Determination and distribution of 16 polycyclic aromatic hydrocarbons in water samples from Blood and Mokolo Rivers in Limpopo Province, South Africa

The quality of aquatic ecosystems has become increasingly difficult to maintain in recent years due to toxic organic compounds that are introduced into water resources such as rivers and dams by natural and human activities. Some of these toxic organic compounds include polycyclic aromatic hydrocarbons (PAHs). The first step in removal of these compounds requires identification and determination of PAHs. The aim of this study was to determine the levels of PAHs in the water collected from Blood and Mokolo Rivers in Limpopo Province, South Africa. Liquid-liquid extraction (LLE) method was used for the extraction of PAHs from water. The quantification of sixteen (16) PAHs in the water was carried out using gas chromatograph-flame ionisation detector (GC-FID). The efficiencies and accuracy of the technique for the extraction of PAHs were determined by assessing the recoveries of water spiked with known amount of standards. Higher levels of PAHs were observed in Mokolo River (between 0.0219 and 1.53 μg/L) while lower concentrations were recorded in Blood River (between 0.0121 and 0.433 μg/L). The diagnostic ratios indicate that PAHs obtained in water from both Mokolo and Blood Rivers are likely due to pyrogenic sources. The Toxic Equivalence Quotient (TEQ) values recorded in the water were very low, and these suggest that water from both rivers is at relatively low toxicity risk.