Effects of cadmium and lead on the biodegradation of diesel-contaminated soil

In this research, the soil samples were contaminated with 0.05% and 0.1% of cadmium and lead. Seventy pots containing 200 g of soil were polluted with 5% diesel (w/w) (10 g). The physicochemical parameters of the soil were determined. There was a decrease in the pH, and electrical conductivity but the nitrogen, phosphorous, organic carbon and organic matter increased during the 84 days of biodegradation. The bacteria isolated from diesel oil contaminated soil were species of Bacillus and Pseudomonas. The GC-MS analysis revealed a significant decrease in the alkane and an increase in the ester constituents of the biodegraded oil samples after 84 days. Diesel oil co-contaminated soil supplemented with 0.1% of cadmium and lead had a percentage degradation of 89.5% and 80.54% respectively while compared to the un-supplemented samples (28.36%) after 84 days. This indicates that lead and cadmium as co-contaminant in diesel contaminated soil improved the rate of biodegradation of diesel.