Heavy Metals and Phytoremediation
López-Chuken, Ulrico J , Young, Scott D .
The Use of Chloro-complexation to Enhance Cadmium Uptake within a Phytoextraction System.
Several studies have reported that Cd uptake by plants is influenced by salinity levels in soil. However, the effect of Cl- in long-term sewage sludge amended soils at high salinity levels (>100 mM in solution) is still poorly understood. A selection of maize (Zea mays) and Indian mustard (Brassica juncea) plants were studied to investigate the effect of Cl- complexation on Cd uptake from soil historically amended with sewage sludge and to model the uptake of Cd by these plants with a Free Ion Activity Model (FIAM). The plants were treated with chloride solutions applied as NaCl at rates between 50 and 300 mM in the soil pore water. Separation of the confounding effects of different ionic strength stresses was attempted by including equivalent Na2SO4 treatments. Cadmium speciation was calculated using the WHAM (VI) speciation model. The results of these experiments showed that Cl- concentration in soil is an important factor in determining the phytoavailability of Cd in long-term sewage sludge amended soil. Activities of Cd-chloro complexes showed the best correlations with the Cd concentrations found in the plants compared to the activity of Cd2+. It can be concluded that soil salinity per se or ion exchange reactions of Na+ for Cd2+ are unlikely to cause the levels of Cd phytoavailability observed at high concentrations of chloride. The FIAM showed a reasonable good fit for the plants when assuming competition by Cd2+ and CdCl+ for 1 hypothetical site parameterisation of the model. The potential application of Cl- salts to soils to enhance Cd phytoavailability for phytoremediation purposes was beyond the scope of this research. Intentional addition of Cl- salts, as amendments for phytoextraction purposes, if intended, needs to be carefully evaluated.
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Universidad Autonoma de Nuevo Leon, Mexico
1 - Facultad de Ciencias Quimicas, Universidad Autonoma de Nuevo Leon, Academia Ambiental, QFB, Carrera de QFB, FCQ, Calle Pedro de Alba S/N, Ciudad Universitaria, San Nicolas de los Garza, NL, 64440, Mexico
2 - University of Nottingham, Environmental Science Department, School of Biosciences
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM