Environmental Monitoring of Tritium (3H) and Radiocarbon (14C) Levels in Mafikeng Groundwater Using Alpha/Beta Spectrometry

Abstract

With the current state of water scarcity in Mafikeng, South Africa, due to low water levels and an increasing population, it is therefore crucial to ensure the sustainability and availability of the existing water resources. In this study, the levels of tritium and radiocarbon in groundwater (boreholes) at selected villages in Mafikeng were determined using the Perkin Elmer Ultra Low Liquid Scintillation Counter 2000. The mean activity concentrations of tritium are 3.61304 ± 0.00612 Bq/L and 3.86014 ± 0.00739 Bq/L for samples from Dibate and Lokaleng villages, respectively, whereas 1.83392 ± 0.02265 Bq/L is for Moletsamongwe, Lekung, Airport View and Seweding. Moreover, the mean activity concentrations of radiocarbon from Dibate and Lokaleng are 0.59296 ± 0.00886 Bq/L and 0.8333 ± 0.0126 Bq/L, respectively, whereas for, Moletsamongwe, Lekung, Airport View and Seweding, they are 1.3752713 ± 0.01968 Bq/L. Two (2) out of the forty (40) samples analysed for radiocarbon are below the minimum detectable activity of 0.33627 Bq/L. The average annual effective dose (AED) of tritium for analysed samples from Dibate and Lokaleng villages are 0.04754 μSv/y and 0.05079 μSv/y, respectively, whereas it is 0.02413 μSv/y for Moletsamongwe, Lekung, Airport View and Seweding. The average AED for radiocarbon is 0.251404 μSv/y and 0.36604 μSv/y for samples from Dibate and Lokaleng, respectively, whereas it is 0.58309 μSv/y for Moletsamongwe, Lekung, Airport View and Seweding village. The evaluated lifetime cancer risk for mortality and morbidity in adults is lower than the radiological cancer risk limit of 1.63 × 10−3 set by regulatory agencies; hence, the consumption of the studied groundwater from the selected villages will not pose any health risks in terms of tritium and radiocarbon levels.