Assessment of the PAHs contamination threat on groundwater: a case study of the Niger Delta region of Nigeria
Contamination of the environment by polynuclear aromatic hydrocarbon (PAHs) is becoming a rising environmental concern. The interest this subject attracts has continually increased by the day because of the threat these compounds pose to human health. Water samples from several hand-dug wells in the Niger Delta region of Nigeria where extensive crude oil production activities take place were analysed for the presence of 16 US EPA priority PAHs and their consequent health implication on the population extrapolated. The analyses were done using a gas chromatograph coupled to an ion trap mass spectrometer. Individual PAHs were identified through both retention time match with authentic standards and simultaneous maximisation of several ions from GC/MS data. The quantitation was done by means of internal standardisation using four isotopically labelled internal standards namely acenaphthene-d10, chrysene-d12, phenanthrene-d10 and perylene-d12. The sums of the 16 PAHs in the samples vary depending on the proximity of the sample source to crude oil production facility. The concentrations ranged from 1.92 μg/L to 40.47 μg/L. High molecular mass PAHs such as benzo(ghi)perylene, dibenz(a,h)anthracene and indeno(1,2,3-cd)pyrene were mostly absent confirming low water solubility of these compounds. These concentrations were above the WHO recommended maximum for safe drinking water.
Keywords: polynuclear aromatic hydrocarbons, PAHs, Niger Delta, Nigeria, well water, GC-MS, carcinogens, environmental pollution, semi-volatile organic compounds, SVOCs, crude oil, WHO, water pollution, health implications, safe drinking water