Fitoextração e Bioacessibilidade de As, Cd, Pb E Zn em solos contaminados por resíduos metalúrgicos

Abstract

The generation of residues through mining is a potential risk of contamination of soil, water, plants and animals. For decades, the municipality of Santo Amaro da Purificação - BA has suffered the impacts caused by improper and inadequate release of thousands of tons of siderurgy slag contaminated mainly by Cd and Pb, and exposure of these contaminants to the population through the distribution of this material to landfills in squares, streets and homes. The city is now known for presenting the greatest human contamination by Pb in the world. In order to understand the impacts of residues in soil and the risk of human contamination from contaminated soil, this study investigated the phytoextraction by maize and castor as a technique for remediation of these soils and to evaluate the risk of human contamination by heavy metals added to the soil by waste. For this, an experiment was conducted in a greenhouse with the use of the two plant species and soil application of inducing agents Phytoextraction (NTA and citric acid). After the cultivation, they evaluated the levels of As, Cd, Pb and Zn in soil and plant to evaluate the potential remediation technique. Fractionation of metals in the soil and bioaccessibility tests to assess the risk of contamination were also performed. The application of chelating agents citric acid and NTA and increased absorption of heavy metals by maize and castor. Despite the removal of metals by application of citric acid is smaller, this is more suitable due to its higher degradability and assist in inhibiting the phytotoxicity of the metals. Corn showed better phytoextraction ability to As, Cd, Pb and Zn in the study. The castor, despite having high concentrations of metals translocated, presented accumulation in roots, can be used as phytoextabiletion plant and generating economic benefits for the production of non-edible vegetable oil. The presence of metal contaminants from the ground indiscriminately in the area of the former COBRAC presents a high risk of contamination of humans through exposure of metals.