Sequential extraction of heavy metals in two contaminated soils (Andisol and Vertisol) amended with humic acids

摘要

Purified Humic Acids were added to 0%, 2.5% and 5% (w / w), to two soils Andisol and Vertisol, contaminated individually with five heavy metals, followed by incubation at 60 and 90 days, with the aim of observe their mobility and their possible effect on the environment. Fractionation of metals (Ni, Cu, Zn, Cd and Pb) in contaminated soils amended with humic acids and was performed by sequential extraction of Tessier. The mobility of the metals are reduced by the addition of such acids, achieving greater retention of Ni, Cu, Zn and Cd in the soil matrix (residual fraction). The Pb in both soils, and Zn in the vertisol, showed significant increase in their mobility, greater bioavailability and affectation potential for different environmental components. Increased incubation time allowed for interaction of metals with the components of the soil, generating decreasing its mobility for mechanisms such stable complex formation and / or increased CIC of soils. The humic acids can be used, in general, as an organic amendment for the recovery of contaminated soils with heavy metals.