Potencial do guapuruvu (Schizolobium parahyba var. amazonicum) na fitorremediação de metais pesados

Abstract

Heavy metals are present in agrochemicals used in agriculture, in petroleum derivatives, in domestic and industrial organic waste, among other diverse uses. Due to accidents or incorrect disposal, metals can accumulate in soil, sediments and water. Soil contamination by metals results in damage to ecosystem functions, and potentially to public health. One of the forms of decontamination is phytoremediation, which consists of using tolerant plants to reduce soil pollution. Among the great plant diversity in Brazil, some native species may have phytoremediation potential. Guapuruvu is a tree species that has not yet been explored as a possible remedial plant. Therefore, the objective of this study was to evaluate the phytoremediation of metals in the soil by the growth of Schizolobium parahyba var. amazonicum in clayey soil. The treatments consisted of 5 increasing doses of Cu, Cr, Mn and Zn in the soil. After growing the seedlings for 60 days, the levels of Cu, Cr, Mn and Zn in the soil, roots, shoots and leachate, the bioconcentration factor and the translocation factor of these toxic elements in plants were determined. Plant height, stem diameter, root dry mass, aerial part dry mass and root length were also evaluated. The trial was conducted in a greenhouse with a randomized block design with six replications. S. parahyba seedlings demonstrated significant potential as a phytoremediation plant in conditions of heavy metal contamination as they showed hyperaccumulation of Cu, Mn and Zn as demonstrated by the application of 100 mg of Cu, 150 mg of Mn and 225 mg of Zn; and 200 mg of Cu, 300 mg of Mn and 450 mg of Zn. Application of doses: 300 mg of Cu, 225 mg of Cr, 450 mg of Mn and 675 mg of Zn; and 400 mg of Cu, 300 mg of Cr, 600 mg of Mn and 900 mg of Zn were lethal to seedlings. It is noteworthy that guapuruvu can play an important role in environmental remediation programs, especially in areas with a history of contamination by heavy metals.