Comparative evaluation of Cd and Zn uptake by two eucalyptus species

Nowadays, phytoremediation is considered as a new technique to remove a variety of contaminants from the environment. The present study was conducted to evaluate and compare the uptake rate of heavy metals such as cadmium and zinc by two species of eucalypt including Eucalyptus microtheca and E. camaldulensis. For this purpose, the uniform 6-months seedlings of Eucalyptus were selected from the nursery of Golestan agricultural and natural resources research and education center. Eighteen seedlings of each E. microtheca and E. camaldulensis species were subjected to the heavy metals treatment, three concentrations for each elements of Cd (5, 10, 15 ppm) and Zn (1, 3, 10ppm).In total108 samples were taken from leaf, root and stem of each seedling in three replicates. Dry acid digestion method was used for samples extraction. The concentrations of heavy metals in the samples were measured using ICP-OES. The results revealed that Zn content significantly differs between leaves and roots of two species with an average of 518.6, 426.5for leaves and 476.2, 382.2 for roots in E. microtheca and E. camaldulensis, respectively. In contrast, there was no significant difference between stems of two species in terms of Zn content. Furthermore, Cd content in leaves and roots of two species showed significant differences with an average of 124.9, 179.7 for leaves and 435.8, 399.7(unit?) for roots, respectively. Under low concentration of heavy metals in the soil, no significant difference was observed between two species. However, increasing heavy metal concentration in soil (Zn from 1 to 3 mM and Cd from 10 to 15 mM) demonstrated higher efficiency in E. microthecarather than E. camaldulensis. These findings suggest that in general, in the wide use of two mentioned eucalyptus species in forestation projects for phytoremediation, the E. microthecawould have higher efficiency than E. camaldulensis in terms of Cd and Zn absorption.