Occurrence, distribution, sources and toxic potential of polycyclic aromatic hydrocarbons (PAHs) in surface soils from the Kumasi Metropolis, Ghana

As a developing country, the economic and population growth rates in Ghana over the past few years have seen a tremendous increase. The growing rate of industrialization is gradually leading to contamination and deterioration of the environment and pollution is likely to reach disturbing levels. Surface soil samples were collected randomly from 36 communities in the Kumasi Metropolis, Ghana, to determine the concentrations, distribution, sources and toxic potential of emission of polycyclic aromatic hydrocarbons (PAHs) since no such comprehensive study had been conducted. The mean concentration of total PAHs in the surface soils in each community ranged from 14.78 at Ahinsan to 2084ng/g dry weight at Adum with an average of 442.5±527.2ng/g dry weight. Diagnostic ratios and chemical mass balance models of the results showed that PAHs in surface soil samples from the study area were mainly from fuel combustion. Carcinogenic potency of PAH load from the city centre was approximately 150 times higher as compared to a pristine site, Kwame Nkrumah University of Science and Technology's Botanical Garden. BaP, a human carcinogen, contributed 70% of the total PAHs toxicity level from the city centre of Kumasi. •The distribution of 22 PAHs including the 16 listed by USEPA in soils were studied.•Levels of PAHs found in the city centre were higher than KNUST and other sample sites.•PAHs sources were identified by CMB model and their contributions were estimated.•BaP contributed 70% of the total PAHs toxicity level from the city centre.