Water Quality Assessment and Evaluation of Human Health Risk in Mutangwi River, Limpopo Province, South Africa

Rofhiwa T Madilonga; Joshua N Edokpayi; Elijah T Volenzo; Olatunde S Durowoju; John O Odiyo

doi:10.3390/ijerph18136765

Water Quality Assessment and Evaluation of Human Health Risk in Mutangwi River, Limpopo Province, South Africa

Int J Environ Res Public Health. 2021 Jun 24;18(13):6765. doi: 10.3390/ijerph18136765.

Authors

Rofhiwa T Madilonga¹, Joshua N Edokpayi¹, Elijah T Volenzo¹, Olatunde S Durowoju¹, John O Odiyo^{1

2}

Affiliations

¹ Department of Hydrology and Water Resources, University of Venda, Thohoyandou 0950, South Africa.
² Office of the DVC Research Innovation Commercialization and Internationalization (RICI), Vaal University of Technology, Vanderbijlpark 1911, South Africa.

Abstract

Freshwater supply is essential to life on Earth; however, land use activities such as mining and agriculture pose a significant danger to freshwater resources and the wellbeing of aquatic environments. This study temporarily assesses the water quality characteristics of Mutangwi River. Physicochemical parameters (pH, temperature, total dissolved solids (TDS), salinity, electrical conductivity (EC), and turbidity) were determined in situ using an Extech multimeter and turbidity meter. The concentration of the selected metals (Mg, Cr, Fe, Cd, Mn, Pb, Ca, and Na) were analysed using an Atomic Absorption Spectrophotometer. Membrane filtration method was used to analyse microbiological parameters (Escherichia coli and Enterococci). The physicochemical water quality parameters as well as basic anions (fluoride, phosphate, sulfate, nitrate, and chloride) determined complied with the regulatory guideline of the World Health Organization (WHO) and the South Africa National Standards (SANS). Some of the trace metals (Mn, Ca, Fe, and Mg) were found below the guideline values, while others (Pb and Cd) exceeded the threshold limit. The counts for E. coli (814.5-2169 cfu/100 mL) and Enterococci (333-9396 cfu/100 mL) in the study did not comply with the regulatory guidelines. The water quality status using the water quality index (WQI) indicated that on the average, the water quality from Mutangwi River is poor (WQI > 100). The hazard quotient through ingestion exposure did not exceed the threshold limit of 1, for adults and children. This implies that there is no potential non-carcinogenic health risk from trace elements via ingestion of drinking water for children and adults. However, cancer risk for adults and children was computed in relation to Cd and Pb levels and exceeded the threshold limit 10^-4, indicating a possible carcinogenic risk. Water from the river should be adequately treated prior to domestic and agricultural use.

Keywords: E. coli; Mutangwi River; carcinogenic risk; land use activities; water quality; water quality index.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Child
Environmental Monitoring
Escherichia coli
Humans
Metals, Heavy* / analysis
Risk Assessment
Rivers
South Africa
Water Pollutants, Chemical* / analysis
Water Quality

Substances

Metals, Heavy
Water Pollutants, Chemical