Accumulation Of Cesium Research Articles

Accumulation of Strontium and Cesium by Kale as a Function of Age of Plant

AbstractThe accumulation of Sr and Cs throughout the growth cycle of a hydroponically grown vegetable crop (Brassica oleracea var. acephala D.C. ‘Blue Curl’) was studied. The cumulative effect of supplying the radionuclides through the nutrient solution to kale throughout the growth cycle, simulating a continuous discharge, was compared to exposure at each stage of the growth cycle to a single dose of radioactivity, simulating an accidental release. The time course of accumulation of 137Cs supplied continuously through the nutrient solution resembled the sigmoidal dry weight growth curve of the vegetable. Accumulation of this nuclide after exposure of kale to radioactivity for 48 hours at each stage of growth decreased with age of the plant. The time course of 90Sr supplied continuously resembled the pattern of the periodic 48‐hour accumulation for this radionuclide, although there was a 1‐ to 2‐week lag period between the two uptake patterns.

Investigation of alkali metal migration and accumulation in the SiO 2/Si system: Structure of the interface

An electrochemical method was applied to the determination of accumulation parameters of alkali metal ions in SiO 2 film as well as to detecting the specific features of the SiO 2Si interface structure. The activation energies for accumulation of sodium, potassium and caesium in thermally grown films were determined. An assumption of the presence in the interface of a barrier layer to alkali metal ion movement was made.

Fuel-cladding mechanical interaction in fast breeder fuel pins; observations and analysis

The problems of fuel-cladding mechanical interaction are considered, and a survey is given of the causal processes in oxide fuel pins. Their importance is judged by relevant results from irradiation experiments in thermal and fast test reactors, and by corresponding modelling computations. It is demonstrated that critical cladding strain has to be expected only in case of large, fast rod power increase, primarily from reduced power to full power, and maybe also in case of serious cesium accumulation at the fuel/blanket interface. Steady-state fuel swelling does not make any considerable contribution to cladding strain by thermal creep or plastic flow.

The accumulation of radioactive caesium from food by the plaice (Pleuronectes platessa) and the brown trout (Salmo trutta)

The patterns of accumulation of caesium‐137 from food by the tissues and organs of a marine teleost, the plaice (Pleuronectes platessa) and a freshwater teleost, the brown trout (Salmo trutta) are described and compared. Estimates of the biological half‐times and steady‐state concentrations are derived and individual organ intakes calculated. Rate constants are similar to those obtained from the accumulation from water studies. Plaice gut and liver have an 11 % increase and trout gut a 6 % increase in their share of the [137Cs] intake arising from accumulation from food, compared with that arising from the accumulation from water. These increases were balanced by decreases in the muscle share of the intake. The overall absorption of [137Cs] from food was 42% for plaice and 67% for trout.

The accumulation of radioactive caesium from water by the brown trout (Salmo trutta) and its comparison with plaice and rays

The patterns of accumulation of caesium‐137 from water by the tissues and organs of the freshwater teleost, the brown trout (Salmo trutta) are described. Estimates of the biological half‐times and steady‐state concentrations are derived, using a simple exponential equation. In all tissues and organs examined, other than muscle, the rate processes of the trout fall between those of the plaice and the ray. It is concluded that most of the caesium accumulated by the brown trout from water enters other than by the gut, probably through the gills, but as with plaice and ray, the main source of the caesium, possibly 90%, must come from the food. Despite differences in the levels of accumulation, the ratios of the tissue to blood steady state concentrations are very similar in all three species. The steady state caesium concentration of the blood appears to be directly related to the red blood cell count of the fish.

