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PubMedDate not supplied

[The simulation of 137Cs distribution in forest ecosystems and prediction of its accumulation by forest products].

A mathematical model of 137Cs migration in forest ecosystem is presented, which describes the behaviour of this radionuclide in the forest litter-soil system, trees, understory and forest animals. The model's parameters for different types of forest ecosystems are estimated and model's adequacy is tested through the use of independent experimental data. The sensitivity of the model's output variables is analyzed to variations in the most significant parameters. The differences in the seasonal and mean annual dynamics of 137Cs concentration in muscles of roe deers and mooses are shown to be defined by specific features of the diets of these animals and variations in 137Cs content in the main diet components.

Cesium Radioisotopes↗
PubMedDate not supplied

[Quantitative evaluation of 90Sr, 137Cs, 239Pu, 241Am transfer from polluted soil to gastric and intestine juice of cows].

Quantitative parameters of 90Sr, 137Cs, 239Pu and 241Am transfer from solid phase of soil to gastric, intestine juice of cows as well as to imitating solutions have been estimated on the base of results of laboratory incubation experiments. A prevailing role of enzyme complex and microflora of gastrointestinal tract in radionuclides transfer from solid phase of soil to solution has been shown.

Americium↗
PubMedDate not supplied

[Reconstruction of I-131 in milk and exposure doses to the thyroid gland of cattle after the Chernobyl AES].

Suggestions are made concerning the restoration of 131I content in cow milk of six districts in the Gomel region based on radiometric measurements of the overall activity of milk samples in the iodine period of the Chernobyl NPP accident, reconstruction of doses to thyroid of cattle and calculation of dose distribution among the live-stock by separation the function of activity changes in milk samples in time into the basic components formed by the contribution of 131I, 134Cs and 137Cs. The best approximation to the description of the function of milk activity variations was found to be achieved by the representation of forage activity changes as a sum of exponents with the half-life periods of 5 and 30 day with a partial contribution of 0.8 and 0.2. The calculations showed, that the average absorbed doses to the thyroid varied between 10 and 40 Gy.

Animal Feed↗
PubMed2003

Relative biological effectiveness (RBE) of 210Po alpha-particles versus X-rays on lethality in bovine endothelial cells.

PURPOSE: Alpha-radiation from polonium-210 ((210)Po) can elevate background radiation dose by an order of magnitude in people consuming large quantities of meat and seafood, particularly caribou and reindeer. Because up to 50% of the ingested (210)Po body burden is initially found in the blood, a primary target for the short range alpha-particles is the endothelial cells lining the blood vessels. This study examined the relative biological effectiveness (RBE) of (210)Po alpha-particles versus 250 kVp X-rays in producing injury to cultured bovine aortic endothelial cells. MATERIALS AND METHODS: Radiation effects on cells were measured in four different ways: the percentage viable cells by trypan blue dye exclusion, the number of live cells, the lactate dehydrogenase (LDH) release to medium and the ability to form colonies (clonogenic survival). RESULTS: Comparison of dose-response curves yielded RBE values of 13.1+/-2.5 (SEM) for cell viability, 10.3+/-1.0 for live cell number and 11.1+/-3.0 for LDH activity. The RBE values for clonogenic survival were 14.0+/-1.0 based on the ratio of the initial slopes of the dose-response curves and 13.1, 9.9 and 7.7 for 50, 10 and 1% survival rate, respectively. At X-ray doses <0.25 Gy, a pronounced stimulatory effect on proliferation was noted. CONCLUSIONS: Exposure to (210)Po alpha-particles was seven to 14 times more effective than X-ray exposure in causing endothelial cell damage.

Alpha Particles↗
PubMed1992

[Examination of gastric juice in animals fed with fodder containing power plant ashes and loess dusts].

Normal metabolism, regulation of stimulation and checking of electrolyte secretion in the gastric juice depend on the way of feeding and its nutritional ingredients. Feeding experimental animals with fodder containing power plant ashes or loess dusts causes a change in the gastric juice reaction, thus resulting in a different assimilation of elements contained in the fodder. There was shown an increase of some elements content (Mg, Na, Cu, Fe), a decrease in the content of some others (Pb,Zn) in the gastric juice and a positive tendency for blocking by calcium ions of heavy metals contained in the fodder by the mucous membrane of the stomach.

Animals↗
PubMed1992

[Dietary intake of Cs-137 and Sr-90 by the population of the Gomel region, Byelarus, 1986-1989].

The authors provide the results of measuring the content of radionuclides in foods in the first 4 years after the Chernobyl accident and the data on the diet of the population. Pollution of foods was demonstrated to decrease with time. The supply of 137Cs to the body fell 3-fold from 1986 to 1989. The rejection of foods in the most polluted Vetkovsk and Narovlyansk regions made it possible to reduce 3-6-fold the mean daily supply of 137Cs with the diet and up to 2-fold the supply of 90Sr.

Accidents↗
PubMed1992

[The mechanism of milk contamination in the territory of Gomel Oblast].

