Soil gas radon concentration measurement in estimating the geogenic radon potential in Abeokuta, Southwest Nigeria

Abstract

The soil gas in-situ radon-222 concentration was measured at 28 locations in Abeokuta, Nigeria using a RAD7 solid-state detector. The measurement sites were chosen based on the extent of the 6 geological formations chosen in a cell, with a spatial sample of at least 3 km between them. The measuring sites' geographical coordinates were established using the Global Positioning System compass. The hydraulic conductivity measuring technique was also used to determine the soil-air permeability for the soil samples collected at the various locations. The measured soil gas radon concentration and the soil-air permeability were used to estimate the geogenic radon potential. The soil gas radon activity ranged from (1004–19250) Bq/m3. The soil-air permeability ranged from (9.7 × 10−13 to 2.64 × 10−11) m2. The Geogenic Radon Potential ranged from 0.5 to 33 whereby 7.69% of the study area had a medium GRP value (10<GRP<35) while 92.31% had a low GRP value (GRP<10) as based on Classification of GRP according to Neznal. Therefore, the GRPs for Abeokuta are low compared with the level where remedial action is needed.