The Rietspruit is located in Gauteng Province, South Africa, within the Witwatersrand Basin. The basin is noted for its vast gold deposit. The river extends for about 60 km before joining the Vaal River. The aim of this study was to determine the concentration of uranium in the Rietspruit and the factors that influenced the concentration of U at each of the sites. The source of uranium in the river is the discharge from the gold mine and the mine wastes. Inductively coupled plasma mass spectrometry was used for water and sediment analysis in order to determine the concentration of U. High concentration of U was found in the river water and sediment, which is above the permissible limit of U. The water is used for irrigation of farmlands, cattle watering and for human consumption despite the high concentration of uranium in it. Ingestion of uranium is dangerous to human health. Due to the toxic nature of uranium, consumption of the water for domestic use and agriculture purpose must be discouraged.

Uranium, U, as a toxic element has detrimental radiological and chemical impacts on human health when ingested at elevated concentration in water. The establishment of gold mining operations upstream to the Rietspruit is assumed to be a source of uranium into this water body which ows through residential and agricultural land. Water samples from the stream were collected and analysed using inductively coupled plasma mass spectrometry to determine the concentration of U. Uranium concentrations above South African regulatory limit were recorded in the stream water which is used for domestic, agricultural and religious activities as observed during eld visits. Results from calculations showed that the maximum annual effective dose within this mining environment was above 1 mSv/year for all age groups. Furthermore, the probability of radiological risk is lower than the chemical risk which is due to the ingestion of U in the Rietspruit water. The chemical risk analysis showed that within 24 km of this mining environment, stream users are in danger of U chemical toxins therefore, it is important to educate the stream users about their health risk of U and recommend adequate interventions by relevant government agencies to this effect.

The mining of mineral deposits abundant in South Africa has led to the release of toxic heavy metals into the environment. The aim of this study was to investigate heavy metal pollution from a gold mining area. The concentrations of arsenic, cadmium, lead, and zinc were analyzed in soil and plants found within 500 m and 1000 m radius of a gold mine established in North-West. The concentrations of these heavy metals were determined using Inductively Coupled Plasma Mass Spectrometry. The results showed that the concentrations of the studied heavy metals were all below the national and international threshold but higher than the concentrations found several kilometers away from the mining area, the natural background concentration. The results from the pollution load index shows that the topsoil is contaminated for the selected heavy metals. There was accumulation of the studied heavy metals in the studied Eragrostis hypnoides plant’s leaves and roots. In this study, it was revealed that zinc and cadmium bioaccumulated in the plant via the soil. These findings suggests that the consumption of agricultural products from farms within the 1 km radius of the mining site could be detrimental to the wellbeing of direct and indirect consumers.

Due to gold mining operations in the Witwatersrand Basin, rivers’ sediment has been polluted with uranium. In this study, we looked at factors that influenced uranium remobilisation by rewetting a dry sediment collected from a uranium polluted dam with rainwater and the daily changes in water chemistry were analysed. The rapid oxidation of uranium by oxygen led to the dissolution of uranium adsorbed by iron and carbonate while the presence of nitrate ensured that uranium was not completely immobilised eight hours after rewet. The result of the diurnal stream water chemistry indicated an increase in water pH and decrease in electrical conductivity during the day and vice-versa at night. This resulted in higher concentration of dissolved uranium at night than during the day. From the result, it can be concluded that dissolved uranium can be remobilised from dry polluted sediment by rainwater and uranium remobilisation is not linear due to the heterogeneity of sediment and the difference in solubility rate of each component of the sediment which uranium is adsorbed onto. Dissolved uranium released from sediment can remain in the water column for several hours even after rainfall, which can be harmful to the health of people that use the water for various purposes.

Since the discovery of gold in the Witwatersrand Basin, the Basin has experienced over 100 years of mining activities. However, the removal of the precious stones buried several meters below the earth surface has led to water and sediment pollution by heavy metals. In this study, the concentration of arsenic, cadmium, mercury and lead were determined using inductively coupled plasma mass spectrometry in the water and sediment samples collected in the Rietspruit. The Rietspruit is a perennial stream located in the Witwatersrand Basin, the source of the water is attributed to the discharge of mine water by a gold and uranium mine located upstream of the river. High concentration of the studied heavy metals were recorded within and some distance away from the mining environment. In this study, the maximum concentrations of arsenic, cadmium, mercury and lead recorded were 45.5 µg/l, 0.43 µg/l, 11.8 µg/l and 3.5 µg/l respectively in Rietspruit water. In the sediment, the maximum concentrations recorded were 550.4 mg/kg, 3.88 mg/kg, 2.44 mg/kg and 184.3 mg/kg in arsenic, cadmium, mercury and lead respectively. In areas where human exposure was observed, the concentrations of mercury was higher than the guideline limit of the metal in water. As a result, the use of the Rietspruit water for agricultural, domestic and religious purposes must be discouraged and adequate intervention of the study area is needed.