Effect of heavy metal concentration on the physiological responses and heavy metal accumulation of three tropical plant species used for phytoremediation of landfill leachate

Abstract

This study evaluated the effect of the different concentrations of heavy metals (HM) (Hg+2,  Cd+2,  Cr+6,  Pb+2),  on  the  physiological response and HM accumulation of three plant species: Colocasia esculenta (Ce), Heliconia psittacorum (He) y Gynerium  sagittatum (Gs), planted in subsurface horizontal flow wetland for landfill leachate (LL) treatment. Factorial design was used with 16 bioreactors were operated in two experimental blocks. Chlorophyll, water potential and heavy metal content in plant tissues were measured. The results obtained showed significant differences (p < 0,05) between chlorophyll values and tested variables over time. The water potential did not differ between the three plant species, as all values were found in a range between -0.2 and -2.0 MPa. The distribution of heavy metals in plant tissues decreased in the following order: root> leaf> stem. Ce and in some cases He, showed higher removal capacity of HM. The translocation factor (TF) was lower. He was the specie that showed higher TF> 1 for Pb (II), Cr (total) and Hg (II) and 0.4-0.9 for Cd (II) y Cr (VI). The tested plants demonstrated that they are suitable for phytoremediation of LL and all of them can be categorized as HM accumulators.