Elemental uptake by edible herbs and lettuce (Latuca sativa)
The total concentration of toxic elements (aluminum, cadmium, chromium and lead) and selected macro and micro elements (iron, manganese, copper and zinc) are reported in six leafy edible vegetation species, namely lettuce, spinach, cabbage, chards and green and red types of Amaranth herbs. Although spinach and chards had greater than 125 mv of iron, both the amaranthus herbs recorded > than 320 μ g g− 1 dry weight. In both the spinach and chard species, the Mn and Zn levels were appreciable recording > 225 μ g g− 1 and 150 μ g g− 1 dry weight, respectively. Aluminum concentrations were (in μ g g− 1 dry weight) lettuce (10), cabbage (11), spinach (167), chards (65), amaranthus green (293) and amaranthus red (233). All the micro and macro elements and the toxic elements (Ni, Cr, Cd and Pb) elements analyzed, were below the recommended maximum permitted levels (RMI) in vegetables. Further the elemental uptake and distribution of the nine elements, at three growth stages of the lettuce plant grown on soil bed under controlled conditions are detailed. In the soil, except for iron (16%), greater than 33% of the other cations were in exchangeable form. Generally in the lettuce plant, roots retained much of the iron (> 224 μ g g− 1) and aluminum (> 360 μ g g− 1), while leaves had less than 200 μ g g− 1 of iron and 165 μ g g− 1 of Al. Although the concentrations of elements marginally decreased with growth, the lettuce leaves had significant amounts of Mn (30 μ g g− 1), Zn (50 μ g g− 1) and Cu (3.6 μ g g− 1). Some presence of lead in leaves (2.0 μ g g− 1) was noticed, but all the toxic and other elements analyzed were well below the RMI values for the vegetables.