Uptake Of Radionuclides Research Articles

Uranium-series nuclides in the Golden fault, Colorado, U.S.A.: dating latest fault displacement and measuring recent uptake of radionuclides by fault-zone materials

Concentrations and isotopic ratios of U, Th and Ra were measured in a fault zone near Golden, Colorado where major displacement occurred between about 190 and 615 ka. Faulting created new surfaces for leaching and provided the pathways for U-rich ground water. Uranium and 230Th, the latter produced by the decay of dissolved 234U, are adsorbed by fault gouge, hematite-stained sand and brecciated sand- and claystones. The observed U enrichment is as much as six times baseline value and the simultaneous enrichment of 230Th is estimated at about ninefold relative to 238U. The adsorption of radionuclides chemically analogous to Th, such as Pu (IV) and Np, and 237Np decay products, on fault-zone materials would contribute to the immobilization of high-level radioactive waste in the vicinity of a repository in the event of leakage from engineered barriers into fractured rock-mass.

Uptake of Radionuclides onto Suspended Particulate Matter in Coastal Water

Uptake of Radionuclides onto Suspended Particulate Matter in Coastal Water

Book reviews

This book is the proceedings of a workshop held under the joint sponsorship of the CEC Radiation Protection Programme and the French Atomic Energy Commission Institute of Nuclear Protection, Fontenay aux Roses. One of the major problems in estimating radiation doses from the uptake of radionuclides in the environment, or in developing models with which to predict such doses and to set emergency reference levels for public safety, is the fact that the metabolism of and response to such nuclides vary considerably with age or stage of development of the organism.

Plant uptake of radionuclides

Abstract. The factors influencing uptake of radionuclides from soils into vegetation are discussed with reference to soil type, radionuclide, plant species and organ, and time since initial contamination. Gaps in knowledge are identified, particularly as highlighted by the unexpected behaviour of radiocaesium in many upland areas of Britain, following deposition after the Chernobyl accident. The importance of resuspended soil for contamination of aerial plant parts is also considered in relation to radionuclide type, vegetation height, and meteorological conditions.The development of an international database by the International Union of Radioecologists for soil to crop transfer factors of radionuclides derived from European experiments is briefly described. This database is now being used for statistical analyses aimed at quantifying the importance of environmental and biological factors in influencing uptake of radionuclides from the soil.

A study of radionuclides in vegetation on abandoned uranium tailings

A study has been carried out of the uptake of uranium and other radionuclides by plants growing on abandoned tailings from an uranium mining operation. Assay methods included instrumental neutron activation analysis, delayed neutron counting, fission track imaging, and counting of natural radioactivity. Care was taken to avoid contamination of the plant material and a number of methods are described to identify such contamination. All plants observed showed high uptake of radionuclides, compared to plants studied from naturally uraniferous and control areas. Graminoid (grass-like) plants showed significant uptake in the above-ground parts while woody plants showed exceedingly high uranium accumulation in the root portions. These results have significance in determination of the spread of radioactive material from such sites.

The uptake of radionuclides from inadvertent consumption of soil by grazing animals

Investigations of the transfer to man of artificially-produced radionuclides through food chains have shown that the inadvertent consumption of soil by grazing animals can give variations in estimates of transfer coefficients, especially for radionuclides that are poorly absorbed by plant roots. Even small masses of soil adhering to herbage or directly ingested can make a significant contribution to the intake inventory in terms of activity. Although the activity concentrations of soil-contaminated herbage are elevated, the radionuclides associated with the soil may not necessarily be in a form which is easily absorbed by the animal. Attempts must be made, therefore, to quantify soil intake and the subsequent radionuclide uptake by this mechanism. A field investigation of the uptake of radionuclides by farm animals grazing near the Sellafield nuclear reprocessing plant has been pursued. The aims of the study were to estimate the transfer to muscle and other tissues. This paper describes the methods used to estimate both the soil intake and the consequent availability of radionuclides associated with the soil. The measurements were used to evaluate the contribution to tissue content of inadvertent consumption of soil by cows and sheep.

