The purpose of this work was to obtain the retarding factor (R) and the dispersion-diffusion coefficient (D) for chromium (III) in two highly weathered soils collected in São Paulo, Brazil. The influence of the following factors on these two parameters were analyzed: textures, pH and soil organic matter. Samples of the A and B horizons of two soils were used, differing significantly in organic matter contents (a) a Typic Eutrorthox (LVe) and (b) a Typic Haplorthox (LVd). Soil pH of the surface samples was modified by adding calcium carbonate to alter base saturation to 70 %. Batch techniques and soil column experiments using miscible displacement theory were performed. Higher values of R were obtained in the Eutrorthox than in the Haplorthox. The rising of soil pH by liming resulted in higher values for R. In the Eutrorthox, the presence of fulvic acids seems to have favored a lower value for R in the surface horizon than in the subsurface one. A clear relationship between D and soil type, liming level and soil horizon was not found.
Oxisols; heavy metals; adsorption; movement