Effects of physico-chemical properties on uptake of lead and cadmium in tobacco grown in medially polluted soils
Ngorwe, E. N.
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Background and Aims Tobacco is a heavy metal accumulator that uptakes Cd and Pb in large amounts depending on soil type and soil physicochemical properties. Cadmium and lead are heavy metals of greatest concern because of their toxicity and cumulative nature. Tobacco bio-accumulates Cd and Pb incorporated in the soil as a result of excessive use of fertilizers and pesticides, irrigation with polluted water, contaminated mulches and polluted run-off that interacts with the soil. This study used six sets of experimental soils with different pH, EC, % OM to investigated influence of soil physico-chemical properties on uptake of Cd and Pb in tobacco. Methods Tobacco seedlings were transplanted to fields for growth till 75, 90 and 105 days for first, second and third harvest respectively. Harvested leaves were cleaned, dried, ground and acid digested before analyzed for Cd and Pb by AAS. Results The soil with lowest pH (6.63+0.01) recorded highest uptake of Cd (23.53 + 0.14) and Pb (38.28+0.17), while soil with highest % OM (soil 1, 17.17%, EC 1.38ds/m) had the lowest Cd and Pb concentration levels of 7.3 and 20.30 ugg-1 respectively. Conclusions Physico-chemical properties affects levels of Cd and Pb uptake in tobacco. The tobacco grown in amended soils is within WHO/FAO limits. The results suggest that heavy metals uptake in tobacco is reduced by soil amendments that alters soil physico-chemical properties indicating that tobacco can be grown in heavy metal polluted areas using soil amendments.