Factors affecting the uptake of radionuclides by cattle grazing on pasture reclaimed from the sea

A considerable area of land has already been reclaimed from the sea along the north-west coast of England and more remains potentially suitable for this purpose. Sea-washed areas along this coast receive radionuclide-bearing sediment as a result of discharges of liquid effluent from the Sellafield nuclear fuel reprocessing plant into the Irish Sea. Thus, land reclamation is an important phenomenon from the point of view of radiological protection. This paper presents some preliminary results from an investigation intended to quantify the factors governing the transfer of radionuclides from feed to milk in cattle that graze predominantly on an area isolated from the sea in 1977. For caesium-137, the transfer coefficient from feed to milk determined at the end of the grazing season in 1985 was about an order of magnitude less than that found in earlier experiments at an inland site close to Sellafield. This implies that most of the intake is associated with soil rather than incorporated into herbage and that the activity is in a form unavailable for systemic uptake. A determination of the disposition of caesium-137 between soil phases supports this view, since more than 90% was found in the residual phase.

Uptake of radionuclides onto suspended particulate matter in coastal water.

Distribution coefficients K ds of several radionuclides on suspended particulate matter (SPM) have been determined with laboratory batch experiments using samples collected in the Kinki district, Japan. Most SPM in coastal water was retained on the initial filter of four sequential filtering stages (20, 5, 1 and 0.45 μm pore size), maximum K d also being found for the SPM retained in this first stage. When the filtrations were not performed in series, however, but were conducted from the same tracer solution in parallel, the K d values were identical for the smaller filter sizes (5, 1 and 0.45 μm) and were greater, by ca. 150% than those derived from the 20 μm filter. The degree of association of the radionuclides with SPM was 85Sr<137Cs<65Zn<54Mn<60Co. The particulate radioactivity fraction of the SPM in coastal water was estimated at most 0.1 for radionuclides with K d of ca. 5 X 104 ml/g, i.e. which are highly associated with the SPM (2 mg/l). The scavenging effect by SPM seemed to be, however, conside...

Uptake of radionuclides by plants after the Chernobyl accident

Gamma-radioactivity of a wide variety of plant samples was measured. Measurements showed that radioactivity in plants depended on the area of surface exposed, the developmental season of the plants, and on the external morphology of their above-ground parts. Autoradiographs on several plants showed the presence of radioactivity in certain spots (hot spots) which were distributed randomly on the surface of the plants and differed in size and activity.

Uptake of dry-deposited radionuclides in Fucus—A field study after the Chernobyl accident

The dry deposition of various radionuclides emanating from the plume from the Chernobyl reactor accident was measured at two locations in southern Sweden at the beginning of May, 1986. Samples of Fucus, taken at or near these locations, were also analysed. No precipitation had fallen during the time between the accident and the time of sampling. The ratios between activity concentrations in Fucus and dry depositions on the water surface have been calculated. For any specific radionuclide, this ratio was found to be the same at the two locations, after differences in salinity and in uptake between F. vesiculosus and F. serratus had been taken into account.

Studies of 131I, 137Cs and 103Ru in milk, meat and vegetables in North East Scotland following the Chernobyl accident

Uptake and clearance of radionuclides in foodstuffs have been studied in the neighbourhood of Aberdeen in North East Scotland following the Chernobyl accident. The level of 131 I in goats' milk was 100–200 Bq litre −1 in early May and declined with an effective half-life of 4sd3 days, but that in cows' milk was only a few Bq litre −1 as most cattle were kept indoors. 137Cs and 103Ru activities in broccoli declined with effective half-lives of 11 and 6 days respectectively, while 137Cs in grass decresed with a half-life of 22 days, the reduction appearing to show a relationship to weekly rainfall. Studies of tissues from groups of lambs initially grazed on contaminated pasture and later (a) fed indoors on concentrates or (b) continuing to graze outdoors, showed the 137Cs concentrations to decline with half-lives of (a) 17 days and (b) 25 days, while the half-lives describing the reduction in total 137Cs activity were (a) 20 days and (b) 35 days.

