Distribution and Source of Polycyclic Aromatic Hydrocarbons in Water and Sediments from Egbe Dam in Southwestern Nigeria

Abstract

Egbe dam is capable of supplying potable water to the whole Ekiti State. The need for water quality is not just to protect the public health but also to support the economy and maintain a rich ecosystem. The aim of this study was to assess the level of polycyclic aromatic hydrocarbons (PAHs) in surface water and sediments of Egbe dam and also to investigate their sources using profiles and ratios. A gas chromatography (GC) coupled with flame ionization detector (FID) was used for PAHs identification and quantification after careful extraction and clean-up. The results showed the presence of the studied PAHs except naphthalene with mean concentration range of 0.009 mg/L (fluorene)-1.08 mg/L (benzo(a)pyrene) and 0.071 mg/Kg (phenanthrene)-1.37 mg/Kg (benzo(a)anthracene) in water and sediments respectively. The coefficient of variation revealed high spatial variation in the PAHs distribution level with the predominance of high molecular PAHs. The results reflected high percentage (91.6%) levels of HMW-PAHs as compared to LMW-PAHs. Some samples exceeded the compared PAHs international standard guidelines for groundwater and drinking water. Sources identification showed that the PAHs are pyrogenic. The detectable amounts of PAHs in the dam make it inevitable to conduct regular monitoring so as to ensure that the levels remain below prescribed limits by national and international standards.