Test of a Model for Predicting the Body Burden of Trace Contaminants in Aquatic Consumers

A model for predicting the accumulation and retention of trace contaminants obtained through food ingestion in aquatic consumers was tested for short-term exposure conditions. Model parameters were determined in a single-feeding experiment using bluegill (Lepomis macrochirus) and food labeled with 137Cs. Independent of this single-feeding experiment, bluegill were allowed to ingest 137Cs contaminated food over a 16-day period and the predicted and measured body burden of the radionuclide were compared. The model realistically simulated the absorption of 137Cs from the gastrointestinal tract and its accumulation over the 16-day period. Average body burden of 137Cs in bluegill was within 25% of the predicted body burden when the experiment was terminated. Apparent equilibrium of 137Cs in bluegill by day 16 suggests that this two-compartment linear model does not apply to the long-term accumulation of cesium in fish. The model appears most applicable for predicting body burdens of trace contaminants under acute exposure conditions that simulate an accidental release.

Radioecology of Bombay harbour—A tidal estuary

Low level liquid radioactive waste from nuclear facilities at Bhabha Atomic Research Centre, Bombay, are released into Bombay harbour after monitoring and dilution. The interactions of gamma-emitting fission product nuclides, especially cesium-137, with sedimentary particles and biota were studied during 1968-71. Cesium-137 is first scavenged by the sedimentary particles, followed by cerium-144 and ruthenium-106. Zirconium/niobium-95, though present in the effluent, was not sorbed. Cesium-137 was distributed throughout the harbour, whereas cerium and ruthenium deposition were limited to a few stations off Trombay coast. Maximum deposition of cesium-137 activity was around the discharge zone off Trombay; it decreased significantly with distance, the concentration being 100 times lower towards the mouth of the harbour in south. Over the period of surveillance there was about two-three times increase in the accumulation of radioactivity by bed material, though the total radioactivity in the effluent discharge had increased five times. Maximum deposition of activity was found in the upper 5 cm layer of the sediment column; decreasing thereafter either intermittently or exponentially with depth. The sorption sequence of cesium-137, cerium-144 and ruthemium-106 has been explained in terms of rate of sorption, mineral structure and the physicochemical parameters controlling the diffusion mechanism. The occurrence of artificial radioactivity in fish and shell-fish of economic importance in 1965 before regular discharge began was below detection limit. Analysis since then showed accumulation of cesium-137 only. The absolute concentration as such, however, varied from species to species. Other nuclides, cerium-144, ruthenium-106 and zirconium/niobium-95, could not be detected except in the ark-shell bivalve, Anadara granosa, which showed specific accumulation of cesium, cerium and ruthenium nuclides but not of zirconium/niobium-95, although this nuclide was present in the effluent. A. granosa was therefore used as an indicator to detect contamination due to cerium and ruthenium radionuclides. Lamellibranchs and crustaceans, in general, were found to be the most effective integrators of cesium-137. In these benthic species the concentration factors (Cfs) for the nuclide varied from 10 2 to 10 5. Pelagic species, on the other hand, were poor integrators of cesium-137 (Cfs: 10–50). Monthly variation in concentration of cesium-137 in A. granosa, Placenta placenta, Scylla serrata and Periopthalmus sp. could be related to the variation in the amount of activity released. Maximum concentration of cesium-137 occurred in muscle tissues of different species. The radiation dose through the contaminated environment to the benthic communities was far below the limits required to produce any detectable radiation damage. The radiation dose to fishermen, both internally through the consumption of contaminated marine products and externally through fishing over the contaminated bed, was also well below the permissible dose limit.

