Evaluation of the impact of coal mining on surface water in the Boesmanspruit, Mpumalanga, South Africa

Abstract

Abstract Surface water quality has major environmental and socioeconomic consequences, notably in terms of the country’s long-term fresh water supply. This study aimed at assessing the current state of water quality and status of the Boesmanspruit in a coal mining environment. The study used historical water quality data for a period of five years. Aluminium, calcium, iron, manganese, magnesium, sodium, sulphate, electrical conductivity, pH and total dissolved solids were the water quality variables selected for the study. The water quality was evaluated against South African resource quality objectives, the South African water quality guidelines, Vol. 5 and 7, and the water quality indices (WQI) of the Canadian Council of Ministers of the Environment. The following parameters were above the prescribed thresholds: pH, total dissolved solids, electrical conductivity, sulphate, manganese and iron. The data was analysed using such as the CCME-WQI, the comprehensive pollution index (CPI) and multivariate statistics. The CCME-WQI results showed that monitoring locations GR S26 and GR S21 near mining activities had poor water quality (40–44), whereas CPI also had similar category results for the monitoring points, indicating that they were heavily polluted (2.4–4.8). The WQI showed that if certain variables, such as aluminium, iron, magnesium, sulphate, electrical conductivity and total dissolved solids, exceed the permissible range, the water quality would deteriorate in accordance with the CPI classification. Therefore, the CPI was the best way to categorise the water quality. The principal component analysis and cluster analysis identified two primary sources of pollution which are anthropogenic and natural. The utilisation of statistical analysis proved to be effective in determining the ideal quantity of significant variables within the study area. The study recommends low-cost options for reducing the effects of acid mine drainage, which includes passive mine water treatment methods using artificial wetlands.