Evaluation of tree and shrub species of natural regeneration in the phytoremediation process of a decommissioned dump in Rio Branco, Acre, Brasil

Abstract

Phytoremediation is a technique that involves the use of plant species capable of absorbing toxic substances and storing them in their structures. Although promising, there is a lack of studies validating the long-term efficacy of tree species for this purpose. The aim of this study was to identify tree and shrub species with potential for use in the phytoremediation of soils contaminated with heavy metals in a dump decommissioned since 2010 in Rio Branco, Acre. Tree and shrub species with a DBH > 15 cm were selected in a natural regeneration area within the inactivated dump. Chemical analyses of leaves and roots were conducted to determine concentrations of lead, nickel, chromium, copper, and cadmium. Additionally, soil samples were collected to assess nutrient levels and contaminants around the trees. The species Ceiba pentandra, Tectona grandis, Leucaena leucocephala, Aegiphila sp., and Ricinus communis were identified. R. communis and L. leucocephala demonstrated superior performance in metal sequestration without showing signs of toxicity. The study shows that certain tree and shrub species exhibit significant potential for use in the phytoremediation of contaminated soils. However, caution is advised regarding the use of exotic and invasive species for the restoration of degraded areas in the Amazon.