Leaching of chromium from chromium contaminated soil -a speciation study and geochemical modelling

Abstract

The distribution of chromium between soil and leachate was monitored. The natural process of percolation of rainwater through soil was simulated under laboratory conditions and studied by column leaching extraction. Migration of chromium in soil is conditioned by the level of chromium soil contamination, the organic matter content in the soil and rainwater acidity. Chromium(III) and chromium(VI) were determined by a spectrophotometric method with diphenylcarbazide in acidic media. Comparing the results of chromium speciation in the leachate obtained by experimental model systems and geochemical modelling calculations using the Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. 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. Copyright 2012 (CC) SCS.