Wednesday, November 7, 2007
322-1
Stabilization of Heavy Metals using Nanoscale Fe-, Al- and Ti-oxides.
Srimathie P. Indraratne1, Gary M. Pierzynski2, Lucas Baker2, and P.V. Vara Prasad2. (1) University of Peradeniya, Dept. of Soil Science, Peradeniya, Sri Lanka, (2) Kansas State University, Dept. of Agronomy Plt. Sci. Ctr., Manhattan, KS 66506-5501
In this study three nano scale oxides at two rates were evaluated for their efficacy in reducing the bioavailability Cd, Pb and Zn to sudangrass. A greenhouse pot experiment was conducted using contaminated soil and chat. Nanoscale Fe3O4, Al2O3 and TiO2 were separately added at rates of 0, 50, and 100 g kg-1 to soil or chat in a factorial arrangement with 3 replicates. Sorghum-sudangrass (Sorghum bicolor L. Moench) was grown to evaluate the availability of Cd, Pb and Zn. Leachates were collected two times per week from each pot until harvesting. Cd, Pb and Zn concentrations were measured in leachates, in plant tissues and in soil or chat treatments. An adsorption study was conducted for each metal on Fe, Al and Ti oxides, separately. Adsorptive capacities for Zn were observed in the order of Al-oxide > Ti-Oxide > Fe-Oxide, while the affinity of Cd were Al-oxide = Ti-Oxide > Fe-Oxide. Available Cd and Zn were significantly reduced in contaminated soils and chat after addition of Al and Ti nano oxides. Significantly less concentration of Zn and Cd were detected in leachates of Al and Ti nanoscale treatments in comparison to respective controls. Addition of nano-oxides of Al and Ti significantly decreased sudangrass tissue Cd and Zn concentrations as compared to the controls in chat treatments. The data also suggested that nano oxides remove soluble P from soils affecting plant growth negatively. Sudangrass tissue Cd and Zn significantly correlate with Ca(NO3)2-extractable and diffusive gradients in thin films extractable Cd and Zn with correlation coefficient ranged from r=0.91 to r=0.79. Nano oxides of Al and Ti could be used effectively to reduce bioavailable forms of Zn and Cd in contaminated soil and chat.