The authors provide the results of studying 137Cs and 90Sr pollution of soil, plants and milk in the Gomel region in 1986-1989. Describe the dynamics of the ratios soil-grass and milk-soil during that period. The content of 137Cs in milk ranged from n.10(-10) to n.10(-7) Ci/l in polluted regions and from n.10(-10)-n.10(-9) Ci/l in the so-called pure regions. In all the regions examined, the concentration of 90Sr in milk was far lower than that of 137Cs. After the accident the levels of 137Cs in milk rose 18-350-fold and those of 90Sr 3-16-fold on the average in the regions. One can observe a progressive decrease of the ratios of accumulation in the grass-soil and milk-soil systems and a decline of the concentration of 137Cs and 90Sr in milk. However, the percentage of samples with an increase of the temporarily permissible in 1988 levels of cesium radionuclides was fairly high in 1989 in certain regions: in the Vetkovsk region, it was 35.3%, in the Chechersky region, it was 28.0%. During 1987-1989, the concentration of 90Sr in milk did not exceed 1 x 10(-9) Ci/l in the areas examined. The broad range of the indicators of milk pollution with 137Cs and 90Sr is specified by varying density of the area pollution, differences in the physicochemical status of radionuclides in accident fall-outs, and geochemical characteristics of the soil sheet.

Accidents↗
PubMed1992

Biokinetics of tritium incorporation into the tissues of rats during continuous ingestion of tritiated water or tritium-labeled food.

Wistar strain male rats were continuously given tritiated water or tritiated wheat as drinking water or food for 70 days. During the ingestion, the tritium incorporation into rat tissues was examined in both wet and dry samples of liver, kidney, testis and blood. The concentration of organically bound tritium (OBT) in dry tissues of rats exposed to tritiated water (HTO) and 3H-food (tritiated wheat) attained an equilibrium within 2-3 weeks after the exposure. The concentration of OBT in dry tissues of rats exposed to HTO also reached an equilibrium within 3-4 weeks after the exposure. However, rats exposed to 3H-food, except for the liver, such an equilibrium state was not reached in other tissues and the OBT concentrations increased gradually throughout the exposure. The relative concentrations of total 3H and OBT at the end of the chronic ingestion of 3H food (70 day), expressed in percentages of the total activity were 1 and 9 times higher than those in rats exposed to HTO, respectively. In both groups, OBT as well as total 3H was almost uniformly distributed among the tissues examined.

Animals↗
PubMedDate not supplied

[Radioecological environment in the territory of Yakutia].

The present radioecological environment in the territory of Yakutia is analyzed. The general description of the natural gamma-background and the sources of pollution of permafrost landscaped with natural and artificial radionuclides is represented. It was revealed that the radiation environment was not good in some regions of Yakutia.

Animals↗
PubMedDate not supplied

[Cytogenetic effects in blood lymphocytes of Slavutich residents having no occupational contact with ionizing radiation].

A comparative cytogenetic examination of the groups of Slavutich and Kiev residents having no occupational contact with ionizing radiation was conducted. It was found a significantly higher chromosome aberration frequency in blood lymphocytes of Slavutich residents (including unstable exchanges--2.5-fold) caused by internal irradiation at the expense of local food stuff consuming. It was revealed no relationship between cytogenetic aberration frequency and initial settling time in Slavutich.

Chromosome Aberrations↗
PubMedDate not supplied

[Prognosis of accumulation of 137Cs and 90Sr in the herbage of the main types of the Belarus Polessje meadows using agrochemical soil properties].

On the basis of long-term stationary experience it was established that the minimum accumulation quantities for 137Cs and 90Sr in the herbage of the dry, lowland and flood-plain types of the Belarus Polessje meadows contaminated with Chemobyl radionuclides are determined when the optimum of basic agrochemical soil properties is achieved with application of the scientifically reasonable protective measures. For remote prognosis of radionuclide contents in natural and cultural meadow herbage the use of transfer factors (TFa, (Bq/kg)(kBq/m2)) based on the complex agrochemical parameters--agrochemical cultivation soil index (Icd) and basic saturation degree (V, %), which take into account some soil characteristics simultaneously, is a streamlined approach. This paper provides the equations of linear and multiple regressions, which can be used to calculate the transfer factors for 137Cs and 90Sr uptake and the herbage contamination degree for the main types of meadows of the region, that will allow reducing the volume of forage production (hay, green bulk), which is not adequate to established permissible levels: "Republican allowable levels of the contents of 137Cs and 90Sr in agricultural raw material and forages".

Animal Feed↗
PubMedDate not supplied

[A mathematical model of 137Cs uptake and removal from the body of cattle in the event of chronic consumption of contaminated fodder].

A two-chamber mathematical model of 137Cs uptake and removal from the body of cattle chronically consuming contaminated fodder has been developed; the model takes into account age dependence of radionuclide absorption from the gastro-intestinal tract. The model parameters were taken from the experiment on calves with chronic peroral uptake of contaminated fodder. In accordance with the model and experiment, 137Cs transfer factor to the muscular tissue one month after birth reaches a maximum value of 56% of the daily uptake per 1 kg of the tissue. By the model, the equilibrium processes of uptake and removal set in two years after the calves birth. The equilibrium TF for muscles in adults approximates 2.8% of the daily uptake per 1 kg tissue. Because of 137Cs absorption from the gastrointestinal tract changes with age, doses of internal exposure of calves over the first two years will be about 5 times higher than doses for any one of the two subsequent years.

Age Factors↗