Determination of Radon-222 (222Rn) in Well and Borehole Water at Nasarawa LG, Kano State, Nigeria

Nassarawa LG is one of Kano's most densely populated local government areas and depends solely on groundwater (well and borehole) for drinking and other domestic purposes. Radon, one of the most important radioactive elements, is abundant due to the presence of uranium and radium. It can dissolve in underground water, leading to internal exposure if ingested. Therefore, there is a need for a radiological assessment of Radon-222 in the water and an evaluation of the health hazards associated with the level (high or low) of radon and background radioactivity. A total of one hundred (100) water samples were collected from the study area. The samples were analysed using a liquid scintillation counter from the Center for Energy Research (CERT), Ahmadu Bello University, Zaria. The mean radon activity concentration in the water was found to be 12.78±0.04 Bq/L, which is higher than the maximum permissible limits of 11.1 Bq/L and 10 Bq/L set by the USEPA and WHO, respectively (WHO, 2004; USEPA, 2003). The mean radon activity concentration in well and borehole water was 11.946±0.04Bq/L and 13.612±0.04Bq/L, respectively, with a range from 3.634±0.04Bq/L to 44.952±0.04Bq/L. The highest recorded radon activity concentration was 44.952±0.04Bq/L in borehole water from Giginyu, and the lowest was recorded in well water from Kawo. 70% of the total samples had a high radon concentration, exceeding the maximum contaminant levels of 11.1 Bq/L set by USEPA and 10 Bq/L set by WHO, as also reported by UNSCEAR. The concentration level was found to be higher in borehole water compared to well water. In conclusion, many of the samples from the study area exceeded the maximum contaminant levels of 11.1 Bq/L (USEPA) and 10 Bq/L (WHO), indicating a significant public health concern that warrants further investigation and mitigation measures. It recommended that continuous monitoring and assessment of Radon-222 levels in drinking water should be implemented to protect public health.