Anthropogenic PAHs in mangrove sediments of the Calabar River, SE Niger Delta, Nigeria

Polycyclic aromatic hydrocarbons (PAHs) in some coastal and mangrove sediments from the Calabar River were determined using GC–MS to assess the degree of contamination. The sediments exhibited significant spatial variations in concentrations of individual and total PAHs (TPAHs) as reflected in the wide range of the values (1670–20,100 ng/g dw) and a mean with a large standard deviation (9370 ± 579), suggesting that the contamination was localized. Mangrove area samples showed much higher TPAH contents, capable of posing a serious health threat to resident flora/fauna, than the coastal samples. A set of seven molecular ratios were calculated to evaluate different PAH sources and their relative importance. The results show that the river was predominated by petroleum-derived PAHs. However, Pyr/Pery and *Pery/PAHpenta profiles indicated the importance of a pyrolytic origin for perylene in relation to its diagenetic production. Factor analysis data confirmed this pattern and explained about 70.8% of the total variance.