Seasonal variation of PAHs in marshy sediments from Warri City, Nigeria

Abstract

Seasonal variation was used to analyse the levels of Polycyclic Aromatic Hydrocarbons (PAHs) in marshy sediments in Warri city, Niger Delta region in Southern Nigeria. Sediment samples were collected from four locations in the city and labelled ST 1, ST 2, ST 3 and ST 4. Control samples were also collected 20 km away from the city and labelled ST 5. The objective of this study is to compare the level of PAHs in dry and rainy season and examine their variation base on the type of PAHs detected in relation to the characteristics of the different locations. The samples were collected from January to March for dry season and June to August for rainy/wet season. Levels of 16 USEPA priority PAHs were determined using GC-FID. Five-ringed benzo(a) pyrene had highest total concentration of 1.342 mg/kg for individual PAHs and it was detected at ST 2 in the dry season. PAHs concentration was higher in dry season than rainy season at all the study sampling stations and the control. ST 4 of the study location had total PAH value of 4.540 mg/kg in dry season. And the control station, ST 5 had total PAH value of 4.18 mg/kg in the same period. In the rainy season, ST 4 had highest total PAH value of 3.029 mg/kg. At ST 5, the highest total value for PAH in rainy season was 1.056 mg/kg. Total PAHs concentration within Warri city was higher than at the control.

Keywords: Benzo(a) pyrene; concentration; dry season; Niger Delta; rainy season.