The conditions favourable to oxidation of Cr (III) to Cr (VI) and the presence of chromium forms on the area contaminated by tannery wastes.

The aim of this paper was to study the conditions favourable to Cr (III) oxidation such as: type of soil, soil water content, presence of organic matter and three oxidisers (MnO2, NaNO3 and Fe2O3). Also concentrations of different species of chromium in water and soils were examined in the area contaminated with tannery wastes containing 5-10% of Cr2O3. The action of oxidisers was studied in batch experiment for 2 h at room temperature at pH=5.35+/-0.2. The highest level of oxidised trivalent chromium was registered for soil with the lowest content of organic matter (0.72% C(org)), when Cr (III) was oxidised by MnO2, Fe2O3 and NaNO3 did not show properties towards Cr (III) oxidation under the conditions described.