Content of natural and technogenic radionuclides in Bulgarian soils

Radoslava Lazarova

Abstract: This study presents data for the content of natural radionuclides from uranium- radium and thorium series, potassium-40 and technogenic cesium-137 measured in soils from North and South Bulgarian regions in the period 2017-2018.
Analysis of results of 238U, 226Ra, 232Th and 40K content showed the values were within the range cited in the literature as typical for the soils from the respective regions. Slightly higher values were observed in the Rhodopes and Mesta River valley due to the presence of rocks such as gneisses, shales, granites, etc., containing higher contents of natural radionuclides, on which the soils in the area were formed.
Comparing the data with those obtained in previous years, it was concluded that there were no significant changes in the content of cesium-137 in the surface layer of soils and the decrease in activity is mainly due to the radioactive decay and not to significant migration along soil horizon or extraction from the soil by plants.
From the results obtained, it can be concluded that no contamination was observed in recent years, either as a result of nuclear accidents or uncontrolled release of radioactive waste.

Keywords: natural and technogenic radionuclide; radiological monitoring of soils

Date published: 2021-08-27