Quantitative analysis of phenols and PAHs in the Nandoni Dam in Limpopo Province, South Africa: A preliminary study for dam water quality management

Abstract This paper assesses the level of phenols and polycyclic aromatic hydrocarbons (PAHs) in the Nandoni dam situated in the Vhembe District, Limpopo Province, South Africa. About 55 villages are supplied with water sourced from the dam which is prone to contamination by different pollutants other than phenols and PAHs, due to its exposure to agricultural, human and animal activities around it. A quantitative determination of these pollutants was conducted using a gas chromatography-time-of-flight mass spectrometer (GC-TOF MS) after sample preparation that involved solid phase extraction (SPE). Water samples were collected on a seasonal basis in spring, summer, autumn, and winter. Several phenolic compounds (phenol, 2-chlorophenol, 2,6-dichlorophenol, 2,4,5-trichlorophenol, 2,4-dimethylphenol, 4-nitrophenol and p-cresol) were detected in the dam at concentration levels not suitable for drinking purposes. The recorded concentrations were generally higher than the SANS 241, US EPA and WHO acceptable limits in drinking water with up to 1.11 mg/L recorded for 2,4,5-trichlorophenol. The concentrations of PAHs (naphthalene, acenaphthene, pyrene, benz(a)anthracene and benzo(a)pyrene) fell within the threshold limits and were typically less than 0.1 μg/L. The water treatment plants sourcing water from the Nandoni dam use conventional treatment processes that focus more on removing contaminants such as microorganisms and heavy metals without considering the danger of long-term effects of organic contaminants, whose harmful health effects are observed after long periods of exposure. Therefore, this dam requires coordinated management of the water resources in order to maximize the economic and social welfare equitably without affecting human life and the ecosystem.