LEAD REMOVAL FROM CONTAMINATED SOILS AND WATER BY VEGETABLES

The negative impacts of lead mining are dominated by widespread soil, air, water and plant contamination. Human exposure to high levels of lead can cause severe health problems and sometimes death. Elevated blood lead concentrations of 200 µg/dL or more have been reported in some of the worst contaminated places, such as Kabwe, a former lead-zinc mining town in Zambia. Lead concentrations at such levels can cause death and various severe illnesses, including hematological, gastrointestinal, and nephropathy problems. In this study we assessed the level of lead contamination in soils and plants from Kabwe. The role of plants in lead removal from contaminated soils and water is investigated. Soils were laced with different levels of lead ranging from 0 to 400 mg/g. Various vegetables were planted in these soils and lead levels measured every six weeks in both plant material and soils. The plants studied were Brassica rapa and Tithonia diversifolia, Brassica juncea, and sunflower. Lead concentrations were quantified using the Aqua Regia method and Atomic Absorption spectrometry. Field measurements of lead levels in soils from Kabwe showed concentrations ranging from 27 to 328 ppm, while plant concentrations were between 0.985 and 8 ppm.