Accumulation of fallout cesium 137 in soils and sediments in selected watersheds

The fallout of certain radioisotopes produced in nuclear explosions and their subsequent dispersion over the earth provide tracers for following the movement of soil particles in the sedimentation cycle. Cesium 137, which is strongly adsorbed by most soil particles, was identified in sampled soils and sediments by gamma differential spectrometric analysis using a 1024‐channel pulse height analyzer ancl a 10‐ × 12.5‐cm NaI (thallium) scintillation crystal detector. The concentration of 137Cs measured ranged from 0.01 to 3.28 pci/g in soils and from 0.01 to 10.05 pci/g in sediments. Uranium, thorium, and potassium were determined simultaneously with 137Cs. Total potassium ranged from a trace to 5.4%, uranium from 0.5 to 9.4 ppm, and thorium from 1.9 to 42.0 ppm. The concentration of 137Cs in reservoir sediments varied with depth. In some reservoirs the years of greatest 137Cs fallout were correlated with layers containing peak concentrations of 137Cs in the sediment profile. The occurrence of 137Cs in sediments was significantly correlated with the amount of clay and of organic matter present. The amount of 137Cs was greater per unit area in sampled sediments than in the contributing watersheds, and the relative concentration factor was as large as 24. This accumulation of 137Cs in reservoir sediments is indicative of the pollution possible in reservoirs as a result of fallout within the watershed but not necessarily within the reservoir.

The accumulation of radioactive cesium, phosphorus, strontium, and yttrium by mosquito larvae and its relevance to radiation dose.

Aedes aegypti (L.) larvae were reared in solutions of 137Cs, 32P, and 90Sr + 90Y and the apparent concentration ratios of the individual radionuclides which were accumulated are reported. A consideration of the significance of accumulation to the internal radiation dose delivered to the larvae reveals that larvae reared in identical concentrations of a radionuclide did not receive the same dose, nor were they exposed to the greatest dose-rate at the same stage of development. The probable dose to larvae reared in radioactive solutions cannot be calculated solely from a knowledge of the radionuclide concentration in the rearing medium.

Effect of rubidium and caesium on electrogenic sodium pumping in rat myometrium

1. 1. Rubidium and caesium substituted for potassium in activating electrogenic sodium pumping in sodium rich rat myometrium. 2. 2. Rubidium was as effective as potassium but caesium was much less effective in activating sodium pumping. 3. 3. The extrusion of sodium produced by caesium was accompanied by accumulation of caesium, both movements being inhibited by ouabain. 4. 4. The permeability to caesium appeared to be very low. 5. 5. During recovery from sodium enrichment in the presence of 4·6–9·2 mM caesium action potentials with large overshoots followed by an extremely prolonged “plateau-type” repolarization phase developed.

Accumulation of caesium and rubidium in vivo by red and white muscles of the rat.

1. Rats were given drinking water containing either 20 mM-CsCl or 20 mM-RbCl for a period of 2 weeks. Samples of blood were then taken from the rats under anaesthetic. They were immediately centrifuged and the plasma taken for analysis. Soleus muscles, diaphragm, extensor digitorum longus, white gastrocnemius and vastus lateralis muscles were then taken from the dead animals and these and the plasma were analysed for potassium, and for caesium or rubidium by means of the flame photometer.2. The concentrations of potassium and rubidium or caesium in the fibre water of these various muscles and in the samples of plasma water were then calculated.3. It was found that the red muscles including soleus and diaphragm generally tended to accumulate caesium and rubidium to a greater extent than did the white muscles such as the white gastrocnemius and vastus lateralis.4. When the concentration ratio [K](i)/[K](o) was divided into the ratio [Rb](i)/[Rb](o) for the different muscles, values of about 1.3 were obtained for the red muscles compared with values about 1.14 for white muscles.5. When in the case of the caesium-treated rats the ratio [K](i)/[K](o) was divided into the ratio [Cs](i)/[Cs](o) values ranged from 1.94 +/- 0.12 for the red soleus to 1.08 +/- 0.09 for the white gastrocnemius.6. When these values in the caesium-treated animals were plotted against the percentage of red fibres in the five muscle types (as obtained from the data of Sreter & Woo, 1963) the graph indicated that the white fibres had similar ionic gradients for Cs(+) and K(+) and that affinity for Cs(+) was confined to the red fibres.7. The membrane potential measured in soleus and extensor muscles immersed in plasma from the same animal was not significantly different from E(K) but was much less than E(Cs).8. These results are interpreted in terms of permeability differences between the slow red fibres and white twitch fibres.

