Bioavailability of radiostrontium in soil: experimental study and modeling.

Parameters related to 90Sr mobility in the soil-plant system are reported: exchangeable content, selectivity coefficient, and transfer factor. Large mobility of 90Sr in different soil types was shown. The fraction of exchangeable 90Sr varied between 70 and 90%. The selectivity coefficient K(C)(90Sr/Ca) values were in the range 1.3-2.5. The radionuclide transfer factors (TF) varied by a factor of 9.6 for barley seedlings and by a factor of 6.6 for lupine seedlings. The exchangeable Ca content was the determinant soil parameter responsible for differences in 90Sr biological availability. A static model was devised that describes 90Sr sorption from soil solution by soil and on the root surface. The parameter of 90Sr bioavailability (A) has been suggested. Parameter A was calculated from data on soil exchangeable Ca content and 90Sr mobility indicators--exchangeable fraction of the radionuclide and the selectivity coefficient K(C)(90Sr/Ca). A correlation was found between TF and parameter A.

[137Cs vertical migration in boggy soils in the long term after the Chernobyl accident]. / Vertikal'naia migratsiia 137Cs v volotnykh pochvakh v otdalenny period posle avarii na ChAES.

137Cs vertical migration in boggy soils has been studied 15 years after the Chernobyl accident. The rate of vertical migration of the radionuclide is shown to be dependent on the peculiarities of formation of peatbogs, their moistening regime and soil properties. 137Cs migration in a high-land peatbog is characterized by higher intensity then in lowland or transitional peatbogs. Differences in 137Cs vertical migration are to a large extent caused by the contents in soil of exhangeable and mobile radionuclide forms. The derived experimental data that describe 137Cs distribution over the profiles of peaty soils of different type are used for parameterization of two-component convective-diffusion model. Ecological and effective half-life periods of 137Cs content reduction in the soil root layer have been calculated. A long-term prediction is given of the dynamics of the radionuclide content in the root layer of peaty soils.

[Evaluation of cell membrane permeability for Ca2+ and adenylate cyclase in sheep peripheral blood cells, exposed to low doses of radiation]. / Otsenka pronitsaemosti plazmaticheskoi membrany dlia Ca2+ i aktivnosti adenilattsiklazy v kletkakh perifericheskoi krovi ovets, obluchennykh v malykh dozakh.

Chronic irradiation of sheep with doses of 2.6 and 12.9 mC.kg was characterized by the modification of the adenylatecyclase activity and Ca2+ permeability of plasma membrane in cells of the peripheric blood, with no changes in the clinical and hematological indicators. The observed effects are assumed to result from structural and dynamic variations in the lipids of membranes.

[Method of assessment of 137Cs biological availability in forest soil]. / Metod otsenki biologicheskoi dostupnosti 137Cs v lesnykh pochvakh.

A method for quantitative assessment of 137Cs availability to plants in forest ecosystems on the basis of soil properties has been developed. It is shown that the experimental dependencies of 137Cs soil-to-plant transfer factor (TFag) for fern and bilberry on the bioavailability factor calculated on the basis of soil characteristics of root layer: 137Cs exchangeability, exchangeable Ca, effective selectivity coefficient, were satisfactory described by linear function. The advantage of the proposed method is that the necessary soil characteristics can be taken from the reference literature, evaluated using empirical correlations or determined with standard agrochemical procedures.

[Evaluation of hormonal status indicators and adenylate cyclase activity in animals in the follow-up of the Chernobyl AES accident]. / Otsenka pokazatelei gormonal'nogo statusa i aktivnosti adenilattsiklazy u zhivotnykh v otdalennye sroki posle avarii na Chernobyl'skoi AES.

Enhancing stimulation effect of prostaglandin E1 on adenylate cyclase, decrease in basal activity of adenylate cyclase in platelets and reducing thyroxine concentration in cow plasma 5 years after radioiodine damage to thyroid gland with doses higher than 200 Gy were detected, whereas only decrease in adenylate cyclase activity in platelets from animals irradiated with 40 Gy to thyroid gland was observed. No changes in platelet adenylate cyclase in cows exposed to less than 1 Gy to thyroid gland after 5 years of maintenance on the territory with 137Cs contamination density lower than 0.37 MBq/m2 were found.

[Total Ca contents in blood cells and plasma of the irradiated animals]. / Obshchee soderzhanie Ca v kletkakh krovi i plazme obluchennykh zhivotnykh.

It was found that the total Ca content in erythrocytes from irradiated sheep and horses increased by 10-40% from 1st till 5th days after irradiation, the intracellular Mg content being unchanged. More than 2-fold increase in total Ca content in lymphocytes during first 15 days was revealed, while in platelets only a trend for a growth in acute period of radiation disease was detected. On the contrary, no reliable changes in total Ca content in plasma after irradiation were observed. This fact indicates that Ca accumulation in blood cells after whole-body irradiation is due to disturbance in intracellular Ca(2+)-homeostasis.

[The content of immunoreactive calmodulin in the blood cells of irradiated animals]. / Soderzhanie immunoreaktivnogo kal'modulina v kletkakh krovi obluchennykh zhivotnykh.

The immunoreactive calmodulin content was shown to increase in the irradiated platelets of rats and cows. Total Ca content did not vary significantly in platelets of exposed animals although there was a tendency toward its increase. At the same time, total Ca content in lymphocytes of irradiated cows increased while the immunoreactive calmodulin level remained unchanged.