The Mobility of 137Cs and 90Sr in Agricultural Soils in the Ukraine, Belarus, and Russia, 1991

Abstract

Results are presented from studies concerning the behavior of the Chernobyl-derived radionuclides 137Cs and 90Sr in soil-plant agricultural systems in the Ukraine, Belarus, and Russia during 1991. The sites, representing ploughed and natural pastures, were located at varying distances between 50 and 650 km and varying directions from the Chernobyl reactor site. The 137Cs activity concentrations in the upper 0-5 cm soil layer ranged from 25-1,000 kBq m-2 and were higher in natural pastures as compared to ploughed pastures. For 90Sr, activity levels ranged from 1.4-40 kBq m-2, and the highest 90Sr deposition was observed in the Gomel Region, Belarus. The highest 90Sr: 137Cs ratio was also observed in the Gomel soils, i.e., 15% as compared to between 0.72 and 7.4% in the other soils. The mobility of radionuclides was studied by means of sequential extraction. For all soils, between 60 and 95% of the 137Cs was found to be strongly bound to soil components. In the Russian and Ukrainian soils, between 40 and 98% of the 90Sr was found in the easily extractable fractions, and the distribution of 137Cs and 90Sr followed that of the naturally occurring stable isotopes of cesium and strontium. However, in the Gomel soils, between 20 and 50% of the 90Sr was easily extractable and the distribution of 90Sr within the extraction fractions did not follow that observed for stable strontium. These results are thought to reflect the association of 90Sr with fuel particles deposited in the Gomel Region. The mobility of 90Sr is expected to increase with time (as the particles weather) in these soils.

Speciation of radionuclides of the Chernobyl origin in aerosol and soil samples

“…above and [11]). Similarly, a large part ofg~ (up to 80%) was found in the same form in a sandy soil sample from the Gomel district, whereas only 50% of strontium was associated with organic fraction in a peaty Dublin soil [7]. 6 shows the fraction distribution of t37Cs after soil heating at different temperatures.…”

“…In the second one, extremely insoluble (residue up to 94%) forms of Cs isotopes were found [1]. Usually the proportion of the residual 137Cs (after acid extraction) varies between 20-40% [5-7], although a relatively high percentage of 137Cs (up to 70%) was found to be associated with the residue in Vilyun soils from the Ukraine [7]. The higher content of the residual Cs in aerosol samples can be explained by a transformation of aerosols during air transport (e.g., size separation).…”

Plant uptake and downward migration of 85Sr and 137Cs after their deposition on to flooded rice fields: lysimeter experiments with and without the addition of KCl and lime

“…It is well known that radiostrontium moves faster down the soil profile than radiocesium (Cline and Rickard, 1972;Kliashtorin et al, 1994;Salbu et al, 1994;Askbrant et al, 1996). Many works (Livens et al, 1991;Salbu et al, 1994;Askbrant al., 1996) have been reported to show the localization of radiocesium with respect to the soil surface in the Chernobyl-affected areas even years after the accident.…”

The influence of Brazilian soils properties in Americium sorption

“…[1][2][3][4][5][6] improving the understanding on the behavior of radionuclides in agricultural ecosystems in the long term. Although the soil can act as physical and geochemical barrier for the retention of deposited radionuclides, changes in its physicalchemical conditions due to agricultural practices, land use, or simply natural edapho-climatic evolution, can modify the fate of the radionuclides, favoring their desorption and release to the soil solution or changing their geochemical partitioning.…”

“…Once released into soil solution, radionuclides can be available for root uptake or for migration to deeper layers into soils profiles. In soils of temperate climate with high soil organic matter content, large mobility of the radionuclides was observed, turning them available for root uptake for a longer period when compared with the strong retention made by clay minerals [1]. Deposited radionuclides on soils are generally fixed by adsorption on reactive sites on clay mineral soil particles, or by ion exchange and precipitation as hydroxide or sulfide, but also by complex formation with organic compounds [7].…”