Phytoextraction and fractionation of heavy metals in soil after multiple applications of natural chelants

Scientia Agricola

Évio Eduardo Chaves De Melo²  Clístenes Williams Araújo Do Nascimento²  Adriana Maria De Aguiar Accioly¹  Ana Cristiane Queiroz Santos² 

[1] ,UFRPE Depto. de Agronomia Recife PE ,Brasil

关键词: phytoremediation;    soil pollution;    soil remediation;    organic acids;    fitorremediação;    poluição do solo;    remediação do solo;    ácidos orgânicos;   

DOI  :  10.1590/S0103-90162008000100009

来源: SciELO

【 摘 要 】

Chelate-assisted phytoextraction of heavy metals is a promising approach to clean up polluted soils. However, the most successful chelants tested so far are synthetic agents that barely degrade in soil, increasing the metal leaching risks. Natural organic acids have been proposed to enhance phytoextraction due to their higher biodegradability, but they can also be a drawback for efficient phytoextraction. This work was carried out to compare the effectiveness of multiple applications of citric and gallic acids on the availability in soil and accumulation of Cd, Pb, Cu, and Zn by velvet bean (Stizolobium aterrimum) plants. The organic acids were added as follows: 5 mmol kg-1 in the 28th cultivation day; two doses of 5 mmol kg-1 at the 28th and 31st day; and three applications at the same rate at the 28th, 31st, and 34th day of velvet bean cultivation. Soil samples were sequentially extracted and soil solution metal concentrations assessed. Neither citric acid nor gallic acid was efficient for metals phytoextraction. In general, low molecular weight organic acids (LMWOA) application increased the metal concentrations in the water soluble and exchangeable fractions. Zinc and Cu were retained mostly in the organic matter fraction. Zn was remobilized from the organic matter fraction through LMWOA application into the water soluble and exchangeable fractions. LMWOA mobilized Pb and Cu from iron oxides, but such an increase in solubility was not high enough to affect phytoextraction.

【 授权许可】

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