Distribution of Polycyclic Aromatic Hydrocarbons and Heavy Metals in Soils from Municipal Solid Waste Landfill

Aims: The distribution of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in soils from Onitsha municipal solid waste landfill were studied.
Study Design: The Onitsha solid waste dumpsite were divided into two groups, the active site labelled (A), where waste dumping is still actively practised and the dormant site labelled (B) with passive or withdrawing waste dumping. Soil samples were obtained in triplicate at each site at the depth of 0-15 cm using calibrated soil auger. At each sampling site, the surface debris were removed and subsurface soil dug to 0-15 cm. Then 20g of soil sample from each depth was taken into a sterile container and transported to the laboratory for analysis.
Place and Duration of Study: The Analysis was done at the Department of Biochemistry, Anambra State University, Department of Applied Biochemistry, Nnamdi Azikiwe University, Awka and Spring Board Research Laboratory, Awka between February and sMarch 2014.
Methodology: Polycyclic Aromatic Hydrocarbons (PAHs) were determined simultaneously using high resolution gas chromatography/mass spectrometry (GC/MS) (GC/MS Shimadzzi QP 2010) while Heavy metals were analysed using Atomic Absorption Spectrophotometer (AAS).
Results: The result showed that Low molecular weight PAHs were not detected in both active and dormant dumpsite. High molecular weight PAHs (HMW PAHs) were predominant in soil from active site. Among the HMW PAHs, Benzo (a) pyrene was highest followed by Benzo(k) fluoranthene and Indeno (1,2,3-cd) pyrene and the least was 1,2 Benzo(a)anthracene. The medium molecular weight PAHs (MMW PAHs) Fluoranthene occurred sparingly in the active dumpsite. The result of heavy metal concentration in the soil were in the order of Fe > Cu > Zn > Cr > Pb > Ni > Cd.
Conclusion: PAHs and Heavy metal concentration were found to be very high and as such the practice of cultivating vegetables on soil from these dumpsites for agricultural purposes should be discouraged.