Radioactivity in the Marine Environment (1971) / Chapter Skim
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MARINE SEDIMENTS AND RADIOACTIVITY
MARINE SEDIMENTS AND RADIOACTIVITY
Pages 147-160
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From page 147... ...
, based on the distribution of trace elements in interstitial waters from marine sediments. In many reactions, the different chemical behaviors under reducing conditions result from formation of different complexes rather than from direct reduction of the element.
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From page 148... ...
suggested that biological activity could account for the apparent rapid mixing of radionuclides in the upper 2 cm of several cores taken near the Columbia River mouth. Mixing due to biological activity can be treated as a diffusive process, and a biological diffusion coefficient can be calculated.
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From page 149... ...
In these areas, loss and exchange of radionuclides from the sediments to the overlying seawater will be primarily dependent on the reactions of the radionuclides. On the shallow continental shelf near major rivers, where sediment is accumulating relatively rapidly, the radioactive sediment may be deposited rapidly enough that it is not substantially disturbed by physical processes (currents and wave action)
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From page 150... ...
10 II 12 13 14 I5 (cpm/g DRY) FIGURE 10 Variation of gross beta activity from atmospheric fallout observed at Ispra, Euratom Centre, Italy, and gross beta activity in sediment from a core collected in the Adriatic Sea near the Po river mouth in 1966(Schreiberef J/., 1968)
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From page 151... ...
Studies of radioactive sediment dispersal on the continental shelf provide some of the best information about actual sediment movement in this area. Large amounts of radioactive materials discharged from the Windscale plant on the Irish Sea (Templeton and Preston, 1966)
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From page 152... ...
of 2.27 g/ml for a radionuclide with a distribution coefficient of 10 . 0 10 20 30 40 50 60 70 80 90 100 PERCENTAGE LEFT IN S0LUT10N FIGURE 11 Predicted relationship between the fraction of the original radionuclide concentration remaining in solution as a function of the amount of sediment that has settled out from suspension, for different distribution coefficients.
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From page 153... ...
1968. Trace elements in the interstitial waters of marine sediments.
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From page 154... ...
1964. Recent marine sediments in Saanich Inlet; A stagnant marine basin.
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From page 155... ...
These interactions should be considered in studies of the effects of biological activity upon the distribution patterns of radionuclides and trace elements in the sea. The sources of radioactivity and the inorganic interactions of the radionuclides and associated stable elements with the sea have been reviewed in detail in Chapter 2 and will be discussed here only with respect to their influences upon the availability of radionuclides to marine organisms.
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From page 156... ...
Although the metal in the device and the support sources would provide less mass than the sodium chloride in the vaporized seawater, the centers of nucleation would be provided by the oxides of iron, calcium, and magnesium. Underwater detonations in shallow bodies of water may produce sufficient heat to convert interstitial water of the bottom sediments into steam, dislodging sediments that may be incorporated into the fireball.
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From page 157... ...
In areas of extensive scouring and resuspension of bottom sediments by tidal currents, several radionuclides introduced by river waters may be adsorbed onto sediment surfaces. Some of the adsorption may be due to inorganic processes, but significant amounts of added radionuclides and trace elements may be bound to sediment surfaces by the periphyton (Pomeroy et al., 1965)
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From page 158... ...
The removal of adsorbed stable or radioactive nuclides from the surfaces of organic detritus and sediment during digestive processes of marine infaunal invertebrates is strongly influenced by pH, total electrolyte content, enzymic digestion of biological substrates, and other factors that determine the degree of association between adsorbed ions or colloids and the exposed surfaces of ingested material. Not all trace elements associated with organic detritus in estuarine areas are adsorbed onto the surface but may have been incorporated into the living material.
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From page 159... ...
Under these conditions, the organism is unable to arrive at equilibrium with the environment. The smaller marine organisms, including the phytoplankton and some zooplanktons, frequently have turnover rates for trace elements with half-times measured in hours.
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From page 160... ...
RESULTS OF BIOLOGICAL ACTIVITY Accumulation and Concentration of Elements by Benthic Algae, Phytoplankton, Zooplankton, Molluscs, Crustacea, and Fish The average concentration factors for benthic algae, phytoplankton, zooplankton, and the muscle tissue of molluscs, crustacea, and fish are shown in Table 1. The concentration
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