Potencial fitorremediador da espécie Tecoma stans em solo contaminado com cobre, cromo, manganês e zinco

Abstract

Phytoremediation is a technique that consists of recovering soil contaminated with metals, using plants to extract or reduce the toxicity of pollutants from the environment. Therefore, the phytoremediation potential of seedlings of the Tecoma stans species was evaluated in soil contaminated simultaneously with different doses of Cu (0, 100, 200, 300 and 400 mg dm-3), Cr (0, 75, 150, 225 and 300 mg dm-3), Mn (0, 150, 300, 450 and 600 mg dm-3) and Zn (0, 225, 450, 675 and 900 mg dm-3). For this, the experiment was carried out in the city of Patrocinio/MG, adopting a completely randomized design, with five treatments and six replications each, with seedlings growing for 120 days. Mehlich-1 was used to extract metals from the soil and extraction using the nitro-perchloric method for plant tissues. With the increase in metal doses, the seedlings reduced their plant growth, and the two highest doses resulted in the death of all seedlings in these treatments. Metal concentrations in the shoots ranged from 0,03 to 0,05 mg/kg-1 for Cr; 0,2 to 2,0 mg/kg-1 for Cu; from 0,9 to 335,4 mg/kg-1 for Mn and 0,7 to 130,9 mg/kg-1 for Zn. In roots, concentrations ranged from 0,04 to 0,09 mg/kg-1 for Cr; 3,6 to 16,1 mg/kg-1 for Cu, 10,6 to 208,6 mg/kg-1 for Mn and 9,0 to 105,4 mg/kg-1 for Zn. The translocation factor was greater than 1 at doses of 150 mg dm-3 for Mn and 225 and 450 mg dm-3 for Zn, indicating phytoextractive potential for translocating these metals from the root to the shoot. The bioconcentration factor in all doses of Cr was greater than 1, indicating that there was accumulation of Cr in the aerial part of the seedlings. Therefore, the seedlings had the potential to be used as phytoremediation species for Mn up to a contamination of 150 mg dm-3 and for Zn up to a concentration of 450 mg dm-3 contamination. To estimate the remediation potential per area or volume of contaminated soil, studies with longer plant growth time are necessary to allow for the accumulation of biomass and, therefore, accumulated metal.