Concentration characteristics of polycyclic aromatic hydrocarbons (PAHs) in dept – wise soils, Sapele, Nigeria

Abstract

Polycyclic Aromatic Hydrocarbons (PAHs) are byproducts of incomplete combustion of organic materials during industrial and anthropogenic activities and their toxicity has been established. The objective of this investigation was to determine the depth-wise distribution and profile characteristics of 16 priority PAHs which is lacking in the study area. After extraction and purification quantification of PAHs was done using GC-FID with strict adherence to standard quality control/assurance measures. Results of descriptive statistics showed that the obtained concentrations of PAHs in most sample points are log-normal. Also, results revealed the concentration (%) of PAHs in top-sample D, E and F varied from 0.18 (Flu) – 20.25% (B[ghi]p), 0.78 (Ace) – 18% (I[123-cd]p)  and 2.06 (B[k]f)/(B[b]f)  – 18.02% (Phe) respectively. While in sub-profile sample D, E and F ranges from 0.37(Flu) – 41% (B[ghi]p), 0.73 (Flu) – 20.02% (B[ghi]p) and 0.61(Flu) – 23.04% (B[ghi]p) respectively.  Percentage distribution of PAHs profile showed the prevalence of LPAHs in top-samples over HPAHs and HPAHs over LPAHs in sub-samples. Agglomerative dendogram of top and sub-samples showed that most PAHs homogeneity were built along molecular structure  were LPAHs dominated the first and second cluster groups, while third and fourth cluster groups having HPAHs. The obtained PAHs values in this study could help to set a baseline concentration benchmark and evaluation of exposure risk to terrestrial and aquatic ecosystem in the rapidly urbanizing area since recorded mean concentrations are above permissible limits for soil use.

Keywords: PAHs profile, distribution pattern, homogeneity and toxicity.