Uptake and translocation of heavy metals by medicinal plants growing around a waste dump site in Pretoria, South Africa

The study investigated the uptake and translocation pattern of trace metals from two different plant species from a waste dump site in Pretoria, South Africa. Datura stramonium is used as an anti-asthmatic treatment and Amaranthus spinosus may either be used as a medicinal herb or consumed as a vegetable. The trace metal contents from different parts of these plants (leaf, stem and root) were determined by the use of ICP-OES. The concentrations of trace metals from the leaves and stems of both plants were in the order Fe > Mn > Zn > Cu > Cr > Ni > Pb. However, from the roots of D. stramonium the concentration were in the order Zn > Mn > Fe > Cr > Ni > Cu > Pb, while from the root of A. spinosus the trend of accumulation was in the order of Fe > Zn > Cr > Ni > Mn > Cu > Pb. From both plants, the concentrations of determined trace metals were in the order roots > leaves > stems. The overall concentration of heavy metals from leaves and stems appeared to be within the limit laid down for safe human consumption (17.35-78.65μg/g Fe, 16.84-52.94μg/g Zn, 5.65-7.31μg/g Cu, 0.51-1.98μg/g Pb, 4.36-5.69μg/g Ni and 18. 20-33.56μg/g Mn). © 2011 South African Association of Botanists.