Características anatômicas e fisiológicas de aguapé e índice de fitorremediação de alface d´água cultivados na presença de arsênio, cádmio e chumbo

Abstract

Environment contamination by toxic elements is a growing problem worldwide, and the phytoremediation is a clear and low cost technology to remove soil and water pollutants. This work aimed to verify the potential of Eichhornia crassipes to cope with five levels of As, Cd and Pb and what mechanisms are involved to the stress tolerance, and to explore a mathematical model that explain the phytoremediation. Plants of E. crassipes were grown in Hoagland nutrient solution in greenhouse under five As, Cd and Pb concentrations. Gas exchanges, antioxidant system, and modifications on the leaf and root anatomy were evaluated. Plants exhibited increase in photosynthesis, stomatal conductance, transpiration rate, Ci/Ca rate and in all antioxidant system enzymes with higher activities on leaves compared to roots in all As, Cd and Pb treatments. Anatomical traits in leaves showed increase in stomatal density, stomatal index and spongy parenchyma. Root anatomy showed no toxic effects of As, Cd, and Pb and improvement of xylem and phloem characteristics. Arsenic, cadmium and lead in the tested levels don´t promoted toxic effects on E. crassipes, and the tolerance mechanisms showed large potential of this specie to phytoremediation. The mathematic model was tested Pistia stratiotes plants grown under the same conditions described to water hyacinth. Phytoremediation index was able to detect differences between treatments and to predict the time need to phytoremediation.