Title: Soil gas radon concentration measurement in estimating the Geogenic radon potential in Abeokuta, Southwest Nigeria

Abstract

The majority of natural source radiation comes from radon, which accounts for more than half of all natural-source radiation. Rn – 222 (T1/2=3.82 days) in the U – series builds up more easily in homes than its other isotope Rn – 220 (T1/2=50s ) in the Th – series, this make it significant as far as radiological health hazard is concerned. The study aimed at determining what the earth delivers in term of radon emanating or diffusing from the ground to the surrounding especially in areas underlined by a geological layer showing high potential of uranium 238, and it is been estimated from the measured values of soil gas radon concentration and soil air permeability in the environment. 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 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 where 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 are had a minimum GRP value (10