Physicochemical and microbio effects of coal mining on the quality of Naauwpoortspruit river, Mpumalanga, South Africa

Abstract

Coal mining has been shown to affect both surface water and groundwater quality, primarily because of the presence of acidity in mine drainage, heavy metals, and microbial contaminants. Hence, this study aimed to determine the environmental impacts of coal mining and processing activities on the quality of water of the Naauwpoortspruit River in eMalahleni, Mpumalanga Province. This study used an integrated mixed-methods approach to capture the responses and lived experiences of residents as to how coal mining influences water quality within the Naauwpoortspruit River in eMalahleni, Mpumalanga, South Africa. Qualitative data on perceived water quality and associated health risks were obtained from focus group discussions. Quantitatively, we collected 18 water samples from Masakhane, Coalfield, and Boat Camp during both dry and wet seasons. Qualitative feedback showed that the residents perceived the water as discoloured, foul-smelling, and not safe, with frequent diarrhoea, stomach cramps, and skin irritations. The physicochemical analyses indicated a pH within the range of 7.17-7.35. Iron (Fe) ranged between 0.10-0.30 mg/L, manganese (Mn) within 0.00-0.04 mg/L, while aluminium (Al) ranged from 0.04 to 0.22 mg/L and sulphate (SO₄²⁻) within 143 to 188 mg/L. Aluminium and iron were found to exceed the permissible limits set by SANS 241:2015 at some sites. Microbiological testing showed significant contamination. Total coliform bacteria ranged from 555 to 920 CFU/100 mL, and faecal coliforms varied between 34 and 766 CFU/100 mL. Of these sampling sites, the Boat Camp site showed the highest level of faecal pollution. The study concluded that coal mining environment and related human activities have degraded the water quality of the Naauwpoortspruit River, presenting notable environmental and public health risks. It emphasized the urgent need for improved mine water management and more effective wastewater control