Occurrence of contaminants of emerging concern in the uMhlathuze and uThukela river systems, KwaZulu-Natal, South Africa

Abstract

Contaminants of emerging concern (CECs), which include inorganic substances, exhibit potential adverse effects on aquatic life even though they commonly occur at very low concentrations in aquatic resources. The lack of data available about the risk of CECs to the environment is a hindrance to environmental protection.To this end, we examined the extent to which the uMhlathuze and uThukela rivers are exposed to selected CECs. Pharmaceuticals and lifestyle drugs (58 compounds), pesticides (27 compounds), microplastics (fibres and films), and inorganic metals (Al, Cr, Cu, Fe, Mn, Ni, Pb, Si, Ti and Zn) were detected in both river systems. Additionally, a bioaccumulation of metals was detected in Chiromantes eulimene. In both river systems, the highest frequency of CECs and concentration of microplastics and metals were detected downstream of the wastewater treatment plant’s (WWTP’s) effluent discharge points. The WWTPs’ effluent was a notable source of CECs and metals in the water resources. However, industrial and agricultural activities in the respective catchments were potential diffusers of the contaminants.