Gamma activity of plants from monazite-bearing soils of the west coast of Sri Lanka

Gamma activity measurements were obtained for 16 plant species growing on monazite-bearing soils occuring along the West Coast of Sri Lanka. The individual radionuclide contents of five members of the thorium series, thorium-228, radium-224, actinium-228, bismuth-212 and thallium-208, for the different plant species are reported. This investigation establishes the uptake of radionuclides of the thorium series by plants growing on monazite-bearing soils. The extent of absorption of the radionuclides by plants is discussed in terms of plant growth habit and soil characteristics.

203Hg and other gamma-emitting radio-isotopes as labels for Dirofilaria immitis microfilariae.

The in vitro uptake of gamma-emitting radionuclides by microfilariae of Dirofilaria immitis was investigated. Radionuclides tested were 133Ba, 207Bi, 82Br, 109Cd, 51Cr, 60Co, 59Fe, 203Hg, 125I, 54Mn, 32P, 125Sb, 46Sc, 75Se and 65Zn. Only 207Bi, 59Fe, 203Hg, 54Mn and 46Sc showed more than 2% of the available radioactivity to bind to the microfilariae. When tested for retention in vitro only 203Hg showed retention levels approaching 90%. Moreover, when dimethyl-sulphoxide was incorporated into the medium at levels of 1% (v/v) the uptake of 203Hg could be increased by 3-5 times; no other radio-isotope tested responded in this manner. The uptake of 203Hg was directly related to temperature and time of incubation. Mercury, as mercuric chloride, was toxic to the microfilariae and represents an impediment to the incorporation of high levels of 203Hg in microfilariae.

Metabolism and possible health effects of aluminum.

Literature regarding the biochemistry of aluminum and eight similar ions is reviewed. Close and hitherto unknown similarities were found. A hypothetical model is presented for the metabolism, based on documented direct observations of Al3+ and analogies from other ions. Main characteristics are low intestinal absorption, rapid urinary excretion, and slow tissue uptake, mostly in skeleton and reticuloendothelial cells. Intracellular Al3+ is probably first confined in the lysosomes but then slowly accumulates in the cell nucleus and chromatin. Large, long-lived cells, e.g., neurons, may be the most liable to this accumulation. In heterochromatin, Al3+ levels can be found comparable to those used in leather tannage. It is proposed that an accumulation may take place at a subcellular level without any significant increase in the corresponding tissue concentration. The possible effects of this accumulation are discussed. As Al3+ is neurotoxic, the brain metabolism is most interesting. The normal and the lethally toxic brain levels of Al3+ are well documented and differ only by a factor of 3-10. The normal brain uptake of Al3+ is estimated from data on intestinal uptake of Al3+ and brain uptake of radionuclides of similar ions administered intravenously. The uptake is very slow, 1 mg in 36 years, and is consistent with an assumption that Al3+ taken up by the brain cannot be eliminated and is therefore accumulated. The possibility that Al3+ may cause or contribute to some specific diseases, most of them related to aging, is discussed with the proposed metabolic picture in mind.

Quantitative analysis of tight junctions and the uptake of 99mTc in human gliomas.

The structural dimensions of capillary tight junctions and the uptake of 99mTc pertechnetate in human gliomas were studied. Quantitative analysis revealed a correlation between the uptake of radionuclides and the length of endothelial tight junctions. It is suggested that brain scintigraphy might be used for the selection of malignant brain tumors with altered tight junctions which might be accessible to chemotherapy with water-soluble agents.

Studies on the67Ga uptake mechanism by Ehrlich ascites tumor cells

In order to obtain more information concerning the mechanism of Gallium (67Ga) accumulation in malignant tissue, an investigation was carried out using Ehrlich ascites tumor cells. Chlorpromazine, a phospholipid stabilizer decreased the uptake of 67Ga and Calcium 45 (45Ca) by the cells at low dose, but increased them at high dose. On the other hand, the uptake of both radionuclides by the cells was inhibited by ruthenium red, a Ca ATPase inhibitor in a dose dependent manner. The time course of 67Ga and 45Ca uptake were quite different from each other. Moreover, the subcellular distribution patterns of 67Ga and 45Ca were also different from each other; 67Ga accumulated in the lysosomal fraction and 45Ca mainly in the mitochondrial fraction. These results suggest that there may be a commonality for 67Ga and 45Ca uptake by the tumor cells, whereas the behaviour of these two radionuclides in the cells is dissimilar.

