Heavy metals concentration in tree species used for revegetation of contaminated area

Abstract

This study aims to evaluate the potential of tree species Cordia africana Lam., Mimosa caesalpineafolia Benth., Acacia angustissima (Mill.) Ktze. and Anadenanthera colubrina (Vell.) Brenan in the phytostabilization of heavy metal from a substrate contaminated. Four specimens of each tree specie were randomly determined for evaluations. Substrate samples were collected in the projection of the canopy trees of each specimen at depths 0-10; 10-30 and 30-50 cm for determining pseudototal concentration and chemical fractionation of heavy metals.Were collected data on roots depth, diameter at breast height, canopy diameter and plant height for each specimen. Samples of root, stem, bark and leaf were collected for analysis of heavy metals zinc (Zn), manganese (Mn), cadmium (Cd), lead (Pb) and copper (Cu). The Cd concentration in the substrate was above the investigation value defined by CONAMA (3,0 mg kg-1), showing contamination with this element. However, the highest concentrations of other studied heavy metals were found in the residual fraction (F5), indicating low availability of these elements in the substrate. High concentrations of Cd were also found in the exchangeable fraction F2, which is considered a fraction in which contaminants are present with some mobility and bioavailability. The plants showed development within the normal patterns, showing tolerance to Cd-contaminated areas, which tended to accumulate in the roots, except in the Córdia – africana.