Analytical Survey of The Distribution of Hydrocarbons from an Oil Spillage Site in Nigeria
Assessing the environmental impact of petroleum hydrocarbon pollutants when spillages occur requires reliable analytical tools that can be easily deployed to the field with no sample preparation. An investigation was done using a reference method – gas chromatography to examine the distribution of an oil spillage in the Niger-Delta region of Nigeria. Soil samples contaminated as a result of oil exploitation and exploration activities from Akata village settlement in South Niger Delta region of Nigeria was investigated. In all, 45 Soil samples (200g) were collected at several points at 3 different depths of 0-20cm, 20-40cm and 40-60cm. The soil samples were prepared for analysis using Soxhlet extraction technique with more than 80% recovery achieved. Samples were analysed by gas chromatography fitted with a flame ionisation detector. It was found that total petroleum hydrocarbon concentrations varied from 6750 mg/kg for depth 0-20 cm (P1), 15125 mg/kg for depth 20-40 cm (P2) and 8125 mg/kg for 40-60 cm depth (P3) which far exceeded the legal limit allowed of 50 mg/kg. These experimental studies have ascertained the presence and concentrations of specific organic compounds in these regions. These results show a distribution of types of hydrocarbons ranging from (C8 to C31) which were assessed using Kovats Indices. The findings obtained also revealed the sensitivity of each compound using the standard mixture, identifying C16 & C40 as the carbon compounds with highest and lowest sensitivity respectively. These findings are vital and form the basis when characterising the sensor(s) for the design of a portable chemical sensing system.
Index Terms— GC-FID, oil spill, petroleum hydrocarbons, soil contamination