Translocation factor of heavy metals by elephant grass grown with varying concentrations of landfill leachate.

Abstract

The aim of this study is to obtain the translocation factor by application of landfill leachate (LL) diluted in public irrigation water (IW). Pennisetum purpureum Schum (elephant grass) was cultivated for 83 days in an experimental water reuse unit. The present work was developed at the Experimental Water Reuse Unit (UERA), on the UFERSA campus in Mossoró, RN, Brazil. Plot irrigation was based on water balance and crop evapotranspiration (ETc). The concentration in the plant tissue (root and leaf) of the following heavy metals was measured to determine the respective translocation factors: manganese (Mn), zinc (Zn), copper (Cu), nickel (Ni), cadmium (Cd), and lead (Pb). The experiment was set up in a randomized block design with five treatments (T1, plots irrigated only with IW; T2, 50% of LL dose plus IW; T3, 100% of LL dose plus IW; T4, 150% of LL dose plus IW; and T5, 200% of LL dose plus IW) and five replications. All treatments received LL plus IW depth of 491.02 mm for 83 days of P. purpureum cultivation. The data obtained were submitted to multivariate analysis plus the nonparametric Kruskal-Wallis test to compare the means. Pennisetum purpureum showed a potential to accumulate metals in its tissues, mainly Mn, Zn, and Cu. The treatments that most favored the extraction of these metals were T2 and T5; in this sense, P. purpureum was not efficient in translocating heavy metals, since the translocation factor observed in all treatments was below 1.0, indicating that the species used extract heavy metals from soil solution and keeps in yours roots. This suggests planting P. purpureum may not be a viable option to remediate environments highly contaminated with heavy metals.