Phytoremediation Potential of Chromolaena odorata (L.) King and Robinson (Asteraceae) and Sida acuta Burm. f. (Malvaceae) Grown in lead-Polluted Soils

Abstract

Heavy metals are non-biodegradable substances that can become deleterious and toxic if accumulated in higher concentrations in the environment. Translocation of nutrients from the plant to the soil is one of the key processes of human exposure to heavy metals through the food chain. The abilities of Chromolaena odorata and Sida acuta to bioaccumulate and translocate lead (Pb) are studied here under organic fertilizer amendment in order to determine their phytoremediation potentials. The experiment was a factorial combination of Lead at five levels of concentrations in a completely randomized design, replicated three times with two plants and two levels of an organic fertilizer. Seedlings of uniform height were transplanted from the nursery to experimental pots and were grown for ten weeks. The plants were then harvested and dried for the analysis of Pb accumulation both in the soil and the plant tissues using AAS. The results showed that the organic fertilizer enhanced the bioavailability of Pb because all the tested plants displayed a higher absorption of Pb. Significant concentrations of lead were easily taken up by the plants from the soil and were accumulated in the root, while only a small fraction was translocated upwards to the shoots. The two plants exhibited characteristics of a phytostabilizer because their transfer factors were less than one. The uptake of Pb observed in these plants were in the order of: Sida acuta > Chromolaena odorata, so Sida acuta remediates the soil better than Chromolaena odorata.