Ionic regulation in the squat lobsterGalathea squamifera, with special reference to the relationship between potassium metabolism and the accumulation of radioactive caesium

The absorption of radioactive Cs from sea water in relation to K metabolism has been examined in the squat lobsterGalathea squamifera. A general study has been made of the ability ofGalatheato carry out osmotic and ionic regulation as a comparison with better known decapod crustaceans which have previously been used for radioactive Cs experiments.Galatheaappears to be a truly marine decapod in that it is probably unable to osmoregulate and the body surface is very permeable to water and to Cs and Kions. Despite this high permeability,Galatheais able to regulate K and radioactive Cs at blood plasma levels which are 1.3 and 1.1 times those of sea water. The Na and Cl concentrations in the plasma are not regulated and the Ca concentration is variable, but Mg and SO4are maintained at concentrations below those of sea water. Urinary excretion does not assist in the conservation of K or radioactive Cs in the plasma but assists in removing Mg and SO4.

The accumulation of radioactive caesium by marine invertebrates : Bryan G. W., 1963. J. Mar. Biol. Ass., U.K., 43 (2): 519–539

The accumulation of radioactive caesium by marine invertebrates : Bryan G. W., 1963. J. Mar. Biol. Ass., U.K., 43 (2): 519–539

The accumulation of radioactive caesium by marine invertebrates

The accumulation of radioactive Cs has been studied in species from the principal marine invertebrate phyla. In some species the accumulation of radioactive Cs has been compared with that of42K and equilibrium levels of both isotopes have been related to the distribution of inactive K.Radioactive Cs is always absorbed more slowly than42K. Most of the inactive K is readily exchangeable with42K so that at equilibrium inactive and active concentration factors are nearly equal. Whole animal concentration factors for radioactive Cs at equilibrium varied between 1·2 and 14 in unfed animals. These factors usually exceed those for inactive K because, although body fluid concentration factors are similar for both ions, the tissue/body fluid ratios for radioactive Cs exceed those for inactive K. Radioactive Cs penetrates rapidly into body fluids, so that uptake by the tissues is the limiting factor in accumulation. Although Cs is absorbed much more slowly than K, the eventual distribution of Cs between the tissues and body fluid of a particular species appears to bear a relationship to the distribution of K.No evidence has been found to suggest that Cs is a necessary element which is absorbed specifically.

Effect of nutrient potassium on the uptake of caesium-137 and potassium and on discrimination factor.

PREDICTIONS of the potential hazards from fall-out radioisotopes in man's food chain have often been based on ion-pair relationships1,2. For example, because of close chemical similarities between strontium and calcium, the transfer of strontium-90 through biological materials has been correlated with calcium. The ratio of strontium-90/calcium of the tissue to the same ratio in the substrate, that is, strontium-90/calcium(tissue)/strontium-90/calcium(substrate), has been termed by Comar the observed ratio3. More recently caesium-137 hazards have been considered in terms of caesium-137/potassium ratios. Certain applications of these ratios have been criticized by Kornberg4, and the conditions necessary for their valid application in hazard assessment discussed. This report presents results which demonstrate the absence of any consistent relationship between the accumulation of caesium and potassium in bean plants, and further demonstrates the limited applicability of caesium-137/potassium ratios in hazard predictions.

Accumulation of Potassium, Cesium, and Rubidium in Bean Plants Grown in Nutrient Solutions

Adding potassium to the nutrient substrate reduced Cs/sup 137/ and Rb/sup 86/ uptake by bean plants less than expected from an assumed physiological equivalence of these ions. Plants discriminated against cesium at low potassium nutrient concentrations, but with increasing substrate potassium, this discrimination diminished. Discrimination of Rb/sup 86/ from potassium approximated that observed for Cs/sup 137/. Potential errors from the use of ratios in predicting uptake of Cs/sup 137/ were discussed. Some toxicity was noted when significant quantities of non-radioactive cesium were in the nutrient solution.