137 Cs (about 630 g). If all this was released at once
and diluted in the immediate surrounding 1 km
3 of
water the radioactive concentration would have been
1550 Bq l
À1 for
90
Sr and 2030 Bq l
À1 for
137 Cs, the
concentration in weight per volume would have been
0.000 3 mg l
À1 90 Sr and 0.000 63 mg l
À1 137
Cs. This
means that even if the radioactive material was kept
in the extremely small volume of 1 km
3
, compared to
the volume of the deep water of the Norwegian Sea
available for a primary dilution, the proportion of
radioactive to nonradioactive isotopes of strontium
and cesium, available for uptake in marine organisms, would have been about 2.7 Â 10
6 and
7.9 Â 10
À5 , respectively.
From the examples above it can be seen that if
uptake, and thereby impact, in marine organisms
follows regular chemical–physiological rules there is
a ‘competition’ in seawater in favor of the nonradioactive isotopes for elements normally present in
seawater. Measurable amount of radionuclides of
cesium and strontium are detected in marine organisms but at levels far below the concentrations in
freshwater fish. Average concentrations of
137 Cs in
fish from the Barents Sea during the period with the
most intensive nuclear weapon tests in that area,
1962–63, never exceeded 90 Bq kg
À1 fresh weight,
whereas fallout from Chernobyl resulted in concentrations in freshwater fish in some mountain lakes in
Norway far exceeding 10 000 Bq kg
À1
.
For radionuclides like technetium and plutonium,
which will persist in the marine environment, uptake
will be based only on the actual concentrations in
seawater of radionuclide. The levels of
99
Tc, for
example, increased in seaweed (Fucus vesiculosus)
from 70 Bq per kg dry weight (December 1997) to
124 Bq kg
À1 in January 1998 in northern Norway
which reflected the increased concentration in the
water as the peak of the technetium plume from
Sellafield reached this area.
Previously the effects of anthropogenic radioactivity have been based on the possible dose effect
to humans. Most of the modeling work has been
concentrated on assessing the dose to critical population groups eating fish and other marine organisms.
But even if the radiation from anthropogenic radionuclides to marine organisms is small compared to
natural radiation from radionuclides like potassium,
40 K, the presence of additional radiation may give a
chronic exposure with possible effects, at least on
individual marine organisms.
The input of radioactivity, NORM, from the offshore oil and gas production may also give reason for
concern. The input will increase as it is a continuous
part of the production. Even if radium as the main
radionuclide is not likely to be taken up by marine
organisms the use of chemicals like scale inhibitors
may change this making radium more available for
marine organisms.
Conclusion
The sea began receiving radioactive waste from anthropogenic sources in 1946, in a rather unregulated
way in the first decades. Both national and international regulations controlling disposals have now
slowly come into force. Considerable amounts are
still discharged regularly from nuclear industries and
the practice of using the sea as a suitable wastebasket is likely to continue for ever. In 1994 an
international total prohibition on radioactive waste
disposal at sea came into force, but the approximately 85 PBq of solid radioactive waste that has
already been dumped will sooner or later be gradually released to the water masses.
Compared to other wastes disposed of at sea the
amount of radioactive waste by weight is rather diminutive. However, contrary to most of the ‘ordinary’ wastes in the sea, detectable amounts of
anthropogenic radioactivity are found in all parts of
the world oceans and will continue to contaminate
the sea for many thousands of years to come. This
means that anthropogenic radioactive material has
become an extra chronic radiation burden for marine
organisms. In addition, the release of natural occurring radionuclides from offshore oil and gas production will gradually increase the levels of radium,
in particular, with a possible, at present unknown,
effect.
However, marine food is not, and probably never
will be, contaminated at a level that represents any
danger to consumers. The ocean has always received
debris from human activities and has a potential for
receiving much more and thereby help to solve the
waste disposal problems of humans. But as soon as a
waste product is released and diluted in the sea it is
almost impossible to retrieve. Therefore, in principal,
no waste should be disposed of in the sea without
clear documentation that it will never create any
damage to the marine environment and its living
resources. This means that with present knowledge
no radioactive wastes should be allowed to be released into the sea.
See also
Nuclear Fuel Reprocessing and Related Discharges.
Single Compound Radiocarbon Measurements.
Uranium-Thorium Decay Series in the Oceans
Overview.
