Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

The distribution of chromium between soil and leachate was mo- nitored. The natural process of percolation of rainwater through soil was simulated under laboratory conditions and studied by column leaching ex- traction. Migration of chromium in soil is conditioned by the level of chro- mium soil contamination, the organic matter content in the soil and rainwater acidity. Chromium(III) and chromium(VI) were determined by a spectrophoto- metric method with diphenylcarbazide in acidic media. Comparing the results of chromium speciation in the leachate obtained by experimental model sys- tems and geochemical modelling calculations using the Visual MINTEQ mo- del, a correlation was observed regarding the influence of the tested parame- ters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influences of pH and soil organic matter content were in compliance after their experimental and theoretical definition. The Stockholm humic model used to evaluate the leaching results corresponded rather well with the measured values.