Effects of Soil Amendments and EDTA on Lead Uptake by Chromolaena Odorata: Greenhouse and Field Trial Experiments

Abstract

Greenhouse and field trial experiments were performed to evaluate the use of Chromolaena odorata with various soil amendments for phytoextraction of Pb contaminated soil. Pb mine soils contain low amount of nutrients, so the additions of organic (cow manure) and inorganic (Osmocote and NH₄NO₃ and KCl) fertilizers with EDTA were used to enhance plant growth and Pb accumulation. Greenhouse study showed that cow manure decreased available Pb concentrations and resulted in the highest Pb concentration in roots (4660 mg kg⁻¹) and shoots (389.2 mg kg⁻¹). EDTA increased Pb accumulation in shoots (17-fold) and roots (11-fold) in plants grown in soil with Osmocote with Pb uptake up to 203.5 mg plant⁻¹.  Appli- cation of all fertilizers had no significant effects on relative growth rates of C. odorata. Field trial study showed that C. odorata grown in soil with 99545 mg kg⁻¹ total Pb accumulated up to 3730.2 and 6698.2 mg kg⁻¹ in shoots and roots, respectively, with the highest phytoextraction coefficient (1.25) and translocation factor (1.18). These results indicated that C. odorata could be used for phytoextraction of Pb contaminated soil. In addition, more effective Pb accumulation could be enhanced by Osmocote fertilizer. However, the use of EDTA in the field should be concerned with their leaching problems.

KEY WORDS:

• Chromolaena odorata
• Pb
• greenhouse experiment
• field trial experiment
• soil amendments

ACKNOWLEDGMENTS

This research work was supported by the grant from the Center on Environmental Health, Toxicology and Management of Toxic Chemicals under Science & Technology Postgraduate Education and Research Development Office (PERDO) of the Ministry of Education, and Mahidol University, Bangkok, Thailand. We are grateful to Assist. Prof. Philip Round for editing the manuscript.