Levels of polycyclic aromatic hydrocarbons (PAHs) in the Densu River Basin of Ghana

Abstract

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in Densu River Basin in Ghana were measured using gas chromatograph. Surface water samples were collected from nine stations, namely, Potroase, Koforidua Intake, Suhyien, Mangoase, Asuboi, Nsawam Bridge, Afuaman, Ashalaga, and Weija Intake in the Densu Basin. Total PAH concentrations varied from 13.0 to 80.0 μg/mL in the Densu River, with a mean value of 37.1 μg/mL. The two- to three-ring PAHs (low-molecular-weight PAHs) were found to be dominant in the Densu River Basin. Total PAH concentrations showed the following pattern: Koforidua Intake (80.0 μg/mL) > Asuboi (50.8 μg/mL) > Afuaman (47.9 μg/mL) > Weija Intake (45.0 μg/mL) > Suhyien (27.6 μg/mL) > Nsawam (23.5 μg/mL) > Ashalaja (22.9 μg/mL) > Potroase (23.3 μg/mL) > Mangoase (13.0 μg/mL). According to the Agency for Toxic Substances and Disease Registry (ATSDR), background levels of PAHs in drinking water supplies in the USA range from 0.004 to 0.024 μg/mL. PAH levels from all sites exceeded the range set by ATSDR. B[a]P contributed the highest carcinogenic exposure equivalent (0.3 μg/mL), followed by B[a]A (0.132 μg/mL) and B[b]F (0.08 μg/mL), contributing 52.6%, 23.2%, and 4.6%, respectively, of the total carcinogenicity of surface water PAH in the Densu River Basin. The carcinogenic potency was estimated to be 0.57 μg/mL. The presence of PAHs was an indication of the water sources being contaminated, with potential health implications.