Polycyclic Aromatic Hydrocarbons in Water, Soils and Surface Sediments of the Msunduzi River

Abstract

The concentration of seven Polycyclic Aromatic Hydrocarbons (PAHs) (namely Naphthalene, Acenaphthylene, Fluorene, Phenanthrene, Anthracene, Pyrene and Chrysene) were determined in 28 surface waters, 8 wastewaters, 26 soils and 26 surface sediments from the Msunduzi River, a major supply of portable water in KwaZulu-Natal (KZN) province, South Africa. Water samples were extracted using a conventional liquid-liquid extraction technique into Dichloromethane (DCM) while soils and surface sediments were extracted with an equal mixture of DCM and nhexane using the Soxhlet extraction technique. Purified extracts were analysed by Gas Chromatography-Mass Spectroscopy (GC-MS). Trace levels of PAHs were detected in some water, river bank soils and surface sediments. The concentration of PAHs was found to be comparatively higher in the soils and surface sediments than in the water. The concentration levels as well as distribution of the selected PAHs varied from season to season, however with no clear pattern. The occurrence pattern of PAHs along the river points to human-related activities as the major input sources of PAHs into Msunduzi water. Paired-up isomeric concentration ratios for surface sediments suggested pyrolysis as the major input source of PAHs, especially at sites closer to the city of Pietermaritzburg (PMB).