Assessment of natural radioactivity and associated radiological health hazards in Mooifontein gold tailings

Soil samples were collected from the Mooifontein gold tailings in the west of Johannesburg. In this study, a coaxial HPGe $$\gamma $$-spectroscopy system was used to measure the $$\gamma $$ -signals emitted by the soil samples. In some areas of Soweto, particularly Riverlea, residents complain about the irritating yellow dust from gold tailings being blown into their homes during the windy season. The radioactivity concentration was assessed, followed by an evaluation of comprehensive radiological indices. The mean activity concentrations, in descending order, were 226U, 226Ra, 40K, and 232Th, with values of 309.27 ± 37.00, 271.81 ± 14.02, 113.34 ± 20.80, and 8.25 ± 1.31 Bq/kg, respectively. The radiological indices exceed globally recommended values. The Pearson correlation showed that the 226Ra distribution in the samples is controlled by changing the 226U specific activity. Pearson correlation, ANOVA, and the radiological health hazard parameters were analysed to identify similarities and correlations among the various samples. The Pearson correlation showed that the 226Ra distribution in the samples was independent of 232Th and 40K concentration due to their poor correlation. The specific activity of 40K was higher than that of 232Th, even though it was below the global average. For both 226U and 40K, their specific activities can be attributed to the geological formation in the area. The gold tailings may present a serious long-term health danger to the local community because these indices are higher than what is advised, and the soil should never be used for building.