Variations in bacterial spectrum and physicochemistry of top soils exposed to gas flaring in Ologbo community, Edo state

Abstract

Nigeria is a major exporter of petroleum and natural gas and a majority of the petroleum exploratory activities takes place in the Niger Delta area, where  high rates of gas flaring associated with exploration and production of these products occur. The study investigated changes in bacterial flora and  physicochemistry of soils within the Oredo flow station facility. Seven soil samples were collected in triplicates at radial distances of 40m, 80m, 120m,  160m, 200m, 1km from the flare stack and the control sample was collected from a farmland far from the flow-station but within the community.  Standard methods were employed in evaluating the physicochemical parameters and bacteriological analysis was conducted using serial dilution and  pour plate methods. The results revealed that gas flaring had significant effects on some soil physicochemical parameters. The impact of gas flare was  found to lower the moisture content at 4.44 % for soils collected at 40m whilst for the control soil, it was 12.83%. The nitrate and total nitrogen content of  the soil varied from 9.96±1.44 to 12.21±0.13mg/kg and 0.01±0.00 to 0.2±0.01%. The total heterotrophic bacteria count varied from 0.4 ± 0.33 to  14.67±3.77 ×10⁶ cfu/g. Identified bacterial species were; Streptococci sp., Corynebacterium sp., Stenotrophomonas sp., Staphylococcus sp., Micrococcus sp.,  Bacillus sp., Acinetobacter sp., Burkholderia sp. and Bacillus sp. The results revealed that gas flaring had a negative effect on soil bacteria population and   physicochemical properties.