Partitioning of polycyclic aromatic hydrocarbons in sediment and porewater from Ondo coastal area, Nigeria

Abstract

The seasonal trends and partitioning behavior of polycyclic aromatic hydrocarbons (PAHs) in sediments and their corresponding porewater were investigated in Ondo coastal region, Nigeria. The mean total PAH concentrations varied from 0.16 to 8.88 μg g−1 in sediments and from below limits of detection to 2.95 μg L−1 in porewaters during both seasons. Levels were dominated by phenanthrene and anthracene. The in situ sediment-porewater partition coefficients (K oc’s) of PAHs increased with the organic carbon content (R 2 = 0.85) and even more strongly with the amount of clay and silt (R 2 = 0.87) during both seasons and significantly correlated with their octanol–water partition coefficients (logK ow, with R 2 ≥ 0.74) when logK ow values were less than 6.0. Linear relationships were observed between in situ logK oc and those predicted from reviewed papers, suggesting heterogeneity within the sediment organic carbon matrices. This partition coefficient is helpful to predict the PAHs distributions in the river sediments in order to better understand their fate and assess their potential environmental risks.