Ecological Risk Assessment of High Molecular Weight Polycyclic Aromatic Hydrocarbons in Sediments from Qua Iboe River Estuary, South-South, Nigeria

Abstract

This study sought to assess ecological risk of Polycyclic aromatic hydrocarbons (PAHs) in sediments collected from Qua Iboe River Estuary (QIRE).Sediment samples were collected from five stations and a control station along the estuary in the dry and wet seasons. PAHs in sediments were measured using gas chromatography coupled with a flame ionisation detector (GC/FID), and ecological risk on benthic organisms exposed to PAHs in sediment were evaluated using threshold effect concentration hazard quotient (TEC-HQ) and mean effect range median quotient (m –ERM-q) method prescribed by USEPA. The concentration of high molecular weight PAHs (HMW-PAHs) in the dry season ranged from1.225E-03 to 1.328E-01 whereas during the wet season it ranged from 2.420E-03 to 7.690E-02. The were no significant differences (P<0.05) between the PAH levels for the wet and dry seasons.The results for the TEC-HQ and m –ERM-q values of HMW-PAHs for both seasons were less than the threshold values of 1 and 0.1, respectively. Hence, exposure to PAHs in sediments from QIRE may not pose any adverse biological effect on benthic organisms. However, regular monitoring of the level of HMW-PAHs in the sediment within QIRE is advocated to avoid bioaccumulation of organic pollutants.