MIMICKED IN-SITU STABILIZATION OF METALS IN A CROPPED SOIL - BIOAVAILABILITY AND CHEMICAL FORM OF ZINC

Agricultural lime, natural zeolite (clinoptilolite), hydroxyapatite, a nd an iron oxide waste byproduct (Ferich, a trademark name of E. I. du Pont de Nemours) were added to an artificially contaminated Appling s ilt loam soil to stabilize and limit the uptake of Zn by crops. A gree nhouse pot study involved spiking the soil with flue dust (FD) at 0, 1 50, 300, 600, 1200, and 2400 mg of Zn kg(-1). As much as 40% of the to tal Zn occurred in an exchangeable form, the form considered most bioa vailable to plants, when the pH of the FD-spiked soil was below 6.0, T he ameliorants (lime, zeolite, apatite, and Fe-rich) decreased the con centration of the exchangeable form of Zn at each level of FD in soil; however, the largest decrease occurred with the lowest dose. Maize (Z ea mays), barley (Hordeum vulgare), and radish (Raphanus sativus) were grown to determine the effects of Zn on the plant growth and Its upta ke. The addition of ameliorants to soil enhanced the growth and yield of maize and barley, but only Fe-rich enhanced the growth of radish at all FL) rates. Lime, zeolite, and apatite significantly reduced the Z n concentration in tissues of the 3-week-old maize, in mature maize ti ssues (roots, young leaves, old leaves, stems, grain), and in barley. The largest reduction (over 80%) in Zn uptake by all crops was effecte d by Fe-rich, which is consistent with the greatest: reduction in soil -exchangeable Zn by this ameliorant.