The Effects of Atomic Radiation on Oceanography and Fisheries (1957) / Chapter Skim
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GENERAL CONSIDERATIONS CONCERNING THE OCEAN AS A RECEPTACLE FOR ARTIFICIALLY RADIOACTIVE MATERIALS
GENERAL CONSIDERATIONS CONCERNING THE OCEAN AS A RECEPTACLE FOR ARTIFICIALLY RADIOACTIVE MATERIALS
Pages 1-25
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From page 1... ...
from the rapid, uncontrolled reactions involved in testing of weapons or in warfare. Up to the present time, the largest quantities of fission products introduced into the aquatic environfi ment have been from weapons tests; most of the products from controlled reactions have been isolated on the land, and only relatively small quantities have been introduced into the 1 Contribution from the Scripps Institution of Oceanography, New Series, No.
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From page 2... ...
This thermocline, or pycnocline, separates the surface mixed layer from the layers of intermediate and deep water, the latter extending to the bottom, within which there are gentle gradients of decreasing temperature and increasing salinity and density with depth. Vertical movement in the intermediate and deep layers is much slower than in the mixed layer, and horizontal currents are more sluggish.
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From page 3... ...
In other areas, the surface waters are cooled near to freezing in the winter, become heavy and sink, and mix with the deep waters. Elsewhere, violent mixing occurs along the boundaries between ocean currents, and deeper waters are thereby brought into the brightly lighted zone.
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From page 4... ...
For example, a single cubic kilometer of sea water contains over a million tons of magnesium, about five times the peak world annual production of this metal. The floor of the deep sea is known to contain low-grade deposits of cobalt, nickel and copper (0.1 to 0.7 per cent by weight of the metals)
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From page 5... ...
Due to the rather rapid mixing in the upper layers of the sea, and to its very large volume, even large quantities of activity introduced at the surface in the open sea become sufficiently dispersed to constitute no direct hazard after a relatively short time, as has been shown by the dispersion of the activity resulting from weapons tests in the Pacific. If the direct hazard were the only consideration, sea disposal of radioactive wastes would give rise to difficulties only in small areas near the disposal sites.
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The Committee on Disposal and Dispersal of Radioactive Wastes, also a part of the National Academy of Sciences' study of the biological effects of atomic radiation (1956) , estimates that by 1965 the United States will be generating about 11,000 megawatts of reactor heat, some 20 per cent of which will be for naval vessels.
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From page 7... ...
Even the relatively narrow territorial seas are amenable only to juridical and not physical control; no nation can effectively modify the natural interchange of the biological and physical contents of its territorial sea with those of the high seas or of the territorial seas of other nations. The continuity of the oceans, and their status as international common property require that the oceanic disposal of radioactive wastes be treated as a world problem.
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From page 8... ...
Although we are urgently concerned with preventing possible deleterious effects of atomic wastes, atomic radiations can also be of benefit. Large-scale experiments employing radioactive isotopes might contribute importantly to our knowledge of the flux of materials through the food chains from the phytoplankton to the harvestable fishes, invertebrates, and whales (Schaefer, Chapter 13 of this report)
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IV. CHEMICAL PROCESSES AND RADIOACTIVE MATERIALS Elements in sea water Sea water is a solution of a large number of dissolved chemicals containing small amounts of suspended matter of organic and inorganic origin.
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Thus they estimate that the residence time for iron is of the order of a hundred years. Introduction of radioactive materials Radioactive materials in large quantities can be introduced into the sea from reactor wastes, from weapons tests, or in warfare.
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Except in the case of deep underwater bursts, all of the fission products reaching the sea from weapons tests are deposited in the upper layer of the ocean. Removal into the deeper water is relatively slow.
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V PHYSICAL PROCESSES AND RADIOACTIVE MATERIALS Physical structure of the sea The physical properties of sea water of importance to the present study are functions of temperature, salinity, and pressure.
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From page 13... ...
Thus, although there is eventual complete interchange of water between all oceans and seas, some parts are partially isolated from others, the exchange between these parts being much slower than within them. Near-surface currents and mixing within the upper layer Currents in the upper, mixed layer of the sea are primarily generated by winds, and, consequently, the major horizontal surface currents of the ocean correspond to the field of wind stress (Munk, 1950)
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It appears that the mean current in many parts of the deep sea may be less than the periodic variable currents. The turbulence of these variable tidal currents, especially near the bottom, contributes to vertical and horizontal mixing in deep water.
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From page 15... ...
In regions where increase of surface density by evaporation, freezing out of ice, or cooling, causes the surface waters to sink and be replaced by the formerly deeper water. Deep thermal convection occurs in high latitudes and extends in some areas to the bottom; for example, Antarctic bottom water is formed in the Weddell Sea by the cooling and sinking of the surface waters, and the Atlantic deep water is formed in a similar manner east of Greenland.
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From page 16... ...
Fishes can take up ionic calcium and strontium directly from the sea water. Observations in conjunction with weapons tests, reported in Chapter 7 of this report, have shown that particulate feeders among the zooplankton ingest particles of inorganic compounds and retain them.
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From page 17... ...
Migration of organisms may result in a net transport of elements from areas of high concentration to areas of lower concentration. Thus, for example, the vertical migrations of the organisms of the deep scattering layer can result in a transport from the deeper layers into the upper mixed layer.
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From page 18... ...
has shown that the deposition of 1,000 tons per year of fission products in the deep sea would, at secular equilibrium, almost triple the average radiation level in the deep water. This could, conceivably, result in genetic effects in the marine populations in these waters, which might seriously upset the ecological system of the oceans.
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From page 19... ...
Depending on the quantity of materials to be dealt with, we may need to consider either or both of these possibilities. Introduction in the upper mixed layer Radioactive materials introduced into the upper mixed layer will, because of the rapid transport and large horizontal and vertical mixing within this layer, be carried away from the site of introduction and rapidly dispersed.
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From page 20... ...
, assuming an estimated average residence time in the deep sea of 300 years, the introduction into the deep sea of 1,000 tons per year of fission products after 100 days cooling, and complete uniform mixing within the deep water, has calculated the activity in the deep and surface layers at secular equilibrium. This calculation indicates that the total fission product activity in the mxed layer would be about equal to that at present from natural sources (primarily K<0)
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From page 21... ...
Although we cannot say at this time with any precision what quantities of reactor-waste products can be safely deposited in the deep sea, it appears certainly safe to employ quantities up to a few tons a year in careful experimental studies. It is not impossible that 1,000 tons a year can be safely disposed of in deep, isolated basins where the residence time is much greater than the 300-year average estimated for the deep sea generally.
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From page 22... ...
It is vitally necessary that the biological processes be studied in sufficient detail to enable their effects to be quantitatively evaluated. Such investigations need to include: The flux of various elements through the different trophic levels, and the variations in different ecological realms such as inshore coastal waters, offshore surface waters and the deep sea; the effects of vertical and horizontal migrations of organisms on redistribution of elements; the effects of the uptake, modification of the physical state, and elimination of elements by members of the marine biosphere on their subsequent distribution in the sea.
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2. Within the foreseeable future the prob'• lem of disposal of atomic wastes from nuclear fission power plants will greatly overshadow the present problems posed by the dispersal of radioactive materials from weapons tests.
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1954. Physical state of fission product elements following their vaporization in distilled water and sea water.
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From page 25... ...
1957. Report on the current velocities, volume transports and mixing effects in the Atlantic deep sea as physical processes important to the transport and dispersal of radioactive wastes.
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