Biodegradation of Petroleum Hydrocarbons Under Tropical Estuarine Conditions

Abstract

The physic-chemical parameters of water samples collected from three points in the Lagos lagoon were studied for 12 months. Salinity varied seasonally but the temperature, pH, dissolved O2, conductivity, NO3 and HPO42- concentrations were relatively constant. There was a direct proportionality between the population density of hydrocarbon-utilizing bacteria and the oil content of water samples. Twelve hydrocarbon-utilizing bacteria were isolated by selective enrichment and characterized as species of Pseudomonas, Alcaligenes, Acinetobacter and Bacillus. The organisms grew mainly on long-chain aliphatic hydrocarbons. Laboratory and field biodegradation studies showed both quantitative and qualitative changes in the hydrocarbon content of crude oil due to microbial degradative activities and a faster rate of oil depletion from the Lagos lagoon during the rainy season. The results obtained could offer a predictive model for estimating the rate of disappearance of petroleum hydrocarbons from the tropical estuarine environment.