304 RADIOACTIVE WASTES
and diluted in the immediate surrounding 1 km
3 of
water the radioactive concentration would have been
1550 Bq l
À1 for
90
Sr and 2030 Bq l
À1 for
137 Cs, the
concentration in weight per volume would have been
0.000 3 mg l
À1 90 Sr and 0.000 63 mg l
À1 137
Cs. This
means that even if the radioactive material was kept
in the extremely small volume of 1 km
3
, compared to
the volume of the deep water of the Norwegian Sea
available for a primary dilution, the proportion of
radioactive to nonradioactive isotopes of strontium
and cesium, available for uptake in marine organisms, would have been about 2.7 Â 10
6 and
7.9 Â 10
À5 , respectively.
From the examples above it can be seen that if
uptake, and thereby impact, in marine organisms
follows regular chemical–physiological rules there is
a ‘competition’ in seawater in favor of the nonradioactive isotopes for elements normally present in
seawater. Measurable amount of radionuclides of
cesium and strontium are detected in marine organisms but at levels far below the concentrations in
freshwater fish. Average concentrations of
137 Cs in
fish from the Barents Sea during the period with the
most intensive nuclear weapon tests in that area,
1962–63, never exceeded 90 Bq kg
À1 fresh weight,
whereas fallout from Chernobyl resulted in concentrations in freshwater fish in some mountain lakes in
Norway far exceeding 10 000 Bq kg
À1
.
For radionuclides like technetium and plutonium,
which will persist in the marine environment, uptake
will be based only on the actual concentrations in
seawater of radionuclide. The levels of
99
Tc, for
example, increased in seaweed (Fucus vesiculosus)
from 70 Bq per kg dry weight (December 1997) to
124 Bq kg
À1 in January 1998 in northern Norway
which reflected the increased concentration in the
water as the peak of the technetium plume from
Sellafield reached this area.
Previously the effects of anthropogenic radioactivity have been based on the possible dose effect
to humans. Most of the modeling work has been
concentrated on assessing the dose to critical population groups eating fish and other marine organisms.
But even if the radiation from anthropogenic radionuclides to marine organisms is small compared to
natural radiation from radionuclides like potassium,
40 K, the presence of additional radiation may give a
chronic exposure with possible effects, at least on
individual marine organisms.
The input of radioactivity, NORM, from the offshore oil and gas production may also give reason for
concern. The input will increase as it is a continuous
part of the production. Even if radium as the main
radionuclide is not likely to be taken up by marine
organisms the use of chemicals like scale inhibitors
may change this making radium more available for
marine organisms.
Conclusion
The sea began receiving radioactive waste from anthropogenic sources in 1946, in a rather unregulated
way in the first decades. Both national and international regulations controlling disposals have now
slowly come into force. Considerable amounts are
still discharged regularly from nuclear industries and
the practice of using the sea as a suitable wastebasket is likely to continue for ever. In 1994 an
international total prohibition on radioactive waste
disposal at sea came into force, but the approximately 85 PBq of solid radioactive waste that has
already been dumped will sooner or later be gradually released to the water masses.
Compared to other wastes disposed of at sea the
amount of radioactive waste by weight is rather diminutive. However, contrary to most of the ‘ordinary’ wastes in the sea, detectable amounts of
anthropogenic radioactivity are found in all parts of
the world oceans and will continue to contaminate
the sea for many thousands of years to come. This
means that anthropogenic radioactive material has
become an extra chronic radiation burden for marine
organisms. In addition, the release of natural occurring radionuclides from offshore oil and gas production will gradually increase the levels of radium,
in particular, with a possible, at present unknown,
effect.
However, marine food is not, and probably never
will be, contaminated at a level that represents any
danger to consumers. The ocean has always received
debris from human activities and has a potential for
receiving much more and thereby help to solve the
waste disposal problems of humans. But as soon as a
waste product is released and diluted in the sea it is
almost impossible to retrieve. Therefore, in principal,
no waste should be disposed of in the sea without
clear documentation that it will never create any
damage to the marine environment and its living
resources. This means that with present knowledge
no radioactive wastes should be allowed to be released into the sea.
See also
Nuclear Fuel Reprocessing and Related Discharges.
Single Compound Radiocarbon Measurements.
Uranium-Thorium Decay Series in the Oceans
Overview.
304 RADIOACTIVE WASTES