Use of Cordia Africana in the Phytostabilization of Substrates from Excavations of the Ore Courtyard at the Port of Itaguai, Brazil

Abstract

The objective of this study was to evaluate the phytostabilization of two substrates contaminated with heavy metals from excavations of the ore courtyard at the port of Itaguai, Brazil. Initially, an inventory of tree species located near the study area was performed to select species for phytostabilization. The species Cordia africana exhibited deeper roots, a larger diameter at chest height (DCH) and crown diameter, as well as higher concentrations of Zn, Cd, and Pb in the trunk, bark, and roots compared to the other investigated species. The tolerance of the selected species to the metals Zn, Cd, and Pb was subsequently assessed through a greenhouse test. The substrates used in the experiment also obtained from excavations at the ore courtyard and showed different levels of heavy metals, indicating either low contamination (Substrate 1) or high contamination (Substrate 2). Alkaline industrial waste steel slag (SS) was used as an amendment to reduce the solubility of heavy metals. Application of the amendment agent to the substrates reduced the bioavailability of heavy metals, favoring the growth of C. africana. This species presents potential for use in phytostabilization programs due to its tolerance for heavy metals and the observed higher accumulation of these metals in the roots and especially the trunk of this species compared to other vegetal parts.

Keywords:

• Heavy metals
• industrial residues
• tree species