Biomedical subjects

A I Kryshev

Publications and source records attributed to A I Kryshev.

9 recordsLinked to original sources

PubMed2006

90Sr in fish: a review of data and possible model approach.

Data on the relationship between the equilibrium concentration factor of (90)Sr in fish and concentration of Ca in water have been collected and analyzed. The dataset contains 115 values of the concentration factors at different environmental concentrations of Ca. The data included in the dataset are based primarily on publications in Russian and relate to the whole-body concentration factors. An empirical formula was derived to estimate the equilibrium concentration factor of (90)Sr in fish as a inverse relationship of Ca: CF((90)Sr, Bq/kg w.w.)=3940/[Ca, mg/l](water). The derived relationship adequately accounts for the equilibrium concentration factor of (90)Sr in freshwater and marine fish species. A dynamic model was proposed to calculate the (90)Sr bioaccumulation of fish for non-equilibrium situations, for instance, immediately after accidental contamination of water bodies. The model was applied to reconstruct the dynamics of (90)Sr in fish from highly contaminated lake in the Southern Ural (Lake Uruskul). A comparison with data of observations showed that the model is well suited for estimating the dynamic characteristics of (90)Sr bioaccumulation by fish.

Animals↗

PubMed2006

Mathematical simulation of dose-effect relationships for fish eggs exposed chronically to ionizing radiation.

A mathematical model which simulates the observed dose-effect relationships for fish eggs exposed to chronic irradiation is presented. The model assumes that the exposed fish eggs may exist in one of the following states: normally developing, reversibly damaged, and lethally damaged. Reversible damages may be recovered by repairing mechanisms which are spent for the repairing processes. The model was applied to describe the observed differences in effects of chronic exposure for quickly (2 weeks) and slowly (up to 20 weeks) developing fish eggs. Calculations were performed for dose rates of chronic irradiation ranging from 10 to 300 mGy/day. Two types of radiation effects were considered-the effect on eggs survival (percentage of survived eggs at time t), and the depletion of the repairing pool (in percentage of its maximal value). The model predictions have been compared with the experimental data from the EPIC database. This comparison showed that the model adequately describes the radiation effects in fish eggs of different species, within a wide range of chronic radiation exposures.

Animals↗

PubMed2005

Model testing using data on 137Cs from Chernobyl fallout in the Iput River catchment area of Russia.

Data collected for 10 years following the Chernobyl accident in 1986 have provided a unique opportunity to test the reliability of computer models for contamination of terrestrial and aquatic environments. The Iput River scenario was used by the Dose Reconstruction Working Group of the BIOMASS (Biosphere Modelling and Assessment Methods) programme. The test area was one of the most highly contaminated areas in Russia following the accident, with an average contamination density of 137Cs of 800,000 Bq m-2 and localized contamination up to 1,500,000 Bq m-2, and a variety of countermeasures that were implemented in the test area had to be considered in the modelling exercise. Difficulties encountered during the exercise included averaging of data to account for uneven contamination of the test area, simulating the downward migration and changes in bioavailability of 137Cs in soil, and modelling the effectiveness of countermeasures. The accuracy of model predictions is dependent at least in part on the experience and judgment of the participant in interpretation of input information, selection of parameter values, and treatment of uncertainties.

Cesium Radioisotopes↗

PubMed2005

Model testing using data on 131I released from Hanford.

The Hanford test scenario described an accidental release of 131I to the environment from the Hanford Purex Chemical Separations Plant in September 1963. Based on monitoring data collected after the release, this scenario was used by the Dose Reconstruction Working Group of BIOMASS to test models typically used in dose reconstructions. The primary exposure pathway in terms of contribution to human doses was ingestion of contaminated milk and vegetables. Predicted mean doses to the thyroid of reference individuals from ingestion of 131I ranged from 0.0001 to 0.8 mSv. For one location, predicted doses to the thyroids of two children with high milk consumption ranged from 0.006 to 2 mSv. The predicted deposition at any given location varied among participants by a factor of 5-80. The exercise provided an opportunity for comparison of assessment methods and conceptual approaches, testing model predictions against measurements, and identifying the most important contributors to uncertainty in the assessment result. Key factors affecting predictions included the approach to handling incomplete data, interpretation of input information, selection of parameter values, adjustment of models for site-specific conditions, and treatment of uncertainties.

