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At least 19 recordsLinked to original sources
PubMed1991

[The role of individual segments of the gastrointestinal tract in the elimination of cesium radioisotopes].

The transfer of radiocesium from blood to the lumen of individual sections of the gastro-intestinal tract was quantitatively determined. The water suspension of ion exchange resin was injected to the lumen of the individual sections of the gastro-intestinal tract. The sections were ligated. The highest amount of radiocesium absorbed to the resin in the lumen of gastro-intestinal tract was observed 3 hrs after intravenous administration 137CsCl and reached 17.7% of the administered dose. It was shown that the small intestine and the ileum play the biggest role in absorption and excretion of the radiocesium. The role of the duodenum, the large intestine and the stomach is much smaller in this process.

Animals↗
PubMed1987

Transport of the radioisotopes iodine-131, cesium-134, and cesium-137 from the fallout following the accident at the Chernobyl nuclear reactor into cheesemaking products.

The transport of radiation contamination from milk to products of the cheese making process has been studied. The concentration of radioactive iodine and cesium in samples of sheep milk and cheese (Gruyère) products was measured for 10 consecutive production d. Milk with concentration 100 Bq/L in each of the radionuclides 131I, 134Cs, and 137Cs cheese with concentration 82.2 +/- 3.9 Bq/kg in iodine and an average of 42.3 +/- 2.3 Bq/kg in the cesium isotopes is produced. The corresponding concentrations in cream extracted from the same milk are 26.7 +/- 2.8 Bq/kg (131I) and 18.6 +/- 1.9 Bq/kg (134Cs, 137Cs).

Accidents↗
PubMed1994

Fallout radioactivity in soil and food samples in the Ukraine: measurements of iodine, plutonium, cesium, and strontium isotopes.

To estimate the level and distribution of fallout attributable to the 26 April 1986 Chernobyl nuclear power station accident in the Ukraine, we sampled several kinds of substances at Korosten, Zhitomir and at Katyuzhanka, Vishgorod, Kiev in the Ukraine, and measured the radioactivity of 137Cs, 134Cs, 90Sr, 129I, 238Pu, 239,240Pu, and the density of 127I (stable). The substances investigated were soil, dry milk, wheat, rye, drinking water, and mushrooms. Except for the mushrooms collected, which were sampled at Katyuzhanka, Vishgorod, and at Kiev, all substances were at Korosten, Zhitomir. The activity of 137Cs, 134Cs, 90Sr, 238Pu, and 239,240Pu were all higher in soil and mushrooms than in the other four substances. The activity of 137Cs was 960 and 1,210 Bq kg-1 in the two soil samples and 6,110 Bq kg-1 in the mushrooms. The activity of 134Cs was approximately 15% of 137Cs in the two soil samples while < 3% of 137Cs in the mushrooms. The activity concentration level of 90Sr as compared to 137Cs concentration was 15-31% in food samples other than mushrooms but only 1.9% in mushrooms and 1.4 and 1.2% in the two soil samples. The radioactivity ratios, 238Pu: 239,240Pu and 239,240Pu: 137Cs, suggested that the proportion of cesium radioisotopes and 239,240Pu in the soil attributable to the Chernobyl accident was approximately 100% and 10-20%, respectively, while approximately 100% of 239,240Pu in the mushrooms was attributable to the accident. The activity of 129I was small but the ratio of 129I: 127I in the two soil samples was 4.3 x 10(-8) and 1.0 x 10(-7), which is approximately 10 times larger than that in the global fallout. These results suggest that the areas where the soil was sampled are iodine-deficient and were contaminated slightly by the Chernobyl accident.

Accidents↗
PubMed1991

[The radioecology of the grapevine. 2. Effects of the nuclear reactor accident in Chernobyl on the radioactivity in the soil, leaves, grapes and wine].

Natural (tritium, 14C, 40K, 226Ra) and man-made radionuclides (90Sr, 134Cs, 137Cs) were determined in soil (top 30 cm), vine leaves, grapes and wine in eight locations of the most important viticultural regions in the Federal Republic of Germany. The results obtained in 1983-1985 have been published previously. Part II of this study presents results obtained in 1986 and 1987, i.e. after the reactor accident at Chernobyl in the Soviet Union. The mean content of 137Cs before (after) Chernobyl was 4 (9) Bq/kg dry matter in soil, 0.07 (3) Bq/kg fresh matter in leaves, 0.02 (0.4) Bq/kg in grapes, and 0.008 (0.9) Bq/L in wine. As compared with 1986, distinctly lower levels were found in leaves, grapes and wine in 1987. In 1986 the content of 134Cs was about half that of 137Cs. Owing to its shorter half-life, 134Cs was below the detection limit in many of the 1987 samples. Transfer factors such as from soil to leaves and from soil to grapes for caesium agreed well in 1983-1985 and 1987, but showed considerable deviations in 1986, due to the ubiquitous contamination of the environment. Results of 90Sr determinations confirmed other reports showing this radionuclide to be a very minor contributor to the total radioactivity released at Chernobyl. No effect of the reactor accident on levels of the other radionuclides was detected.

