Lead Contamination and Microbial Lead Tolerance in Soils at Major Road Junctions in Benin City

Lead pollution and lead tolerance levels of microbes in soil at major road junctions in Benin City were investigated. Results revealed that distance from the road junctions affected the concentrations of lead in soil, as well as the microbial population density and types of microbes present in the soil. The highest concentrations of lead were recorded with soil samples obtained at 0 and 10m distance closer to road junctions, while the lowest concentrations were recorded with soil samples obtained at 30m distance away from road junctions. The highest concentrations recorded for lead, copper and iron were 32 x 10^1 mg kg^-1, 8 x 10^-1 mg kg^-1 6.3 x 10^-1 respectively. All these levels decreased rapidly as the distance from the road increased. Bacterial counts increased as the distance from the road junctions increased. While fungal counts decreased as distance from road junctions increased. Lead tolerance range of bacterial and fungal isolates was between 10 to 1000 mg 1^-1. Non-significant, negative correlation was found between lead concentration and microbal counts. The bacteria and fungi most frequently isolated at 0 and 10m distance were Pseudomonas sp., Micrococcus sp., Bacillus sp., Candida utilis, Penicillium sp and the yeast Saccharromyces cerevisiae.