Iodine Radioisotopes↗

PubMed2004

Evaluation of the biological transfer of 32P, 137Cs and 65Zn by fish in the Yenisei River.

The biological transfer of three radionuclides ((32)P, (137)Cs, (65)Zn) by fish in the Yenisei River (Central Siberia, Russia) was evaluated using a radioecological model. The modelling is based on the general ECOMOD methodology, where radionuclide behavior in an aquatic organism is linked with the processes of growth and metabolism, also with the concentrations of stable analogous elements in the organism, its food and the environment. The model was applied to explain the peculiarities of (32)P, (137)Cs and (65)Zn accumulation in different ecological groups of fish, including non-migratory and migratory fish, non-predatory and predatory fish species. The highest activity concentrations in non-migratory fish from the Yenisei River were found for (32)P. The accumulation of (32)P by fish was shown to depend on the fish size (age, weight); however, it did not depend on the trophic status of fish. The modelling approach was developed to evaluate the biological transfer of radionuclides by the migratory fish, which spend the most part of life in the Yenisei delta, inlet or bay, and go upstream the Yenisei River for spawning. The results of the ECOMOD model calculations are in good agreement with available measurement data.

Animals↗

PubMed2003

Model reconstruction of 90Sr concentrations in fish from 16 Ural lakes contaminated by the Kyshtym accident of 1957.

The paper outlines the results of the ECOMOD model application to simulate 90Sr dynamics in fish dwelling in Southern Ural lakes and contaminated as a result of the Kyshtym accident. The detailed reconstruction of 90Sr behavior in fish for the 40-year period (1957-1997) was made for the most contaminated lakes (Uruskul and Berdenish). The adapted ECOMOD model was applied for the other 14 Ural lakes to explain the peculiarities in 90Sr accumulation by fish in lakes with different concentrations of Ca2+ ions in lake water.

Animals↗

PubMed2003

EPIC database on the effects of chronic radiation in fish: Russian/FSU data.

The paper presents the extraction of data from the EPIC database, outlining the effects of chronic radiation exposure in fish. The EPIC database 'Radiation effects on aquatic biota' is compiled as part of the current EC Project EPIC (Environmental Protection from Ionizing Contaminants in the Arctic). The EPIC database is based on information from publications in Russian (Russian/former Soviet Union data). The data are focused on the effects in fish at relatively low doses of chronic radiation exposure. The effects are grouped by three key endpoints: morbidity, reproduction, and mortality/life shortening. A preliminary scale of dose-effects relationships for fish has been constructed.

Animals↗

PubMedDate not supplied

[Modeling of different types of size-effect in accumulation of 137Cs in fish from the cooling pond of the Chernobyl Power Plant].

All known types of size-effect in accumulation of radiocesium in fish are described on the basis of the dynamic model of distribution and migration of the radionuclide in aquatic ecosystem. The time-dependent activity of 137Cs in different age classes of carp and pike-perch from the Chernobyl Nuclear Power Plant Cooling Pond is calculated. It is shown that during the first year after the accident the activity of 137Cs in the young generations of fish was higher (negative size-effect) owing to higher feeding rate of young fish. During the following years the increase of activity in the older fish generations takes place (positive size-effect). It is shown that size-dependence is more clear for the predatory species.

Animals↗

PubMedDate not supplied

[Model for calculation of fish contamination by 137Cs and its application for Lake Kozhanovskoe (Bryansk Region)].

A dynamic model was developed for evaluation of the fish contamination by 137Cs. The dynamics of the accumulation of the radionuclide and the elimination is calculated taking into account the ecological and physiological characteristics of the fish, such as growth and metabolic rates, its position in the food chains of the aquatic ecosystem. The biological elimination of 137Cs from the freshwater fish is proportional to the metabolic rate of the fish. The dimensionless coefficient of the proportionality is equal to epsilonA = 0.3 +/- 0.1. The model was applied for the reconstruction of the long-term dynamics of 137Cs in the food chain "goldfish-pike" from Lake Kozhanovskoe (Bryansk Region, Russia). In 1990-1999 the specific activity of 137Cs in goldfish (generation of 1990) varied in range about 5-20 kBq/kg, whereas the specific activity of 137Cs in pike (generation of 1989) varied in range about 20-40 kBq/kg. The comparison with the data of the observations confirmed that the presented method allows to evaluate adequately the levels and the dynamics of 137Cs accumulation by the freshwater fish.

Animals↗