Accidents↗
PubMed1988

Effect of microbial biomass reduction by gamma-irradiation on the sorption of 137Cs, 85Sr, 139Ce, 57Co, 109Cd, 65Zn, 103Ru, 95mTc, I by soils.

Six soils, two Sphagnum peat samples and a clay mineral were irradiated with 40 and 80 kGy (4 and 8 Mrad) from a 60Co source. As a result the microbial biomass, determined separately for each sample, decreased considerably. Depending on the radionuclide, the sorption, as characterised by the distribution coefficient, decreased, increased or remained unchanged. The effect of the irradiation on the sorption of the radionuclides depended, in general, also on the type of the sample, especially whether well humified soils, (e.g. crop soils), poorly humified samples (Sphagnum peat, O-horizon from woodland), or a clay mineral was employed. The data reveal that irradiation produces, besides sterilization, also other effects in soils, which can change their sorption properties.

Adsorption↗
PubMed1998

Measurement of resuspended aerosol in the Chernobyl area. Part II. Size distribution of radioactive particles.

Size distribution measurements of particulate radionuclides were performed at two sites in the Chernobyl 30-km exclusion zone using several cascade impactors. The results obtained in the period September 1986 till June 1993 were discussed with regard to the general assumption of a log-normal activity size distribution in inhalation dose assessment. At Zapolie (a site 14 km from the Chernobyl reactor) a bimodal distribution was observed in 91% of all measured distributions. In most cases the medians were about 4 microns and in the range 20-30 microns. According to soil granulometric data this finding was explained by superimposing two processes: local resuspension and advective transport of radioactive aerosol from highly contaminated territories. The mean air concentration showed an increasing proportion of inhalable particles over the years since the accident. In 1993 the inhalable fraction was about 48% of the total concentration. At Pripyat, a site situated within a highly contaminated area, unimodal types of size distributions were predominant with the median diameters in the range 5-10 microns for 137Cs. For the three nuclides 137Cs, 144Ce and 106Ru, very similar types of distribution were observed. Apparently, the radioactive aerosol was of fuel origin. During a forest fire at a distance of 17 km, the majority of the radioactivity was associated with submicrometer particles with median diameters in the range 0.28-0.50 micron.

Aerosols↗
PubMed1984

The use of mosses as indicators of airborne radionuclides near a major nuclear installation.

Samples of naturally growing moss (mainly Pseudoscleropodium purum and Hypnum cupressiforme ) were used to investigate the distribution of photon-emitting radionuclides, notably 129I , 137Cs, 144Ce and 241Am, at distances up to 12 km from the nuclear fuel reprocessing plant at Sellafield in West Cumbria . The relative activities of the naturally occurring radionuclides, 7Be and 210Pb, in moss and air indicated that the removal half-time of these radionuclides on moss is very long (best estimate of half-time, corrected for radioactive decay, was 240 days) and that the mosses are very efficient collectors of airborne particulates (product of deposition velocity and interception factor was 2.4 X 10(-2) ms-1). Hence the activities of artificially-produced radionuclides on the mosses present an effective record of local airborne radionuclide pollution integrated over a number of years. The activity of 210Pb in each sample was used to standardize the activities of artificial radionuclides in the samples. It was found that the activity ratio of 129I /210Pb, 137Cs/210Pb and 144Ce/210Pb declined with distance from Sellafield indicating that the major local source of these radionuclides has been material discharged to air from the site. The activity ratio of 241Am/210Pb declined with distance from the site and also with distance from the sea confirming that the resuspension of material originally discharged to sea is an important local source of 241Am.

Air Pollutants↗
PubMed1977

Rationale and radiopharmaceuticals for myocardial imaging.

Static radionuclide imaging procedures are now available for evaluating regional myocardial perfusion and for detecting acute myocardial infarction. Thallium-201, a radiopharmaceutical that possesses many of the characteristics of potassium analogues, at present is receiving the greatest attention as a regional blood flow indicator. Ischemic lesions appear as areas of decreased tracer uptake. Unfortunately, this agent is expensive, is in limited supply, and has a photopeak that is low for optimum imaging. Positive infarct images can be obtained with various Technetium-99m chelates. Pyrophosphate appears to be the best of the technetium compounds studied to date, although the mechanism of uptake of the chelates has not yet been fully elucidated. Therefore, quantitative measurements of infract size are not justified. As perfusion imaging and infarct imaging provide useful, complementary data, a dual tracer approach to evaluating patients with suspected coronary artery disease and/or myocardial infarction, is probably justifiable.

