Assessing heavy metal pollution in the Rietspruit, Far West Rand Goldfield, South Africa

Abstract

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.