Environmental Risk Assessment of Exposure to Selected Emerging Contaminants in Dams and Wastewater Effluent Around the City of Bloemfontein, South Africa

Abstract

The number of emerging contaminants in the aquatic environment is growing continuously every year. Their occurrence in water sources could be a troubling problem to aquatic ecosystem and human health. The aim of this study was to assess the environmental risks of selected emerging contaminants in dams/reservoirs and wastewater effluent samples around the city of Bloemfontein, South Africa. The high-performance liquid chromatography connected to a QTRAP hybrid triple quadrupole ion trap mass spectrometer was used to analyse emerging contaminants such as acetaminophen, carbamazepine, ibuprofen, triclosan, 17-alpha-ethynyl-estradiol, estradiol, progesterone and testosterone in dams/reservoirs and wastewater effluents. The single and mixture substance ecological risks were evaluated using the risk quotient (RQ) and risk mixture (RQmix) methods respectively. For acute toxicity in dams, results showed that emerging contaminants such as carbamazepine, and 17-alpha-ethynyl-estradiol posed high ecological risks on all aquatic organisms. In effluent, carbamazepine, ibuprofen, triclosan, 17-alpha-ethynyl-estradiol, estradiol, and progesterone posed high risks to all selected species. For chronic toxicity, ibuprofen posed high ecological risks on algae, daphnids, and fish in dams and effluents. The RQmix values in all water sources exceeded the acceptable limit for both acute and chronic toxicity on algae, daphnids, and fish. Their acute mixture risks on aquatic species were as algae>daphnids>fish in targeted water sources while chronic mixture risks were as fish>algae>daphnids in the targeted water sources. Therefore, the level of emerging contaminants in dams/reservoirs and wastewater effluent in this study is likely to negatively pose serious adverse implications on aquatic life and human beings. The outcomes of this study constitute the initial contribution for a better understanding of emerging contaminants risks on aquatic ecosystems and human health and may help in pollution control, protection of aquatic ecosystem and water consumers.