Biogeochemical Migration of Technogenic Radionuclides in Forest Ecosystems (by the materials of a multiyear study in the areas affected by the Chernobyl fallout) (original) (raw)
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The Science of the total environment, 1994
In an attempt to understand the mechanisms governing the transfer and retention of radiocaesium in the understorey vegetation, 39 macromycetes species and 33 plant species, together with humus samples, were systematically collected from the undercover vegetation in a boreal coniferous forest. The results indicate that the main factors determining interspecific differences in contamination level are the rooting depth in plants, the depth of mycelium in fungi, and the ecophysiological behaviour of fungi, mycotrophism or plant parasitism. A comparison between the investigated species and the same species growing in similar ecosystems, albeit under different climatic conditions, resulted in an almost identical ranking in terms of radiocaesium contamination levels; the contamination ratios between species were also relatively constant. From an experiment involving humus samples, it was shown that up to 40% of the radiocaesium could be retained by the microflora, particularly by mycelia.
Downward migration of Chernobyl-derived radionuclides in soils in Poland and Sweden
Applied Geochemistry, 2011
The Chernobyl accident on April 26, 1986 resulted in significant fallout of radionuclides such as 137 Cs and 239,240 Pu on surface soils throughout northern Europe. Knowledge of the dynamics and mechanisms of the migration of these radionuclides in soils is important for determining animal and human dose exposure rates, determining exposure from food-chain transfer, and in planning environmental remediation and clean-up. In addition, both natural ( 7 Be, 210 Pb xs ) and anthropogenic ( 137 Cs, 239,240 Pu) fallout radionuclides have been extensively employed to determine short-term soil erosion rates, to trace sediment source regions, to characterize and quantify erosion mechanisms, to constrain sediment budgets, and to better understand the delivery ratios, transit distance and transit time of fine sediment and adsorbed pollutants. Despite the use of these radionuclides and their activity-depth profiles, little is known about how the profile shapes develop or why they differ with location. There is a substantial amount of information that is embedded in the distribution of radionuclides with depth that could be extracted to refine our ability to understand significant radiochemical behavior, to predict dose exposure rates, to better plan environmental remediation, to use these and other radionuclides to understand soil erosion mechanisms, to identify sediment source areas and to calculate watershed inventories and residence times for better understanding of watershed retention and erosion processes. Moreover, ignoring this evidence may lead to a real risk of drawing incorrect conclusions from an incomplete understanding of the radionuclide profiles.
Ukrainian Journal of Ecology, 2021
The territories of Bila Tserkva district, located in the northeastern part of the right-bank Forest-Steppe of Ukraine, have been studied. This area is dominated by chernozems that are typically low-humus. In vegetable crops grown in Yosypivka and Tarasivka of Bila Tserkva district, which was exposed to radioactive contamination and is located in the southern part of Kyiv region, Central Forest-Steppe Ukraine, contamination of 137 Cs and 90 Sr were determined. The content of 137Cs and 90Sr in soils was studied, and the density of pollution of privately-owned vegetable plots in these villages was calculated. The transition coefficients of 137Cs and 90Sr radionuclides from the soil of typical chernozem into plants, in particular cucumbers, potatoes, onions, beets, carrots, tomatoes, and white cabbage, have been calculated and established, which makes it possible to calculate the transfer coefficients to vegetable crops to be grown in radioactively contaminated areas of the Central Forest-Steppe of Ukraine. Reducing 137Cs and 90Sr radionuclides from soil to vegetable crops is one of the leading agricultural production tasks on lands contaminated with radionuclides. These studies make it possible to elucidate the current state of migration of these radionuclides in the "soil-plant" link of agroecosystems of the Central Forest-Steppe of Ukraine for further forecasting.
Migration of 134,137Cs Radionuclides in the Soil and Uptake by Plants in German Spruce Forests
Radiochimica Acta, 1994
In southern German spruce forests on different geological substrates the depth distributions of the activity inventories of 134 Cs and ,37 Cs radionuclides from Chernobyl and nuclear weapons testing fallout and the corresponding activity concentrations in the dry mass of different plants were measured. Using a compartment model based on first order kinetics, the vertical residence half-times and migration rates of 137 Cs were calculated. Migration rates decrease with increasing soil depth and retention time of the 137 Cs radionuclides in the soil. The aggregated soil to plant transfer factors [m 2 /kg] on the other hand, are comparatively high: Up to 1.1 m 2 /kg for fern, and smaller values for bilberry and raspberry. It is suggested that a fixation of cesium radionuclides in the organic matter of the litter debris occurs and that the transfer to plants is mediated by carrier substances produced by microorganisms responsible for the degradation of the litter.
