Chromium Movement in Columns of Two Highly Weathered Soils

Abstract

The movement of contaminants through soils is an important environmental task. Chromium (Cr), a heavy metal that is potential hazardous to the environment (including human health), has been sometimes added to agricultural soils of some regions through the disposal of tannery wastes. There is a lack of knowledge about the movement of this metal in highly weathered soils frequently found in the tropics. The purpose of this work was to study the movement of Cr in soil columns considering the influence of the pH and the horizons of the soils. It was also applied a mathematical model to quantify some parameters of this movement, although in an exploratory way. Miscible displacement experiments were carried out in A and B soil horizon samples, that received two liming levels, collected in São Paulo State, Brazil: a Typic Eutrorthox (TE), and a Typic Haplorthox (TH). Liming showed little effect on the elution curve forms for both soils. The Cr movement in the A horizon for the TE soil was greater than the observed in the B horizon, possible due the formation of soluble compounds between the metal and fulvic acids. It was also applied a simplified version of the MRTM (Multireaction and Transport Model), which showed good fit to experimental data.