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Behavior of 137Cs in the System Soil – Plant in the Stationary Sampling Sites Located Within the 30-Kilometer Zone of the Chernobyl NPP in the Period 1987-1992: Forms of Fallout and Chemical Speciation Dynamics of 137Cs Located in Soilsстатья
- Авторы: Anisimov Vyacheslav S., Sanzharova Natalia I., Alexakhin Rudolph M.
- Журнал: Biogeosystem Technique
- Номер: 1 (7)
- Год издания: 2016
- Первая страница: 17
- Последняя страница: 40
- DOI: 10.13187/bgt.2016.7.17
- Аннотация: When studying the behaviour of radionuclides - fission products of nuclear fuel, released into natural ecosystems after the Chernobyl accident, significant differences were found in migration capacity of 137Cs global fallout and Chernobyl origin. This is because the radionuclide in the Chernobyl fallout, in contrast to the global, entered to the surface of the earth not only in water-soluble form, but also in the composition of particles of nuclear fuel and composite materials of different dispersion. On the territory of 30-km zone around Chernobyl NPP were allocated to 2 areas, which differ in the form of depositions of radionuclides. The first, which was called the "near" area (2-15 km from the emergency unit of the ChNPP), dominated by the fuel component (the coefficients of fractionation of the non-volatile 144Се and 90Sr to 137Cs ≥ 1). In the second zone, named "remote" (15-35 km from ChNPP), was dominated the condensation component ( f 144Се/137Cs and f 90Sr/137Cs < 1). In "near" to the damaged reactor zone properties of 137Cs, 90Sr and 144Се are largely determined by its localization within fuel particles, which are transforming in turn under the influence, primarily, of air oxygen and water. Thus, the content in the soils of mobile 90Sr in 1987, was 26.8 % in the "near" zone (v. Krasnoe) and 45.7 % in the "remote" zone (v. Radin). This is 3.6 and 1.3 times less of the relative content of mobile 90Sr in 1990. By 1990 there was a complete transformation of a primary fuel particles, as indicated the data about: almost complete 144Ce extraction from soils by 1 N solution of hydrochloric acid in 1990; about the reduction of the quantity of unleacheable 137Cs in soil in 1988 and especially in 1990 compared to 1987; and the fact that there is huge increase in the relative content of mobile 90Sr in 1990 as compared to 1987 in the soils of "near" zone where was dominated the fuel component of fallout. Due to the transformation of the fuel particles already in 1988 the mobility in soil and, consequently, the availability for the root uptake by plants of 137Cs, which is incorporated within the transformed fuel matrix, was higher than the mobility of the radionuclide in the soil exchange complex. The content of exchangeable and mobile forms of 137Cs was relatively high in the first year after the accident (9.5-30.1 and 12.7-41.2 %, respectively) and then decreased according to the exponential law due process of irreversible fixation of radionuclide by soils: dC/dt=-bС, where C is the content of the corresponding form of the radionuclide in soil; b - coefficient of proportionality. Calculated for automorphous soils located in "near" to the reactor zone, half-reduction periods of relative content of exchangeable and mobile forms of 137Cs in soil was equal to 3.7 and 7.0 years, respectively, and for automorphous soils of the "remote" zone - 2.7 and 4.8 years. For hydromorphous soils of "near" zone the half-reduction periods of the relative content of exchangeable and mobile forms of 137Cs was 1.8 and 3.2 years, for "remote" zone soils - 1.4 and 1.9 years, respectively.
- Добавил в систему: Котельникова Анна Дмитриевна