English

Abstract

In the Niger delta, due to the large-scale exploration and exploitation of crude petroleum, hydrocarbon spills frequently occur. The adverse impacts of these occurrences have frequently been causes for concerns in the area. However, in open estuarine environments, minor spills have short-term effects due to washout by stream water and increased microbial action. The microbial degradation of low level spills is enhanced by the ‘continuous’ input of nitrogenous fertilizer (NPK) components. The ‘continuous’ input assists in mitigating dilution effects of the stream water thus increasing the availability of nutrients to the petroleum degrading microbes. The net result is the increased recovery potential of this estuarine environment in the event of pollution by crude oil hydrocarbons. Enumeration of viable aerobic heterotrophic bacteria showed that counts were higher in hydrocarbon amended nitrogenous fertilizer plant effluent than in the raw effluent. The higher counts were accompanied by a rapid decline in the level of crude petroleum in the amended effluent. The ability of aerobic heterotrophic mudflat bacteria to grow on three different refined petroleum products namely kerosine, diesel and engine oil was also studied. At the levels tested, there were no appreciable differences in growth patterns of petroleum utilizing bacteria in three refined products after 5 weeks incubation at ambient temperature.   Key words: Crude, petroleum, degradation, heterotrophic, bacteria, fertilizer, effluent.