Hydrochemistry and Environmental Isotopes for the Investigation of Water Quality in the Upper Olifants River Catchment in the Mpumalanga Province, South Africa

The Upper Olifants River Catchment in the Mpumalanga Province has experienced water contamination in the past few decades due to existing land use and land cover. This study employed hydrochemical and environmental isotopes to investigate the water quality and understand the sources of contaminants within tertiary catchments B11F and B11G of the Upper Olifants River Catchment. The hydrochemistry results indicate that the shallow weathered aquifers are more susceptible to contamination with major pollutants being TDS, SO4, Ca, Mg, Fe, and Mn, which can be associated with the geology and coal mining activities in the area. Additionally, the environmental isotopes suggest that the climate, fractionation, and elevation play a major role in the evolution of the water. The correlation of major ion ratios suggests that processes such as silicate and carbonate weathering and cation exchange reactions play a significant role in making the water vulnerable to pollution. In general, the overall water quality index of the study area indicates poor water quality falling within the range of 0 < WQI ≤ 44, making it undesirable for domestic use. Furthermore, approximately 35% of the samples are not suitable for irrigation purposes based on the SAR and PI.