Ammonia↗
PubMed1999

Sediment deposition rates on the continental margins of the eastern Arabian Sea using 210Pb, 137Cs and 14C.

Eight gravity cores from the active eastern continental margins of the Arabian Sea were dated using 210Pbxs, 137Cs and 14C. The short-term (< or = 100 years) sedimentation rates range from 0.06 to 0.66 cm/year where as the long-term (> or = 1000 years) ones using AMS 14C on planktonic foraminifera varied from 0.004 to 0.13 cm/year. For long-term chronology (< or = 50,000 years) AMS dating of well-cleaned planktonic foraminifera is most suited.

Animals↗
PubMed2001

Qualitative estimates of soil disturbance in the vicinity of CANDU stations, utilizing measurements of 137Cs and 210Pb in soil cores.

Anthropogenically derived 14C has been used to trace recent carbon input in a study of carbon accumulation and turnover in Canadian soils. In order to do so, documentation of the undisturbed nature of the soil horizons sampled was of prime concern. Although all the sites chosen for coring were currently uncultivated, detailed information on long-term land usage was not available. To overcome this problem, 137Cs profiles were measured in all the cores used in the study. 210Pb measurements were also made in cases where total 137Cs deposition was lower than predicted. For some sample sites, the data obtained showed correlated losses of both radionuclides, indicating that land disturbance and/or erosion had indeed occurred in these areas over the past 50 years, hence invalidating the use of those cores for carbon cycling studies. In a few cases a marked lack of correlation between these two radionuclides has made it necessary to hypothesize that chemical, rather than physical, processes have been partially responsible for the observed anomalies. Since results of this nature raise doubts about the reliability of the 137Cs method for identification of land disturbance, further investigation is warranted.

Agriculture↗
PubMed2001

Attenuation coefficients of soils and some building materials of Bangladesh in the energy range 276-1332 keV.

The linear and mass attenuation coefficients of different types of soil, sand, building materials and heavy beach mineral samples from the Chittagong and Cox's Bazar area of Bangladesh were measured using a high-resolution HPGe detector and the gamma-ray energies 276.1, 302.8, 356.0, 383.8, 661.6 and 1173.2 and 1332.5 keV emitted from point sources of 133Ba, 137Cs and 60Co, respectively. The linear attenuation coefficients show a linear relationship with the corresponding densities of the samples studied. The variations of the mass attenuation coefficient with gamma-ray energy were exponential in nature. The measured mass attenuation coefficient values were compared with measurements made in other countries for similar kinds of materials. The values are in good agreement with each other in most cases.

Bangladesh↗
PubMed2000

Sedimentology and geochemistry of a perennially ice-covered epishelf lake in Bunger Hills Oasis, East Antarctica.

A process-oriented study was carried out in White Smoke lake, Bunger Hills, East Antarctica, a perennially ice-covered (1.8 to 2.8 m thick) epishelf (tidally-forced) lake. The lake water has a low conductivity and is relatively well mixed. Sediments are transferred from the adjacent glacier to the lake when glacier ice surrounding the sediment is sublimated at the surface and replaced by accumulating ice from below. The lake bottom at the west end of the lake is mostly rocky with a scant sediment cover. The east end contains a thick sediment profile. Grain size and delta 13C increase with sediment depth, indicating a more proximal glacier in the past. Sedimentary 210Pb and 137Cs signals are exceptionally strong, probably a result of the focusing effect of the large glacial catchment area. The post-bomb and pre-bomb radiocarbon reservoirs are c. 725 14C yr and c. 1950 14C yr, respectively. Radiocarbon dating indicates that the east end of the lake is >3 ka BP, while photographic evidence and the absence of sediment cover indicate that the west end has formed only over the last century. Our results indicate that the southern ice edge of Bunger Hills has been relatively stable with only minor fluctuations (on the scale of hundreds of metres) over the last 3000 years.

Antarctic Regions↗
PubMed2005

Neutrons from fragmentation of light nuclei in tissue-like media: a study with the GEANT4 toolkit.

We study energy deposition by light nuclei in tissue-like media taking into account nuclear fragmentation reactions, in particular, production of secondary neutrons. The calculations are carried out within a Monte Carlo model for heavy-ion therapy (MCHIT) based on the GEANT4 toolkit. Experimental data on depth-dose distributions for 135-400 A MeV (12)C and (18)O beams are described very well without any adjustment of the model parameters. This gives confidence in successful use of the GEANT4 toolkit for MC simulations of cancer therapy with beams of light nuclei. The energy deposition due to secondary neutrons produced by (12)C and (20)Ne beams in a (40-50 cm)(3) water phantom is estimated to be 1-2% of the total dose, that is only slightly above the neutron contribution (approximately 1%) induced by a 200 MeV proton beam.

Carbon Radioisotopes↗