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Spatiotemporal concentrations and risk assessment of sediment-bound PAHs in coastal lagoons of Ghana


DEPARTMENT:      Department of Biological, Physical and Mathematical Sciences

DESIGNATION:      Lecturer        



Previous reports have long established that exposure to Polycyclic Aromatic Hydrocarbons (PAHs), even at moderate levels, is acutely toxic to aquatic life and humans. These persistent organic pollutants are released by domestic and industrial activities, as well as by incomplete combustion of fossil fuels. In spite of their harmful health effect, their occurrence and impact on ecosystems in Ghana is not fully assessed. Hence, as part of a project aimed at sustainable coastal development in Ghana, 16 PAHs identified as priority pollutants by international environmental protection agencies were analysed focusing on three coastal lagoons – Benya, Brenu and Fosu lagoons in the Central Region. Sediment-bound PAHs in the lagoons were extracted and analysed using QUECHERS method and GC-MS. In addition, the sources of the pollutants were determined using diagnostic ratios. Combined, the total concentration of all the 16 PAHs ranged from 20.81 to 24801.38 µg per kg dry weight. The analysis suggests that the PAHs originated from both pyrogenic and petrogenic sources. PAHs were spatially distributed and were also influenced by climatic conditions. Over 50 % of the individual PAHs exhibited a moderate level of ecological risk for aquatic life. PAH-associated cancer risk associated with the lagoon sediments varied from 2.5 x 10-6 to 6.0×10-5 , above the safety limit (1×10-6 ) recommended by WHO. These observations highlight health risk associated with the sediments in some of the lagoons in Ghana. They provide a vital base for appropriate management interventions to improve the health of Ghana’s coastal lagoons as these systems are surrounded by dense human settlements.