This work evaluated the bioremediation potential of Jatropha tanjorensis leaf extract at different masses (250g, 500g and 750g) over a 40-day period. To achieve this, crude oil contamination of sandy loam soil was stimulated in twelve plastic reactors containing fixed masses of soil (4kg each) of topsoil homogenized with 500g of Bonny light crude oil. The Jatropha tanjorensis leaves were cultivated, rinsed with distilled water, blended, and purified by filtration. The leaf extract was applied at the stated concentrations including a control reactor (without leaf extract). The plastics reactors were kept in an open air shielded away from rainfall. The physicochemical characteristics determined were particle size distribution (PSD), potential of hydrogen (pH), electrical conductivity (EC), organic matter (OM), organic carbon (OC), selected heavy metals (Cr, Cd, Zn, Pb) and sample management were all in line with standard procedure. After 40 days of treatment, results obtained showed that plastic reactor with 750g of leaf extract produced the highest amount of cadmium reduction of 97% (from an initial of and there was significant difference among treatment (P < 0.05). The sequence of reduction among treatment was 750g > 500g > 250g of the leaf extract. Chromium, Lead and zinc followed similar trend. Thus, the Jatropha tanjorensis leaf extract has the potential to ameliorate crude oil-contaminated soil.

Petroleum hydrocarbon contamination of soils has become a global concern, which is often caused by anthropogenic activities, posing serious threat to all living beings. The study for evaluation of the variability of crude oil on the physicochemical characteristics of sandy loam soil was conducted at demonstration farm, Rivers state university, Port-Harcourt, Nigeria. The Bonny light crude oil was obtained from an oil and gas production company. Uncontaminated soil was mixed with crude oil. Standard procedures were adopted for the laboratory analysis, the parameters analyzed include bulk density, total porosity, pH, available phosphorus (P), Total hydrocarbon content (THC), organic carbon, organic matter, exchangeable cation (Mg, K, Na, Ca), effective cation exchange capacity (ECEC), total exchangeable acidity (TEA), and base saturation were monitored for a period of 21 days. 10 kg of sandy loam soils were mixed with 100, 300, 500, and 700ml of crude oil while no crude oil serves as the control using plastic reactors. The reactor with 700ml of crude oil recorded the highest THC of 1734.33 mg/kg, followed by 500ml with a THC of 1601mg/kg while the control with no contamination recorded the least THC of 534.33mg/kg. However, the values of all concentrations did not meet 5000 mg/kg of Department of Petroleum Resources (2018) intervention value but exceeded the target value of 50 mg/kg. Other parameters followed same trend except porosity which decreased with increase in crude oil volume. There were significant differences at P< 0.05 except for pH, available P, and base saturation. Therefore, this study calls for the utilization of its findings for adoption of remediation on crude oil contaminated soils.