Radon Concentration in Groundwater and Soil Gas Radon in Agbabu Bituminous Deposit Area: Mapping, GR Potential and Health Risks Assessments

Agbabu community in Ondo State Southwestern, Nigeria, is characterized by the high volume of bitumen deposit. The level of radon concentrations in soil gas and groundwater was assessed using RAD 7. Soil gas radon concentration ranged from 0.2 ± 0.1 kBqm −3 to 92.7 ± 2.4 kBqm −3 with an average of 20.6 ± 0.8 kBqm −3 . The radon concentration in shallow wells water samples ranged from 9.8 ± 3.6 Bql −1 to 64.5 ± 10.6 Bql −1 with a mean value of 30.2 ± 6.7 Bql −1 . The total annual effective dose due to ingestion and inhalation of radon ranged from 28.1 to 185.1 µSvy −1 , 27.3 to 179.4 µSvy −1 and 26.8 to 176.1 µSvy −1 with mean values of 86.6, 83.9 and 82.4 µSvy −1 for infants, children and adults, respectively. The total annual effective dose obtained in 33% of the shallow wells water samples exceeded 100 µSvy −1 safe limits recommended by the World Health Organization (WHO). Radon concentration ranging from low to high was revealed in mapping, 3D surface mapping and geogenic radon potential. The groundwater in shallow wells that exceeded the recommended limit could pose significant radiological burdens such as occurrences of cancer among the populace. Therefore, water samples from those wells should be aerated before consumption.