Phytoextractor Potential of Cultivated Species in Industrial Area Contaminated by Lead

Silvânia Maria De Souza Gomes Nascimento,Adailson Pereira De Souza,Clístenes Williams Araújo Do Nascimento,Joab Josemar Vitor Ribeiro Do Nascimento,Vera Lúcia Antunes De Lima

doi:10.1590/18069657rbcs20140805

Abstract

High growth rate is one of the criteria used for the selection of species to be used in metal phytoextraction programs. This study was carried out to characterize the growth characteristics of sunflower ( Helianthus annuus L.), castor bean ( Ricinus communis L.), corn ( Zea mays L), and vetiver [ Vetiveria zizanioides (L.) Nash] grown on a soil contaminated with lead (Pb), with and without pH correction, to improve agronomic practices regarding phytoremediation programs. The experiment was designed as a randomized block with four replications; treatments were arranged in a split-plot arrangement, with the main plot representing the species (sunflower, castor bean, corn, and vetiver), with or without pH correction and soil fertilization, and the split-plot representing harvest periods (60, 90, and 120 days after planting). After variance analysis and mean comparison analysis of the data by the Tukey test (p≤0.05), a significant effect was observed from soil pH correction for vetiver in all of the growth variables evaluated, except for the leaf area index at 120 days after planting (DAP). Castor bean and sunflower plants in soil with high acidity conditions, without pH correction (pH˂4.0), were affected by soil Pb levels. Corn plants benefited from soil pH correction and had improved results for the plant height, diameter, and leaf area variables at 60 and 90 DAP, as well as leaf area index at 60 DAP. There was no increase in these variables between the harvest periods evaluated. Regarding phytoextraction potential, corn and vetiver had the highest Pb translocation to the plant shoots at 90 DAP and were therefore considered the most suitable species for phytoremediation of the area under study. Overall, liming was essential for improving species biomass production for all the species studied in soils with high Pb availability in solution. Key words: phytoremediation; soil pollution; heavy metal; biological indicator

Highlights

An increase in contamination of the soil ecosystem by heavy metals, such as lead (Pb), and expansion of this problem to other ecosystems, requires the establishment of technologies for remediation of contaminated environments
The experiment was designed as a randomized block with four replications; treatments were arranged in a split-plot arrangement, with the main plot representing the species, with or without pH correction and soil fertilization, and the split-plot representing harvest periods (60, 90, and 120 days after planting)
There was an increase in root collar diameter, number of leaves, leaf area, leaf area ratio, and leaf area index throughout the growth period of vetiver in contaminated soil (120 days after planting (DAP)); this was not observed in the other species analyzed (Table 1)

Summary

Introduction

An increase in contamination of the soil ecosystem by heavy metals, such as lead (Pb), and expansion of this problem to other ecosystems, requires the establishment of technologies for remediation of contaminated environments. It is believed that using plants with a capacity to tolerate and simultaneously extract and/or degrade certain compounds (phytoremediation) may be an adequate alternative against the pollution in contaminated areas For this technology to succeed, plants need to have a high growth rate, high biomass production, tolerance to the metal in question, and ability to take up and accumulate the metal. Practices such as soil pH correction in acidic environments are fundamental for establishing plants used in phytoremediation (Clement Carrillo et al, 2005; Pedron et al, 2009; González-Alcaraz et al, 2011; Joris et al, 2012; Aragão et al, 2013)

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