UPTAKE OF CADMIUM BY HYDROPONICALLY GROWN, MATURE EUCALYPTUS CAMALDULENSIS SAPLINGS AND THE EFFECT OF ORGANIC LIGANDS

The potential suitability of Eucalyptus camaldulensis for Cd phytoextraction was tested in a hydroponic study. Saplings were exposed to 4.5 and 89 mu M Cd for one month, with and without EDTA and s,s-EDDS at 0.1, 1, and 5 mM. The saplings growth was not affected at the 4.5 mu M Cd concentration, yet it decreased 3-fold at 89 mu M, and almost all the Cd taken up was immobilized in the roots, reaching 360 and 5300 mg Cd kg-1, respectively (approximately 75% of which was non-washable in acid). The respective Cd root-to-shoot translocation factors were 0.14 and approximate to 5*10-4. At 0.1 mM concentration, EDTA and EDDS had no effect or even a positive effect on the saplings growth. This was reversed at 1 mM, and the chelants became lethal at the 5 mM concentration. At 89 mu M Cd in the growth medium, 0.1 mM EDTA increased Cd translocation into the shoots by almost 10-fold, however it strongly reduced Cd content inside the roots. This hydroponic study indicates the feasibility of E. camaldulensis use for cleanup Cd-contaminated soils at environmental concentrations, both for site stabilization (phytostabilization) and gradual remediation (phytoextraction). EDTA was shown to be much more efficient in enhancing Cd translocation than s,s-EDDS.