station,
Ukraine, in 1986; nuclear-powered submarines and ice-
breakers; and the secret dumping of nuclear wastes in
Arctic waters by the former Soviet Union. There was a
major input of caesium-137 in Scandinavia after the
Chernobyl nuclear accident. Radionuclides are absorbed
by lichens, which are eaten by reindeer or caribou in
North America, and native people living off the meat and
