Determination of natural radioactivity and hazards in volcanic soils of Kisoro district in south-western Uganda

Abstract

In this study, the activity concentrations of natural radionuclides U-238, Th-232, and K-40
were measured in soil samples collected from various spots where there are volcanic soils,
in Kisoro district, in South Western Uganda. Then to assess the radiological hazard of the
natural radioactivity, the absorbed dose rate (D r ), the radium equivalent activity (Ra eq ), the
effective dose rate (E r ), the annual effective dose equivalent (E y ), Excess Lifetime Cancer
Risk (ELCR), and the external (H ex ) and internal (H ? ) hazard indices were calculated. NaI (TI)
was used to determine the activity concentration of these radionuclides in soils where NPK
was applied and where it was not applied. The results were compared with standard values
and it was concluded that no risk may be eminent to the residents in Kisoro district with an
exception of areas near quarrying places and mines. This is because these places have high
activity. The use of NPK only depletes potassium from the soil where it is applied. Hence, the
probability of occurrence of any of the health effects of radiation is low. The measurements
have been taken as representing baseline values of these radionuclides in the volcanic soils
from the area under study.