Natural and induced radioactive nuclides in the soils of forest and long fallow lands of the background and polluted territories of Kaluga region of the Russian Federationтезисы докладаТезисы
Дата последнего поиска статьи во внешних источниках: 23 сентября 2021 г.
Аннотация:The level of contamination with the natural (K-40, Th-232, Ra-226) and induced (Cs-137) radioactivenuclides of the following forest soils(pine- trees, fir-trees, birch-trees) and of the long fallowecological systems at the polluted (southern part) and not polluted (northern part) territories ofKaluga region of the Russian Federation, was evaluated in 2017. The analysis showed that thespecific activity of the natural radioactive nuclides Ra-226 and Th-232 is low and it changesinsignificantly in the soils' profile of the studied ecological systems. Higher levels of K-40 areregistered, reaching the maximum in the long fallow soils, which arises from a heaviergranulometric composition of the differences that were formed here. In general the density of soilcontamination with the natural radioactive nuclides in various ecological systems varies:3,14-11,70 for Ra-226, 0,33-3,22 for Th-232 and 3,52-94,19 kBq/m2 for K-40, which corresponds tothe background indexes and complies with the regional lithological features of the territory. Thedensity of the soils contamination with Cs-137 varies from 60.8 to 273,8 kBq/m2 at the pollutedterritories(it does not exceed 3 kBq/m2 at the background territories). Among the studiedecological systems the forest ones (especially coniferous) are the most contaminated with Cs-137,the long fallow ecological systems are the least contaminated with Cs-137. In comparison with theinitial period starting with the precipitation in 1986, the density of soils' contamination with Cs-137has presently decreased by more than 3 times in average. However this index still significantlyexceeds the admissible level of 37kBq/m2. Cs-137contributes most significantly into the summaryspecific activity of the soils and gives the power of the equivalent absorbed dose for theecological systems of the polluted territories. K-40 provides this effect for the backgroundterritories.