Abstract

The problems associated with heavy metal contamination are widespread and are especially common in developing countries. A pot study was carried out to evaluate the effectiveness of Sunflower (Helianthus annuus), Sorghum (Sorghum bicolor) and Chinese cabbage (Brassica chinensis) at removing lead from the soil. Lead contaminated soils were collected from Kabwe near the old Lead mine and characterized for total and extractable lead, pH, organic matter, texture and cation exchange capacity. The average total and extractable lead concentrations were 23 313 and 5876 mg/kg, respectively, in contaminated soil compared to 57.75 and 10.02 mg/kg in uncontaminated soil. The contaminated soil was then diluted with uncontaminated soil to achieve five contamination levels of 5876, 2500, 1000, 500 and 10.02 mg/kg. Test plants were grown for 10 weeks after which below and above ground dry biomass yields were determined and tested for lead concentration and uptake. Results from this study show that Chinese cabbage is more effective at lead uptake than Sunflower and Sorghum. Results also show that high soil lead concentration results in poor plant growth, low biomass yield and increased lead accumulation in plant tissue.

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