Using radionuclides of aerial precipitation in researches of their geochemical migration in soils (review)

Abstract

The article provides an overview of the results of long-term studies of the migration of radionuclides in the composition of lysimetric waters. The features of lysimetric studies at various stages of radioecology development are considered. It is noted that the use of lysimeters for a long time was limited to low levels of radionuclides in soil solutions, and large-scale studies began after the Chernobyl fallout (1986). It is shown that the greatest output of radionuclides in lysimetric waters occurs in forest, especially coniferous phytocenoses, the least — in meadow and agrophytocenoses. In the long-term dynamics, the maximum intensity of radionuclide migration in the lysimetric waters is observed in the initial period after aerial precipitation, in the seasonal period — in the summer. A small amount of radionuclides migrates with downward water flow. Annual outflow with vertical subsurface runoff varies depending on soil-climatic conditions, the period after precipitation, the thickness and depth of the layer. Annual outflow from the forest litter layer varies from tenths to units of percentage, from the layer 0–20 cm — from hundredths to tenths of a percentage from the total radionuclide supply in these layers. The relative output of ⁹⁰Sr is much bigger than ¹³⁷Cs. In soil solution from 70% to 90% radionuclides [¹⁴⁴Ce, ²³⁹Pu ¹⁰⁶Ru ,¹³⁷Cs and ⁹⁰Sr] are in the form of radionuclide-organic compounds of various molecular weights.