<i>Can tithonia diversifolia</i> (Hemsl). A. Gray, a pantropic invasive weed species, cleanup spent lubricating oil polluted soils?

Abstract

Two pot trials were conducted in the crop garden of the Department of Crop Protection and Environmental Biology, University of Ibadan between March and June 2005, to evaluate the phytoremediating potential of Tithonia diversifolia in spent oil polluted soil to enhance the agricultural productivity. The study was a completely randomized design with three replicates. Varying pollution levels were created by administering spent lubricating oil at 0, 50, 100, 150 and 200 ml per 4-kg soil in pots. Two Tithonia seedlings were transplanted into each pot and were monitored for 12 weeks. At commencement of the two trials, lead concentrations in the soil averaged 3.78 mg/kg and 37.75 mg/kg in the control and in 200-ml treatment respectively, and cadmium concentrations averaged 0.73 mg/kg
and 2.05 mg/kg in the control and 200-ml treatment respectively. At the end of the two trials, lead content was reduced to 0.00 and 11.88 mg/kg and cadmium content was reduced to 0.00 to 0.43 mg/kg in the control and 200-ml treatments respectively. Tithonia seedlings were able to absorb lead and cadmium in the polluted soils, and contents in the root were more than contents in the shoot. The lead and cadmium contents in the shoot compared to the root were about 54% and 30% respectively. The
implication of the results for the quality of vegetable produced at urban and peri-urban roadside and wetland gardens is discussed.