Environmental Engineering Reference
In-Depth Information
the Chernobyl nuclear power plant in Ukraine resulted in the injection of a new inventory
of fission products into the atmosphere. The weather patterns present at that time resulted
in a substantial increase in 137 Cs and 90 Sr deposition rates in Fennoscandia. However, this
proved to be a temporary setback to the long-term trend of diminishing deposition. Within
five years, annual deposition of 137 Cs and 90 Sr at Arctic monitoring sites was back to pre-
Chernobyl levels.
What is more important from environmental and human health perspectives is the
fate of deposited radionuclides. Several characteristics of Arctic terrestrial ecosystems lead
them to conserve certain radionuclides rather than rapidly burying them in the organic lay-
ers of soils. For example, lichens, mosses and mushrooms are major components of the
Arctic flora. They are slow growing, obtain much or all of their water directly from the at-
mosphereandareconsequentlymuchmoreefficientcollectorsandretainersofatmospheric
fallout than are rapidly growing mid-latitude plants and agricultural crops. In winter, they
form a vital food source for caribou and reindeer, to which they transfer their burden of
radionuclides. The berries of slow-growing Arctic shrubs, such as cloudberry, bilberry and
cranberry, also tend to accumulate and conserve radionuclides. Reindeer in north-western
Europe and caribou in North America, together with wild berries, make up a large por-
tion of the traditional diet of Arctic peoples who live in these regions. Therefore, looking
back, it is not surprising that by the early 1960s, several studies reported that Sami peoples
in northern Europe were accumulating body burdens of 137 Cs and 90 Sr that were of con-
cern to national health agencies. The Sami subsequently found themselves facing difficult
decisions when dietary advisories recommended restrictions on how much reindeer meat
should be consumed. Such decisions related not just to their diet but also to the basis of
their culture that is so closely linked to reindeer.
In comparison, AMAP assessments found that marine pathways were far less im-
pacted by 137 Cs and 90 Sr deposition. Freshwater food chains (particularly those involving
oligotrophiclakes)weresubjecttoagreaterlevelofcontamination, butthiswaswellbelow
that involving reindeer, caribou and mushrooms.
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