Anions, Total Petroleum Hydrocarbons and Aromatic Hydrocarbons in Soils of Aba Dumpsites

Abstract

  This study was intended to evaluate the extent of contamination of soils in the vicinity of some selected dumpsites (Enyimba, Ogbor Hill and World Bank) in Aba Metropolis by anions (nitrate, sulphate and phosphate), polycyclic aromatic hydrocarbon and total petroleum hydrocarbon. Soil samples were obtained in triplicate on monthly intervals for three consecutive months during dry seasons in three different dumpsites and a neighborhood reference site (Aba North Industrial Layout). These soil samples were then analysed for anions, total aromatic hydrocarbons and total petroleum hydrocarbon.  Analysis of total aromatic hydrocarbons and total petroleum hydrocarbons were performed by gas chromatographic method whereas spectrophotometer (model 2000) was used in evaluating nitrate, sulphate and phosphate concentrations in the soil samples. Nitrate content ranged from 980.0 to 2120.3 mg/Kg (Enyimba dumpsite), 850.25 to 1120.3 mg/Kg (Ogbor Hill Dumpsite) and 102.43 to 1980.72 mg/Kg (World Bank Dumpsite). Sulphate concentrations which ranged from 78.99 to 121.21 mg/Kg at the dumpsites were higher when compared to values obtained from reference samples (21.65 to 94.50 mg/Kg). The levels of phosphate in the soil samples from the dumpsites ranged from 9.63 – 15.10 mg/Kg, 7.13 – 12.25 mg/Kg and 5.10 – 10.80 mg/Kg, in Enyimba Dumpsite, Ogbor Hill Dumpsite and World Bank Dumpsite respectively. The concentration of phosphate in the reference samples demonstrated lower values (2.78 – 5.80 mg/Kg) when compared with those from dumpsites. The total polycyclic aromatic hydrocarbons (PAHs) distribution in the dumpsites and the reference site were Enyimba dumpsite (3.27 to 4.32 mg/Kg), Ogbor Hill Dumpsite (2.51 to 3.85 mg/Kg), World Bank Dumpsite (2.15 to 3.98 mg/Kg) and Aba North Industrial Layout (0.05 to 0.09 mg/Kg) respectively. The concentration of TPH ranged from 102.7 to 1340.4 mg/Kg, 93.9 to 1107.3 mg/Kg and 99.10 to 1098 mg/Kg for Enyimba, Ogbor Hill and World Bank dumpsites respectively. The samples from Aba North Industrial Layout recorded the least concentration levels ranging from non detectable limits to 0.09 mg/Kg. The results however, revealed a depth-wise steady decrease in concentrations across the soil (depth) profile with Enyimba dumpsite having elevated levels of all the parameters evaluated when compared with  other study stations. There was no contamination activity found in samples obtained from reference site (Aba North Industrial Layout) unlike in the dumpsites besides the levels of total petroleum hydrocarbon (TPH) indicates potent health risk in the environment of the dumpsites.