INFLUENCE OF ZEOLITE, APATITE AND FE-OXIDE ON CD AND PB UPTAKE BY CROPS

Natural zeolite (clinoptilolite), hydroxyapatite and an iron-oxide was te by-product (Fe-rich(TM), a trademark name of E.I. du Pont de Nemour s) were added to an artificially contaminated Appling soil to immobili ze and limit the uptake of metals by crops. A greenhouse pot study emp loyed spiking the soil with Cd and Pb from metal flue dust. Maize (Zea mays) and barley (Hordeum vulgare) were planted in 7-kg potted soil t o determine the effects of Cd and Pb on plant growth and uptake. Seque ntial extraction of soil indicates the substantial influence of soil p H and type of ameliorant on the chemical form and bioavailability of t he metals. Data indicates that a dose of 50 g/kg of soil of iron-oxide appears to be very effective, based on the yields, metal contents of plant tissues and available forms of Cd and Pb in the soil. Lower dose s of zeolite and apatite (15 g/kg and 4 g/kg soil, respectively) in mo st cases also reduced significantly the uptake of Cd and Pb by crops. (C) 1997 Elsevier Science B.V.