The disposal of radioactive wastes into the marine environment: the presence of hot particles containing Pu and Am in the source term

AbstractRadioactive particulate matter (identified as hot particles) is present in the effluent discharged by the British Nuclear Fuels Ltd (BNFL) uranium reprocessing plant at Sellafield, Cumbria, UK. There is very little information on the abundance or chemical and physical forms of solid matter in the effluent; even less is known of the significance of particulate debris in relation to the uptake of radionuclides for non-occupationally exposed people as a result of transfer along marine foodchains. Some observations on the occurrence and abundance of hot particles in the vicinity of Sellafield are reported, with special reference to those that contain transuranic radionuclides (Pu,Am,Cm). Some of the uncertainties are discussed in an evaluation of the significance of hot particles, albeit aggregates of colloids for the smallest particles, and exposure to man from ionizing radiation. There is no evidence that hot particles derived from BNFL and subsequently dispersed into the marine environment represent a hazard to man. However, further studies are required in order to determine whether or not the pathways followed by the particles are significant, or different to those of other radionuclides through which the radiation exposure of man within this region of Cumbria is assessed.

Assessment of and therapy following contamination through the lungs or gastrointestinal tract

Incorporated radionuclides are excreted from the body by naturally-occurring processes. Some radionuclides, however, are retained for very long periods by tissues such as bone and liver. The objective of successful therapy is to block the uptake of radionuclides from the respiratory and gastrointestinal tracts, or to prevent circulating radionuclides from reaching critical tissues. It is essential, therefore, for the clinician to have a rapid means of identifying the contaminating material and to have some knowledge of its solubility before planning treatment. Many techniques and therapeutic agents have been claimed to be totally or partially successful when tried out in experimental animals, but few of these procedures have been used effectively in man. Some success has been achieved by the use of Prussian Blue in blocking the gastrointestinal uptake of radiocaesium; in blocking the uptake of radioiodines by the thyroid gland with stable iodide; and in the complexation of circulating transuranium and lanthanide elements with chelating agents, thereby enhancing their renal excretion. The author discusses some of the problems in assessing the magnitude of an accidental intake and summarises the treatments used.

Aspects of the uptake of radionuclides by sheep grazing on an estuarine saltmarsh. 1. The influence of grazing behaviour and environmental variability on daily intake

Sea water contaminated with diluted radioactive effluent originating from the Sellafield reprocessing plant inundates saltmarshes in the Esk estuary in west Cumbria (UK). Much of the radioactivity on the saltmarsh vegetation was found to be associated with a surface deposit of silt, brought onto the area during tidal inundation. Large temporal variations in the radionuclide concentrations of the vegetation were found, these being due probably to seasonal fluctuation in the extent of silt deposition. The grazing habits of sheep were studied on one of these saltmarshes and the consequent ingestion of radionuclides by the sheep was estimated. The sheep ingested different quantities of radionuclides according to time of year as a result of a combination of two factors; the considerable temporal variation in the concentration of radionuclides on the saltmarsh vegetation and the seasonal grazing behaviour of the sheep.

Aspects of the uptake of radionuclides by sheep grazing on an estuarine saltmarsh. 2. Radionuclides in sheep tissues

The transfer 137Cs, 238Pu, 239/240Pu and 241Am to sheep which graze a saltmarsh in the Esk estuary, 7 km south of the sellafield reprocessing plant in west Cumbria (UK), has been estimated. The concentrations of gamma-emitting radionuclides and of 238Pu, 239/240Pu and 241Am were measured in liver, lung, muscle, kidney and bone from saltmarsh ewes and lambs. 137Cs concentrations in the soft tissues were similar in liver, lung and muscle but were consistently higher in kidney and much lower in bone. The highest concentration of the transuranics was found in liver. Transfer coefficients and concentration factors were calculated for both ewes and lambs. The concentration of 137Cs in the tissues of 5-month old lambs was higher than in those of their mothers. Therefore, a higher transfer coefficient was obtained for lamb muscle (1·8 × 10 −1 d kg −1) than for ewe muscle (6·4 × 10 −2 d kg −1). Concentration factors were consistently higher for 137Cs than for the transuranics.