Dynamics of 137Cs in the forests of the 30-km zone around the Chernobyl nuclear power plant
Science of The Total Environment, 1997
Dynamics of the 13'Cs content in the components of the forests in the 30-km zone around the Chernobyl nuclear power plant (NPP) in 1986-1994 are associated mainly with such factors as the size of radioactive particles in the fallout, ecosystem humidification and soil type, tree age. The influence of particle size was especially noticable between 1986--1987 and was displayed by low biological availability of radionuclides in the near part of the zone (within the IO-km radius circle around the NPP) in comparison with more distant regions (within the 30-km radius circle). Later. the expression of this influence decreased and transfer factor (the ratio of i3'Cs content in overground phytomass to the soil contamination density) became approximately the same for all plots with similar ecological and fallout characteristics. Humidity of landscape and soil type determined the velocity of radionuclide vertical migration in the soil and '37Cs biological availability. These parameters were maximum for the hydromorphic soils of wet landscapes enriched in organic substance and poor clayey minerals. Differences of '37Cs accumulation in overground phytomass of trees caused by tree age are displayed in the higher '37Cs concentration in structural parts of young trees as compared with old ones. Copyright 0 1997 Elsevier Science B.V.
Vertical distribution of radionuclides in soil of a grassland site in Chernobyl exclusion zone
Journal of Environmental Radioactivity, 2004
Five soil profiles from a site about 8 km SE of the Chernobyl NPP were investigated for the vertical distribution of radionuclides. The average 137 Cs-inventory at the site is about 2.6 MBq/m 2 (reference date 1 May 1986). Apart from 137 Cs, the following radionuclides have been identified (their activity ratios to 137 Cs in brackets): 134 Cs (0.537), 125 Sb (0.068), 60 Co (0.0022), 154 Eu (0.016), 155 Eu (0.020), 94g Nb (9.5E-5), 239/240 Pu (0.0088), 238 Pu (0.040), 90 Sr (0.30) and 241 Am (0.011). Apparent vertical migration velocities are between 0.14 and 0.26 cm/a, apparent dispersion coefficients range from 0.02 to 0.13 cm 2 /a. The rankings of the velocities v for different radionuclides are ðSr; Cs; Sb; Co; PuÞ < Am < Eu and Sr < ðCs; NbÞ, for D, the following rankings have been found: ðNb; Sr; CsÞ < Am < Eu, Cs < Sb and Nb < Co (all on p ¼ 0:1 level). #
Radionuclides’ content in forest ecosystem located in southwestern part of Serbia
Nuclear Technology and Radiation Protection, 2021
The results of the gamma-spectrometric measurements in a 16500 ha large region of south-western Serbia, are presented. Activity concentrations of 40K, 137Cs, and 210Pb in different deciduous and evergreen trees in the region are investigated. For all the investigated isotopes, there is a tendency that, on average, the lowest activity concentrations were found in tree stems, then in leaves, while the highest ones were in the soil. Statistical analysis did not show any differences between activity concentrations of leaves and needles, showing that both leaves and needles could be equally well used as a biomonitors.
Chernobyl Radionuclide Distribution, Migration, and Environmental and Agricultural Impacts
Health Physics, 2007
The distribution and migration of radionuclides released into the environment following the Chernobyl accident in 1986 are described. The Chernobyl disaster resulted in the consumption of farm products containing radionuclides as a source of irradiation of the population due to the prevalence of a rural type of human nutrition in the affected region. Economic and radiologic importance of countermeasures for reducing the impacts of the accident are described. The basic radioecological problem is described in which the area where direct radiation contamination of biota was observed is considerably smaller than the zone where concentrations of radionuclides through the food chain exceeded the permissible standards. The radiation-induced effects in biota in the affected area are described. In the long-term post-accident period, the radionuclide distribution between components of ecosystems (including humans) and doses are considered in comparison to a technologically normal situation of nuclear power plant operation. This analysis demonstrates that if radiation standards protect humans, then biota are also adequately protected against ionizing radiation.