EVALUATION OF POLYCYCLIC AROMATIC HYDROCARBONS IN SOIL WITHIN THE VICINITY OF AN INDUSTRIAL ESTATE, SANGO OTTA, NIGERIA

Abstract

Soil samples were collected at different locations in the vicinity of an industrial estate in Sango-Ota Ogun State, Nigeria. The polycyclic aromatic hydrocarbons (PAHs) were quantitatively and qualitatively analyzed using gas chromatography (GC) coupled with flame ionization detector (FID). The total concentration of thirteen PAHs ranged from 3.33 mg/kg to 34.00 mg/kg. The highest concentration of total PAHs was observed from sampling point  Q, while the lowest concentration (3.33 mg/kg) was found in soil sample S. No value was recorded for samples H, J and M. The PAHs ratio was also calculated to know the source(s) of the pollution. Phen/An, Flu/Pyr, An/(Phen+An), Flu/(Flu+Pyr), BaA/(BaA+Chry). BaA/Chry ratios ranged from 0.00 -1.09,0.35 -1.02, 0.48-1.00, 0.26 -1.00, 0.00 -0.81 and 0.00 -3.38, respectively. The calculated ratios showed that the source of pollution is majorly pyrogenic with minor contribution from petrogenic source which might have occurred as a result of industrial effluent from some industries, grass/wood and petroleum combustion, as well as vehicular emission in the studied area. In addition, low molecular weight PAHs (i.e. 3-rings) contributed 9.3%, while the high molecular weight PAHs (i.e 4+5+6-rings) accounted for 91.7% to the total PAHs in the samples. The distribution largely supports pyrogenic source for PAHs in the area under study. In conclusion, point Q with the highest concentration of PAHs is the most polluted, while point S that has the lowest concentration of PAHs is the least polluted. The degree of pollution decreases with the distance away from the location of industries which establishes the fact that presence of the manufacturing industries contributed significantly to the PAHs pollution in the study area. However, it should be noted that pollution level at sampling points H, J & M were insignificant. Keywords:  PAHs, GC-FID, Soil, Pollution, Environment