Abstract:
Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous and persistent organic pollutants. Their dynamics in aquatic environments have been extensively studied, but studies mainly focused on their distribution in single compartment of the aquatic environment. A study on 16 PAHs were analysed in water, sediments, and fish tissues from Benya, Brenu and Fosu Lagoons in Ghana, using GC-MS. The potential application of activated charcoal for the remediation of PAH-contaminated sediment was also investigated. PAHs were extracted using SPE cartridges and QUECHERS, whilst diagnostic ratios were used to determine the sources of the PAHs. The concentrations of 16 PAHs ranged from 32.37 (fillet) to 2050.47 (visceral) μg/kg/w.w, 20.81 to 24801.38 μg/kg/d.w and 1.17 to 3.39 μg/L for fish tissues, sediment and water respectively. The total PAHs recorded in the sediments demonstrated both spatial and seasonal variations in the distribution of PAHs. Environmental factors such as temperature and pH, as well as the total organic carbon {F (4, 292) = 18.19, p <0.001, R2 = 0.20} were also noted to influence the dynamics of PAHs in these lagoons. Indiscriminate burning of wastes, shipping activity, vehicular emissions and sewage were among the main sources of PAHs. More than 50 % of individual PAHs in the sediments exhibited a moderate level of ecological risk for aquatic life. The calculated ILCR for sediments (varied from 2.5 x 10-6 to 6.0×10-5) and fish tissues (from 2.0×10-5 to 4.6×10-5) were above the USEPA safety limit (1×10-6); an indication of cancer-related effects to humans who are exposed to the sediments and consumption of Sarotherodon melanotheron in these lagoons. Activated charcoal is recommended as an effective carbonaceous material to remediate the sediments of these lagoons.
