Activity and Mass Concentration of 226Ra, 228Ra and 232Th in Groundwater around the Zona Uranium Occurrence, Peta Gulf Syncline, Northeast Nigeria

Abstract

In this study, eighteen groundwater samples were collected from wells in villages around Zona, an area reported to host uranium mineralization and these were analyzed for mass/activity concentration of ²²⁶Ra, ²²⁸Ra and ²³²Th. Consumption of groundwater with elevated levels of ²²⁶Ra, ²²⁸Ra and ²³²Th may result to cancer, kidney and/or developmental defects in humans and other animals. The results obtained were compared for compliance with international guidelines for radionuclides in drinking water. Results of the study showed that activity concentration of ²²⁶Ra, ²²⁸Ra and mass concentration of ²³²Th ranged from 0.05 to 6.7pCi/L, 0.2 to 4.8pCi/L and 0.02 to 1.10µg/L, respectively. The higher levels of ²²⁶Ra in the studied samples compared with ²²⁸Ra in same sample might be as a result of ²²⁶Ra being part of ²³⁸U decay series as a results of which ²²⁶Ra is found over wide range of aquifer, it might also be an indication of secondary mineralization of uranium. Based on international guidelines regulating these radionuclides in groundwater, levels recorded at the time of the study fall within permissible limits of 20pCi/L for ²²⁶Ra and ²²⁸Ra while ²³²Th which is insoluble in water, therefore, has no regulated limit. All radionuclides analyzed fall within international guideline despite occurrence of uranium mineralization in the study area.