Phytoremediation Potential of Leucaena Leucocephala on Heavy Metal and Crude Oil Polluted Soils Amended with Biochar and Compost

Abstract

Soil contamination from heavy metals and crude oil is a global concern globally with the challenge being felt most in developing countries where remediation options are limited. In this study, the phytoremediation potential of Leucaena leucocephala and the ameliorative effects of biochar and compost on plant growth in contaminated soils were investigated. Lead-contaminated soil collected from a battery waste dumpsite was mixed with normal soil to get 50% contamination level, Soil artificially spiked with crude oil at 5% w/w was used as crude oil polluted soil. Both soil types were treated with compost and biochar at four application rates (0, 2.5, 5, and 10 t/ha). The compost and biochar were applied singly or combined depending on the treatment. Leucaena leucocephala seeds were planted one week after application. Data were collected on plant height, number of leaves, biomass, secondary metabolites (proline and phenolics) and lead accumulation in plant tissues. Lead contamination caused stunted plant growth in unamended soil, while addition of organic amendments enhanced plant’s performance despite different levels of soil contamination. On the osmolyte production, plants in untreated lead-contaminated soil produced more proline and phenolic compounds than those grown on amended soil. The translocation factor for Pb exceeded 1.0, in most treatment combinations, but the biological absorption factor was relatively low. In conclusion, Leucaena leucocephala could be considered as a credible candidate for phytoremediation of lead contaminated soil particularly in the presence of organic soil amendments.